METAL COMPLEXES OF (OXYGEN-NITROGEN-SULFUR) SCHIFF BASE DONORS: PREPARATION, CHARACTERIZATION, FLUORESCENT EMISSION AND SOME BIOLOGICAL ACTIVITIES
A thesis Submitted to the Council of College of Science at the University of Sulaimani in partial fulfillment of the requirements for the degree of Master of Science in Chemistry
BY KARZAN AZIZ ABDALKARIM B.Sc. CHEMISTRY (2011), UNIVERSITY OF SULAIMANI
SUPERVISED BY Dr. DIARY IBRAHIM TOFIQ Lecturer
2016 Aug.
2716 Kharmanan
بسم هللا الرحمن الرحيم
ين آ َمنُوا ِمن ُك ْم يَ ْرفَ ِع هللاُ الَّ ِذ َ ت َوالَّ ِذ َ ين أُوتُوا ا ْل ِع ْل َم َد َر َجا ٍ ون َخبِير َوهللاُ بِ َما تَ ْع َملُ َ المجادلة /آية 11
Supervisor Certification I certify that this thesis entitled “Metal Complexes of (Oxygen-Nitrogen-Sulfur) Schiff Base Donors; Preparation, Characterization Fluorescent Emission and Some Biological Activities’’ accomplished by Karzan Aziz Abdalkarim, was prepared under my supervision in the College of Science, at the University of Sulaimani, as a partial requirement for the degree of Master of Science in (Chemistry).
Signature: Supervisor: Dr. Diary Ibrahim Tofiq Scientific Title: Lecturer Date: 13/7/ 2016
In view of the available recommendation, I forward this thesis for debate by the examining committee.
Signature: Name: Dr. Bakhtyar Kamal Aziz Scientific Title: Assistant Professor Head of the Department of Graduate Studies in Chemistry Date: 13/7/ 2016
Examining Committee Certification We certify that we have read this thesis entitled “Metal Complexes of (OxygenNitrogen-Sulfur) Schiff Base Donors; Preparation, Characterization Fluorescent Emission and Some Biological Activities” by (Karzan Aziz Abdalkarim). As Examining Committee, we examined the student in its content and what is connected with it. In our opinion it meets the basic requirements forward the degree of Master of Science in Chemistry.
Signature:
Signature:
Name: Dr. Muhammad A. Abdullah
Name: Dr. Bayazeed H. Abdullah
Title: Professor
Title: Assistant Professor
(Chairman)
(Member)
Date:17 / 8 / 2016
Date: 17 / 8 / 2016
Signature:
Signature:
Name: Dr. Emad A. Al-Khaffaji
Name: Dr. Diary Ibrahim Tofiq
Title: Lecturer
Title: Lecturer
(Member)
(Supervisor-Member)
Date: 17 / 8 / 2016
Date: 17 / 8 / 2016
Approved by the Dean of the College of Science. Signature: Name: Dr. Bakhtiar Qader Aziz Title: Professor Dean of the College Date: /
/ 2016
Linguistic Evaluation Certification I hereby certify that this thesis entitled “Metal Complexes of (Oxygen-NitrogenSulfur) Schiff Base Donors; Preparation, Characterization, Florescent Emission and Some Biological Activities “ is by (Karzan Aziz Abdalkarim), has been read and checked. After indicating all the grammatical and spelling mistakes, the thesis was given again to the candidate to make the adequate corrections. After the second reading, I found that the candidate corrected the indicated mistakes. Therefore, I certify that this thesis is free from mistakes.
Signature: Name: Zhino Jabbar Mohammed Position: English Department, School of Languages, University of Sulaimani Date: 18 / 7 / 2016
Dedication This Thesis is Dedicate to: Whoever taught me and supported me in my life My parents My sisters and brothers My wife, Payam All my close friends
Karzan A. Abdalkarim
I
Acknowledgements Firstly, I thank God for helping me in every moment and giving me health and strength to perform and complete this study. It is my pleasure to express my gratitude and sincere appreciation to my supervisor Dr. Diary Ibrahim Tofiq whose contribution in stimulating suggestions and encouragement helped me to coordinate my project especially in rectifying my report writing. My gratitude and thanks go to the Council of the College and all of the staff of Chemistry Department, especially Dr. Bakhtyar, Head of the Department, and Mr. Yassin, decider of the department, for helping and offering all necessary requirements for the completion of this work. I would like to thank Mr. Swara and Dr. Dara who helped me in identifying the compounds by performing IR and Mass spectroscopy. I greatly appreciate Dr. Dler’s help in analyzing metals in my samples by ICP instrument. My thanks and appreciations also go to Dr. Tara for helping me in using emission spectrophotometer in Koya University and Dr. Muhammad for performing CHNS analysis for my samples in Ibn al-Haytham University. I would like to thank a lot Dr. Khalid for helping me in some important idea for my thesis. Also, Mr. Rebaz and Miss. Renas for helping me obtain references. I would like to thank Ms. Nazk for helping me posting my samples for analysis in Baghdad city. I am very grateful for Dr. Emad Al Khaffaji, Dr. Omed, Dr. Dlzar, Mr. Omed, Mr. Hassan, Ms. Khanda, Mr. Aso, Mr. Zhewar, Mr. Mozart and Mr. Barham for helping me making my project. I would also like to thank Mr. Bahjat, Mr. Azad, and Mr. Bakr for providing the chemicals and the equipments for the project. My utmost regards and thanks go to my family for their blessings. Without them I would not be here. Thanks very much for the extra help you gave me so I could complete my project. Last but not least, I want to thank whoever taught me and supported me in my life. II
Abstract The present work consists of three chapters: chapter one is an introduction and literature review. Chapter two deals with the experimental part which contains materials, instrumentation and procedures for preparation of Schiff base ligands and their metal complexes. Chapter three includes the results and discussion which includes five parts. The first part, the reaction of novel Schiff base ligand [2,2'-((1E,1'E)-((5,5'-(propane1,3 diylbis(sulfanediyl)) bis(1,3,4-thiadiazole-5,2 diyl))bis(azanylylidene))bis(methanylylidene)) diphenol](PSTMH2) with metal chloride salts gave metallic complexes of different
shapes:
octahedral
geometry
of
[Cr(PSTM)(H2O)2]H2O.Cl
and
[Fe(PSTM)(H2O)2]H2O.Cl, tetrahedral geometry of [Co(PSTM)]H2O, Square planar geometry of [Cu(PSTM)]H2O, [Pd(PSTM)]H2O and [Pt(PSTM)]3H2O. In all PSTMH2 metal complexes, the PSTMH2 ligand acts as a tetra dentate which coordinates with the metal ion centers through nitrogen atom of azomethine groups and phenolic oxygen atoms via deprotonation.
The second part, the reaction of another new Schiff base ligand [2,5-bis(5-mercapto1,3,4-thiadiazole-2-imino)hexane](BMTHH2) with metal chloride salts, gave metallic complexes
of
types
the
following:
binuclear
tetrahedral
geometry
of
[Co2(BMTH)(H2O)4]Cl2 and mononuclear square planar geometry of [Cu(BMTH)]H2O, [Zn(BMTH)]H2O, [Cd(BMTH)]H2O, [Hg(BMTH)]H2O, [Pd(BMTH)]H2O, and [Pt(BMTH)]2H2O was suggested. In all BMTHH2 metal complexes, the BMTHH2 ligand acts as a tetradentate which coordinates to the metal ion centers through nitrogen atom of azomethine groups and sulfur atom of thiol groups.
The third part, a new procedure used for preparation of a ligand [N,N-1,4-PhenyleneBis(2-(Iminomethyl)Phenol)](PBIPH2) which was prepared in previous studies by classical methods. The reaction of PBIPH2 ligand with metal chloride salts gave
III
mononuclear metal complexes of Mn(II), Fe(III), and Zn(II) and binuclear metal complexes of Co(II), Cu(II), Pd(II) and Pt(II) metal ions in types of: Octahedral geometry of [Mn(PBIP)(H2O)2]H2O and [Fe(PBIP)(H2O)3Cl]H2O, tetrahedral geometry of [Co2(PBIP)(H2O)2Cl]H2O and [Cu2(PBIP)(H2O)4]Cl.H2O, square planar geometry of [Zn(PBIP)]H2O, Na2[Pd2(PBIP)Cl4]2H2O and [Pt2(PBIP)(H2O)2Cl2]2H2O. The PBIPH2 ligand behaves as tetradentate in all metal complexes except Fe(III) complex which acts as a bidentate ligand through phenolic oxygen atoms via deprotonation.
The fourth part includes anti-bacterial activity of prepared compounds in, which all three ligands and their metal complexes screened against Escherichia coli (Gram -) and Staphylococcus aureus (Gram +) bacteria. Most of the compounds showed good sensitivity. When the activity results of the metal complexes compared with the activity of free ligands, the enhancement of activity by some metal ions after complexation with ligands was observed.
The fifth part includes study of spectroscopic properties of the metal complexes and the free ligand when the interest fluorescence emission of the ligand and the metal complexes were studied. Decline of the emission was observed after complexation of the ligand whereas all metals caused complete decay of the emission except Fe(III) which has less than half emission of the free ligand. Also Zn(II), Pd(II) and Pt(II) complexes show weak emission. Pd(II) and Pd(II) complexes show weak emission as well. However they show emission in near ir region, assigning of triplet emission (phosphorescence).
BATP Ligand precursor, PSTMH2 and BMTHH2 ligands are characterized by mass spectroscopy. Ligands of PSTMH2, BMTHH2, and PBIPH2 with their metal complexes are characterized by elemental analysis, infrared and Uv-Vis. Spectroscopy, conductivity, magnetic susceptibility measurement, and thermal gravimetric analysis.
IV
Table of Contents
Title
Page No.
Abstract………………………………………………………………..…………….III
Contents…………………………………………………..………………………….V List of Figures……………………………………………………..…………..….....IX List of Tables……………………………………………………..…………….…XIV
Chapter One: Introduction and Literature Review 1. Introduction ............................................................................................................ 1 1.1 Schiff Bases and Their Metal Complexes .............................................................. 1 1.2 Ligands Containing N, S, O Heteroatoms .............................................................. 3 1.3 Thiadiazole and its Derivatives .............................................................................. 5 1.3.1 1, 2, 3-Thiadiazoles Moiety: ............................................................................ 5 1.3.2 1, 2, 4-Thiadiazole Moiety: .............................................................................. 6 1.3.3 1, 2, 5-Thiadiazoles Moiety: ............................................................................ 6 1.3.4 1, 3, 4 –Thiadiazoles Moiety:........................................................................... 7 1.4 Literature Review of 1,3,4-Thiadiazole Metal Complexes Bears Schiff Base Moiety........................................................................................................................... 9 1.5 Para-phenylenediamine and its Derivatives ........................................................ 18 1.6 Literature Review of P-phenylenediamine Schiff Base Metal complexes .......... 18
Chapter Two: Experimental Part
2. Materials and Methods: .......................................................................................... 25 2.1 Materials ............................................................................................................ 25 2.1.1 Chemicals .................................................................................................... 25 V
2.1.2 Instrumentations.......................................................................................... 26 2.2 Preparations of the Starting Materials: ............................................................. 28 2.2.1 Preparation of 1,3-Bis(5-amino-1,3,4-thiadiazole-2-thio)propane [BATP] Ligand Precursor .................................................................................................. 28 2.2.2 Preparation of Sodium Tetrachloropalladate (II), Na2[PdCl4].................... 28 2.3 Preparation of 2,2'-((1E,1'E)-((5,5'-(propane-1,3 diylbis(sulfanediyl)) bis(1,3,4thiadiazole-5,2 diyl))bis(azanylylidene))bis(methanylylidene)) diphenol [PSTMH2] Ligand...................................................................................................................... 28 2.3.1
Preparation of [Cr(PSTM)(H2O)2]H2O.Cl (140) .................................... 29
2.3.2
Preparation of [Fe(PSTM)(H2O)2]H2O.Cl (141) ................................... 29
2.3.3
Preparation of [Co(PSTM)]H2O (142) ................................................... 29
2.3.4
Preparation of [Cu(PSTM)]H2O (143) ................................................... 29
2.3.5
Preparation of [Pd(PSTM)]H2O (144) .................................................... 30
2.3.6
Preparation of [Pt(PSTM)]3H2O (145)................................................... 30
2.4
Preparation of BMTHH2 Ligand ................................................................... 30
2.4.1
Preparation of [Cu(BMTH)]H2O (146) .................................................. 31
2.4.2
Preparation of [Co2(BMTH)(H2O)4]2Cl (147) ....................................... 31
2.4.3
Preparation of [Zn(BMTH)]H2O (148) .................................................. 31
2.4.4
Preparation of [Cd(BMTH)]H2O (149) .................................................. 31
2.4.5
Preparation of [Hg(BMTH)]H2O (150) .................................................. 32
2.4.6
Preparation of [Pd(BMTH)]H2O (151)................................................... 32
2.4.7
Preparation of [Pt(BMTH)]2H2O ........................................................... 32
2.5
Preparation of PBIPH2 Ligand ...................................................................... 32
2.5.1
Preparation of [Mn(PBIP)(H2O)2]H2O (153) ......................................... 33
2.5.2
Preparation of [Fe(PBIP)(H2O)3Cl]H2O (154) ....................................... 33
2.5.3
Preparation of [Zn(PBIP)]H2O (155)...................................................... 33
2.5.4
Preparation of [Cu2(PBIP)(H2O)4]H2O.Cl (156) .................................... 33
2.5.5
Preparation of [Co2(PBIP)(H2O)2Cl2]H2O (157) .................................... 34
2.5.6
Preparation of [Pd2(PBIP)Cl4]2H2O (158) ............................................. 34
2.5.7
Preparation of [Pt2(PBIP)(H2O)2Cl2]2H2O (159) ................................... 34
VI
Chapter Three: Results and Discussion
Part One. ................................................................................................................... 35 3.1 Preparation and Characterization of 2,2'-((1E,1'E)-((5,5'-(propane-1,3 diylbis (sulfanediyl)) bis(1,3,4-thiadiazole-5,2 -diyl))bis(azanylylidene)) bis -(methany lylidene)) diphenol [PSTMH2] Ligand and its Metal Complexes: ......................... 35 3.1.1 Preparation of 1,3-bis(5-amino-1,3,4-thiadiazole-2-thio)propane [BATP] Precursor .............................................................................................................. 35 3.1.2 Preparation of 2,2'-((1E,1'E)-((5,5'-(propane-1,3 diylbis(sulfanediyl)) bis(1,3,4-thiadiazole-5,2diyl))bis(azanylylidene))bis(methanylylidene)) diphenol [PSTMH2] Ligand ................................................................................................ 36 3.1.3
Mass Spectroscopy of BATP Precursor and PSTMH2 Ligand .............. 36
3.1.4
Thin Layer Chromatography of BATP Precursor and PSTMH2 Ligand 37
3.1.5 Preparation and Characterization of [PSTMH2] Metal Complexes of Cr(III), Fe(III), Co(II), Cu(II), Pd(II), and Pt(II) ................................................. 42 3.1.6
Elemental Analysis C, H, N, S and Metals ............................................. 42
3.1.7
Conductivity Measurements ................................................................... 43
3.1.8
Infrared Spectra....................................................................................... 45
3.1.9
The Far Infrared (650-200 Cm-1) Region ............................................... 47
3.1.10 Electronic Spectra .................................................................................. 60 3.1.11 Magnetic Susceptibility Measurements .................................................. 62 3.1.12 Thermal Gravimetric Analysis .............................................................. 68 3.1.13
Proposed Structures of PSTMH2 Metal Complexes ............................. 73
Part Two .................................................................................................................... 74 3.2 Preparation of 2,5-bis(5-mercapto-1,3,4-thiadiazole-2-imino)hexane [BMTHH2] and its Metal Complexes. ................................................................. 74 3.2.1
Mass Spectroscopy of BMTHH2 Ligand ................................................ 75
3.2.2
Thin Layer Chromatography of BMTHH2 Ligand ................................. 75
3.2.3 Preparation and Characterization of [BMTHH2] Metal complexes of Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II), and Pt(II) ...................................... 78 3.2.4
Conductivity Measurements ................................................................... 79
3.2.5
Infrared Spectra....................................................................................... 79
3.2.6
The Far Infrared (650-200 Cm-1) Region ............................................... 81
3.2.7
Electronic Spectra Measurements........................................................... 94 VII
3.2.8
Magnetic Susceptibility Measurements .................................................. 95
3.2.9
Thermal Gravimetric Analysis ............................................................. 101
3.2.10 Proposed Structures for BMTHH2 Ligand Metal Complexes .............. 106 Part Three ............................................................................................................... 107 3.3 Preparation of N,N-1,4-PhenyleneBis(2-(Iminomethyl)Phenol) [PBIPH2] and its Metal Complexes ................................................................... 107 3.3.1 Preparation and Characterization of [PBIPH2] Metal Complexes of Mn (II), Fe(III), Cu(II), Co (II), Zn(II), Pd(II), and Pt(II). ....................................... 108 3.3.2
Conductivity Measurements ................................................................. 109
3.3.3
Infrared Spectra..................................................................................... 109
3.3.4
The Far Infrared (650-200 Cm-1) Region ............................................. 111
3.3.5
Electronic Spectra Measurements......................................................... 123
3.3.6
Magnetic Susceptibility Measurements ................................................ 125
3.3.7
Thermal Gravimetric Analysis ............................................................. 131
3.3.8
Proposed Structures for PBIPH2 Ligand Metal Complexes ................. 136
Part Four ................................................................................................................. 137 3.4
Biological Activities .................................................................................... 137
Part Five .................................................................................................................. 140 3.5
Fluorescence Emission of the Ligands and Their Metal Complexes .......... 140
References ............................................................................................................... 146
VIII
List of Figures Figure No.
Figure Title
Page No.
Figure 1: Structure of 1,2,3-Thiadiazole Moiety....................................................... 5 Figure 2: Structure of 1,2,4-Thiadiazole Moiety........................................................ 6 Figure 3: Structure 1,2,5-Thiadiazole Moiety ............................................................ 6 Figure 4: Structure of 1,3,4-Thiadiazole Moiety........................................................ 7 Figure 5: Resonance Form of 1,3,4-Thiadiazole ........................................................ 7 Figure 6: Drugs Containing 1,3,4-Thiadiazole Moiety in Markets ............................ 8 Figure 7: Structure of Metal Complexes 1, 2, 3 and 4 ............................................... 9 Figure 8: Reaction to Formation of Metal Complex 5 .............................................10 Figure 9: Structure of Metal Complexes 6, 7, 8, 9 and 10 .......................................10 Figure 10: Structure of Metal Complexes 11-22 ......................................................11 Figure 11: Structure of Metal Complex 23 ..............................................................11 Figure 12: Structure of Metal Complexes 24 and 25 ...............................................12 Figure 13: Structure of Metal Complexes 26 and 27 ...............................................12 Figure 14: Structure of Metal Complexes 28 and 31 ...............................................13 Figure 15: Structure of Metal Complexes 32-35 ......................................................13 Figure 16: Structure of Metal complexes 36-47.......................................................14 Figure 17: Structure of Metal complexes 48, 49 and 50 ..........................................14 Figure 18: Structure of Metal complexes 51-58.......................................................15 Figure 19: Structure of Metal complexes 59, 60, 61 and 62 ....................................15 Figure 20: Reaction to Form of Metal complex 63 ..................................................16 Figure 21: Using the Metal complex no. 63 as a Catalyst in Epoxidation of Olefins ..................................................................................................................................16 Figure 22: Structure of Metal complexes 64-69.......................................................17 Figure 23: Reaction of Formation the Metal complexes 70, 71 and 72 ...................17 Figure 24: Structure of Para-phenylenediamine.......................................................18 IX
Figure 25: Structure of Metal Complexes 73 and 74 ...............................................19 Figure 26: Structure of Metal Complexes 75-79 ......................................................19 Figure 27: Structure of Metal Complexes 80 and 81 ...............................................20 Figure 28: Structure of Metal Complexes 82-87 ......................................................20 Figure 29: Structure of Metal Complexes 88 and 89 ...............................................21 Figure 30: Structure of Metal Complexes 90-134 ....................................................22 Figure 31: Structure of Metal Complexes 135-139 ..................................................23 Figure 32: Mass Fragmentation of BATP Ligand Precursor ...................................38 Figure 33: Mass Fragmentation of PSTMH2 Ligand ...............................................39 Figure 344: Mass Spectrum of BATP Precursor ......................................................40 Figure 35: Mass Spectrum of PSTMH2 Ligand ......................................................41 Figure 36: FTIR Spectrum of BATP precursor ........................................................50 Figure 37: FTIR Spectrum of PSTMH2 Ligand .......................................................51 Figure 38: FTIR Spectrum of [Cr(PSTM)(H2O)2]H2O.Cl .......................................52 Figure 39: FTIR Spectrum of [Fe(PSTM)(H2O)2]H2O.Cl .......................................53 Figure 40: FTIR Spectrum of [Co(PSTM) )(H2O)2]H2O .........................................54 Figure 41: FTIR Spectrum of [Cu(PSTM)]H2O ......................................................55 Figure 42: FTIR Spectrum of [Pd(PSTM)]H2O .......................................................56 Figure 43: FTIR Spectrum of [Pt(PSTM)].3H2O .....................................................57 Figure 44: Far-IR Spectra of A=Cr(III), B=F(III), C=Co(II) Complexes with PSTMH2 Ligand .......................................................................................................58 Figure 45: Far-IR Spectra of D=Cu(II), E=Pd(II), F=Pt(II) Complexes with PSTMH2 Ligand .......................................................................................................59 Figure 46: UV-Vis Spectrum of PSTMH2 Ligand ...................................................65 Figure 47: UV-Vis. Spectrum of [Cr(PSTM)(H2O)2]H2O.Cl ..................................65 Figure 48: UV-Vis. Spectrum of [Fe(PSTM)(H2O)2]H2O.Cl ..................................66 Figure 49: UV-Vis. Spectrum of [Co(PSTM)]H2O .................................................66 Figure 50: UV-Vis. Spectrum of [Cu(PSTM)]H2O .................................................67 Figure 51: UV-Vis. Spectrum of [Pd(PSTM)]H2O ..................................................67
X
Figure 52: UV-Vis. Spectrum of [Pt(PSTM)]3H2O .................................................68 Figure 53: TGA Curve for [Cr(PSTM)(H2O)2]H2O.Cl ............................................70 Figure 54: TGA Curve for [Fe(PSTM)(H2O)2]H2O.Cl ............................................70 Figure 55: TGA Curve for [Cu(PSTM)]H2O ...........................................................71 Figure 56: TGA Curve for [Co(PSTM)]H2O ...........................................................71 Figure 57: TGA Curve for [Pd(PSTM)]H2O............................................................72 Figure 58: TGA Curve for [Pt(PSTM)]3H2O ..........................................................72 Figure 59: Proposed Structure for [Cr(PSTM)(H2O)2]H2O.Cl, [Fe(PSTM)(H2O)2]H2O.Cl, [Co(PSTM)]H2O, [Cu(PSTM)]H2O, [Pd(PSTM)]H2O and [Pt(PSTM)]3H2O Complexes ............................................................................73 Figure 60: Mass Fragmentation of BMTHH2 Ligand ..............................................76 Figure 61: Mass Spectrum of BMTHH2 Ligand ......................................................77 Figure 62: FTIR Spectrum for 5-amino-1,3,4-thiadiazole-2-thiol ...........................83 Figure 63: FTIR Spectrum of BMTHH2 Ligand ......................................................84 Figure 64: FTIR Spectrum of [Co2(BMTH)(H2O)4]2Cl ..........................................85 Figure 65: FTIR Spectrum of [Cu(BMTH)]H2O .....................................................86 Figure 66: FTIR Spectrum of [Zn(BMTH)]H2O......................................................87 Figure 67: FTIR Spectrum of [Cd(BMTH)]H2O .....................................................88 Figure 68: FTIR Spectrum of [Hg(BMTH)]H2O .....................................................89 Figure 69: FTIR Spectrum of [Pd(BMTH)]H2O ......................................................90 Figure 70: FTIR Spectrum of [Pt(BMTH)]2H2O .....................................................91 Figure 71: Far-IR Spectra of A=Co(II), B=Cu(II), C=Zn(II) Complexes with BMTHH2 Ligand ......................................................................................................92 Figure 72: Far-IR Spectra of D=Cd(II), E=Hg(II), F=Pd(II), G=Pt(II) Complexes with BMTHH2 Ligand .............................................................................................93 Figure 73: Uv-vis. Spectrum of BMTHH2 Ligand ...................................................97 Figure 74: Uv-vis. Spectrum of [Co2(BMTH)(H2O)4]2Cl .......................................97 Figure 75: Uv-vis. Spectrum of [Cu(BMTH)]H2O ..................................................98 Figure 76: Uv-vis. Spectrum of [Zn(BMTH)]H2O ..................................................98
XI
Figure 77: Uv-vis. Spectrum of [Cd(BMTH)]H2O ..................................................99 Figure 78: Uv-vis. Spectrum of [Hg(BMTH)]H2O ..................................................99 Figure 79: Uv-vis. Spectrum of [Pd(BMTH)]H2O.................................................100 Figure 80: Uv-vis. Spectrum of [Pt(BMTH)]2H2O ...............................................100 Figure 81: TGA Curve of [Co2(BMTH)(H2O)4]2Cl ..............................................102 Figure 82: TGA Curve of [Cu(BMTH)]H2O .........................................................102 Figure 83: TGA Curve of [Zn(BMTH)]H2O..........................................................103 Figure 84: TGA Curve of [Cd(BMTH)]H2O .........................................................103 Figure 85: TGA Curve of [Hg(BMTH)]H2O .........................................................104 Figure 86: TGA Curve of [Pd(BMTH)]H2O ..........................................................104 Figure 87: TGA Curve of [Pt(BMTH)]2H2O .........................................................105 Figure 88: Proposed Structures for [Co2(BMTH)(H2O)4]2Cl, [Cu(BMTH)]H2O, [Zn(BMTH)]H2O, [Cd(BMTH)]H2O, [Hg(BMTH)]H2O and [Pd(BMTH)]H2O and [Pt(BMTH)]2H2O complexes.................................................................................106 Figure 89: FTIR Spectrum of PBIPH2 Ligand .......................................................113 Figure 90: FTIR Spectrum of [Mn(PBIP)(H2O)2]H2O ..........................................114 Figure 91: FTIR Spectrum of [Fe(PBIP)(H2O)3Cl]H2O ........................................115 Figure 92: FTIR Spectrum of [Co2(PBIP)(H2O)2Cl2]H2O .....................................116 Figure 93: FTIR Spectrum of [Cu2(PBIP)(H2O)4]Cl.H2O .....................................117 Figure 94: FTIR Spectrum of [Zn(PBIP)]H2O .......................................................118 Figure 95: FTIR Spectrum of Na2[Pd2(PBIP)Cl4]2H2O ........................................119 Figure 96: FTIR Spectrum of [Pt2(PBIP)(H2O)2Cl2]2H2O ....................................120 Figure 97: Far-IR Spectrum of A=Mn(II), B=Fe(III), C=Co(III) Complexes with PBIPH2 Ligand .......................................................................................................121 Figure 98: Far-IR Spectrum of D=Cu(II), E=Zn(II), F=Pd(II), G=Pt(II) Complexes with PBIPH2 Ligand ..............................................................................................122 Figure 99: Uv-Vis. Spectrum of PBIPH2 Ligand ...................................................127 Figure 100: Uv-Vis. Spectrum of [Mn(PBIP)(H2O)2] H2O ...................................127 Figure 101: Uv-Vis. Spectrum of [Fe(PBIP)(H2O)3Cl]H2O ..................................128
XII
Figure 102: Uv-Vis. Spectrum of [Co2(PBIP)(H2O)2Cl2]H2O ..............................128 Figure 103: Uv-Vis. Spectrum of [Cu2(PBIP)(H2O)4]Cl.H2O ..............................129 Figure 104: Uv-Vis. Spectrum of [Zn(PBIP)]H2O.................................................129 Figure 105: Uv-Vis. Spectrum of Na2[Pd2(PBIP)Cl4]2H2O ..................................130 Figure 106: Uv-Vis. Spectrum of [Pt2(PBIP)(H2O)2Cl2]2H2O ..............................130 Figure 107: TGA Curve of [Mn(PBIP)(H2O)2] H2O .............................................132 Figure 108: TGA Curve of [Fe(PBIP)(H2O)3Cl]H2O ............................................132 Figure 109: TGA Curve of [Co2(PBIP)(H2O)2Cl]H2O ..........................................133 Figure 110: TGA Curve of [Cu2(PBIP)(H2O)4]Cl.H2O..........................................133 Figure 111: TGA Curve of [Zn(PBIP)]H2O ...........................................................134 Figure 112: TGA Curve of Na2[Pd2(PBIP)Cl4]2H2O ............................................134 Figure 113: TGA Curve of [Pt2(PBIP)(H2O)2Cl2]2H2O ........................................135 Figure 114: Proposed Structures for [Mn(PBIP)(H2O)2]H2O, [Fe(PBIP)(H2O)3Cl]H2O, [Zn(PBIP)]H2O, [Cu2(PBIP)(H2O)4]H2O.Cl, [Co2(PBIP)(H2O)2Cl2]H2O, [Pd2(PBIP)Cl4]2H2O and [Pt2(PBIP)(H2O)2Cl2]2H2O Complexes ..............................................................................................................136 Figure 115: The Inhibition Zone of Some Complexes on The Plate. ....................139 Figure 116: Excitation and Emission Spectra of PBIPH2 in THF:H2O (1:1) ........140 Figure 117: Excitation and Emission Spectra of PBIPH2 in THF .........................141 Figure 118: Excitation and Emission Spectra of [Fe(PBIP)(H2O)3Cl]H2O ...........142 Figure 119: Excitation and Emission Spectra of [Zn(PBIP)]H2O .........................143 Figure 120: Emission Spectra of [Pt2(PBIP)(H2O)2Cl2]2H2O. ..............................144 Figure 121: Excitation and Emission Spectra of Na2[Pd2(PBIPa)Cl4]2H2O .........145
XIII
List of Tables
Table No.
Table Title
Page No.
Table 1: Abbreviations .........................................................................................XVI Table 2: Chemicals Used in This Work and Their Suppliers ..................................25 Table 3: Mass Data for BATP precursor and PSTMH2 Ligand .............................. 37 Table 4: Rf of 5-amino-1,3,4-thiadiazole-2-thiol, BATP Precursor and PSTMH2 Ligand ......................................................................................................................38 Table 5: Physical Properties and Elemental Analysis of BATP Precursor, PSTMH2 Ligand and Metal Complexes of PSTMH2 .............................................................43 Table 6: Molar Conductivity of (1×10-3M) Observed Electrolyte Types in Different Solvents ....................................................................................................................44 Table 7: Data of Major IR Bands for BATP Precursor, PSTMH2 Ligand, and Metal Complexes of PSTMH2 in (cm-1) ............................................................................49 Table 8: Magnetic Susceptibility and Uv-Vis Spectrum Data with Their Assignments of PSTMH2 and its Metal Complexes ...............................................64 Table 9: Weight Loss with Temperature Range of Water Molecules in PSTMH2 Metal Complexes ......................................................................................................69 Table 10: Mass Spectroscopy Data of BMTHH2 Ligand ........................................75 Table 11: Rf of BMTHH2 Ligand ...........................................................................75 Table 12: Physical Properties and Elemental Analysis of BMTHH2 and its Metal Complexes ...............................................................................................................78 Table 13: Data of Major IR Bands of BMTHH2 and its Metal Complexes in cm-1 82 Table 14: Magnetic Susceptibility and Uv-Vis Spectrum Data with Their Assignments of BMTHH2 and its Metal Complexes ..............................................96 Table 15: Weight Loss with Temperature Range of Water Molecules in PBIPH2 Metal Complexes. ...................................................................................................101 Table 16: Physical Properties and Elemental Analysis of PBIPH2 and its Metal Complexes ..............................................................................................................108 XIV
Table 17: Data of Major IR Spectrum Bands for PBIPH2 and its Metal Complexes in cm-1. ....................................................................................................................112 Table 18: Magnetic Susceptibility and Uv-Vis Spectrum Data with Their Assignments of PBIPH2 and its Metal Complexes ...............................................126 Table 19: Weight Loss Percentages with Temperature Ranges of Water Molecules on PBIPH2 Metal Complexes ................................................................................131 Table 20: Biological Activities of PSTMH2 Ligand and its Metal Complexes ....138 Table 21: Biological Activities of BMTHH2 Ligand and its Metal Complexes ...138 Table 22: Biological Activities of PBIPH2 Ligand and its Metal Complexes ......138
XV
List of Abbreviations
Table 1: Abbreviations Symbols BATP
Terms 1,3-Bis(5-amino-1,3,4-thiadiazole-2-thio)propane 2,2'-((1E,1'E)-((5,5'-(propane-1,3 diylbis(sulfanediyl)) bis(1,3,4-thi-
PSTMH2
adiazole-5,2 diyl))bis(azanylylidene))bis(methanylylidene)) diphenol
BMTHH2
2,5-bis(5-mercapto-1,3,4-thiadiazole-2-imino)hexane
PBIPH2
N,N-1,4-PhenyleneBis(2-(Iminomethyl)Phenol)
PSTM
Deprotonated PSTMH2
BMTH
Deprotonated BMTHH2
PBIP
Deprotonated PBIPH2
FTIR
Fourier transform infrared spectroscopy
TGA
Thermal Gravimetric Analysis
Uv-vis
Ultra violet - visible
MS
Mass Spectroscopy
CHNS
Carbon, Hydrogen, Nitrogen and Sulfur
OLED
Organic Light Emitting Device
ICP
Inductively Coupled Plasma
Pract.
Practical values
Theo.
Theoretical Values
XVI
Chapter One Introduction and Literature Review
Chapter One
Introduction and Literature Review
Chapter One: Introduction and Literature Review
1. Introduction
1.1 Schiff Bases and Their Metal Complexes
Schiff base is an imine or azomethine compound that contains a carbon-nitrogen double bond, with the nitrogen atom connected to an aryl or alkyl group. The general formula of Schiff base is R1-CH=N-R2 where R1 and R2 are an alkyl or aryl group that makes the Schiff base a stable amine[1]. The synthesis route involves condensation of any primary amine with an aldehyde or ketone under specific conditions. The reaction can be accelerated by acid or base catalyst[2].
Reaction 1: General Reaction of Schiff Base Preparation.
Schiff bases derived from various heterocycles were reported to possess analgesic, anti-inflammatory and anti-bacterial activity[3], anticancer[4], and cytotoxic[5]. The Schiff bases have been reported to possess higher degree of anti-tubercular[6], antibacterial[7], anti-inflammatory[8], and antifungal[9].
1
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Introduction and Literature Review
Previous studies show that the Schiff base ligands and transition metal ions are the two parents and necessary components for designing stable metal complexes. They play an important role in the development of Coordination Chemistry[10]. A large number of Schiff bases and their metal complexes have been studied for their interesting and important properties, e.g., their ability to reversibly bind oxygen (inhibitor of corrosion)[11], transfer of an amino group[12], complexing ability towards some toxic metals[13], catalytic activity in hydrogenation of olefins[14], and photochromic properties[15].
2
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Introduction and Literature Review
1.2 Ligands Containing N, S, O Heteroatoms
It is well known that the chemical properties and structure of the partially or fully N-functionalized macrocyclic compounds are distinctly different from those of the unsubstituted ones[16][17]. An investigation of metal complexation studies across a range of related ligands has provided a useful background which is a base for further ligand design. In the case of N- and C- based functionalized macrocyclic ligands, the mode of metal in corporation is very much similar to that of metalloproteins in which the requisite metal is bound in a macrocyclic cavity or cleft produced by the conformational arrangement of the protein [18][19]. Macrocyclic ligands containing various binding functionalities are the subject of current interest due to their ability to selectively bind, and transfer a large variety of substrates from charged species to neutral molecules [20][21]. Structural factors such as ligand rigidity, the type of donor atoms, and their disposition have been shown to play significant roles in determining the binding features of macrocycles toward metal cations [22]. Hetero-atomic subunits are often introduce as an integral part of the host molecules. Incorporation of these moieties onto macrocyclic structures is to combine within the same ligand the special complexation features of macrocycles with the photophysical and photochemical properties displayed by the metal complexes of these heterocycles [22].
It is well documented that heterocyclic compounds play a significant role in many biological systems, especially N-donor ligand systems that are components of several vitamins and drugs. It is not surprising, therefore that many authors have investigated heterocyclic compounds, and examined them as ligands in co-ordination compounds of several central atoms[23].
3
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Introduction and Literature Review
Heterocyclic compounds are well known for their pharmacological potential that is exploitable in the synthesis of new bioactive molecules. Moreover, nowadays, heterocyclic chemistry becomes more and more advanced in the development of new polyheterocyclic compounds. These compounds are extremely valuable because they possess not only the pharmacological potential owned by the heterocycles themselves, but also a new one due to the reciprocal influence between the contained heterocycles[24].
Several heterocyclic thioethers have been reported as potent anti-microbial [25] and anti-inflammatory agents[25],[26]. Thioethers are very useful building blocks in the synthesis of various organosulfur compounds. They have useful applications in organic synthesis, bioorganic, medical and heterocyclic chemistry. Thioethers can also act as safety-catch linker in peptides chemistry. Moreover, thioethers have been employed as sulfur-based ligands in transition metal complexes in industrial metal sulfide catalysts[27].
The importance of the sulfur atom in drugs as sulfide or disulfide linkages provides great stability for the three-dimensional structure of the molecule. Besides, the presence of sulfur can have a great contributions to the antimicrobial activities. Disulfide derivatives of 1,3,4-thiadiazole have shown antimicrobial activities against gram (+) bacteria and fungi [28].
One of the most interesting heterocyclic compounds in the world for organic chemistry and coordination inorganic chemistry is 2,5-disubstituted-1,3,4-thiadiazole which had been a wide range of applications in the most of fields according to the previous studies and next literature review.
4
Chapter One
Introduction and Literature Review
1.3 Thiadiazole and its Derivatives Thiadiazole is a 5-membered heterocyclic ring system containing “hydrogen-binding domain” two electron donor nitrogen system and one sulfur atom (–N=C–S) that exhibit a wide variety of biological activities[29].
There are various types of thiadiazole rings are present:
1, 2, 3-Thiadizole
1, 2, 4-Thiadizole
1, 2, 5-Thiadizole
1, 3, 4-Thiadizole
1.3.1 1, 2, 3-Thiadiazoles Moiety:
1,2,3-Thiadiazole moiety contains a heterocyclic ring in which sulfur presents at position-1, and two nitrogen atoms at position-2 and position-3[30] (Figure 1).
Figure 1: Structure of 1,2,3-Thiadiazole Moiety
5
Chapter One
Introduction and Literature Review
1.3.2 1, 2, 4-Thiadiazole Moiety: 1,2,4 –Thiadiazole moiety contain sulfur at position -1, and two nitrogen atoms at position -2 & position -4 (Figure 2). The photochemistry of 1, 2, 4-thiadiazoles is of interest because the ring system can be viewed as a combination of a thiazole and an isothiazole.
Figure 2: Structure of 1,2,4-Thiadiazole Moiety
Therefore, 1, 2, 4-thiadiazoles would be expected to undergo photo transposition reaction via both sulfur migration around four sides of the photo chemically generated bicyclic intermediates, and photo cleavage of the ( S-N ) bond similar to those of thiazoles and isothiazoles [30].
1.3.3 1, 2, 5-Thiadiazoles Moiety:
1,2,5- Thiadiazole moiety contains a heterocyclic nucleus in which sulfur presents at position 1, and two nitrogen atoms at position -2 and position -5 (Figure 3).
Figure 3: Structure 1,2,5-Thiadiazole Moiety
6
Chapter One
Introduction and Literature Review
1.3.4 1, 3, 4 –Thiadiazoles Moiety:
1,3,4-Thiadiazole moiety contains a heterocyclic nucleus in which sulfur presents at position-1, and two nitrogen atoms at position-3 and position-4 (Figure 4).
Figure 4: Structure of 1,3,4-Thiadiazole Moiety
Among these four types of thiadiazole, 1, 3, 4-thiadiazole is well known. 1,3,4Thiadiazole and its derivatives continue to be of a great interest to a large number of researchers owing to their great pharmaceutical and industrial importance. Some important canonical forms of 1,3,4-thiadiazole with dienic behavior is the maximum contributing structure (Figure 5) [29].
Figure 5: Resonance Form of 1,3,4-Thiadiazole
It has been shown that 1,3,4-thiadiazole derivatives possess interesting industrial and biological applications such as Radio protective, cyanine dyes, oxidation inhibitors, metal complexing agent, anti-corrosion[31], liquid crystal, optical brightening and fluorescent properties[32], dye stuff industry, photography[33][34], anti-microbial[28], anti-inflammatory[24], anti-bacterial[35], anti-anxiety, anti-tubercular[36], analgesic[37], anti-oxidant, cardiotonic action[38], anti-leishmanial, anti-insects, 7
Chapter One
Introduction and Literature Review
and anti-pyretic activities[29]. Also, it presents anti-depressant[39], tranquilizing agent, and hypoglycemic activities[40]. It could be applied in vitro inhibition of enzymes such as cyclooxygenase, 5-lipooxygenase[41], Carbonic Anhydrase-II (hCAII) Receptor[42], anti-depressant[39], anti-tumor[43], anti-cancer[35], anti-diabetic[44], and anti-viral[45] activities. However, little progress has been made in deducing central nervous system activities of thiadiazole derivatives which needs to be investigated thoroughly[46].
From the literature review it was notified that most of these activities appear when 1,3,4-thiadiazole bears Schiff base moieties. Many drugs containing 1,3,4-thiadiazole nucleus such as acetazolamide I, methazolamide II, megazol III (Figure 6) are available in the markets[47][48].
Figure 6: Drugs Containing 1,3,4-Thiadiazole Moiety in Markets
8
Chapter One
Introduction and Literature Review
1.4 Literature Review of 1,3,4-Thiadiazole Metal Complexes Bears Schiff Base Moiety
Transition metal complex of Schiff bases with tetradentate (N2X2) ligands (N= imine nitrogen; X = O- (salen), S- (thiosalen), OR, SR, PR2, etc.) had been extensively studied[11]. Some of these metal complexes have interesting applications, e.g., in metalloenzyme mediated catalysis[49], catalytic oxidation reactions, electro-chemical reduction processes[50], and asymmetric catalysis as catalytically active materials to develop surface modified electrodes in many reactions [51].
Zahid and coworkers (2001) prepared some metal complexes of 1,3,4-Thiadiazole Schiff bases derived from 2-amino-l,3,4-thiadiazole and 5-substimted-salieylaldehydes (Figure 7). They have been screened for antibacterial activity against several bacterial strains. The antibacterial potency of these Schiff bases increased upon complexation against the tested bacteria and opening new approaches in the fight against antibiotic resistant strains [52].
Figure 7: Structure of Metal Complexes 1, 2, 3 and 4
9
Chapter One
Introduction and Literature Review
Oxovanadium (V) complexes of Dithiocarbazate, based on Schiff base ligands [VO(acac)2] have been reported by Subodh and Coworkers (2002) which undergoes reaction with S-methyl-3-((2-hydroxyphenyl)methyl)dithiocarbazate (H2L1) and its bromo derivative (H2L2) under an oxidative environment in acetonitrile-water medium contains a catalytic amount of alkali metal ion (Figure 8). The products obtained are Oxovanadium (V) Complexes [VOL(Lcyclic)] (L = L1 and L2 ) that contain one molecule of ligand which undergoes metal-induced cyclization to form a thiadiazole ring [53].
Figure 8: Reaction to Formation of Metal Complex 5
Titanium (IV) complexes with Schiff bases derived from 2-amino-5-phenyl-1,3,4thiadiazole and different aromatic aldehydes (Figure 9) were reported by Srivastava et al (2005). The characterized metal complexes show the potential growth-inhibiting activities against fungal and bacterial strains[54].
Figure 9: Structure of Metal Complexes 6, 7, 8, 9 and 10
10
Chapter One
Introduction and Literature Review
A series of metal complexes of N-[5`-amino-2,2`-bis(1,3,4-thiadiazole)-5-yl]-2hydroxybenzaldehyde imine (HL) with different geometrical structures were prepared by Nevin Turan and Memet Sekerci (2009). The analytical data showed 1:2 metal-to-ligand ratio for Co(II), Ni(II), Cd(II), and Fe(II) and 2:2 metal-to-ligand ratio for Cu(II) complexes. The suggested structures for complexes of Fe(II), Co(II), and Cd(II) were octahedral, the Ni(II) complex was tetrahedral (Figure 10), and the Cu(II) complex was square-planar (Figure 11) [55].
M=
Co(II)
Ni(II)
Cd(II)
Fe(III)
X
2C2H5OH 11
14
2 C2H5OH 17
2 H2O 20
4 C2H5OH 12 13
3 C2H5OH 15 2 H 2O 16
C2H5OH 18 4 H2O 19
2 H2O 21 3 C2H5OH 22
Y Z
Figure 10: Structure of Metal Complexes 11-22
Figure 11: Structure of Metal Complex 23
.
11
Chapter One
Introduction and Literature Review
Rufen et al (2009) reported the synthesis and characterization of triorganotin (IV) complexes of Schiff base derived from 5-amino-1,3,4-thiadiazole-2-thiol with pphthalaldehyde whose characterizations revealed that complexes 24 and 25 were binuclear structures (Figure 12). Complexes 26 and 27 form a macrocyclic structure linked by intermolecular N→Sn interactions (Figure 13)[56].
Figure 12: Structure of Metal Complexes 24 and 25
Figure 13: Structure of Metal Complexes 26 and 27
Metal complexes of 1,3,4-thiadiazole Schiff base derived from Tetephthalaldehyde and 2-amino-5-Ethyl-1,3,4-Thiadiazole have been synthesized and characterized by Nevin and Memet (2009) (Figure 14). From the magnetic moment and UVvis spectra data, it was found that the geometrical structures of these metal complexes were octahedral[57].
12
Chapter One
Introduction and Literature Review
Figure 14: Structure of Metal Complexes 28 and 31
Suman et al (2011) reported some 3d-metal Schiff base metal complexes derived from 5-acetamido-1,3,4-thiadiazole-2-sulphonamide and their biological activities (Figure 15). Synthesized compounds and Schiff base ligand were screened against A.niger and A.flavus. It can be observed that the metal complexes showed the greater activities as compared to the Schiff base ligand[58].
Figure 15: Structure of Metal Complexes 32-35
Ajay and his coworkers (2013) reported the preparation of new Zinc(II) anti-microbial active metal complexes of Schiff bases derived from 2-hydrazino-5-[substituted phenyl] -1,3,4-thiadiazole and benzaldehyde/2-hydroxyaceto-phenone/indoline-2,3-dione (Figure 16). All these Schiff bases and their metal complexes have been screened against fungal and bacterial strains. The antimicrobial activities have shown that upon metal complexation the activity increases [59]. 13
Chapter One
Introduction and Literature Review
Figure 16: Structure of Metal complexes 36-47
Metal
chelates,
[M(DBTT)Cl].4EtOH,
[M(DBTT)OAc(H2O)2Cl].H2O,
[M(DBTT)Cl2(H2O)].2EtOH. (Where M = Cd, Mn, and Fe respectively) and (DBTT=Potassium
2-N(4-N,N-dimethylaminobenzyliden)-4-trithiocarbonate
-
1,3,4-thiadiazole ) have been synthesized by M. Alias and Coworkers (2013) (Figure 17). The complexes of Fe(III) and Mn(II) were octahedral structures whereas Cd(II) was tetrahedral geometrical structure. The ligand and their metal complexes have been screened in vitro against microorganisms which some metal complexes showed evident activities when compared to ampicillin as the standard drug[60].
Figure 17: Structure of Metal complexes 48, 49 and 50
14
Chapter One
Introduction and Literature Review
Preparation of some metal complexes of S,S'-1,3,4-thiadiazole-2,5-diylbis[2-(2hydroxybenzylidene)hydrazinecarbothioate]
and
S,S'-1,3,4-thiadiazole-2,5-
diylbis{2-[(2-hydroxynaphthalen-1-yl)-methylene]hydrazinecarbo- -thioate} was reported by R. Ahmed and I. Majed (2014) (Figure 18). Metals coordinated with the nitrogen of the azomethine group, oxygen of the amide carbonyl group and the oxygen of the hydroxyl group attached to the benzyl group were shown. Octahedral geometrical structure was the suggested structure for all metal complexes[61].
Figure 18: Structure of Metal complexes 51-58
Nano-sized particle of oxovanadium(IV) complexes with Schiff bases derived from 5-(phenyl/substituted phenyl)-2-hydrazino-1,3,4-thiadiazole and indoline-2,3dione was reported by M. K. Sahani et al (2014) (Figure 19). In-vitro antifungal and antibacterial activities were determined by screening the compounds against microorganisms. The oxovanadium(IV) complexes have greater antimicrobial effect than free ligands[62].
Figure 19: Structure of Metal complexes 59, 60, 61 and 62 15
Chapter One
Introduction and Literature Review
New molybdenum (VI) complex of 4-[(2-(5-(methyl(phenyl)amino)-1,3,4-thiadiazol-2-yl)hydrazono)methyl]-benzene-1,3-diol was reported by Z. Moradi and Coworkers (2015) which prepared in 1:1 ratio (metal: ligand) (Figure 20). The measurements indicated distorted octahedral geometry that the ligand is coordinated with the molybdenum(VI) in tridentate manner through the hydrazinic nitrogen, thiadiazole nitrogen, and phenolic oxygen[63].
Figure 20: Reaction to Form of Metal complex 63
The metal complex (63) was experienced as a catalyst for homogeneous epoxidation of olefins with tert-butyl hydrogen peroxide as an oxidant (Figure 21). In the homogeneous catalytic system, the reactions are efficiently carried out with high yields and selectivity[63].
Figure 21: Using the Metal complex no. 63 as a Catalyst in Epoxidation of Olefins
Sulekh Chandra and coworkers (2015) published synthesis of novel Schiff base that was benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) which involved in the complexation with Ni(II) and Cu(II) metals. The complex [Cu(L)(SO4)] (68) has square pyramidal geometry, while [Ni(L)](NO3)2 complex (69) tetrahedral and the rest of 16
Chapter One
Introduction and Literature Review
complexes (64-67) were six coordinated octahedral/tetragonal geometry (Figure 22). A new synthesized ligand with its metal complexes were studied against the adaptable pathogens. Results showed that metal complexes were more biological sensitive than free ligands[64].
Figure 22: Structure of Metal complexes 64-69
Umit Demirbas et al (2016) synthesized novel Cu(II), Fe(II) and Ti(IV)O complexes with 4-Thiadiazole substituted phthalonitrile and peripherally tetra-substituted phthalocyanine (Figure 23). Electrochemical studies of the metal complexes were performed with different voltammetric and spectroelectrochemical measurements. Electrochemical results of the metal complexes will give information about the possible usage of the metal complexes in various electrochemical application fields[65].
Figure 23: Reaction of Formation the Metal complexes 70, 71 and 72 17
Chapter One
Introduction and Literature Review
1.5 Para-phenylenediamine and its Derivatives
Para-phenylenediamine is an organic compound with the formula C6H4 (NH2)2. This derivative of aniline is a white solid, but it can be darken due to air oxidation[66]. It has many industrial applications for vulcanization accelerators, antioxidants for rubber industries and anti-wear additives for lubricants[67]. The most widely used anti-oxidants or antiozonants derived from 1,4-phenylenediamine were N-Isopropyl-N`-phenyl-p-phenylenediamine[68], N-Cyclohexyl-N`-phenyl-p-phenylenediamine [69], N,N`-Diphenyl-p-phenylene -diamine[70] and N-(1,3-dimethylbutyl)-N`-phenyl-p-phenylenediamine[71].
N,N`-Diphenyl-p-phenylenedi--
amine was used as an antioxidant and stabilizer for rubber and petroleum oils. Also it has been used as a retardant against copper degradation. It was found in dyes, drugs, plastics, and detergent additives[70]. N,N`-bis(salicylidene)-4,4-diaminodiphen- ylenemethane was used as additives to lubricants to provide protection against wear[67].
Figure 24: Structure of P-phenylenediamine
1.6 Literature Review of P-phenylenediamine Schiff Base Metal complexes
J. M. Vila and coworkers (1992) reported synthesis and crystal structures of [1,4{Pd[2,3,4-(MeO)3 C6HC(H)=N](Br)}2C6H4]2 (Figure 25): a novel tetranuclear cyclometallated palladium(II) complex which has been cyclometallated complexes of 1,4-phenyl-bis(benzylidene amine) ligands with either Pd(OAc)2 followed by NaX (X= Cl, Br), or PdCl2 followed by LiBr [72]. 18
Chapter One
Introduction and Literature Review
Figure 25: Structure of Metal Complexes 73 and 74
Sushanta K. Pal et al (1999) reported the treatment of N,N`-Bis(ferrocenylmethylidene)-p-phenylenediamine with I2, CA, TCNQ, TCNE, and DDQ to form charge transfer metal complex (Figure 26). IR spectroscopy suggests an increase in the amount of charge transferred from the ferrocenyl ring to the oxidant in the order, I 2 < CA < TCNQ < TCNE ~ DDQ [73].
Figure 26: Structure of Metal Complexes 75-79
Akmal S. Gaballa (2007) reported the synthesis, characterization and biological activities of some platinum(II) complexes of 1,4-phenylenediamine Schiff bases (Figure 27). The data of obtained characterization showed that Schiff bases were interacted with Pt(II) ions in the neutral form as a bidentate ligand, and the oxygen atoms rather than the nitrogens were the most probable coordination sites. Square planar geometrical structure which contains two coordinated water molecules were proposed for all metal complexes. The free ligands, and their metal complexes were screened for their antimicrobial activities against some bacterial species. The activity 19
Chapter One
Introduction and Literature Review
data showed that the platinum(II) complexes were more potent antimicrobials than the parent Schiff base ligands against one or more microorganisms[74].
Figure 27: Structure of Metal Complexes 80 and 81
M. Tunçel et al (2008) reported synthesis and characterization of thermally stable Schiff base polymers and their copper(II), cobalt(II) and nickel(II) complexes (Figure 28) which p-phenylenediamine Schiff bases have been used as monomers. The Schiff base polymers (SBPs) having double azomethine groups were prepared by oxidative polycondensation reaction of monomers in aqueous alkaline medium with NaOCl [ poly-(N,N-p-phenylenebis(salicylideneimine))] as the oxidant at 90oC [75].
Figure 28: Structure of Metal Complexes 82-87
Niraj Kumari and his team worker (2008) reported the treatment of Schiff base N,N`-bis(salicylidene)-p-phenylenediamine with Pt(en)Cl2 and Pd(en)Cl2 binding with hexafluorobenzene (Figure 29) [76]. 20
Chapter One
Introduction and Literature Review
Figure 29: Structure of Metal Complexes 88 and 89
Lius Adrio and his coworker (2009) reported the reaction of the tetranuclear halide-bridged complexes (90-97) with (dppm) or Ph2P(CH=CH)PPh2 (vdpp) in (1:2 molar ratio) and NH4PF gave the novel tetarnuclear palladacycles (123-134) as 1:2 electrolytes with bridging diphosphine and halogen ligands. The structure of complex (124) has been determined by X-ray diffraction analysis, and represents the first example of a tetranuclear palladacycle with bridging dppm and halogen ligands. Reaction of Complexes (90-97) with (Ph2PCH2CH2)2PPh (triphos) in 1:2 molar ratio gave products (119-122) bearing two penta-coordinated palladium atoms. The structure of complex (110) as determined by X-ray diffraction analysis shows the distorted square pyramidal geometry around the metal centers. Treatment of complex (90-97) with dppm, vdpp or Ph2PN(Me)PPh2 (dppma) in 1:4 molar ratio gave the dinuclear palladacycles complexes (98-109) with a chelating diphosphine ligand at each metal center. Further treatment of Complexes (102-104) with the nucleophiles pyrrolidine, piperidine, morpholine or 4-methylpiperidine gave the Michael addition derivatives (110-118) promoted by the withdrawing effect of the palladacycle which activates the C=CH2 double bond (Figure 30) [77].
21
Chapter One
Introduction and Literature Review
Figure 30: Structure of Metal Complexes 90-134
The interaction of 4,4`(1,4-phenylene bis(azan-1-yl-1-ylidene))bis(methan-1-yl1-1-ylidene)-1,2-diol with a series of some metals was reported by A.M. Nassar et al (2012). The five new neutral metal complexes have been prepared in 2M:1L molar ratio (Figure 31). The data showed tetrahedral geometry for Co(II), Ni(II), Cu(II) and Zn(II) complexes (135, 136, 137 and 138, respectively) and octahedral geometry for Fe(III) complex (139). The in-vitro antibacterial activity against some G +ve bacteria, G -ve bacteria and antifungal activity of the metal complexes were studied 22
Chapter One
Introduction and Literature Review
and compared with that of free ligand. Also MIC of the compounds against test microorganisms was detected [78].
Figure 31: Structure of Metal Complexes 135-139
23
Aim of the Study
.
Karzan A. Abdalkarim
1.7 Aim of the Present Study:
The major aims for this research work are:
First, Synthesis and characterization of new Schiff base ligands derived from 5-amino-1,3,4-thiadiazole-2-thiol
with salicylaldehyde and a
diketone which are ( PSTMH2, BMTHH2, and PBIPH2) ligands.
Second, Synthesis and characterization of new metal complexes of the new Schiff base ligands.
Third, Studying anti-bacterial activity and fluorescence emission properties of the prepared ligands and their metal complexes.
24
Chapter Two Experimental Part
Chapter Two
Experimental Part
Chapter Two: Experimental Part
2. Materials and Methods:
2.1 Materials
2.1.1 Chemicals The chemicals used in this work and their suppliers are listed in the following table: Table 2: Chemicals Used in This Work and Their Suppliers Compounds
Suppliers
1
5-amino-1,3,4-thiadiazole-2-thiol
Fluka
2
Salicylaldehyde
Merck
3
1,3-dibromopropane
J&K
4
Formic acid
Fluka
5
Diethyl ether
6
1,4-phenylenediamine
Merck
7
2,5-Hexandione
Merck
8
Potassium hydroxide
Merck
9
Sodium hydroxide
Merck
10 Ethanol
Merck
11 Methanol
Merck
12 Cupper(II) chloride dihydrate
Merck
13 Cobalt(II) chloride hexahydrate
Alfa Aesar
14 Cadmium(II) chloride monohydrate 25
Merck
Chapter Two
Experimental Part
Continuation of Table 2 15 Mercuric(II) chloride
HOPKIN&WILLIAMS
16 Manganese(II) chloride tetrahydrate
Merck
17 Iron(III) chloride hexahydrate
Merck
18 Zinc(II) chloride
Merck
19 Chromium(III)Chloride hexahydrate
Merck
20 Palladium(II) chloride
ALDRICH
21 Potassium tetrachloroplatinate
ALDRICH
22 Triethylamine 23 dichloromethane
BDH Fluka
24 Tetra hydro furan
Alfa Chemika
25 Hexane
Fluka Rashmi Diagnostics Pvt.,Ltd. India Rashmi Diagnostics Pvt.,Ltd. India
26 Mueller Hinton Agar 27 Broth Culture agar (Nutrient agar)
2.1.2 Instrumentations
1. Melting points were measured on Electrothermal digital melting point apparatus Model 1102D in Sulaimani University. 2. Electronic spectra of the ligands and their metal complexes were measured in DMSO using pg Instrument model T80+ UV-Visible Spectrophotometer in Sulaimani University. 3. Thermal gravimetric analysis of samples were measured using SHIMADZU TGA-50 in Sulaimani University. 4. The conductivities of the metal complexes were measured in DMSO using Fisher scientific Multimeter model XL600 in Sulaimani university. 26
Chapter Two
Experimental Part
5. Sensitive balance (4-digit) OHAU Explorer EX224. 6. UV-lamp San Gabriel model UVGL-58 MULTIBAND UV-254/366nm. 7. Mass spectroscopy spectra were measured using Agilent Technology (HP), MS Model: 5973 Network Mass Selective Detector at the Central Research Laboratory in Tehran. 8. The IR Spectra were recorded on a Perkin-Elmer FT/IR spectrometer in the (400-4000 cm-1) range using KBr pellets (νmax in cm-1), and on Shimadzu FTIR spectrophotometer Model 8000 series in (200-600 cm-1) range using CsI discs in Sulaimani and Al-Mustansiriyah university respectively. 9. Elemental analysis were carried out on EURO-EA3000 CHNS analyzer in Education College of Pure Sciences-Ibn al-Haytham/University of Baghdad and ICP Spectrometer (Perkin Elmer-Optima 2100-Dv.Spectrometer) in University of Sulaimani. 10. Sherwood Scientific Auto Magnetic susceptibility balance in Sulaimani University. 11.The Emission of Fluorescence was measured by Cary Eclipse Fluorescence Spectrophotometer –Agilent Technologies in Koya University.
27
Chapter Two
Experimental Part
2.2 Preparations of the Starting Materials: 2.2.1 Preparation of 1,3-Bis(5-amino-1,3,4-thiadiazole-2-thio)propane [BATP] Ligand Precursor 1,3-dibromopropane (5.8 mmol, 1.170 gm) was added to a solution of compound 5-amino-1,3,4-thiadiazole-2-thiol (11.6 mmol, 1.545 gm) dissolved in EtOH (50 ml)KOH (11.6 mmol, 0.65 gm). The resulting mixture was heated under reflux until the 5-amino-1,3,4-thiadiazole-2-thiol was disappeared on TLC. The yellow precipitate filtered off and washed with (%5 NaOH solution) and water. Then dry the precipitate in Oven at 80oC, according to previous study with few modifications (Yield, 78%) [79].
2.2.2 Preparation of Sodium Tetrachloropalladate (II), Na2[PdCl4] This compound was prepared from Palladium (II) Chloride using literature method [80] (Yield, 92%).
2.3 Preparation of 2,2'-((1E,1'E)-((5,5'-(propane-1,3 diylbis(sulfanediyl)) bis(1,3,4-thiadiazole-5,2 diyl))bis(azanylylidene))bis(methanylylidene)) diphenol [PSTMH2] Ligand We added (1.221 gm, 10 mmol) of salicylaldehyde with few drops of formic acid to (1.53 gm, 5 mmol) of [BATP] in 100 ml of ethanol, the solution was reflexed for 48 hours. Then the hot mixture filtrated and evaporated the solvent gently under vacuum. The residue washed with 10 ml of hexane twice and the yellow precipitate was obtained after filtration (Yield, 40%). Both of the preparation steps was followed up by using TLC. 28
Chapter Two
Experimental Part
2.3.1 Preparation of [Cr(PSTM)(H2O)2]H2O.Cl (140)
Suspended methanolic solution of (0.514 gm, 1 mmol in 30 ml) PSTMH2 with few drops of triethylamine was heated and followed by addition of (0.2664 gm, 1 mmol) of CrCl3.6H2O in 5 ml of methanol. The reaction mixture was refluxed continually for 24 hours, then the obtained brown precipitate filtrated off, washed with hot methanol and ether, and dried in vacuum desiccator. (Yield, 94.6%)
2.3.2 Preparation of [Fe(PSTM)(H2O)2]H2O.Cl (141) This complex was prepared by a similar method (2.3.1) to that used to prepare [Cr(PSTM)(H2O)2]H2O.Cl as a brawn solid. (Yield, 90.8%)
2.3.3 Preparation of [Co(PSTM)]H2O (142)
This complex was prepared by a similar method (2.3.1) to that used to prepare [Cr(PSTM)(H2O)2]H2O.Cl as a black solid (Yield, 96.7%)
2.3.4 Preparation of [Cu(PSTM)]H2O (143)
This complex was prepared by a similar method (2.3.1) to that used to prepare [Cr(PSTM)(H2O)2]H2O.Cl as a light green solid. (Yield, 93.1%)
29
Chapter Two
Experimental Part
2.3.5 Preparation of [Pd(PSTM)]H2O (144)
This complex was prepared by a similar method (2.3.1) to that used to prepare [Cr(PSTM)(H2O)2]H2O.Cl as a dark yellow solid. (Yield, 78.9%)
2.3.6 Preparation of [Pt(PSTM)]3H2O (145)
Suspended methanolic solution of (0.0514 gm, 1 mmol in 30 ml) PSTMH2 with few drops of triethylamine was heated and followed by adding a solution of {K2[PtCl4] that was prepared by dissolving (0.04151 g, 0.1 mmol) in a mixed solvent of (3ml D.W and 2 ml methanol)}. The reaction mixture was refluxed continually for 24 hours, then the obtained yellow precipitate filtrated off, washed with hot methanol and ether, and dried in vacuum desiccator. (Yield 71.3%)
2.4 Preparation of BMTHH2 Ligand We added (1.1414 ml, 10 mmol) of 2,5-Hexandione drop wise to a refluxed methanolic solution (30 ml) of (2.6638 g, 20 mmol) 5-amino-1,3,4-thiadiazole-2-thiol with few drops of formic acid. The reflux is made continually for another 15 hours, after that the reflexed solution was evaporated using rotary evaporator. The final product was isolated from the reaction mixture by adding 30ml dichloromethane to the residue. Thus all unreacted starting materials were removed by filtration and the product violet-bulbar precipitate was obtained by evaporating the solvent. Then the product was washed with Hexane and dried in vacuum (Yield, 75%).
30
Chapter Two
Experimental Part
2.4.1 Preparation of [Cu(BMTH)]H2O (146) Methanolic solution of [CuCl2.2H2O (0.1704 g, 1 mmol) in 5 ml] was added to a solution of BMTHH2 (0.344 g, 1 mmol) in 10 ml methanol with a few drops of triethylamine. The reaction mixture was stirred at room temperature for 30 min. Then it was refluxed for another 30 min. After cooling the solution, the pale green precipitate was filtrated off, and washed with both methanol and ether. Then it was dried in vacuum (Yield, 75.3%)
2.4.2 Preparation of [Co2(BMTH)(H2O)4]2Cl (147) Methanolic solution of [CoCl2.6H2O (0.5478 g, 2 mmol) in 5 ml] was added to a solution of BMTHH2 (0.344 g, 1 mmol) in 10 ml methanol with a few drops of triethylamine. The reaction mixture was stirred at room temperature for 30 min. Then it was refluxed for another 30 min. After cooling the solution, the green precipitate was filtrated off, and washed with both methanol and ether. Then it was dried in vacuum (Yield, 71.3% )
2.4.3 Preparation of [Zn(BMTH)]H2O (148)
This complex was prepared by a similar method (2.4.1) to that used to prepare [Cu(BMTH)]H2O as a white-gray solid. (Yield, 76.1% )
2.4.4 Preparation of [Cd(BMTH)]H2O (149)
This complex was prepared by a similar method (2.4.1) to that used to prepare [Cu(BMTH)]H2O as a white-gray solid. (Yield, 74.3%) 31
Chapter Two
Experimental Part
2.4.5 Preparation of [Hg(BMTH)]H2O (150)
This complex was prepared by a similar method (2.4.1) to that used to prepare [Cu(BMTH)]H2O as a brown solid. (Yield, 61.4%)
2.4.6 Preparation of [Pd(BMTH)]H2O (151)
This complex was prepared by a similar method (2.4.1) to that used to prepare [Cu(BMTH)]H2O as a brown solid. (Yield, 92.5%)
2.4.7 Preparation of [Pt(BMTH)]2H2O A solution of {K2[PtCl4] was prepared by dissolving (0.04151 g, 0.1 mmol) in a mixed solvent of (3ml D.W and 2 ml methanol)} was added to a solution of BMTHH2 (0.0344 g, 0.1 mmol) in 10 ml methanol with a few drops of triethylamine. The reaction mixture was stirred at room temperature for 30 min. Then it was refluxed for another 30 min. After cooling the solution, the brown precipitate was filtrated off, and washed with both methanol and ether. Then it was dried in vacuum (Yield, 94.6%).
2.5 Preparation of PBIPH2 Ligand Para-Phenylenediamine (1.0814 gm, 10 mmol) was mixed gently with (20 mmol, 2.442 gm) of salicylaldehyde. Then few drops of formic acid were added to the mixture and stirred for a few minutes. The obtained orange precipitate was washed with ethanol several times. After filtration, the product was recrystallized in THF to obtain the orange crystal (85% Yield).
32
Chapter Two
Experimental Part
2.5.1 Preparation of [Mn(PBIP)(H2O)2]H2O (153) A solution of MnCl2.4H2O (0.1979 gm, 1 mmol) in 5 ml THF was added to a refluxed solution of (0.316 gm, 1mmol) of PBIPH2 in 25 ml THF with a few drops of Triethylamine. The reaction mixture was refluxed for another 10 hours. The hot solution was filtered, and washed several times with hot THF and methanol. Then the dark brown product was dried in vacuum desiccator. (Yield, 76.6%)
2.5.2 Preparation of [Fe(PBIP)(H2O)3Cl]H2O (154)
This complex was prepared by a similar method (2.4.1) to that used to prepare [Mn(PBIP)(H2O)2]H2O as a brown solid. (Yield, 89.1%)
2.5.3 Preparation of [Zn(PBIP)]H2O (155)
This complex was prepared by a similar method (2.5.1) to that used to prepare [Mn(PBIP)(H2O)2]H2O as a orange solid. (Yield, 65.6%)
2.5.4 Preparation of [Cu2(PBIP)(H2O)4]H2O.Cl (156)
A solution of CuCl2.2H2O (0.341 gm, 2 mmol) in 5 ml THF was added to a refluxed solution of (0.316 gm, 1mmol) of PBIPH2 in 25 ml THF with a few drops of Triethylamine. The reaction mixture was refluxed for another 10 hours. The volume was reduced to half, and the hot solution was filtered, and washed several times with THF and methanol, then the black product was dried in vacuum desiccator. (Yield, 50.9%) 33
Chapter Two
Experimental Part
2.5.5 Preparation of [Co2(PBIP)(H2O)2Cl2]H2O (157) A solution of CoCl2.6H2O (0.5478 gm, 2 mmol) in 5 ml THF was added to a refluxed solution of (0.316 gm, 1 mmol) of PBIPH2 in 25 ml THF with a few drops of Triethylamine. The reaction mixture was refluxed for another 10 hours. The hot solution was filtered, and washed several times with hot THF and methanol. Then the reddish brown product was dried in vacuum desiccator. (Yield, 69.4%)
2.5.6 Preparation of [Pd2(PBIP)Cl4]2H2O (158) A solution of Na2[PdCl4] (0.0588 gm, 0.2 mmol) in 5 ml THF was added to a refluxed solution of (0.0316 gm, 0.1mmol) of PBIPH2 in 25 ml THF with a few drops of Triethylamine. The reaction mixture was refluxed for another 10 hours. The hot solution was filtered, and washed several times with hot THF and methanol. Then the brown product was dried in vacuum desiccator. (Yield, 52.2%)
2.5.7 Preparation of [Pt2(PBIP)(H2O)2Cl2]2H2O (159) A solution of {K2[PtCl4] was prepared by dissolving (0.0830 g, 0.2 mmol) in a mixed solvent of (3ml D.W and 2 ml THF)} was added to a refluxed solution of (0.0316 gm, 0.1mmol) of PBIPH2 in 25 ml THF with a few drops of Triethylamine. The reaction mixture was refluxed for another 10 hours. The hot solution was filtered, and washed several times with hot THF and methanol. Then the dark brown product was dried in vacuum desiccator. (Yield, 56.9%)
34
Chapter Three Results and Discussion
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
Chapter Three: Results and Discussion
Part One. 3.1 Preparation and Characterization of 2,2'-((1E,1'E)-((5,5'-(propane-1,3 diylbis (sulfanediyl)) bis(1,3,4-thiadiazole-5,2 -diyl))bis(azanylylidene)) bis -(methany -lylidene)) diphenol [PSTMH2] Ligand and its Metal Complexes: 3.1.1 Preparation of 1,3-bis(5-amino-1,3,4-thiadiazole-2-thio)propane [BATP] Precursor Previous research works used BATP in the preparation of some other thiadiazole derivatives [79], whereas in the present work we used this compound (BATP) as a precursor for preparation of a new Schiff base ligand (as show in Reaction 3), due to the wide range of Schiff base metal complex applications which was described in chapter one. This (BATP) compound was prepared from the reaction between 5amin-1,3,4-thiadizole-2-thiol and 1,3-dibromopropane as nucleophilic substitution reaction in basic medium as shown in (section 2.2.1)[79] according to the following reaction ( Reaction 2):
Reaction 2: Preparation of BATP From 5-amino-1,3,4-thiadiazole-2-thiol
35
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
3.1.2 Preparation of 2,2'-((1E,1'E)-((5,5'-(propane-1,3 diylbis(sulfanediyl)) bis(1,3,4-thiadiazole-5,2diyl))bis(azanylylidene))bis(methanylylidene)) diphenol [PSTMH2] Ligand PSTMH2 was prepared from 1,3-bis(5-amino-1,3,4-thiadiazole-2-thio) and 2hydroxybenzaldehyde propane according to the following reaction:
Reaction 3: Preparation of PSTMH2 Ligand From BATP Precursor
3.1.3 Mass Spectroscopy of BATP Precursor and PSTMH2 Ligand Mass spectrometry is a spectroscopic method which irradiates substances with highly energetic electrons. This energy causes ionization of the molecules. The ions are separated in a magnetic field, and the mass spectrometry measures the masses of these ions. MS allows chemists to determine the molecular weight of a compound. High-resolution MS can determine molecular formula of compounds as well. The fragmentation pattern of an ionized molecule also provides data that can assist in the identification of the compound [81]. Both BATP precursor and PSTMH2 ligand contain even numbers of nitrogen which have chemical formula (C7H10N6S4 and C21H18N6S4O2 respectively) and molecular weight (306 and 514 g/mole respectively).
It is a noble evidence toward following both mass Spectrum of BATP precursor (Fig. 32) and PSTMH2 ligand (Fig. 33) of nitrogen rule that “molecules of odd molecular weight must contain an odd number of nitrogen atoms, molecules of even molecular weight must contain either an even number of nitrogen atoms or no nitrogen atoms”[82]. 36
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
The presence of an aromatic nucleus stabilizes the molecular ion, and the molecular ion peak is almost always detectable. The favored cleavages preserve the aromatic ring and benzylic cleavage. Ions from the breakdown of an aromatic nucleus are of relatively low abundance, but have some characteristic of molecular ions like (m/z 39, 50, 51, 65, and (76), 77, (78)]; which some of these molecular ions were detected in the Mass spectrum of PSTMH2 ligand (Fig.32) like (m/z 51, 65, 77 ), though the metastable ion peak at m/z (77 → 51) for the fragmentation of the aromatic nucleus must be detectable. This another supporting assignment to the PSTMH2 ligand structure. However this peak is undetectable in mass spectrum of BATP precursor due to the absence of benzylic group in the BATP precursor structure[83]. In addition, Fragments of (174, 160, 146 and 132 molecular weight) for BATP precursor and Fragments of (278, 264, 250 and 236 molecular weight) for PSTMH2 ligand, shows loss of -CH2 group stepwise. Also the fragment (93 to 77) show mass loss of phenolic -OH group in the PSTMH2 ligand. Table 3: Mass Data for BATP precursor and PSTMH2 Ligand MS, m/z
Compounds
BATP
PSTMH2
[M+]
C7H10N6S4, 174[C5H8N3S2+],
306 160[C4H6N3S2+], 146[C3H4N3S2+], 132[C2H2N3S2+] 514 [M+] C21H18N6O2S4, 278[C12H12N3OS2+], 264[C11H10N3OS2+], 250[C10H8N3OS2+], 236[C9H6N3OS2+], 204[C9H6N3OS+], 120[C7H6NO+], 93[C6H5O+], 77[C6H5+]
3.1.4 Thin Layer Chromatography of BATP Precursor and PSTMH2 Ligand
In the preparation of an organic compound we may have multiple compounds in the reaction mixture. Also the starting reagents may be the only known compounds available. TLC analysis is a very useful method in determining both of these results. First, the consummation of limiting reagent and second, number of compounds are formed during the reaction [81]. 37
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
Table 4: Rf of 5-amino-1,3,4-thiadiazole-2-thiol, BATP Precursor and PSTMH2 Ligand Compound
Solvent
Rf
thiadiazole-2-thiol
Ethanol:hexane:toluene(3:3:4)
0.53
BATP PSTMH2
Ethanol:hexane:toluene(3:2:5) Ethanol:hexane:toluene(3:3:4)
0.6 0.31
5-amino-1,3,4-
Figure 32: Mass Fragmentation of BATP Ligand Precursor
38
Chapter Three/Part One
Results and Discussion
1 2 3
Figure 33: Mass Fragmentation of PSTMH2 Ligand 39
PSTMH2 Ligand
m/z --->
5
4
Figure 344: Mass Spectrum of BATP Precursor
40
273
304.6
300.5
295.2
289.2
Thousands
Results and Discussion
283.4
278.3
259
273.3
267.2
262.4
246
255.4
250.2
231
243.5
238.5
233.2
190
227.3
221.8
217.3
146
212.5
128
207.2
160
200.2
196.4
192.3
187.4
181.3
176.3
106
168.3
162.2
153.3
148.2
114
142.3
136.2
129.3
200
121.2
85
116.2
100
110.2
104.3
97.4
91.2
100
85.3
80.2
75.3
70.3
64.2
58.3
52.3
47.2
800
41.3
Abundance
Chapter Three/Part One PSTMH2 Ligand
1000
900 60
41
700
600
132
500
174
400 74
300 205
207 306
0
Thousands
Chapter Three/Part One
Results and Discussion
40
77
237 204
35
30
278 106
146
25
Abundance
PSTMH2 Ligand
173
132
20 60
120
15
161
51
309
264
115
10
350
393
410
514 481
5
93
497
0 41
69
100
130
161
191
222
253
283
m/z
6
Figure 35: Mass Spectrum of PSTMH2 Ligand 41
314
344
375
406
434
465
495
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
3.1.5 Preparation and Characterization of [PSTMH2] Metal Complexes of Cr(III), Fe(III), Co(II), Cu(II), Pd(II), and Pt(II)
All metal complexes of [PSTMH2] were obtained by the reaction of [PSTMH2] ligand with metal chloride salts of Cr(III), Fe(III), Co(II), Cu(II), Pd(II), and Pt(II) in an alcoholic solution containing few drops of Triethylamine. The prepared metal complexes were characterized by elemental analysis, conductivity measurement, infrared spectroscopy, Uv-visible and emission spectroscopy, magnetic susceptibility measurement and thermal gravimetric analysis.
3.1.6 Elemental Analysis C, H, N, S and Metals CHNS elemental analysis is a technique used for determination of carbon, hydrogen, nitrogen, and sulfur percentage in organic matrices and other types of materials. Also, the metal percentage of metal complexes were determined by ICP instrument. The elemental analysis data with the metal percentages for the prepared ligands and their metal complexes are arranged in (Table 5). These data are consistent with the suggested stoichiometries for the prepared metal complexes. All the data are tabulated with the color and melting points of the prepared metal complexes in (Table 5).
42
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
No.
Table 5: Physical Properties and Elemental Analysis of BATP Precursor, PSTMH2 Ligand and Metal Complexes of PSTMH2 Ʌm (Ω-1.cm2.mol-1)
BATP
C7H10N6S4
Light Yellow
212-214
-
-
-
-
-
-
PSTMH2
C21H18N6S4O2
Yellow
204-206
48.617 (49.01)
3.414 (3.53)
15.825 (16.33)
23.987 (24.92)
---
10.69
140
[Cr(PSTM)(H2O)2]H2O.Cl
Brown
>370
38.228 (38.56)
3.288 (3.39)
12.672 (12.85)
18.694 (19.61)
(7.95)
43.89
141
Metal
[Fe(PSTM)(H2O)2]H2O.Cl
Black
95-98
37.346 (38.33)
3.478 (3.37)
12.812 (12.77)
18.76 (19.49)
6.92 (8.49)
39.61
142
C
% Found (Calculated) H N S
[Co(PSTM)]H2O
Brown
>365
42.010 (42.78)
2.981 (3.08)
13.83 (14.25)
20.821 (21.75)
9.0 (10.00)
24.29
143
M.P o C
[Cu(PSTM)]H2O
Light Green
194-196
40.953 (42.45)
3.280 (3.05)
13.611 (14.14)
20.244 (21.58)
9.40 (10.69)
13.18
144
Color
[Pd(PSTM)]H2O
Dark Yellow
~350d
38.944 (39.59)
2.624 (2.85)
13.108 (13.19)
19.359 (20.13)
-(16.70)
15.79
145
Compounds
[Pt(PSTM)]3H2O
Yellow
~350d
32.181 (33.11)
2.320 (2.91)
10.299 (11.03)
15.901 (16.84)
-(25.61)
14.49
d
= decompose
3.1.7 Conductivity Measurements The degree of ionization of metal complexes was determined by measuring the electrical conductivity in the solution. The higher molar ions that a metal complex liberates in the solution, shows the higher molar conductivity and vice versa. The non-ionized metal complexes have negligible value of molar conductance [84]. The molar conductivities of 10-3 molar solutions of the metal chelates in DMSO at room temperature are measured. The data obtained are listed in (Table 5). The decisions 43
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
about the conductibility of all metal complexes come from comparisons of results with table of molar conductivity observed in different solvents (Table 6).
Table 6: Molar Conductivity of (1×10-3M) Observed Electrolyte Types in Different Solvents Solvent
Electrolyte Type Non Electrolyte
1:1
1:2
1:3
1:4
0
120
240
360
480
Ethanol
0-20
35-45
70-90
~120
~ 160
Nitro methane
0-20
75-95
150-180
220-260
290-330
Methyl Cyanide
0-30
120-160
220-300
340-420
~500
Dimethylformamide
0-30
65-90
130-170
200-240
~300
Dimethyl Sulfoxide
0-20
30-40
70-80
-
-
Water
In the conductivity measurement study, the molar conductivities of all prepared ligands and metal complexes were measured for (1*10-3 Molar) solution in DMSO at 25oC. The recorded values of the molar conductance’s are displayed in (Table 5).
Molar conductance values of PSTMH2 metal complexes suggest that the metal complexes (142-145) are non-electrolytes, while metal complexes (140,141) are 1:1 electrolytes in DMSO.
44
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
3.1.8 Infrared Spectra
The infrared spectra of ligand and metal complexes were measured in the (4004000) cm-1 range using (potassium bromide discs for spectroscopy). Also the infrared spectra of all metal complexes were measured in (200-400) cm-1 range that Cesium iodide discs was used. All frequencies of the main characteristic bands were shown in (Table 7) with their description and assignments. The infrared spectra of the precursor (BATP) and the ligand (PSTMH2) with their metal complexes were shown in (Figures 36-43). The formation of (PSTMH2) ligand was indicated by the presence of the aliphatic azomethine (CH=N) stretching band at (1625 cm-1) which not present in (BATP) precursor according to their IR spectra (Figure 37 and 38). This was combined with the disappearance of the NH2 stretching band at (3377 cm-1 and 3261 cm-1) of the ligand precursor in the IR spectrum of the ligand. In addition, another evidence about the correct structure of the ligand (PSTMH2) was obtained through detection of a broad band at (3433 cm-1) for OH of the phenolic group and the appearance of two bands at (3057 cm-1 and 2851 cm-1) which are characteristics for C-H stretching of aromatic ring and imine groups respectively. In addition, a sharp stretching band appeared at (1496 cm-1) which was referred to of C=C of aromatic ring. Finally, another stretching bands were observed at (1282 cm-1) which are assigned to stretching of CO bond of the phenolic hydroxyl group[85]. Strong absorption band at 755 cm-1 (759 in IR Spectrum of PSTMH2 ),(without the accompanying strong band at 700 cm-1) indicates o-disubstitution on the phenyl nucleus[86].
45
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
The infrared spectral data were discussed according to the functional groups present in the metal complexes as follow:
υ O-H and C-O The infrared spectrum of ligand (PSTMH2)(Figure 37) showed a strong broad band in the region 3433 cm-1, which is attributed to stretching vibration of phenolic O-H group of the ligand, and a band at 1281 cm-1 is attributed to ν C-O of C-O-H group [87]. In the IR spectra of metal complexes, the characteristic bands of ν C-O are shifted to a lower frequency in metal complexes of Fe(III), Cr(III), Co(II), Cu(II), Pd(II), Pt(II) (1275, 1272, 1272, 1270, 1273, 1253 cm-1 respectively). This shows the bonding of phenolic oxygen atoms to the metal centers via deprotonation. So, the band of hydroxyl group must disappear while the infrared spectra of complexes Fe(III), Cr(III), Co(II), Cu(II), Pd(II), Pt(II) shows a strong broad band at (3395, 3368, 3445, 3446, 3401, 3414 cm-1 respectively). The essential features of this band suggest the present of lattice or coordinated water molecules which is confirmed by thermal gravimetric analysis and elemental analysis.
υ C=N The infrared spectrum of free ligand (PSTMH2) shows a sharp band at 1625 cm-1 (Figure 37), due to a stretching vibration of C=N of the azomethine group of the free ligand [88]. It is shifted to a lower frequency by (12-21 cm-1) at ( 1607, 1613, 1604, 1604, 1612, 1607 cm-1 respectively)(Figure 38-43) for all prepared metal complexes of (PSTMH2) ligand[55]. This suggests that C=N group is involved in bonding with the metal center. 46
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
υ C=N of Thiadiazole ring Two weak to medium characteristic bands of C=N of thiadiazole ring in the IR spectra of the ligand (BATP) ligand and (PSTMH2) ligand (Figure 36 and 37) is appeared at 1602 cm-1 and 1604 cm-1 respectively[55][57]. These vibrational frequencies in the IR spectra of all six metal complexes (Figure 38-43) remain at the same region without significant change. It indicates of non-ligated C=N of thiadiazole ring with the metal centers. The band of C=N in the thiadiazole ring overlapped with the band of C=N of the azomethine group in some prepared metal complexes of (PSTMH2) ligand.
υ CH2-S Another characteristic band at 688 cm-1 can represent CH2-S bond of the free ligand in the IR spectrum of the (PSTMH2) ligand (Figure 37)[85]. This band does not significantly change during complexation of the (PSTMH2) ligand with all six metals. It shows that the sulfur atom does not coordinate with metals as reported in the literature review. Therefore the thiadiazole ring and thioether group do not undergo complexation as confirmed by previous explanations. 3.1.9 The Far Infrared (650-200 Cm-1) Region The Far Infrared Spectra of all metal complexes shown in (Figures 44 & 45) and their data peaks are listed in (Table 7). Bands in this part of the spectra of compounds containing only carbon, hydrogen, nitrogen, and oxygen atoms are usually due to bending and stretching of weak bonds and are not localized in small groups. The values of the region for structural diagnosis is, therefore, severely limited. When 47
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
heavier atoms are present, localized vibrations including them may, however, fall in this region. Most of the bands related with metal-metal and metal-non-metal bonds fall in this region with obvious applications to metal-organic Chemistry[86].
υ (M-N) In the Far-IR spectra of metal complexes (Figure 44 and 45), the peak which assigned to the bond formation of metal with nitrogen atom of the azomethine groups are detected at 437 cm-1 for (Cr-N), 445 cm-1 for (Fe-N), 453 cm-1 for (Cu-N), 459 cm-1 for (Co-N), 450 cm-1 for (Pd-N), and 441 cm-1 for (Pt-N) [89].
υ (M-O) In the Far-IR region spectra (Figure 44 and 45), the absorption peak which assigned to the coordination of metal through the Oxygen atom of the Phenolic groups([M-O) is detectable at 538 cm-1 for (Cr-O), 547 cm-1 for (Cu-O), 530 cm-1 for (Co-O), 497 cm-1 for (Fe-O), 525 cm-1 for (Pd-O), and 520 cm-1 for (Pt-O) [89][90].
48
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
Table 7: Data of Major IR Bands for BATP Precursor, PSTMH2 Ligand, and Metal Complexes of PSTMH2 in (cm-1) No.
Compounds
O-H
C=N of
C=N of
imine
thiadiazole ring
-
-
-
1282
O-H(H2O)
C-O
-
-
3433
phenolic
BATP PSTMH2
C7H10N6S4 C21H18N6S4O2
-CH2-S
M-O
M-N
1602
690
-
-
1625
1604
688
-
-
140
[Cr(PSTM)(H2O)2]Cl.H2O
-
3368
1272
1613
Overlap with C=N
689
538
437
141
[Fe(PSTM)(H2O)2]Cl.H2O
-
3395
1275
1607
of azomethine group
690
497
445
142
[Co(PSTM)]H2O
-
3445
1272
1604 overlap
688
530
459
143
[Cu(PSTM)]H2O
-
3446
1270
1604 overlap
688
547
453
144
[Pd(PSTM)]H2O
-
3402
1271
1613
Overlap with C=N
690
525
450
145
[Pt(PSTM)]3H2O
-
3430
1252
1607
of azomethine group
691
520
441
49
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
80
70
60
50
2854
1332 2929
690 40
1041
1602 1422
3377
1064
30
3110 1515
20
3261 10
0 4000
3600
3200
2800
2400
2000
cm-1
Figure 36: FTIR Spectrum of BATP precursor
50
1600
1200
800
400
T%
1000
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
80
78
2851
3057
76
972 688
74
2926 1078
T%
72
3433
70
1625
1496 1442
68
1282 759
66
64
1604 62 4000
3600
3200
2800
2400
2000
cm-1 Figure 37: FTIR Spectrum of PSTMH2 Ligand 51
1600
1200
800
400
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
78
973 1076
689 765
1272
2857
73
T%
1441
2923
3368
1497
68
63
1613 58 4000
3600
3200
2800
2400
2000
cm-1
Figure 38: FTIR Spectrum of [Cr(PSTM)(H2O)2]H2O.Cl 52
1600
1200
800
400
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
73
69
690
971
1077
2852
761
61
T%
3395
65
2925 1275 1496
57
1442 53
49
1607 4000
3600
3200
2800
2400
2000
cm-1
Figure 39: FTIR Spectrum of [Fe(PSTM)(H2O)2]H2O.Cl 53
1600
45 1200
800
400
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
82
2851 972 2927
80
688
1051
78
1077
76
1272 758
1497
74
1434
3445
72
1604 70 4000
3600
3200
2800
2400
2000
cm-1
Figure 40: FTIR Spectrum of [Co(PSTM) )(H2O)2]H2O 54
1600
1200
800
400
T%
3056
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
76 74
972
72
688 3065
2927
2854
1051
70
1077
T%
68
3446
66
1496
1270 64
759
1442
62 60
1604 4000
3600
3200
2800
2400
2000
cm-1
Figure 41: FTIR Spectrum of [Cu(PSTM)]H2O 55
1600
58 1200
800
400
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
90
89
690
2854
973 88
1271 1075 1491
87
1443 756
86
85
84
1613 83
3402 82 4000
3600
3200
2800
2400
2000
cm-1
Figure 42: FTIR Spectrum of [Pd(PSTM)]H2O 56
1600
1200
800
400
T%
2926
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
90.1
89.1
691
88.1
758
2853
1252
3007
969 87.1
1444 2925 1495
86.1
1607
85.1
84.1
83.1 3430 82.1
4000
3600
3200
2800
2400
2000
cm-1
Figure 43: FTIR Spectrum of [Pt(PSTM)].3H2O 57
1600
1200
800
400
T%
1075
Chapter Three/Part One
Results and Discussion
Figure 44: Far-IR Spectra of A=Cr(III), B=F(III), C=Co(II) Complexes with PSTMH2 Ligand 58
PSTMH2 Ligand
Chapter Three/Part One
Results and Discussion
Figure 45: Far-IR Spectra of D=Cu(II), E=Pd(II), F=Pt(II) Complexes with PSTMH2 Ligand 59
PSTMH2 Ligand
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
3.1.10 Electronic Spectra
The UV-vis spectra of the ligand and the metal complexes were recorded in the DMSO solution in the wavelength range from 200 to 800 nm which correspond to 50000-12500 cm-1 at ~10-3 concentration (Figures 46-52). The maxima of bands of absorption spectra and their assignments are collected in (Table 8).
In the UV-vis spectra intense bands are observed in the part of the spectra (4000028000 cm-1) that can be assigned to the allowed ligand-centered (π-π*) transitions. Somewhat weaker bands are observed in the lower part of energy (λmax>26000 cm1
). MLCT transitions have been resolved in the range of 26000-22000 cm-1. The long
tail toward lower energy is also assigned to MLCT transitions[91].
The absorption spectrum of the free ligand (Figure 46) shows absorption peaks at 36765 cm-1 and 30303 cm-1, assigned to π→π* and n→π* transitions for the phenolic-OH and azomethine moieties[92]. The values shifted slightly to longer wavelengths indicate the involvement of phenolic-OH and azomethine moieties in metal complexation. The electronic spectra of metal complexes exhibit bands around 32250-34100 cm1
indicate intra-ligand charge transitions[63]. In the spectrum of Iron (III) complex
(Figure 48), it can be seen that it exhibits two bands at 18116 cm-1 and 24631 cm-1, which can be assigned to the 6A1g→4T1g and 6T2g→5Eg transitions of octahedral structure[78][93]. Also, in the spectrum of chromium (III) complex (Figure 47) two bands at 15576 cm-1 and 22831 cm-1 are assigned to 4
4
A2g(F)→4T1g(F) and
A2g(F)→4T2g(F) respectively, which are characteristic to the octahedral structure [94].
60
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
In the absorption spectrum of Cu (II) Complex (Figure 50) a band at 33557 cm-1 that is indication to the intra ligand charge transitions. Square-planar geometry is proposed for Cu (II) complex in the presence of bands at 15291 cm-1 and 23697 cm1
. The first band is assigned to the 2B1g→2Eg and 2B1g→2A1g transitions, while the
second band is due to charge transfer [55].
The electronic spectra of Co (II) complex (Figure 49) showed two bands at 34965 cm–1, 25126 cm–1, which were assigned to charge transfer (CT) bands in the ligand. Moreover, an additional band at 18657 cm–1 was observed in the spectrum, which was assigned, 4A2g→4T1g(P) transition . Thus, Tetrahedral geometry was proposed for the cobalt complex [95].
Electronic spectra of Platinum (II) and Palladium complexes (Figure 51 and 52) shows two bands in range of 32000-34000 cm-1 and 25381 cm-1. The higher-energy band is an internal π→π* transition of the ligand, while the lower is assigned as a Pt, Pd →π* charge transfer [96]. Three d–d spin allowed singlet-singlet, and three spin forbidden singlet-triplet transitions are expected for square-planar complexes of palladium (II). However strong charge-transfer transitions may interfere and inhibit the observation of some of the predictable bands, which is in fact observed in the electronic absorption spectra of the metal complexes. The noticeable strong bands in the range 300- 400 nm are assigned to a combination of intra-ligand and LMCT absorptions and d–d bands. This supports the idea of a square-planar environment for the metal ions [97].
However, these proposed geometrical structures can be confirmed by magnetic susceptibility measurements that is shown in (Table 8) and discussed in section (3.1.11). 61
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
3.1.11 Magnetic Susceptibility Measurements
The effective magnetic moment, ( µeff ) can be obtained from the experimentally measured molar magnetic susceptibility ( χm ), and expressed in Bohr magnetons (µB).
Where
𝒆𝒉
𝟏µ𝑩 = 𝟒𝛑𝐦 = 𝟗. 𝟐𝟕 × 𝟏𝟎−𝟐𝟒 𝐉 𝐓 −𝟏 𝒆
The equation below gives the relationship between µeff and χm:
𝟑𝓚𝓧𝒎 𝑻
𝟏µ𝒆𝒇𝒇 = √𝑳 µ
𝟎 µ𝑩
Where
𝟐
k = Boltzmann constant; L = Avogadro number; µo = vacuum permeability; T = temperature in kelvin.
Magnetic susceptibility measurements continue to play an important role in the characterization and investigation of inorganic compounds, particularly transition metal complexes[98].
The measured Magnetic susceptibility data of prepared metal complexes are collected in (Table 8) and room temperature Magnetic susceptibility measurements were made on a Sherwood Magnetic Susceptibility Balance MSB-Auto. Diamagnetic corrections were carried out using Pascal’s Constant [99].
62
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
The measured magnetic susceptibility value of Cr(III) complex is 3.82 and Fe(III) complex is 5.62 which suggests octahedral arrangements around their ions as compared with the reported values in the literature review [90].
The magnetic momentum measurement indicate that high spin Co(II) complexes are (4.4-4.8 BM) with 3 unpaired electron which suggest a tetrahedral environment around the Cobalt ion. However, octahedral high spin Co (II) complexes, with three unpaired electrons by (4.8-5.2 BM) are the most common. In fact Co (II) has more known tetrahedral metal complexes than any other transition elements except for those with 0, 5 or 10 d electrons, because the octahedral stabilization energy is relatively small in the case of high spin d7 electrons [100]. Therefore, the measured magnetic susceptibility (µeff = 4.53 BM) suggest tetrahedral rearrangement for the Co (II) complex [10][100].
In the square planner geometry, magnetic moment value for Cu (II) complex is (1.2 B.M.) and lower than the expected (1.73 B.M.) value for unpaired electron. This low value may be due to strong interaction with the neighboring molecules [55].
Magnetic susceptibility measurements of Pd(II) and Pt(II) complexes advise square planner arrangements when display diamagnetic assignment [101].
63
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
Table 8: Magnetic Susceptibility and Uv-Vis Spectrum Data with Their Assignments of PSTMH2 and its Metal Complexes
PSTMH2
No.
140
Compounds
Band Absorptions nm cm-1 ε 272
C21H18N6S4O2 [Cr(PSTM)(H2O)2]H2O.Cl
141
[Fe(PSTM)(H2O)2]H2O.Cl
142
[Co(PSTM)]H2O
143
[Cu(PSTM)]H2O
144
[Pd(PSTM)]H2O
145
[Pt(PSTM)]3H2O
36765
1895
n→π
*
π→π
*
330
30303
400
300 438 642 310 406 552 286 398 536 298 422 654 298 394 308 394
33333 22831 15576 32258 24631 18116 34965 25126 18657 33557 23697 15291 33557 25381
1906 971 322 1863 1579 319 1780 1485 322 1775 1214 938 1675 1353 1764 1253
32468 25381
64
Assignment
C.T A2g(F)→4T1g(F) 4 A2g(F)→4T2g(F)
C.T T2g → 5Eg 6 A1g → 4T1g C.T C.T 6
A2g → T1g(P) 4
C.T B1g → 2Eg 2 B1g → 2A1g C.T Pd→π* C.T Pt→π* 2
Pract.
-
4
4
µeff (B.M) Theor.
-
3.82 Oh
3.87
5.62 Oh
5.92
4.53 T.h
3.87
1.2 Sq.p
1.73
0 Sq.pl 0 Sq.pl
0 0
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
2.0 272, 1.895
1.8 1.6 1.4
Abs.
1.2 1.0 0.8 0.6 0.4
330, 0.400
0.2 0.0 200
300
400
500
600
700
800
wavelength nm
Figure 46: UV-Vis Spectrum of PSTMH2 Ligand
2 300, 1.906 1.8 1.6 1.4
Abs.
1.2 1
438, 0.971
0.8
642, 0.322
0.6 0.4 0.2 0 200
300
400
500
wavelength nm
Figure 47: UV-Vis. Spectrum of [Cr(PSTM)(H2O)2]H2O.Cl
65
600
700
800
Chapter Three/Part One
2.0
Results and Discussion
PSTMH2 Ligand
310, 1.863
1.8 406, 1.579 1.6 1.4
Abs.
1.2 1.0 0.8 0.6 552, 0.319
0.4 0.2 0.0 200
300
400
500
600
700
800
wavelength nm
Figure 48: UV-Vis. Spectrum of [Fe(PSTM)(H2O)2]H2O.Cl
286, 1.78
2 1.8
398, 1.485
1.6 1.4
Abs.
1.2 1
0.8 0.6
536, 0.322
0.4 0.2 0 200
300
400
500
wavelength nm
Figure 49: UV-Vis. Spectrum of [Co(PSTM)]H2O
66
600
700
800
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
2.0 1.8
298, 1.775
1.6 1.4
Abs.
654, 0.938
422, 1.214
1.2 1.0 0.8 0.6 0.4 0.2 0.0 200
300
400
500
600
700
800
wavelength nm
Figure 50: UV-Vis. Spectrum of [Cu(PSTM)]H2O
2.0 298, 1.675
1.8 1.6
394, 1.353
1.4
Abs.
1.2 1.0 0.8 0.6 0.4 0.2 0.0 200
300
400
500
wavelength nm
Figure 51: UV-Vis. Spectrum of [Pd(PSTM)]H2O
67
600
700
800
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
2.0 308, 1.764
1.8 1.6 1.4
394, 1.253
Abs.
1.2 1.0 0.8 0.6 0.4 0.2 0.0 200
300
400
500
wavelength nm
600
700
800
Figure 52: UV-Vis. Spectrum of [Pt(PSTM)]3H2O
3.1.12 Thermal Gravimetric Analysis The thermal gravimetric analysis were used to investigate and determine water molecules by using of TGA instrument. The TGA curves were obtained at a heating rate of 20◦C/min. over the temperature range of r.t– 600◦C. The calculated and estimated mass losses with temperature ranges of all metal complexes are shown in (Table 9), and their TGA curves ordered in (Figures 53-58). The hydrated water molecules are related with metal complex formation and found outside of the inner coordination sphere that surrounded the central metal ion. The dehydration of this type of water normally takes place in 50-160oC temperature range. The coordinated water molecules are eliminated at higher temperature than the water molecules of hydration, which was usually eliminated at 150-250oC [102]. The dehydration step of all metal complexes were observed below 170oC. The weight 68
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
loss of Cr (III), Fe (III), Co (II), Cu (II), and Pd (II) complexes matched with one water molecule, whereas three hydrated water molecules were observed in the Pt (II) complex. The coordinated water molecules were found below 250oC. The weight loss of two coordinated water molecules were found for Cr (III), and Fe (III) complexes while no coordinated water molecule was observed for Co (II), Cu (II), Pd (II) and Pt (II) complexes.
Table 9: Weight Loss with Temperature Ranges of Water Molecules in PSTMH2 Metal Complexes TG Range oC
n
Mass Loss Calc. % (Est. %)
27.6-122.6
1h
2.75 ( 2.74 )
122.6-209.5
2c
8.26 ( 8.25 )
24.9-160.3
1h
2.67 ( 2.026 )
160.3-245.0
2c
8.00 ( 8.010 )
142 [Co(PSTM)(H2O)2]H2O
29.2-117.3
1h
2.877 ( 2.866 )
93.2
143 [Cu(PSTM)]H2O
28.4-170.5
1h
3.033 ( 3.026 )
86.02
144 [Pd(PSTM)]H2O
23.7-103.8
1h
2.828 ( 2.815 )
77.2
145 [Pt(PSTM)]3H2O
17.1-149.7
3h
7.095 ( 7.086 )
79.8
No. Compounds 140 [Cr(PSTM)(H2O)2]H2O.Cl
141 [Fe(PSTM)(H2O)2]H2O.Cl
n= no. of moles of water molecule
Total Mass Loss%
86.9
85.2
h, c = hydrated and Coordinated water molecule respectively
69
Chapter Three/Part One
0
100
Results and Discussion
200
300
PSTMH2 Ligand
400
500
600
400
500
600
0% 209.53244, -8.255%
-10% -20%
122.662704, -2.738%
Weight Loss
-30% -40% -50% -60% -70% -80% -90% -100%
Temp.oC
Figure 53: TGA Curve for [Cr(PSTM)(H2O)2]H2O.Cl
0
100
200
300
0% 245.069885, -8.010%
-10% -20% 160.329926, -2.026%
Weight Loss
-30% -40% -50% -60% -70% -80% -90%
Temp.oC
Figure 54: TGA Curve for [Fe(PSTM)(H2O)2]H2O.Cl
70
Chapter Three/Part One
0
Results and Discussion
100
200
300
PSTMH2 Ligand
400
500
600
0% -10% -20%
170.484741, -3.026%
Weight Loss
-30% -40% -50% -60% -70% -80% -90% -100%
Temp.oC
Figure 55: TGA Curve for [Cu(PSTM)]H2O
0
100
200
300
400
0% -10% -20%
122.227463, -3.059%
Weight Loss
-30% -40% -50% -60% -70% -80% -90% -100%
Temp.oC
Figure 56: TGA Curve for [Co(PSTM)]H2O
71
500
600
700
Chapter Three/Part One
0
Results and Discussion
100
200
300
PSTMH2 Ligand
400
500
600
400
500
600
0% -10% 103.865364, -2.815%
-20%
Weight Loss
-30% -40% -50% -60% -70% -80% -90%
Temp.oC
Figure 57: TGA Curve for [Pd(PSTM)]H2O
0
100
200
300
0% -10% -20%
149.653625, -7.086%
Weight Loss
-30% -40% -50% -60% -70% -80% -90%
Temp.oC
Figure 58: TGA Curve for [Pt(PSTM)]3H2O
72
Chapter Three/Part One
Results and Discussion
PSTMH2 Ligand
3.1.13 Proposed Structures of PSTMH2 Metal Complexes
Based on elemental data, magnetic moments, molar conductivity, thermal analysis and spectral studies (IR, UV-Vis) structural formula of the new metal complexes were proposed as in (Figure 60). The ligand acts as tetra dentate through the two nitrogen of the azomethine group, and two phenolic oxygen in an octahedral geometry for chromium, iron, and cobalt complexes and square planer geometry with copper, palladium and platinum complexes.
Figure 59: Proposed Structure for [Cr(PSTM)(H2O)2]H2O.Cl, [Fe(PSTM)(H2O)2]H2O.Cl, [Co(PSTM)]H2O, [Cu(PSTM)]H2O, [Pd(PSTM)]H2O and [Pt(PSTM)]3H2O Complexes
73
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
Part Two 3.2
Preparation of 2,5-bis(5-mercapto-1,3,4-thiadiazole-2-imino)hexane [BMTHH2] and its Metal Complexes.
Schiff bases derived from ketones offer more stability evidence to the ligand and their metal complexes. In this part we used a diketone compound instead of aldehydes compound in the preparation of second new Schiff base ligand (BMTHH2). This Schiff base compound was prepared from the reaction between hexane-2,5-dione and 5-amino-1,3,4-thiadiazole-2-thiol by using few drops of formic acid as a catalyst for increasing nucleaophilicity of the carbonyl group under reflux. Preparation of BMTHH2 was proceeded according to the following reaction.
Reaction 4: Preparation Reaction of BMTHH2 Ligand
74
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
3.2.1 Mass Spectroscopy of BMTHH2 Ligand The electronic impact mass spectrum of BMTHH2 ligand confirmed the proposed formula by showing a molecular ion peak at m/z = 344. This is by corresponding to the molecular weight of the Schiff base ligand and undergoing the nitrogen rule which show even molecular weight with the even number of nitrogen in the chemical formula (C10H12N6S4) of the ligand. Fragments of (186, 172, 158 and 144) molecular weight show loss of –CH2 group stepwise. It is also displayed a series of peak values shown in (Table 10) and the Mass spectrum shown in (Figure 61).
Table 10: Mass Spectroscopy Data of BMTHH2 Ligand MS (m/z)
Compound +
BMTHH2
344 [M] C10H12N6S4, 311 [C10H11N6S3+], 227 [C8H11N4S2+], 213 [C7H9N4S2+], 186 [C6H8N3S2+], 172 [C5H6N3S2+], 158 [C4H4N3S2+], 144 [C3H2N3S2+], 117 [C2HN2S2+]
3.2.2 Thin Layer Chromatography of BMTHH2 Ligand The Rf value of BMTHH2 ligand was shown in (Table 11)with a suitable solvent mixture. Table 11: Rf of BMTHH2 Ligand Compound BMTHH2
Solvent Ethanol:Hexane:Toluene(3:3:4)
75
Rf 0.71
Chapter Three/Part Two
Results and Discussion
Figure 60: Mass Fragmentation of BMTHH2 Ligand 76
BMTHH2 Ligand
41.3 46.3 52.3 58.3 64.2 69.3 76.2 81.3 86.3 93.3 98.3 103.3 108.4 113.3 119.3 124.4 129.3 137.3 142.4 147.3 152.3 157.4 162.4 167.4 172.4 177.4 182.4 187.3 192.4 198.4 204.4 212.3 217.4 222.4 227.5 232 237.5 242.5 247.4 251.5 256.6 261.4 266.4 271.4 276.5 281.5 286.7 292.9 297.6 304.4 309.5 314.3 319.6 325.4 328.5 333.4 337.6 342.6
Abundance
Chapter Three/Part Two
400
Results and Discussion
200
100 186
m/z
Figure 61: Mass Spectrum of BMTHH2 Ligand 77
BMTHH2 Ligand
900
800
700
600
500 213
117
300 172
143 158 227
311 344
0
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
3.2.3 Preparation and Characterization of [BMTHH2] Metal complexes of Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II), and Pt(II)
All prepared metal complexes of [BMTHH2] were obtained by the reaction of [BMTHH2] with metal chloride salts of Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II), and Pt(II) in methanol solvent containing few drops of Triethylamine. The prepared metal complexes were characterized by elemental analysis, conductivity measurement, infrared spectroscopy, UV-visible and emission spectroscopy, magnetic susceptibility measurement and thermal gravimetric analysis.
No.
Table 12: Physical Properties and Elemental Analysis of BMTHH2 and its Metal Complexes Compounds
Color M.P C o
Ʌm
BMTHH2
C10H12N6S4
Bulbar
212-213
32.112 (34.86)
3.102 (3.51)
21.469 (24.39)
35.221 (37.23)
--
12.70
146
[Co2(BMTH)(H2O)4]2Cl.H2O
Green
290d
18.304 (19.91)
2.881 (3.01)
13.011 (13.93)
20.214 (21.26)
17.02 (19.54)
53.55
147
[Cu(BMTH)]H2O
Pale Green
267-269
29.602 (28.32)
2.595 (2.85)
19.014 (19.82)
29.628 (30.25)
13.25 (14.99)
14.45
148
[Zn(BMTH)]H2O
WhiteGray
~290d
27.121 (28.20)
3.001 (2.84)
18.035 (19.73)
29.496 (30.12)
13.19 (15.35)
13.37
149
[Cd(BMTH)]H2O
WhiteGray
228-230
25.012 (25.40)
2.508 (2.56)
16.900 (17.77)
26.61 (27.12)
22.41 (23.77)
19.06
150
[Hg(BMTH)]H2O
Brown
~200d
21.638 (21.41)
2.186 (2.16)
13.723 (14.98)
21.532 (22.86)
-(35.75)
13.33
151
Metal
(Ω-1.cm2.mol-1)
[Pd(BMTH)]H2O
Light Brown
330d
24.181 (25.72)
2.402 (2.59)
17.576 (18.00)
26.207 (27.47)
-(22.79)
5.88
152
C
% Found Calculated H N S
[Pt(BMTH)]2H2O
Brown
~150d
20.786 (20.94)
2.415 (2.46)
13.633 (14.65)
23.322 (22.36)
-(34.01)
7.07
78
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
3.2.4 Conductivity Measurements Molar conductance values of BMTHH2 metal complexes displayed in (Table 12) suggest that all metal complexes are non-electrolytes except Co (II) complex which display (1:2) ionic complex.
3.2.5 Infrared Spectra In the present work the infrared spectra of the ligand and metal complexes were measured in the (400-4000) cm-1 range using potassium bromide discs. For all metal complexes in (200-400) cm-1 range, Cesium Iodide was used. The important IR bands of ligand and their metal complexes along with their assignments are given in (Table 13). The infrared spectra of the ligand (BMTHH2) with their metal complexes are shown in (Figures 63-70).
The structure of the formed (BMTHH2) ligand was identified by recording melting point and IR spectrum. The IR spectrum of this ligand (Figure 63) showed disappearance of the absorption bands for NH2 stretching at 3340 and 3252 cm-1 which appeared in the IR spectrum of 5-amino-1,3,4-thiadiazole-2-thiol and appearing stretching band of C-H of the –CH2 and CH3 in the range of (2700-2900 cm-1)[85]. These are confirming the formation of the ligand Schiff base.
79
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
The infrared spectral data were discussed according to the functional groups present in the metal complexes as the followings:
υ S-H and C-S In the infrared spectrum of BMTHH2 ligand (Figure 63), the absorption bands for free S-H and C-S group were appeared around 2608 cm-1 and 714 cm-1 respectively [86][85][103][104][37][61]. The band of S-H group in the infrared spectra of all metal complexes was disappeared (Figure 62-68), and the band of ν C-S shifted from 714 cm-1 to lower frequency for all Co(II), Cu(II), Zn(II), Cd(II), Hg(II), Pd(II), Pt(II) complexes at (705, 697, 679, 695, 670, 680, 679 cm-1 respectively). This observed shifting was attributed to the coordination of S- atoms with central metal ions.
υ C=N The IR spectrum of free ligand (BMTHH2) (Figure 63) displayed bands in the region 1653 cm-1 and 1538 cm-1. This is corresponding to the presence of the C=N stretching of the azomethine group and C=N endocyclic of thiadiazole ring respectively[55][56]. On all metal complex formations, the band of C=N of azomethine groups in the IR spectra of metal complexes (Figure 64-70) shifts to lower frequency while endocyclic C=N remains in the same region without significant changes. This suggests that the coordination takes place through nitrogen atoms of azomethine group.
υ O-H In the IR spectra of all metal complexes (Figure 64-70) strong broad bands exhibit in the region of (3413-3446 cm-1) due to ν O-H of the lattice or coordinated water 80
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
molecules which is confirmed by thermal gravimetric analysis and elemental analysis. It must be notified that the Ligand (BMTHH2) is slightly hygroscopic. It must be dried to take IR spectrum to prevent the peak of water molecule.
3.2.6 The Far Infrared (650-200 Cm-1) Region The Far Infrared Spectra of all metal complexes shown in (Figures 71 & 72). Also, their data peaks are listed in (Table 13).
υ (M-N) In the Far-IR spectra of metal complexes (Figure 71 and 72), M-N band of the azomethine group was observed at 470 cm-1 for (Co-N), 466 cm-1 for (Cu-N), 474 cm-1 for (Zn-N), 465 cm-1 for (Cd-N), 470 cm-1 for (Hg-N), 468 cm-1 for (Pd-N), and 463 cm-1 for (Pt-N). The presence of the M-N band is another indication for azomethine Nitrogen involving in the coordination sphere [89].
υ (M-O) The IR spectrum of Co(II) complex (Figure 71A) alone show a band of metal oxygen of coordinated water molecule at 524 cm-1, which is not present in the Far-IR spectra of other BMTHH2 metal complexes (Figure 71 and 72) [89][90].
81
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
ν (M-S) Coordination of the central metal to sulfur atoms of the ligand thiol group can be assigned by the presence of M-S band in the Far-IR spectra of all BMTHH2 metal complexes (Figure 71 and 72) which is observed around 395-399 cm-1[105]
82
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
Table 13: Data of Major IR Bands of BMTHH2 and its Metal Complexes in cm-1 No.
Compounds
S-H
O-H
C-S
(H2O) BMTHH2
C10H12N6S4
C=N azomethine
C=N endocyclic
M-O
M-N
M-S
2608
-
714
1653
1538
-
-
-
146
[Co2(BMTH)(H2O)4]2Cl
-
3444
705
1623
1537
524
470
397
147
[Cu(BMTH)]H2O
-
3445
697
1625
1536
-
466
397
148
[Zn(BMTH)]H2O
-
3445
679
1637
1536
-
474
399
149
[Cd(BMTH)]H2O
-
3420
695
1633
1536
-
465
395
150
[Hg(BMTH)]H2O
-
3446
670
1623
1535
-
470
397
151
[Pd(BMTH)]H2O
-
3436
680
1608
1539
-
468
399
152
[Pt(BMTH)]2H2O
-
3413
714
1603
1540
-
463
390
82
Chapter Three/Part Two
Results and Discussion
Figure 62: FTIR Spectrum for 5-amino-1,3,4-thiadiazole-2-thiol 83
BMTHH2 Ligand
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
80
2969 70
667
2608 1653
60
2755
2852
50
760 2897
1219 740 40 1335
1374 30 1538 20 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 63: FTIR Spectrum of BMTHH2 Ligand 84
1600
1200
800
400
T%
714
1438
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
82
80
2855 705 78
2925 761
3444
76
781 1440 74
72
1313
1537
70 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 64: FTIR Spectrum of [Co2(BMTH)(H2O)4]2Cl 85
1600
1200
800
400
T%
1623
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
80
2857 697
78
2919 1625
76
74
3445
72
1321 1440
70
68
1536 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 65: FTIR Spectrum of [Cu(BMTH)]H2O 86
66 1600
1200
800
400
T%
772
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
85
80
679 2858 2920
75
1637
70
776
1437
65
60
1321 1536
55 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 66: FTIR Spectrum of [Zn(BMTH)]H2O 87
1600
1200
800
400
T%
761 3445
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
85
80
2854
695
2922
1633
1302
T%
75
767
1536 70
1437
3420
65
60 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 67: FTIR Spectrum of [Cd(BMTH)]H2O 88
1600
1200
800
400
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
82 81 80
670 79
751 2855
77
2925
1623 76
75
1535
74
1315 1439
3446
73
1495 72 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 68: FTIR Spectrum of [Hg(BMTH)]H2O 89
1600
1200
800
400
T%
78
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
93.8
92.8
91.8
680 90.8
1608 2853
89.8
T%
780
1322
1491
88.8
1440
2922 3436
87.8
86.8
85.8
1539 84.8 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 69: FTIR Spectrum of [Pd(BMTH)]H2O 90
1600
1200
800
400
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
93.1
92.1
91.1
679 2855
90.1 777
1603
2925
89.1
88.1
1438
1323 87.1
86.1
1540 85.1 4000
3600
3200
2800
2400
2000
Frequency cm-1
Figure 70: FTIR Spectrum of [Pt(BMTH)]2H2O 91
1600
1200
800
400
T%
3413
Chapter Three/Part Two
Results and Discussion
Figure 71: Far-IR Spectra of A=Co(II), B=Cu(II), C=Zn(II) Complexes with BMTHH2 Ligand 92
BMTHH2 Ligand
Chapter Three/Part Two
Results and Discussion
Figure 72: Far-IR Spectra of D=Cd(II), E=Hg(II), F=Pd(II), G=Pt(II) Complexes with BMTHH2 Ligand 93
BMTHH2 Ligand
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
3.2.7 Electronic Spectra Measurements
The Uv-Vis. Spectra of BMTHH2 ligand and their metal complexes showed in (Figures 73-80). Also, their data peak labels listed in (Table 14). In the spectrum of the ligand (BMTHH2) (Figure73), the bands 26178 cm-1 is assigned to the n→π∗ transitions of the azomethine group and thiadiazole ring. During the formation of metal complexes, this band is shifted to a lower wavelength, suggesting that the nitrogen atoms of the azomethine group are coordinated to the metal ion. The value of 31056 cm-1 is attributed to the π → π∗ transition of the aromatic and thiadiazole ring [57]. The electronic spectra of metal complexes (Figure 74-80) exhibit bands around 30000-35000 cm-1 indicating intra-ligand charge transitions [63]. The electronic spectrum of the Co (II) complex (Figure 74) exhibits two bands at 33113 cm-1 and 26316 cm-1 which are characteristic to intra-ligand charge transition. It also exhibits another three bands in the range of 19500-14000 cm-1 which can be assigned to 4A2g→4T1g(P) transitions, supporting a tetrahedral geometry of binuclear Co(II) complex[106]. The Cu (II) complex absorption spectrum (Figure 75) shows two bands at 32051 cm-1 that indicates the intra-ligand charge transitions, and another band at 26178 cm1
attributed to S-Cu (II) transition. Square-planar geometry is suggested for Cu (II)
complex in the presence of bands at 16026 cm-1 and 26178 cm-1. The first band is assigned to the 2B1g→2Eg and 2B1g→2A1g transitions, while the second band is due to charge transfer [55].
94
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
The electronic spectra of Cd (II), Hg (II), Zn (II) complexes (Figure 76-78) exhibited bands that were associated to the ligand (π-π*), (n-π*) transitions. This appeared at (33000-36000 cm–1) and (25000-27000 cm-1) respectively. The additional band was observed at (25641 cm-1) which could be assigned to the CT transition. No ligand to metal transitions were observed because of filled d–orbital. Since the d10 configuration afforded no crystal field stabilization, the stereochemistry depended on size and polarizing power of the MII cation, and the steric requirement of the ligand [107][108][109]. Platinum (II) and Palladium (II) complexes (Figure 79 and 80) have two bands in range of 30000-32000 cm-1 and 23000-26000 cm-1. The higher-energy band is an internal π→π* transition of the ligand, whereas the lower is allocated as a Pt, Pd →π* charge transfer [96]. Three d–d spin allowed singlet-singlet. Also three spin forbidden singlet-triplet transitions are predictable for square-planar complexes of palladium (II). However, strong charge-transfer transitions may interfere and inhibit the observation of some of the predictable bands. This fact was observed in the electronic absorption spectra of our prepared complexes [97].
3.2.8 Magnetic Susceptibility Measurements The molar magnetic susceptibility χm which characterizes the extent of paramagnetism of the metal complexes were measured in order to determine the spin properties of the metal complexes. The metal complex can either high spin state or exist at low spin metal complex. The measurement of magnetic susceptibility is important to identify the number of unpaired electrons and in turn to determines their geometrical structure [10].
95
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
In the square planner geometry, magnetic moment value for Cu (II) complex shows diamagnetic susceptibility [55].
The measured magnetic susceptibility of Co (II) complex is (4.61 BM) which suggests a tetrahedral geometry around the cobalt ion[100]. The magnetic moments of the Zn (II), Cd (II), Hg (II), Pd (II), Pt (II) complexes were found to be zero. Thus, they are suggested to possess a square-planar geometry in the metal complexes [101][109].
Compounds
Band Absorptions Assignment nm cm-1 ε 322
31056
1650
n→π*
C10H12N6S4
[Co2(BMTH)(H2O)4]Cl2
[Cu(BMTH)]H2O
149
[Cd(BMTH)]H2O
150
[Hg(BMTH)]H2O
151
[Zn(BMTH)]H2O
[Pd(BMTH)]H2O
152
148
147
146
BMTHH2
No.
Table 14: Magnetic Susceptibility and Uv-Vis Spectrum Data with Their Assignments of BMTHH2 and its Metal Complexes
[Pt(BMTH)]2H2O
382
26178
1421
π→π
302 380 516 610 690 312 382
33113 26316 19380 16393 14493 32051 26178
1995 1779 362 511 911 1680 1471
C.T C.T
624
16026
320
324 430 290 374 300 386 314 424 324 398
30864 23256 34483 26738 33333 25907 31847 23585 30864 25126
1857 2304 1676 1439 1765 1368 1776 1883 1780 1668
96
µeff (B.M) Pract.
-
Theor.
-
*
4
A2→4T1(P)
C.T C.T 2 B1g→2Eg 2 B1g→2A1g C.T C.T C.T C.T Pd→π* C.T Pt→π*
4.61 T.h
3.87
Dia Sq.pl
1.03
Dia Sq.pl Dia Sq.pl Dia Sq.pl
0 0 0
Dia Sq.pl
0
Dia Sq.pl
0
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
2
322, 1.65
1.8
382, 1.421
1.6 1.4
Abs.
1.2 1 0.8 0.6 0.4 0.2 0 200
300
400
500
600
700
800
wavelength nm
Figure 73: Uv-vis. Spectrum of BMTHH2 Ligand
2.500
302, 1.995 380, 1.779
2.000
Abs.
1.500 690, 0.911 1.000
610, 0.511 516, 0.362
0.500
0.000 200
300
400
500
wavelength nm
Figure 74: Uv-vis. Spectrum of [Co2(BMTH)(H2O)4]2Cl
97
600
700
800
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
2 312, 1.68
1.8 1.6
382, 1.471
1.4
Abs.
1.2 1 0.8 0.6
624, 0.320
0.4 0.2 0 200
300
400
500
600
700
800
600
700
800
wavelength nm
Figure 75: Uv-vis. Spectrum of [Cu(BMTH)]H2O
1.8
280, 1.705 378, 1.479
1.6 1.4 1.2
Abs.
1 0.8 0.6 0.4 0.2 0 200 -0.2
300
400
500
wavelength nm
Figure 76: Uv-vis. Spectrum of [Zn(BMTH)]H2O
98
Chapter Three/Part Two
1.8
Results and Discussion
BMTHH2 Ligand
290, 1.676
1.6 374, 1.439 1.4
Abs.
1.2 1 0.8 0.6 0.4 0.2 0 200
300
400
500
600
700
800
600
700
800
wavelength nm
Figure 77: Uv-vis. Spectrum of [Cd(BMTH)]H2O
2
300, 1.765
1.8 1.6
386, 1.368
1.4
Abs.
1.2 1 0.8 0.6 0.4 0.2 0 200
300
400
500
wavelength nm
Figure 78: Uv-vis. Spectrum of [Hg(BMTH)]H2O
99
Chapter Three/Part Two
2
Results and Discussion
BMTHH2 Ligand
424, 1.883
314, 1.776
1.8 1.6 1.4
Abs.
1.2 1 0.8 0.6 0.4 0.2 0 200
300
400
500
600
700
800
600
700
800
wavelength nm
Figure 79: Uv-vis. Spectrum of [Pd(BMTH)]H2O
2
324, 1.78
1.8
398, 1.668
1.6 1.4
Abs.
1.2 1 0.8 0.6 0.4 0.2 0 200
300
400
500
wavelength nm
Figure 80: Uv-vis. Spectrum of [Pt(BMTH)]2H2O
100
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
3.2.9 Thermal Gravimetric Analysis The weight loss in TGA curve of metal complexes are shown in (Figures 81-87) and their values tabulated in (Table 15) shows one hydrated water molecule for Cu (II), Zn (II), Cd (II), Hg (II), Pd (II) complexes, two hydrated water molecule for Pt (II) complex and four coordinated water molecules for Co (II). The hydrated and coordinated water molecules were observed below 164 and 274oC respectively. Table 15: Weight Loss with Temperature Range of Water Molecules in PBIPH2 Metal Complexes No. Compounds
TG Range oC
n
146 [Co2(BMTH)(H2O)4]2Cl
18.90-273.02
4c
11.934 ( 11.939 )
85.96
147 [Cu(BMTH)]H2O
23.17-137.07
1h
4.244 ( 4.245 )
77.31
148 [Zn(BMTH)]H2O
24.13-159.30
1h
4.226 ( 4.230 )
78.14
149 [Cd(BMTH)]H2O
23.81-154.90
1h
3.806 ( 3.812 )
44.99
150 [Hg(BMTH)]H2O
17.85-169.76
1h
3.208 ( 3.212 )
89.51
151 [Pd(BMTH)]H2O
25.60-153.75
1h
3.855 ( 3.863 )
79.86
152 [Pt(BMTH)]2H2O
17.92-163.52
2h
6.276 ( 6.242 )
80.04
n= no. of moles of water molecule
Mass Loss Calc. % (Est. %)
Total Mass Loss%
h = hydrated and Coordinated water molecule.
101
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
Temp.oC 0
100
200
300
400
500
600
0% -10% -20% 273.028809, -11.939%
% wt.Loss
-30% -40% -50% -60% -70% -80% -90% -100%
Figure 81: TGA Curve of [Co2(BMTH)(H2O)4]2Cl
Temp.oC 0
100
200
300
400
0% -10% -20%
137.072174, -4.245%
% wt. Loss
-30% -40% -50% -60% -70% -80% -90%
Figure 82: TGA Curve of [Cu(BMTH)]H2O
102
500
600
700
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
Temp.oC 0
100
200
300
400
500
600
700
400
500
600
700
0% -10% -20%
159.303833, -4.230%
% wt. Loss
-30% -40% -50% -60% -70% -80% -90%
Figure 83: TGA Curve of [Zn(BMTH)]H2O
Temp.oC 0
100
200
300
0% -5% -10%
154.902695, -3.812%
% wt. Loss
-15% -20% -25% -30% -35% -40% -45% -50%
Figure 84: TGA Curve of [Cd(BMTH)]H2O
103
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
Temp.oC 0
100
200
300
400
500
600
700
0% -10%
169.765045, -3.212%
-20%
% wt. Loss
-30% -40% -50% -60% -70% -80% -90% -100%
Figure 85: TGA Curve of [Hg(BMTH)]H2O
Temp.oC 0
100
200
300
400
0% -10% -20%
153.756805, -3.864%
% wt. Loss
-30% -40% -50% -60% -70% -80% -90%
Figure 86: TGA Curve of [Pd(BMTH)]H2O
104
500
600
700
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
Temp.oC 0 0%
100
200
300
400
162.858078, -6.242%
-10% -20%
% wt. Loss
-30% -40% -50% -60% -70% -80% -90%
Figure 87: TGA Curve of [Pt(BMTH)]2H2O
105
500
600
700
Chapter Three/Part Two
Results and Discussion
BMTHH2 Ligand
3.2.10 Proposed Structures for BMTHH2 Ligand Metal Complexes
The Proposed Structures for (BMTHH2) metal complexes was drawn based on elemental data, magnetic moments, molar conductivity, thermal analysis and spectral studies (IR, UV-Vis). The proposed structures of the new metal complexes were shown in (Figure 88). The ligand acts as a tetra dentate and coordinated to the metal ions through the two nitrogen atoms of the Azomethine groups, and two sulfur atoms of thiol groups in a tetrahedral geometry for Cobalt and Copper complexes, and in a square planar geometry for Zinc, Mercuric, Cadmium, Palladium and Platinum complexes.
Figure 88: Proposed Structures for [Co2(BMTH)(H2O)4]2Cl, [Cu(BMTH)]H2O, [Zn(BMTH)]H2O, [Cd(BMTH)]H2O, [Hg(BMTH)]H2O and [Pd(BMTH)]H2O and [Pt(BMTH)]2H2O complexes
106
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
Part Three
3.3 Preparation of N,N-1,4-PhenyleneBis(2-(Iminomethyl)Phenol) [PBIPH2] and its Metal Complexes
In the reported studies the Schiff base derived from P-phenylenediamine. (PBIPH2) were prepared according to the classical methods by using solvents under several hours of reflux or stirring [67][110]. In the present work, the Schiff base (PBIPH2) was prepared in one minute using a fast, low cost, solventless, and environmental friendly method. This Schiff base (PBIPH2) compound was prepared from the reaction between Salicylaldehyde and P-phenylenediamine by using few drops of formic acid as a catalyst for increasing nucleaophilicity of the Salicylaldehyde carbonyl group according to the following reaction:
Reaction 5: Preparation Reaction of PBIPH2 Ligand in New Method
107
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3.3.1 Preparation and Characterization of [PBIPH2] Metal Complexes of Mn (II), Fe(III), Cu(II), Co (II), Zn(II), Pd(II), and Pt(II).
All prepared metal complexes of [PBIPH2] were obtained by the reaction of [PBIPH2] with metal chloride salts of Mn (II), Fe (III), Cu (II), Co (II), Zn (II), Pd (II), and Pt (II) in THF solvent containing few drops of triethylamine. The prepared metal complexes were characterized by elemental analysis, conductivity measurement, infrared spectroscopy, UV-visible and Emission spectroscopy, magnetic susceptibility measurement and thermal gravimetric analysis.
Ʌm
PBIP
C20H16N2O2
Orange
213-215
75.130 (75.93)
4.909 (5.10)
8.142 (8.86)
--
6.75
153
[Mn(PBIP)(H2O)2]H2O
Dark brown
>385
55.915 (56.70)
4.921 (4.76)
5.905 (6.62)
10.33 (12.92)
19.34
154
[Fe(PBIP)(H2O)3Cl]H2O
Brown
>380
50.772 (50.29)
4.770 (4.64)
5.539 (5.86)
10.74 (11.69)
11.52
155
Metal
(Ω-1.cm2.mol-1)
[Cu2(PBIP)(H2O)4]Cl.H2O
Black
>385
45.769 (46.87)
4.372 (4.13)
4.713 (5.47)
21.85 (24.8)
39.35
156
C
% Found Calculated H N
[Co2(PBIP)(H2O)2Cl2]H2O
Reddish brown
>385
42.211 (43.11)
3.504 (3.62)
4.895 (5.03)
19.26 (21.13)
14.75
157
M.P o C
[Zn(PBIP)]H2O
Orange
310d
58.764 (60.40)
4.108 (4.05)
6.037 (7.04)
16.01 (16.44)
17.46
158
Compounds
Color
Na2[Pd2(PBIP)Cl4]2H2O
Brown
>380
30.775 (31.99)
2.354 (2.42)
3.347 (3.73)
-(28.34)
57.47
159
No.
Table 16: Physical Properties and Elemental Analysis of PBIPH2 and its Metal Complexes
[Pt2(PBIP)(H2O)2Cl2]2H2O
Dark brown
280d
29.272 (28.34)
2.294 (2.62)
3.196 (3.31)
-(46.04)
10.03
108
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3.3.2 Conductivity Measurements Molar conductance data values of PBIPH2 metal complexes listed in (Table 16) suggest that metal complexes of (153, 154, 156, 157, 159) are non-electrolytes whereas 155 and 158 are 1:2 electrolytic solution in DMSO.
3.3.3 Infrared Spectra In the present work the infrared spectra of the ligand and metal complexes were recorded in both (400-4000) cm-1 range using potassium bromide discs and (200400) cm-1 range using Cesium iodide discs. The main IR bands of ligand and their metal complexes along with their assignments are given in (Table 17). The infrared spectra of the ligand (PBIPH2) with their metal complexes are shown in (Figures 8996). The formation of (PBIPH2) ligand was identified by the presence of the azomethine (CH=N) stretching band at (1610 cm-1) which not present in ( Para phenylenediamine) starting material structure. This was combined with the absence of the NH2 stretching band in the IR spectrum of the ligand (Figure 89). In addition, another evidence about the correct structure of the ligand (PBIPH2) was obtained through detection of a broad band at (3429 cm-1) for OH of the phenolic group and the appearance of a band at (2853 cm-1) which is characteristic for C-H stretching of the imine group. In addition, a strong absorption band at 755 cm-1 (750 in IR Spectrum of PBIPH2 ),(without the accompanying strong band at 700 cm-1) indicates o-disubstitution on the phenyl nucleus of the phenolic moiety[86]. Finally, another stretching bands were observed at (1282 cm-1) which are assigned to stretching of C-O bond of the phenolic hydroxyl group.
109
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
The infrared spectral data of the free ligand and their metal complexes were compared according to their functional groups as follow:
ν O-H and C-O The infrared spectrum of ligand (PBIPH2) (Figure 89) showed a broad band in the region 3429 cm-1, which is attributed to stretching vibration of phenolic O-H group of the ligand and a band at 1281 cm-1 is attributed to ν C-O of C-O-H group[87]. In the IR spectra of metal complexes (Figure 90-96) the characteristic bands of ν C-O are shifted to a lower frequency in complexes of Mn (II),Fe (III), Co (II), Cu (II), Zn (II), Pd (II), Pt (II) (1251, 1264, 1179, 1230, 1239, 1273, 1240 cm-1 respectively. This shows the bonding of phenolic oxygen atoms to the metal centers via deprotonation. So, the band of hydroxyl group must disappear while the infrared spectra of all prepared metal complexes shows a strong broad band in the range of (3411-3446 cm-1). The essential features of this band suggest it to be lattice or coordinated water molecules which is confirmed by thermal gravimetric analysis and elemental analysis of all metal complexes.
ν C=N The infrared spectrum of the free ligand (PBIPH2) (Figure 89) shows a strong band at 1610 cm-1, due to C=N stretching of the azomethine group [88]. This band was shifted to a lower frequency in the infrared spectra of all metal complexes except Zn(II) and Fe(III) complexes (Figure 90-96). The C=N vibrational frequency of Zn(II) complex was shifted to a higher frequency, whereas in the Fe(III) complex no shifts was observed. The bands for ( Mn (II), Co (II), Cu (II), Pd (II), Pt (II) com-
110
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
plexes were shifted by (11-24 cm-1) at ( 1599, 1595, 1598, 1586, 1593 cm-1 respectively), and it was shifted by (23 cm-1) at (1633 cm-1) for Zn (II) complex [9]. This shifting indicates the involvement of nitrogen atom of azomethine group in coordination with the central metal ion. This involvement of azomethine nitrogen atoms in coordination was not observed with Fe(III) complex.
3.3.4 The Far Infrared (650-200 Cm-1) Region The Far Infrared Spectra of all metal complexes shown in (Figures 97 & 98) and their data peak labels are listed in (Error! Reference source not found.). Bands in this part of he spectra of compounds containing only carbon, hydrogen, nitrogen, and oxygen atoms are usually due to bending and stretching of weak bonds. Also, they are not localized in small groups. The values of the region for structural diagnosis is, therefore, severely limited. When heavier atoms are present, localized vibrations including them may, however, fall in this region. Most of the bands related with metalmetal and metal-non-metal bonds fall in this region, with obvious applications to metal-organic Chemistry [86].
ν (M-N) In the Far-IR spectra of metal complexes (Figure 97 and 98), the peak of bond formation of metal with nitrogen atoms of the azomethine groups were observed at 466, 460, 484, 478, 451, and 457 cm-1 for (Mn-N), (Cu-N), (Co-N), (Zn-N), (Pd-N), and (Pt-N) respectively [89][75].
111
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
ν (M-O) From the Far-IR Spectra of metal complexes (Figure 97 and 98) in the closely FarIR range the absorption peak of metals with the Oxygen atoms of the Phenolic groups or water molecules were observed at 524, 524, 545, 532, (524,578), 563, and (509,574) cm-1 corresponding to the (Mn-O), (Fe-O), (Cu-O), (Co-O), (Zn-O), (PdO), and (Pt-O) respectively [89][90][75] ν (M-Cl) In the Far-IR spectra of metal complexes (Figure 97 and 98), the peak of M-Cl bond formation is detectable at 362, 347, 324 and 341 cm-1 for (Fe-Cl), , (Co-Cl), (Pd-Cl), and (Pt-Cl) respectively [111]. All the previous IR band spectra indicate the coordination of the central metal ions to (O,N and Cl) in the prepared metal complexes. Table 17: Data of Major IR Spectrum Bands for PBIPH2 and its Metal Complexes in cm-1 No.
Compounds
O-H
O-H
C-O
C=N
M-O
M-N
M-Cl
(H2O) PBIPH2
C20H16N2O2
3429
-
1281
1610
-
-
-
153
[Mn(PBIP)(H2O)2]H2O
-
3422
1251
1599
524
466
-
154
[Fe(PBIP)(H2O)3Cl]H2O
-
3430
1264
1611
524
451
362
155
[Cu2(PBIP)(H2O)4]Cl.H2O
-
3446
1179
1598
545
460
-
156
[Co2(PBIP)(H2O)2Cl2]H2O
-
3445
1230
1595
532
484
347
157
[Zn(PBIP)]H2O
-
3438
1239
1633
478
-
158
Na2[Pd2(PBIP)Cl4]2H2O
-
3436
1273
1586
451
324
159
[Pt2(PBIP)(H2O)2Cl2]2H2O
-
3411
1240
1593
457
341
112
524 578 563 509 574
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
87 85
2853
3052
83
2927 81
3429
77
1281
75
750
73
1571
71 69
1610 4000
3600
3200
2800
2400
2000
cm-1
Figure 89: FTIR Spectrum of PBIPH2 Ligand 113
67 1600
1200
800
400
T%
79
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
82.2
2853 3052
80.2
2925
78.2
757
1251
76.2
74.2
72.2
1599 70.2 4000
3600
3200
2800
2400
2000
cm-1
Figure 90: FTIR Spectrum of [Mn(PBIP)(H2O)2]H2O
114
1600
1200
800
400
T%
3422
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
83.2
82.2
3055 2854
81.2
2925
1264
80.2
T%
750
79.2
1572
78.2
3430 77.2
1611 76.2 4000
3600
3200
2800
2400
2000
cm-1
Figure 91: FTIR Spectrum of [Fe(PBIP)(H2O)3Cl]H2O 115
1600
1200
800
400
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
82
81
2857 80
3013
T%
754
2928
79
1179 78
3446
1595 77
76 4000
3600
3200
2800
2400
2000
cm-1
Figure 92: FTIR Spectrum of [Co2(PBIP)(H2O)2Cl2]H2O 116
1600
1200
800
400
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
76
759
74
2855 1230
3079
72
70
68
1598 66
64
3445 62 4000
3600
3200
2800
2400
2000
cm-1
Figure 93: FTIR Spectrum of [Cu2(PBIP)(H2O)4]Cl.H2O
117
1600
1200
800
400
T%
2926
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
83 82
2854
81
2927
80
3054
772
78
1239
3438
77 76 75 74
1633 73 4000
3600
3200
2800
2400
2000
cm-1
Figure 94: FTIR Spectrum of [Zn(PBIP)]H2O 118
1600
1200
800
400
T%
79
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
87 86 85
1273 2854
84
765
2925
82 81
3436 80 79
1586
78 77
4000
3600
3200
2800
2400
2000
cm-1
Figure 95: FTIR Spectrum of Na2[Pd2(PBIP)Cl4]2H2O 119
1600
1200
800
400
T%
83
3035
Chapter Three/Part Three
Results and Discussion
PBIPH2 Ligand
93
91
2855
89
763
2925
87
1240
85
3411 83
1593
81 4000
3600
3200
2800
2400
2000
cm-1
Figure 96: FTIR Spectrum of [Pt2(PBIP)(H2O)2Cl2]2H2O 120
1600
1200
800
400
T%
3027
Chapter Three/Part Three
Results and Discussion
Figure 97: Far-IR Spectrum of A=Mn(II), B=Fe(III), C=Co(III) Complexes with PBIPH2 Ligand 121
PBIPH2 Ligand
Chapter Three/Part Three
Results and Discussion
Figure 98: Far-IR Spectrum of D=Cu(II), E=Zn(II), F=Pd(II), G=Pt(II) Complexes with PBIPH2 Ligand 122
PBIPH2 Ligand
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3.3.5 Electronic Spectra Measurements The UV-Vis spectra of the ligand and the metal complexes were recorded in the DMSO solution in the wavelength range from 200 to 800 nm which correspond to 50000-12500 cm-1 at ~10-3 concentration. The maxima of bands of absorption spectra and their assignments are collected in (Table 18), and all UVVis. Spectra Shown in (Figure 99-106). The absorption spectrum of the free ligand (Figure 99) shows absorption peaks at 31447 cm-1 and 23256 cm-1, assigned to π→π* and n→π* transitions respectively for the phenolic-OH and azomethine moieties[92]. The values shifted slightly to a longer wavelength indicating the involvement of phenolic-OH and azomethine moieties in metal complexation. The electronic spectra of metal complexes exhibit bands around 30800-33800 cm-1 indicating intra-ligand charge transitions [63]. The electronic spectrum of Mn (II) complex (Figure 100) show three bands at 17361 cm-1, 22222 cm-1, and 30864 cm-1 which attributed to the 6A1g→4T1g (4G), 6
A1g→4E2g (4G), 4A1g (4G) and 6A1g→4E2g (4D) electronic transitions respectively.
This suggests octahedral geometry around Mn (II) ion [112]. In the spectrum of Fe(III) complex (Figure 101), it can be seen that it exhibits two bands at 19157 cm-1 and 21008 cm-1 which can be assigned to the 6A1g → 4
T1g and 6T2g→5Eg transitions of octahedral structure [78][93]. The electronic spectrum of Co(II) complex (Figure 102) showed two bands at
31447 cm-1, 21368 cm–1, which were assigned to charge transfer (CT) bands in
123
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
the ligand. Moreover, an additional band at 18315 cm–1 was observed in the spectrum, which was assigned to 4A2g → 4T1g(P) transition. Thus, tetrahedral geometry was proposed for the cobalt complex[95]. In the electronic spectrum of Cu (II) Complex, the bands at 31446 cm-1 and 21186 cm-1 were observed. These are assignments to the intra-ligand and ligand to metal charge transitions respectively. Also, a broad band was observed at 16611 cm-1 elongated to a lower energy attribute to 2T2→2E transition that suggests tetrahedral geometry around Cu (II) ion [95]. The electronic spectrum of Zn (II) complex (Figure 104) exhibited a strong absorption band associated to the ligand (π-π*), (n-π*) transitions. This appeared at (30864 cm-1) and (23256 cm-1) respectively. No ligand field transitions were observed because of filled d–orbital. Therefore, square planner geometry was observed around Zn (II) ion [113][78]. Platinum (II) and Palladium complexes have strong bands around 31000 cm-1 and 20000 cm-1, lower energy bands as shoulder which were assigned to internal n→π* and π→π* transition of the ligand, and Pt, Pd →π* charge transfer [96]. This supports the idea of a square-planar environment for the metal ions[97]. However, these can be attributed by magnetic susceptibility measurements that is shown in (Table 18) and discussed in section 3.3.6.
124
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3.3.6 Magnetic Susceptibility Measurements The molar magnetic susceptibility χm which characterizes the extent of paramagnetism of the metal complexes was measured in order to determine the spin properties of the metal complexes. The metal complex can either perform in the high spin state or be present a low spin metal complex. The measurement is important to identify the number of unpaired electrons, and to determine their geometric structure [10]. The magnetic susceptibility values data suggest octahedral geometry for Mn (II) and Fe (III) which are (5.00 and 5.62BM) respectively [112]. The values of magnetic susceptibility of Cu (II) and Co (II) complexes are (1.76 and 4.47 BM) respectively which suggest tetrahedral geometry around the Metal ions [78][90]. The magnetic moments of the Zn (II), Pd (II), Pt (II) complexes were found to be diamagnetic. Thus, they are suggested to possess a square-planar geometry in their metal complexes [101][109].
125
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
No.
Table 18: Magnetic Susceptibility and Uv-Vis Spectrum Data with Their Assignments of PBIPH2 and its Metal Complexes
PBIPH2
153
[Mn(PBIP)(H2O)2] H2O
154
[Fe(PBIP)(H2O)3Cl]H2O
[Co2(PBIP)(H2O)2Cl]H2O
159
158
157
155
C20H16N2O2
156
Compounds
[Cu2(PBIP)(H2O)4]Cl.H2O [Zn(PBIP)]H2O Na2[Pd2(PBIP)Cl4]2H2O
[Pt2(PBIP)(H2O)2Cl2]2H2O
Band Absorptions nm cm-1 ε 318 31447 1807 430 23256 2229 324 30864 1750 450 22222 2656 576 17361 1966 296 33784 2771 476 21008 2633 522 19157 1856 318 31447 1813 472 21186 2463 546 18315 2087 318 31447 1776 472 21186 2662 602 16611 2290 324 30864 1857 430 23256 2304 320 31250 1822 478 20921 2756 554 18051 2105 322 31056 1818 496 20161 2749 530 18864 2147 600 16667 1818
126
Assignments π →π* n→π* 6 A1g→4E2g (4D) 6 A1g→4A1g (4G) 6 A1g→4E2g (4G) C.T 6 T2g→5Eg 6 A1g → 4T1g C.T 4
A2g → 4T1g(P) C.T 2
T2g→2Eg C.T C.T Pd→π*
µeff (B.M) Pract.
-
Theo.
-
5.00 O.h
5.92
5.62 Oh
3.87
4.47 T.h
3.87
1.76 T.h
1.73
Dia Sq.pl
0
Dia Sq.pl
0
Dia Sq.pl
0
C.T
Pt→π
*
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
2.5 430, 2.229 318, 1.807
2
Abs.
1.5
1
0.5
0 200
300
400
500
600
700
800
wavelength nm
Figure 99: Uv-Vis. Spectrum of PBIPH2 Ligand
450, 2.6560 2.5
576, 1.9660
324, 1.7500 2.0
Abs.
1.5
1.0
0.5
0.0 200
300
400
500
wavelength nm
Figure 100: Uv-Vis. Spectrum of [Mn(PBIP)(H2O)2] H2O
127
600
700
800
Chapter Three/Part Two
3
Results and Discussion
PBIPH2 Ligand
296, 2.771 476, 2.633
2.5
Abs.
2
522, 1.856
1.5
1
0.5
0 200
300
400
500
600
700
800
wavelength nm
Figure 101: Uv-Vis. Spectrum of [Fe(PBIP)(H2O)3Cl]H2O
3
472, 2.463
2.5 546, 2.087
318, 1.813
Abs.
2
1.5
1
0.5
0 200
300
400
500
wavelength nm
Figure 102: Uv-Vis. Spectrum of [Co2(PBIP)(H2O)2Cl2]H2O
128
600
700
800
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3
472, 2.654
602, 2.299
2.5
318, 1.776
Abs.
2
1.5
1
0.5
0 200
300
400
500
600
700
800
wavelength nm
Figure 103: Uv-Vis. Spectrum of [Cu2(PBIP)(H2O)4]Cl.H2O
2.5
430, 2.304 324, 1.857
2
Abs.
1.5
1
0.5
0 200
300
400
500
wavelength nm
Figure 104: Uv-Vis. Spectrum of [Zn(PBIP)]H2O
129
600
700
800
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3 478, 2.756 2.5 320, 1.822
554, 2.105
Abs.
2
1.5
1
0.5
0 200
300
400
500
600
700
800
700
800
wavelength nm
Figure 105: Uv-Vis. Spectrum of Na2[Pd2(PBIP)Cl4]2H2O
3
496, 2.749
2.5
530, 2.147
322, 1.818
600, 1.818
Abs.
2
1.5
1
0.5
0 200
300
400
500
600
wavelength nm
Figure 106: Uv-Vis. Spectrum of [Pt2(PBIP)(H2O)2Cl2]2H2O
130
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3.3.7 Thermal Gravimetric Analysis The calculated and estimated weight loss with temperature ranges of all metal complexes is summarized in (Table 19) and the TGA curves shown in (Figures 107-113). The dehydration step of all metal complexes is observable. One hydrated water molecule of Mn (II), Fe (III), Cu (II), Co (II) and Zn (II) complexes, and two hydrated water molecules of Pd (II) and Pt (II) complexes were observed below 165oC. The weight loss in the TGA curves shows weight loss of Mn (II), Fe (III), Cu (II), Co (II), and Pt (II) corresponding to 2, 3, 4, and 2 moles of water molecules respectively. Table 19: Weight Loss Percentages with Temperature Ranges of Water Molecules on PBIPH2 Metal Complexes No.
Compounds
153 [Mn(PBIP)(H2O)2] H2O 154 [Fe(PBIP)(H2O)3Cl]H2O 155 [Cu2(PBIP)(H2O)4]Cl.H2O 156 [Co2(PBIP)(H2O)2Cl2]H2O 157 [Zn(PBIP)]H2O 158 Na2[Pd2(PBIP)Cl4]2H2O 159 [Pt2(PBIP)(H2O)2Cl2]2H2O n= no. of moles of water molecule
TG Range oC
n
Mass Loss Calc. % (Est. %)
17.2-151.0
1h
4.252 ( 4.244 )
151.0-252.3
2c
12.756 ( 12.762 )
25.9-149.5
1h
3.768 ( 3.767 )
149.5-255.2
3c
15.072 ( 15.035 )
29.5-161.3
1h
161.3-247.6
4c
17.562 ( 17.552 )
28.4-137.2
1h
3.231 ( 3.231 )
137.2-290.9
2c
9.692 ( 9.696 )
24.4-134.6
1h
4.526 ( 4.529 )
83.6
28.6-164.2
2h
4.596 ( 4.596 )
53.3
16.1-151.7
2h
4.248 ( 4.247 )
151.7-264.0
2c
8.496 ( 8.500 )
3.512
(3.504)
Total Mass Loss%
86.3
83.4
36.923
71.6
59.4
h, c = hydrated and Coordinated water molecule respectively
131
Chapter Three/Part Two
0
100
Results and Discussion
200
300
400
PBIPH2 Ligand
500
600
700
0% 252.294479, -12.762%
-10% 151.072296, -4.244% -20%
Wieght Loss %
-30% -40% -50% -60% -70% -80% -90%
Temp.oC
Figure 107: TGA Curve of [Mn(PBIP)(H2O)2] H2O
0
100
200
300
400
500
0% 255.239639, -15.035%
-10% 149.540207, -3.767% -20%
Wieght Loss%
-30% -40% -50% -60% -70% -80% -90%
Temp.oC
Figure 108: TGA Curve of [Fe(PBIP)(H2O)3Cl]H2O
132
600
Chapter Three/Part Two
0
100
Results and Discussion
200
300
400
PBIPH2 Ligand
500
600
0% 290.903412, -9.696%
-10% 137.296722, -3.231%
Wieght Loss %
-20% -30% -40% -50% -60% -70% -80%
Temp.oC
Figure 109: TGA Curve of [Co2(PBIP)(H2O)2Cl]H2O
0
100
200
300
400
0% -5%
161.344437, -3.504%
Wieght Loss %
-10% -15% -20%
247.630417, -17.552%
-25% -30% -35% -40%
Temp.oC
Figure 110: TGA Curve of [Cu2(PBIP)(H2O)4]Cl.H2O
133
500
600
Chapter Three/Part Two
0
100
Results and Discussion
200
300
PBIPH2 Ligand
400
500
600
400
500
600
0% -10% 134.684265, -4.529%
Wieght Loss %
-20% -30% -40% -50% -60% -70% -80% -90%
Temp.oC
Figure 111: TGA Curve of [Zn(PBIP)]H2O
0
100
200
300
0%
-10%
Wieght Loss %
164.26535, -4.596% -20%
-30%
-40%
-50%
-60%
Temp.oC
Figure 112: TGA Curve of Na2[Pd2(PBIP)Cl4]2H2O
134
Chapter Three/Part Two
0
100
Results and Discussion
200
300
400
0% 264.045532, -8.500%
-10% 151.730133, -4.247%
Wieght Loss %
-20% -30% -40% -50% -60% -70%
Temp.oC
Figure 113: TGA Curve of [Pt2(PBIP)(H2O)2Cl2]2H2O
135
PBIPH2 Ligand
500
600
Chapter Three/Part Two
Results and Discussion
PBIPH2 Ligand
3.3.8 Proposed Structures for PBIPH2 Ligand Metal Complexes
The Proposed Structures for (PBIPH2) metal complexes was drawn based on elemental data, magnetic moments, molar conductivity, thermal analysis and spectral studies (IR, UV-Vis). The proposed structural formula of the new metal complexes were shown in (Figure 114). The ligand acts as a tetra dentate through the two nitrogen atoms of the azomethine group and two phenolic oxygen atoms in all metal complexes except Fe(III) which acts as a bidentate ligand. Metal complexes of Fe(III), Mn(II) and Zn(II) are mononuclear and Cu(II), Co(II), Pd(II) and Pt(II) complexes are binuclear complex.
Figure 114: Proposed Structures for [Mn(PBIP)(H2O)2]H2O, [Fe(PBIP)(H2O)3Cl]H2O, [Zn(PBIP)]H2O, [Cu2(PBIP)(H2O)4]H2O.Cl, [Co2(PBIP)(H2O)2Cl2]H2O, [Pd2(PBIP)Cl4]2H2O and [Pt2(PBIP)(H2O)2Cl2]2H2O Complexes
136
Chapter Three/Part Four
Results and Discussion
Biological activities
Part Four 3.4 Biological Activities
The resistance towards available drugs is rapidly becoming a major worldwide problem. The need to design new compounds to deal with this resistance has become one of the most important areas of research today [31]. The Schiff bases constitute one of the most active classes of the compounds possessing diversified biological applications [114]. Also, many studies stressed the role of metal ions in important biological processes [52]. Nitrogen, oxygen and sulfur are considered the most hetero atoms known[61]. Metal complexes of S-, N- and O-chelating ligands have attracted the considerable attention because of their biological properties [115]. In view of the above mentioned fact we prepared some inorganic metal complexes of heteroatom containing compounds, and in vitro screened against Escherichia coli and Staphylococcus aureus. The prepared compounds were screened for their antibacterial activities in vitro against Gram-negative E.coli and Gram-positive Staphylococcus bacteria. The antibacterial activity of the ligands and their metal complexes were determined by well diffusion methods. The recommended medium in this test method is Mueller Hinton agar. Its pH should be between 7.2 and 7.4. Also, it should be poured to a uniform thickness of 4 mm in the Petri plate[116]. This method involves the exposure of the zone of inhibition toward the diffusion of micro–organism on agar plate. The compounds (1000 μg/ml) to be tested were dissolved in DMSO which 40 μL for each hole and 100 μL of microbial suspension was spread onto agar plates. The plates were incubated for 24 hours at 37°C. The zone of inhibition of bacteria growth around the disc was observed, and the diameters of the inhibition zones were measured in millimeters. The in vitro biological screening results of the ligands and their metal complexes are given in (Tables 20, 21 and 22). 137
Chapter Three/Part Four
Results and Discussion
Biological activities
Table 20: Biological Activities of PSTMH2 Ligand and its Metal Complexes No. PSTMH2
140 141 142 143 144 145
Compounds
Inhibition Zone (mm) Escherichia Eoli Staphylococcus Aureus Gram(-) Gram(+)
C21H18N6S4O2
20 16.6 33.3 15 21.6 10 10
[Cr(PSTM)(H2O)2]H2O.Cl [Fe(PSTM)(H2O)2] H2O.Cl [Co(PSTM)]H2O [Cu(PSTM)]H2O [Pd(PSTM)]H2O [Pt(PSTM)]3H2O
30 20 13.3 13.3 15 21.6 15
Table 21: Biological Activities of BMTHH2 Ligand and its Metal Complexes No. BMTHH2
146 147 148 149 150 151 152
Compounds
Inhibition Zone (mm) Escherichia Coli Staphylococcus Aureus Gram(-Ve) Gram(+Ve)
C10H12N6S4
21.6 21.6 16.6 20 18.3 33.3 11.6 25
[Co2(BMTH)(H2O)4]Cl2 [Cu(BMTH)]H2O [Zn(BMTH)]H2O [Cd(BMTH)]H2O [Hg(BMTH)]H2O [Pd(BMTH)]H2O [Pt(BMTH)]2H2O
21.6 21.6 20 23.3 45 41.6 11.6 18.3
Table 22: Biological Activities of PBIPH2 Ligand and its Metal Complexes No.
Compounds
Inhibition Zone (mm) Escherichia Coli Staphylococcus Aureus Gram(-Ve) Gram(+Ve)
PBIPH2 C20H16N2O2 153 [Mn(PBIP)(H2O)2] H2O 154 [Fe(PBIP)(H2O)3Cl]H2O 155 [Cu2(PBIP)(H2O)4]Cl.H2O 156 [Co2(PBIP)(H2O)2Cl]H2O 157 [Zn(PBIP)]H2O 158 Na2[Pd2(PBIP)Cl4]2H2O 159 [Pt2(PBIP)(H2O)2Cl2]2H2O
23.3 11.6 25 26.6 11.6 16.6 10 6.6
138
18.3 13.3 8.3 11.6 11.6 8.66 23.3 6.6
Chapter Three/Part Four
Results and Discussion
Biological activities
In the comparison of activity results between Schiff base ligands and their metal complexes against bacteria, it has been clear that only few metals enhanced the activity against bacteria. Some metal complexes could enhance anti-bacterial activities such as Fe(III) and Cu(II) with PSTMH2 ligand, Cu(II) and Pt(II) with BMTHH2 ligand, and Cu(II) with PBIPH2 ligand against gram negative E.coli, whereas others decline this activities.
In gram positive Staphylococcus aureus activity, the ligand PSTMH2 and their metal complexes showed activities in the following order PSTMH2 > Cr(III) > Cu(II), Pt(II) > Fe(III) and Co(II). In the series, the PSTMH2 ligand has higher activity than their all metal complexes.
From the obtained results, it was observed that the anti-bacterial activity of BMTHH2 ligand was enhanced after metal complexation with Cd (II), Hg (II), and Zn (II) metals against Staphylococcus aureus. However, this enhancement was observed only in Pd (II) among all metal complexes of PBIPH2 ligand.
Figure 115: The Inhibition Zone of Some Complexes on The Plate. 139
Chapter Three/Part Five
Results and Discussion
Fluorescence Emission
Part Five 3.5 Fluorescence Emission of the Ligands and Their Metal Complexes
Fluorescence emission of the metal complexes is of highly interest, because many applications rely of this technique, like, Organic Light Emitting Devices (OLEDs), solar cells, sensors, and biological labeling. New metal complexes with strong and photostable emission are sought by researchers in order to be able to obtain different colors of the metal complexes [117][118][119][91]. The prepared PBIPH2 ligand in THF-water (1:1) mixture shows much enhanced fluorescence emission comparing to the ligand in just THF. It assigns for the strong emission of the ligand in a crystal form, which is a solid-state emitter. The solid PBIPH2 emits yellow emission centered at 550 nm (Figure 116 & 117).
900
428.0, 774.8
322.0, 773.3
550.0, 766.5
800
Intensity ( a.u )
700 600 500 400 300
550.0, 196.8
200 100 0 200
250
300
350
400
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500
550
600
650
wavelength (nm) PBIP Ex Sp at 548 nm Em Intensity (a.u.) PBIP Em Sp at 425 nm Ex Intensity (a.u.) PBIP Em Sp at 250 nm Ex Intensity (a.u.)
Figure 116: Excitation and Emission Spectra of PBIPH2 in THF:H2O (1:1) 140
700
Chapter Three/Part Five
Results and Discussion
Fluorescence Emission
5 4.5
Intensity (a.u)
4 3.5 3 2.5 2 1.5 1 0.5 0 200
250
300
350
400
450
500
550
600
650
700
wavelenght (nm) PBIP Ex spect at 550 nm Emission Intensity (a.u.)
PBIP Emission spect at 430 nm Excite Intensity (a.u.)
Figure 117: Excitation and Emission Spectra of PBIPH2 in THF
The metal complex [Fe(PBIP)(H2O)3Cl]H2O shows almost very weak emission in the THF solution. However, it exhibits fairly yellow emission at solid state (in a crystalline form) (Figure 118). The fluorescence emission is at 550 nm, same as the position of the free ligand PBIPH2 in solid form. This concludes that the emission of the metal complex is mainly from the emission of the ligand. It should be mentioned here, the emission of the ligand is roughly higher than the metal complex around three times. It may be due to the difference in arrangement of the ligand emitter in the metal complex which promote non radiative decay. It could be also due to the quenching effect of the Fe metal ions, as Fe (III) is paramagnetic and can enhance the transfer of electrons from the excited state to the d-orbitals of the metals, and consequently increase quenching. Fluorescence quenching by metal effect and rearrangement of ligands in the metal complexes can also be the reason for other non-emissive complexes, like; manganese, copper, cobalt and etc. 141
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Results and Discussion
Fluorescence Emission
Absence of emission in all other paramagnetic metal complexes Mn(II), Cu(II) and Co(II), except for Fe(III) complex which has weak emission and rule out quenching by metal effect. It will be the sole reason for weak Fe(III) complex emission. Therefore, both quenching and ligand arrangement can interpret the emission of the [Fe(PBIP)(H2O)3Cl]H2O complex. In other words, although Fe(III) is a quencher, weak
emission of its metal complex might be due to its effect to the excited state of the ligand which is not complete.
250.0
440.0, 202.5 550, 193.0
Intensity (a.u)
200.0
150.0
100.0
250, 43.4 550, 43.30353165
50.0
0.0 240.0
290.0
340.0
390.0
440.0
490.0
540.0
590.0
640.0
690.0
wavelenght nm Fe(III) complex, Ex Sp at 548 nm Em Intensity (a.u.)
Fe(III) complex, Em Sp at 250 nm Ex Intensity (a.u.)
Fe(III) complex, Em Sp at 440 nm Ex Intensity (a.u.)
Figure 118: Excitation and Emission Spectra of [Fe(PBIP)(H2O)3Cl]H2O
142
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Results and Discussion
Fluorescence Emission
[Zn(PBIP)]H2O shows very weak emission at 545 nm when excited at 415 nm in the crystalline form (Figure 119). Although Zn (II) ions is diamagnetic and does not show quenching, but the emission of the ligand dramatically changes (weakened but showed emission). This suggests that weak emission in [Zn(PBIP)]H2O attributes to the new conformation and arrangement of PIBP in the Zn(II) complex.
10 9
540
415
8
299
Intensity (a.u)
7 6 5
540
4 3 2 1 0 250
300
350
400
450
500
550
600
650
wavelength nm Zn(II) complex, Ex Sp at 540 nm Em Intensity (a.u.)
Zn(II) complex, Em Sp at 250 nm Ex Intensity (a.u.)
Zn(II) complex, Em Sp at 415 nm Ex Intensity (a.u.)
Figure 119: Excitation and Emission Spectra of [Zn(PBIP)]H2O
143
700
Chapter Three/Part Five
Results and Discussion
Fluorescence Emission
Pd(II) and Pt(II) complexes do not have any emission in the visible region while weak emission in the UV region was observed around (300-400 nm) (Figure 120 & 121).
Weak broad emission spectra appeared between 350-450nm. However, another small and broad peak appeared between 580-650nm which is near infrared region. The second weak energy peak might attribute to the triplet emission, which is common in Pd(II) and Pt(II) complexes[120]
50
312
45 40
312
Intensity (a.u)
35 30 25 20 15 10 5 0 250
300
350
400
450
500
550
wavelength nm Pt(II) complex, Em Sp at 260 nm Ex Intensity (a.u.) Pt(II) complex, Em Sp at 290 nm Ex Intensity (a.u.)
Figure 120: Emission Spectra of [Pt2(PBIP)(H2O)2Cl2]2H2O.
144
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650
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Chapter Three/Part Five
Results and Discussion
Fluorescence Emission
60
Intensity (a.u)
50 40 30
310
360 400
20
300
10 0 250
300
350
400
450
500
550
600
650
700
wavelength nm
Pd(II) Complex, Ex Sp at 410 nm Em Intensity (a.u.)
Pd(II) Complex, Em Sp at 250 nm Ex Intensity (a.u.)
Pd(II) Complex, Em Sp at 300 nm Ex Intensity (a.u.)
Figure 121: Excitation and Emission Spectra of Na2[Pd2(PBIP)Cl4]2H2O
The emission spectroscopy of both PSTMH2 and BMTHH2 ligands with their metal complexes have been studied. The study does not show emission of PSTMH2, BMTHH2 ligands and their metal complexes. The emission of PBIPH2 in solid state was studied[110][121][122]. In the present work, we studied the effect of complexation on the emission of the ligand. Some metals decreased the emission of the ligand completely upon complexation, and some others showed good emission but lower than the emission of the free ligand.
145
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معقدات فلزیة لقواعد الشیف التي تحتوی علی ذرات (نیتروجین ،أوکسجین ،کبریت) المانحة :تحضیر و تشخیص و انبعاث الفلورسینس و بعض نشاطاتها البایولوجیة
رسالة مقدمة إلی مجلس کلیة العلوم -جامعة السلیمانیة کإستکمال جزئي لمتطلبات نیل درجة الماجستیر في علوم الکیمیاء
من قبل کارزان عزیز عبدالکریم بکالوریوس في الکیمیاء١١٢٢/
تحت إشراف د.دیاری ابراهیم توفیق مدرس
٢٣٤١ذو القعدة
١١٢٢ئاب
الخالصة
یتضمن هذا البحث الذي ثالثة فصول ،الفصل األول عبارة عن مدخل البحث و مراجعة المصادر ،الفصل الثاني یتضمن الجانب العملي من البحث و الذي یحتوي علی المواد و األجهزة و طريقة العمل المستخدم لتحضیر لیگاندات قواعد الشیف و مقعداتها الفلزية ،و الفصل الثالث یتضمن النتائج المستحصلة و مناقشتها و یحتوي علی خمسة أجزاء:
الجزء األول یتضمن تفاعل قاعدة الشیف الجدید المحضر ( )PSTMH2مع امالح الکلورید الفلزات أعطی اليمعقدات و ذات أشکال هندسیة مختلفة :معقد ثماني السطوح لـــ [Cr(PSTM)(H2O)2]H2O.Clو ،[Fe(PSTM)(H2O)2]H2O.Clو معقد رباعی السطوح لـــ ،[Co(PSTM)]H2Oو مربع مستوی لــ [Pd(PSTM)]H2O،[Cu(PSTM)]H2Oو .[Pt(PSTM)]3H2Oأن اللیگاند ( )PSTMH2یتصرف کلیگاند رباعي السن في جمیع معقداته المحضرة و الذی یرتبط مع الفلز المرکزي من خالل ذرة النیتروجین لمجموعة ایزومیثین و ذرة األوکسجین لمجموعة الفینول المنزوعة من البروتون.
الجزء الثاني ،یتضمن تفاعل اللیگاند الجدید المحضر ( )BMTHH2مع أمالح للوريد الفلزات و الذي أعط معقدات فلزات من األنوا التالیة :معقد رباعي السطوح ثنائی نواة لـــ [Co2(BMTH)(H2O)4]2Clو أحادي نواة مربع مستوی مع کل من ،[Cu(BMTH)]H2O, [Zn(BMTH)]H2O, [Cd(BMTH)]H2O [Pd(BMTH)]H2O ،[Hg(BMTH)]H2Oو .[Pt(BMTH)]2H2Oحیث أن اللیگاند )(BMTHH2 في جميع المعقداتها الفلزیة المحضرة تصرف کلیگاند رباعي السن و الذی یرتبط بالفلز المرکزي من خالل ذرة النیتروجین لمجموعة ایزومیثین و ذرة الكبريت لمجموعة الثايول .
الجزء الثالث ،حیث تم إعتماد طریقة جدیدة لتحضیر اللیگاند ( ،)PBIPH2التي نتخلف عن الطرق التقليدية. حیث أن تفاعل اللیگاند ( )PBIPH2مع أمالح للوريد الفلزات أعطی معقدات أحادي نواة مع کل من األیونات ( ،Fe)III( ،Mn)IIو ( ،Zn)IIو المعقدات ثنائي النواة مع کل من األیونات ( Pd)II( ،Cu)II( ،Co)IIو (Pt)II
ذات
بأشکال
هندسیة
،[Fe(PBIP)(H2O)3Cl]H2O
مختلفة:
ثماني
رباعي
السطوح
السطوح لــ
لـــ
[Mn(PBIP)(H2O)2]H2O
[Co2(PBIP)(H2O)2Cl]H2O
و و
،[Cu2(PBIP)(H2O)4]Cl.H2Oمربع مستوي لــ Na2[Pd2(PBIP)Cl4]2H2O ،[Zn(PBIP)]H2Oو .[Pt2(PBIP)(H2O)2Cl2]2H2Oأن اللیگاند ( )PBIPH2یتصرف کلیگاند رباعي السن في جميع معقداتها و یرتبط باألیونات المرکزي من خالل ذرة النيتروجين من مجموعة ایزومیثین و ذرة األولسجين الفينولية بعد نز البروتون عدا من المعقد ( ،Fe)IIIأن اللیگاند ) (PBIPH2یتصرف کلیگاند ثنائي السن لهذا المعقد و یرتبط باألیون ) Fe(IIIعن طریق ذرة األولسجين الفينولية بعد نز البروتون.
الجزء الرابع عبارة عن نتائج النشاط البيولوجي المضادة للبكتيريا لجميع اللیگاندات و معقداتها المحضرة ،فإن اللیگاندات ثالثة و جميع المعقداتها الفلزية اختبرت ضد النمو
) Escherichia coli (Gram -و
) .Staphylococcus aureus (Gram +أن جمیع اللیگاندات و معقداتها المحضرة أظهرت حساسية جيدة من حیث النشاط البیولوجي ،و من مقارنة النشاط البیولوجي لللیگاندات الحرة و معقداتها المحضرة تبین أن النشاط البیولوجي للیگاندات یزداد بوجود أیون الفلزات في معقداتها.
الجزء الخامس ،یتضمن دراسة الخصائص الطيفية للمعقدات المحضرة و اللیگاندات الحرة عندما اظهرت اللیگاندات و معقداتها أن الطیف الفلورسین تنخفض في طیف المنبعث للیگاند بعد تناسقە مع الفلز ،و أن فلزات جمیعا تسبب فقدان الطیف الفلورسین ماعدا ) Fe(IIIالذی أعطی انبعاثا ما یعادل نصف انبعاث الذي أظهرە اللیگاند الحر .کذلک أعطت معقدات األیونات ) Pd(II)،Zn(IIو ) Pt(IIإنبعاثات ضعيفة أيضا ،إال أن تلک االنبعاثات تظهر في منطقة األشعة تحت الحمراء القريبة ) ،(near IRوالتي تشير ال انتقاالت الثالثية للفسفرة.
وقد تم تشخیص اللیگاندات ) (BATP , PSTMH2 , BMTHH2باستخدام تحلیل طیف الكتله ،و أن جمیع اللیگاندات و معقداتها تم تشخیصها باستخدام تحلیل العناصر الدقیقة ،األشعة تحت الحمراء ,األشعة فوق البنفسجية ,قیاس التوصیل الکهربائي ,الحساسية المغناطيسية ،التحليل الوزني الحراري.
ئاڵۆزی کانزاکانی شیف بەیسە بەخشەرەکانی (نایترۆجین ،ئۆکسجین ،گۆگرد): ئامادەکردن و ناسینەوە و دانەوەی تیشکی فلۆرسینس و هەندێک چاالکی بایۆلۆجیان.
نامەیەکە پێشکەش کراوە بە ئەنجومەنی کۆلێجی زانست -زانکۆی سلێمانی وەک بەشێک لە پێداویستیەکانی بەدەستهێنانی بڕوانامەی ماستەر لە زانستی کیمیادا
لەالیەن کارزان عزیز عبدالکریم بەکالۆریوس-کیمیا١١٢٢/
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١١٢٢خەرمانان
١١٢٢ئاب
پوختە ئەم توێژینەوەیە سێ بەش لەخۆ دەگرێت :بەشی یەکەم کە پێشەکی و پێداچونەوەی سەرچاوەکانە ،بەشی دووەم باس لە الیەنی ئەزمونکاری توێژینەوەکە دەکات کە هەریەکە لە مادەکان و ئامێر و ڕێگاکانی ئامادەکردن دەگرێتە خۆ بۆ ئامادەکردنی لیگاندە تفتی شیف و ئاڵۆزە کانزاکانیان لەگەڵ کانزاکان .بەشی سێیەم ئەنجامەکان و تاوتوێ کردنیان لەخۆ دەگرێت لە پێنج بڕگەدا: بڕگەی یەکەم کارلێکی لیگاندێکی نوێی ئامادەکراوی تفتە شیفەکانە ) (PSTMH2لەگەڵ خوێی کلۆریدی کانزاکان و دەستکەوتنی چەند ئاڵۆزێکی نوێیە کە چەند شێوازێکی ئەندازەیی جیاوازی هەیە :ئاڵۆزی هەشت ڕوو بۆ [Cr(PSTM)(H2O)2]H2O.Clو ،[Fe(PSTM)(H2O)2]H2O.Clوە هەڕەمی بنکە سێگۆشەیی چوار ڕوو بۆ ،[Co(PSTM)]H2Oوە ڕوو تەختە چوارگۆشە بۆ [Pd(PSTM)]H2O ،[Cu(PSTM)]H2Oو .[Pt(PSTM)]3H2Oلیگاندی ) (PSTMH2لە هەموو ئاڵۆزە ئامادەکراوەکاندا وەک لیگاندێکی چوار ددانی ڕەفتار دەکات کە بە بەندی هاوڕێک دەبەسترێتەوە بە کانزاکان لە ڕێگەی گەردیلەی نایترۆجینی گروپی ئایزۆمیثین و گەردیلەی ئۆکسجینی گروپی فینۆڵەوە بە ون کردنی پرۆتۆنەکەی. بڕگەی دووەم کارلێکی لیگاندێکی نوێی ئامادەکراوە ) (BMTHH2لەگەڵ خوێی کلۆریدی کانزاکان ،وە چەند ئاڵۆزێکی نوێی کانزاکانی داینێ بەم شێوەیە :ئاڵۆزی هەڕەمی بنکە سێگۆشەی چوار ڕووی دوانە ناوکی بۆ [Co2(BMTH)(H2O)4]Cl2وە ئاڵۆزی تاک ناوکی ڕوو تەختە چوارگۆشە بۆ ،[Cu(BMTH)]H2O [Pd(BMTH)]H2O ،[Hg(BMTH)]H2O ،[Cd(BMTH)]H2O ،[Zn(BMTH)]H2O
و
.[Pt(BMTH)]2H2Oلیگاندی ) (BMTHH2لە هەموو ئاڵۆزە ئامادەکراوەکاندا وەک لیگاندێکی چوار ددانی ڕەفتار دەکات کە بە بەندی هاوڕێک بەستراوە بە کانزاکان لە ڕێگەی گەردیلەی نایترۆجینی کۆمەڵەی ئایزۆمیثین و گەردیلەی گۆگردی کۆمەڵەی سایۆڵەوە.
بڕگەی سێیەم بریتیە لە ئامادەکردنی لیگاندی ) (PBIPH2بە بەکارهێنانی ڕێگایەکی نوێی جیاواز لە ڕێگە کالسیکیەکەی کە لە سەرچاوەکانی پێشوودا پێی ئامادەکراوە ،وە کارلێکی ئەم لیگاندە ) (PBIPH2لەگەڵ خوێی کلۆریدی کانزاکان ،ئاڵۆزی تاک ناوکی بۆ هەریەک لە کانزاکانی ) Mn(II), Fe(IIIو ) Zn(IIوە ئاڵۆزی دوانە ناوکی بۆ هەریەک لە کانزاکانی ) Pd(II) ،Co(II) ،Cu(IIو ) Pt(IIلێ ئامادەکرا کە شێوەی ئەندازەیی جیاوازیان هەبوو بەم شێوەیە :ئاڵۆزی هەشت ڕوو بۆ هەریەک لە [Mn(PBIP)(H2O)2]H2Oو [Fe(PBIP)(H2O)3Cl]H2Oوە ئاڵۆزی هەڕەمی بنکە سێگۆشەی چوار ڕوو بۆ هەریەک لە [Co2(PBIP)(H2O)2Cl]H2Oو ،[Cu2(PBIP)(H2O)4]Cl.H2Oوە ئاڵۆزی ڕوو تەختە چوارگۆشە بۆ Na2[Pd2(PBIP)Cl4]2H2O ،[Zn(PBIP)]H2Oو .[Pt2(PBIP)(H2O)2Cl2]2H2Oئەم لیگاندە ڕۆڵی لیگاندێکی چوار ددانی دەبینێت لە هەموو ئاڵۆزە ئامادەکراوەکاندا جگە لە ئاڵۆزی ) Fe(IIIنەبێت کە وەک لیگاندی دوو ددانی ڕەفتار دەکات ،ئەم لیگاندە بە بەندی هاوڕێک دەبەسترێتەوە بە کانزاکان لە ڕێگەی گەردیلەی نایترۆجینی کۆمەڵەی ئایزۆمیثین و گەردیلەی ئۆکسجینی کۆمەڵەی فینۆڵەوە دوای ون کردنی پرۆتۆنەکەی.
بڕگەی چوارەم ئەنجامی چاالکی بایۆلۆجی و دژە بەکتریایی سەرجەم ئامادەکراوەکانی تێدا خراوەتە ڕوو. لیگاندە ئامادەکراوەکان و هەموو ئاڵۆزەکانیان خرانە ژێر ئەزموونی دژە بەکتری لەگەڵ هەردوو جۆری ) Escherichia coli (Gram -و ) .Staphylococcus aureus (Gram +وە بینرا کە زۆرینەی ئاڵۆزەکان چاالکی و هەستیارییەکی باشیان دژ بەم دوو جۆرە بەکتریایە هەیە .وە کاتێک ئەنجامەکانی چاالکی بایۆلۆجی هەریەک لە ئاڵۆزەکان و لیگاندەکانیان بەراوردکران ،دەرکەوت کە هەندێک لە کانزاکان دەبنە هۆی زیادکردنی چاالکی دژە بەکتریایی لیگاندەکان و بونی ئەو کانزایانە لە پێکهاتەی ئەم ئاڵۆزانەدا چاالکی دژە بەکترییان زیاد دەکات.
بڕگەی پێنجەم بریتییە لە لێکۆڵینەوە لە تایبەتماندی شەبەنگی لیگاندی ) (PBIPH2و ئاڵۆزەکانیان ،لە کاتێکدا کە لیگاندی ) (PBIPH2و ئاڵۆزەکانی شەبەنگی فلۆرسنیان پیشاندا ،وە دەرکەوت کە تیشکدانەوەی
لیگاندەکە ڕوو لە کەمی دەکات پاش بەسترانەوەی بە کانزاکانەوە .هەموو کانزاکان بوونە هۆی تەواو لەناوبردنی دانەوەی تیشکەکە جگە لە کانزای ) Fe(IIIنەبێ کە تیشکدانەوەی هەبووە بە ڕێژەی کەمتر لە نیوەی تیشکدانەوەی لیگاندە سەربەستەکە .وە هەروەها هەریەک لە ئاڵۆزی کانزاکانی ) Pd(II) ،Zn(IIو ) Pt(IIتیشکێکی الوازیان دایەوە ،بەاڵم ئەم تیشکدانەوەیە لە ناوچەی نزیک ژێر سووردایە ) (near IRوە دەگوازرێتەوە بۆ ئاستە سیانیەکانی تیشکی فۆسفۆڕی.
دەستنیشانکردن و ناسینەوە بە بەکارهێنانی شیکاری شەبەنگی بارستە بۆ هەموو لیگاندەکانی ( BMTHH2 )PSTMH2, BATP,ئەنجامدراون ،بەکارهێنانی شیکاری ووردی توخمەکان و تیشکەکانی ژێر سوور و سەروو بنەوشەیی و پێوانی گەیاندن و هەستیاری موگناتیسی و شیکاری کێشی گەرمی.
