synthesis and structural characterization of mixed ligand...

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SYNTHESIS AND STRUCTURAL

CHARACTERIZATION OF MIXED LIGAND

COMPLEXES OF COPPER(II) WITH DIAMINES

AND CARBOXYLATES

Submitted By:

SYEDA SHAHZADI BATOOL

2009-Ph. D. Chemistry-05

Supervised By:

Prof. Dr. SYEDA RUBINA GILANI

DEPARTMENT OF CHEMISRTY UNIVERSITY OF ENGINEERING AND TECHNOLOGY

LAHORE-PAKISTAN

2016

SYNTHESIS AND STRUCTURAL

CHARACTERIZATION OF MIXED LIGAND

COMPLEXES OF COPPER(II) WITH DIAMINES

AND CARBOXYLATES

Submitted By:

SYEDA SHAHZADI BATOOL

2009-Ph. D. Chemistry-05

Supervised By:

Prof. Dr. SYEDA RUBINA GILANI


LAHORE-PAKISTAN

2017

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SYNTHESIS AND STRUCTURAL CHARACTERIZATION

OF MIXED LIGAND COMPLEXES OF COPPER(II) WITH

DIAMINES AND CARBOXYLATES

A Research Thesis Submitted

To

The University of Engineering & Technology Lahore

In

Partial fulfillment of the Requirements for the Degree

Of

Doctorate of philosophy

In

Chemistry

By

SYEDA SHAHZADI BATOOL 2009-Ph.D-Chemistry-05


LAHORE-PAKISTAN

2017

This thesis has been evaluated by the following examiners

External Examiners

From Abroad

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i) Dr. Sc. Christian Betzel,

Institute of Biochemistry and molecular biology

Martin-Luther-King Platz 6, 20146 Hamburg.

ii) Dr. Liu Qingguan,

School of Chemistry & Chemical Engineering,

Key Laboratory of Theoretical Chemistry, Ministry of Education,

Human University of Science & Technology,

Xiargtan 411201, China.

iii) Prof. Dr. Mitu Liviu,

Department of Physics & Chemistry,

University of Pitesti, Pitesti, Romania.

b) From Pakistan

Prof. Dr. Ahmad Adnan,

Chairman, Department of Chemistry, GCU, Lahore, Pakistan.

Assoc. Prof. Dr. Muhammad Akhyar furrukh,

Department of Chemistry, GCU, Lahore, Pakistan.

Internal Examiner:

Prof. Dr. Syeda Rubina Gilani,

Chairperson, Department of Chemistry, UET, Lahore, Pakistan.

DEPARTMENT OF CHEMISTRY

UNIVERSITY OF ENGINERING AND TECHNOLOGY

LAHORE

Declaration

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I “SYEDA SHAHZADI BATOOL” declare that the thesis titled: “SYNTHESIS AND

STRUCTURAL CHARACTERIZATION OF MIXED LIGAND COMPLEXES OF

COPPER(II) WITH DIAMINES AND CARBOXYLATES”, is my own research

work. This thesis is being submitted for partial fulfillment of the requirements for the

degree of Ph.D. in chemistry. The thesis contains no material that has been accepted and

published previously for the award of any degree.

____________________ _________

Signature of Candidate Date

I approve that the above titled thesis can be submitted for the examination.

____________________ _________

Signature of Supervisor Date

DEDICATIONS

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Dedicated to

My parents,

My Children,

And my loving family members

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ACKNOWLEDGEMENTS

All praises, deepest thanks and gratitude to Almighty Allah, Who bestowed me with all his

blessings, and gave me enough strength to complete my Ph. D. research work. Peace and

blessings of Allah be upon His Holy Prophet Hazrat Muhammad (PBUH), and his progeny,

who enlightened the path of knowledge and guidance for mankind. In my diligent endeavor in

the pursuit of completion of the researh work, I was lucky to have support of a large number of

people to whom I owe my gratitude.

First of all, I wish to express fervent sense of thankfulness to my mentor and thesis

advisor, Prof. Dr. Syeda Rubina Gilani, Chairperson, Department of Chemistry, University of

Engineering and Technology, Lahore. I shall always be grateful for her inspiring guidance,

encouragement, dedication to excellence in teaching and research, her dynamic supervision

and most importantly, for giving me the honor to be her student, after the resignation of my ex-

supervisor, Dr. Saeed Ahmad. Although his untimely departure affected us a lot, but I would

not forget to acknowledge his efforts in help making me a scientist than a mere experimentalist.

At the same time, I extend my gratitude to Dr. Asif Ali Qaiser, Chairman, Polymer Department,

for allowing me to conduct FTIR analyses of my samples, and Prof. Dr. M. Nawaz Tahir,

University of Sargodha, for single crystal X-ray analyses. I am grateful to Dr. Qurat-ul-ain

Syed, FBRC department, PCSIR laboratories, Lahore, Pakistan, for allowing me to perform

antibacterial studies in her supervision. A special word of gratitude is due to Dr. William T. A.

Harrison for structure solution and structure analyses. I am thankful to all faculty and staff

members for being a source of scholarly guidance in my studies. A special word of thanks is

due to all working staff for always being helpful. I also express my deepest gratitude from the

core of my heart, for the Higher Education Commission, Islamabad, for providing financial

support through Indigenous 5000 Fellowship Program.

Lastly, I wonder if I would be able to find words to express my deepest feelings of love

and compassion for my beloved mother, as it is due to her untiring efforts, that I am now able

to complete my research work. My children Syeda Sakina Zainab, Syed Muhammad Abbas and

Syed Muhammad Mehdi are the joys of my life through whose love and affection, I am able to

accomplish this uphill task.

Syeda Shahzadi Batool

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ABSTRACT

This research work presents one pot synthesis of ternary copper(II) carboxylates of N,N-

chelating diamine ligands. The carboxylate ligands used were sodium salts of benzoic acid,

2-chlorobenzoic acid, cinnamic acid, succinic acid, phthalic acid, terephthalic acid, 4-

aminobenzoic acid, 3-aminobenzoic acid, mefenamic acid, acetyl salicylic acid, and tartaric

acid. The N,N-chelating diamines utilized include N,N,N′,N′-tetramethylethylenediamine

(tmen), while some complexes of carboxylates with ethylenediamine (en), 1,10–

phenanthroline (phen) and 2,2′–bipyridine (bipy) have also been prepared. The structural

aspects and geometrical assignments related to the synthesized complexes have been

investigated with the help of analytical techniques like FT-IR, UV-Visible spectroscopy,

thermal studies (TGA) and single crystal X-ray diffraction analysis. The investigated ternary

copper(II) complexes involving N,N,N′,N′-tetramethylethylenediamine (tmen) include

[Cu(tmen)(BA)2(H2O)2], (1a), [Cu(tmen)(salH)2(H2O)] (2a), {[Cu(tmen)(mef)2] (3a),

[Cu(tmen)(pABA)2]. 1/2 MeOH) (4a), [Cu(tmen)(o-ClBA)2] (5a), [Cu(tmen)(cinn)2]. H2O

(6a), [Cu(tmen)(phtH)2] (7a), [Cu(tmen)(tpht)(H2O)2]n (8a), {[Cu(tmen)(succin)]n.4H2O}

(9a), {[Cu(tmen)(tart)]·2H2O}n (10a). Single crystal analyses of the prepared complexes have

revealed that most of the Cu(II)-N,N,N′,N′-tetramethylethylenediamine adducts with the

carboxylate ligands are mononuclear, in which N,N,N′,N′-tetramethylethylenediamine is

coordinated to Cu(II) in an invariably chelating bidentate mode. In these complexes, the

carboxylate moiety belonging to a carboxylate ligand is coordinated to the central Cu(II) ion,

either in a monodentate (1a, 2a, 4a, 7a), or bidentate (3a, 5a, 6a) fashion. These

mononuclear complexes can be; four-coordinate (4a), with a square planar environment,

five-coordinate (2a, 7a),with a square pyramidal geometry, or six-coordinate (1a, 3a, 5a, 6a )

with an octahedral coordination geometry. Three complexes of Cu-tmen-carboxylato series

are polynuclear in nature (8a, 9a, 10a) and adopt an octahedral coordination environment.

The carboxylate functionality varies in coordination modes, from bis-monodentate bridging

(8a) to chelating bridging (9a-10a).

Another mixed ligand copper(II) complex incorporating ethylenediamine and salicylate

[Cu(en)(salH)Cl]n (where en= ethylenediamine, salH1- = (salicylate1-) (11a) has also been

synthesized. The complex [Cu(en)(salH)Cl]n (11a) is found to be unprecedented because of

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the presence of [Cu-Cl]n back-bone formed by central Cu(II) ion and bridging Cl atoms, also

it had both ethylenediamine and salicylic acid as a part of the inner coordination sphere,

while in most of the known examples, carboxylates usually are found lying uncoordinated in

the outer sphere.

Two ternary copper(II) carboxylate complexes, containing 2,2 ′-bipyridine (bipy = C10H8N2)

having the formulae [Cu(bipy)(cinn)2(H2O)] (1b) [Cu2(bipy)2(pABA)3(pABAH)]. Cl. 3H2O

(2b) {(where cinn1- = cinnamate (C9H7O21-) anion, pABA1- = p-amino benzoate (C7H6NO21-)

anion, and pABAH = p-amino benzoic acid (C7H7NO2)} have been prepared and

characterized. The mononuclear ternary Cu(II) complex incorporating 2,2′–bipyridine and

cinnamate as shown by single crystal X-ray analyses is found to be square pyramidal, formed

by the coordination of bidentate 2,2′–bipyridine, and two monodentate carboxylate groups

from two cinnamates, while the apical position is occupied by an aqua-O atom. The second

dinuclear mixed ligand Cu(II) complex of 2,2′–bipyridine and p-aminobenzoate (1b) is also

found to be unique. It has two copper(II) centers in square pyramidal environments, which

are interlinked by two bridging p-aminobenzoates and by two 2,2′–bipyridine ligands in a

chelating mode. One remaining p-aminobenzoate is attached through its carboxylato-O atom

in a traditional monodentate mode, while the other pABAH is attached to copper(II) through

its N atom.

Two novel mixed ligand copper(II)-phen based carboxylate complexes represented as

[Cu(phen)(benzoate)2] 1c, and [Cu(phen)(m-amb)Cl·½H2O] 2c (where phen = 1,10-

phenanthroline, BA1- = benzoate, m-ABA1- = m-aminobenzoate) have been synthesized and

characterized. The geometry and structure of the mononuclear ternary Cu(II) complex

incorporating 1,10–phenanthroline and m-aminobenzoate, as confirmed through single

crystal X-ray analyses is found to be square pyramidal, formed by the coordination of

chelating 1,10–phenanthroline, a chelating m-aminobenzoate, while the apical position is

occupied by a Cl atom. The second monomeric complex [Cu(phen)(benzoate)2] was square

planar, with one bidentate phen and two monodentate benzoates.

Antimicrobial studies of complexes have also been performed. Some of these copper(II)

complexes are found to be biologically active against bacteria.

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TABLE OF CONTENTS

Acknowledgement i

Abstract ii

Table of contents iv

List of tables x

List of figures xii

List of Schemes xvi

List of abbreviations xvii

Chapter-1 INTRODUCTION 1

1.1 Chemistry of copper 1

1.2 Chemistry of copper(II) 3

1.2.1 General metabolic functions of copper 3

1.3 Biological activities of copper complexes 4

1.4 Metal carboxylate chemistry and their coordination modes 5

1.5 Structures and molecular geometries of copper (II)-carboxylate complexes 7

1.5.1 Geometries of mononuclear copper(II) complexes 7

1.5.1.1 Four-coordinate complexes 8

1.5.1.2 Five-coordinate copper(II) complexes 9

1.5.1.3 Six-coordinate copper(II) complexes 9

1.5.2 Bi-nuclear copper(II) carboxylate complexes 10

1.5.3 Trinuclear copper(II) carboxylate complexes 12

1.5.4 Polynuclear copper(II) complexes 12

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1.6 Supra-molecular architectures based on copper(II) carboxylates: 13

1.7 The diamine ligands 14

1.8 Aims and Objectives 16

Chapter-2 LITERATURE REVIEW 17

Chapter-3 EXPERIMENTAL 27

3.1 Materials and methods 27

3.2 Single crystal X–ray structure determination of complexes 27

3.2.1 Single crystal X–ray structure determination of complexes 1a-11a 28

3.2.2 Single crystal X–ray structure determination of complexes 1b-2b 35

3.2.3 Single crystal X–ray structure determination of complexes 1c-2c 36

3.3 Antimicrobial activity measurement (Agar well diffusion method) 38

3.3.1 Antimicrobial activity of complexes 1a-11a 38

3.3.2 Antimicrobial activity of complexes 1b-2b 39

3.3.3 Antimicrobial activity of complexes 1c-2c 39

3.4 General procedures for the syntheses of complexes 40

3.4.1 General procedures for the syntheses of complexes 1a-11a 40

3.4.1.1 Synthesis of [Cu(tmen)(BA)2(H2O)2] (1a) 40

3.4.1.2 Synthesis of [Cu(tmen)(salH)2H2O] (2a) 41

3.4.1.3 Synthesis of [Cu(tmen)(mef)2] (3a) 42

3.4.1.4 Synthesis of [Cu(tmen)(pABA)2]. 1/2 MeOH) (4a) 42

3.4.1.5 Synthesis of [Cu(tmen)(o-ClBA)2] (5a) 43

3.4.1.6 Synthesis of [Cu(tmen)(cinn)2]. H2O (6a) 43

3.4.1.7 Synthesis of [Cu(tmen)(phtH)2] (7a) 44

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3.4.1.8 Synthesis of [Cu(tmen)(tpht)(H2O)2]n (8a) 45

3.4.1.9 Synthesis of [Cu(tmen)(succin)] .4H2O}n(9a) 45

3.4.1.10 Synthesis of {[Cu2(tmen)2(tart)2]·2H2O}n(10a) 45

3.4.1.11 Synthesis of [Cu(en)(salH)Cl]n(11a) 46

3.4.2 General procedures for the syntheses of complexes 1b-2b 47

3.4.2.1 Synthesis of [Cu(bipy)(cinn)2H2O] (1b) 47

3.4.2.1 Synthesis of Cu2(bipy)2(pABA)3(pABAH)]. Cl. 3H2O (2b) 48

3.4.3 General procedures for the syntheses of complexes 1c-2c 49

3.4.3.1 Synthesis of [Cu(phen)(benzoate)2] (1c) 49

3.4.3.2 Synthesis of [Cu(phen)(m-ABA)Cl].·½H2O (2c) 49

Chapter-4 RESULTS AND DISCUSSION 50

4.1 FTIR Spectroscopic Studies of Complexes 50

4.1.1 FTIR Spectroscopic Studies of Complexes 1a-11a 50

4.1.1.1 FTIR Studies of copper(II)-tmen complex (1) 52

4.1.1.2 FTIR Studies of [Cu(tmen)(BA)2(H2O)2] (1a) 52

4.1.1.3 FTIR Studies of [Cu(tmen)(salH)2H2O] (2a) 55

4.1.1.4 FTIR Studies of [Cu(tmen)(mef)2] (3a) 57

4.1.1.5 FTIR Studies of [Cu(tmen)(pABA)2].1/2 MeOH) (4a) 59

4.1.1.6 FTIR Studies of [Cu(tmen)(o-ClBA)2] (5a) 61

4.1.1.7 FTIR Studies of [Cu(tmen)(cinn)2]. H2O (6a) 63

4.1.1.8 FTIR Studies of [Cu(tmen)(phtH)2](7a) 65

4.1.1.9 FTIR Studies of [Cu(tmen)(tpht)(H2O)2]n(8a) 67

4.1.1.10 FTIR Studies of [Cu(tmen)(succin)] .4H2O}n (9a) 69

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4.1.1.11 FTIR Studies of {[Cu2(tmen)2(tart)2]·2H2O}n (10a) 71

4.1.1.12 FTIR Studies of [Cu(en)(salH)Cl]n (11a) 73

4.1.2 FTIR Spectroscopic Studies of Complexes 1b-2b 75

4.1.2.1 FTIR studies of Cu(II)-2,2′-bipyridine complex (2) 75

4.1.2.1 FTIR Studies of [Cu(bipy)(cinn)2H2O] (1b) 75

4.1.2.2 FTIR Studies of [Cu2(bipy)2(pABA)3(pABAH)]. Cl.3H2O (2b) 76

4.1.3 FTIR spectroscopic studies of complexes 1c-2c 81

4.1.3.1 FTIR Studies of [Cu(phen)(benzoate)2] (1c) 81

4.1.3.2 FTIR Studies of Cu(phen)(m-amb)Cl·½H2O (2c) 83

4.2 Uv-Visible spectroscopic studies of complexes 85

4.2.1 Uv-Visible spectroscopic studies of complexes 1a-11a 85

4.2.2 Uv-Visible spectroscopic studies of complexes 1b-2b 85

4.2.3 Uv-Visible spectroscopic studies of complexes 1c-2c 86

4.3 Thermal studies of complexes 87

4.3.1 Thermal studies of complexes 1a-11a 87

4.3.1.1 Thermal studies of [Cu(tmen)(BA)2(H2O)2] (1a) 87

4.3.1.2 Thermal studies of [Cu(tmen)(salH)2H2O] (2a) 88

4.3.1.3 Thermal studies of [Cu(tmen)(mef)2] (3a) 91

4.3.1.4 Thermal studies of [Cu(tmen)(pABA)2]. 1/2 MeOH) (4a) 91

4.3.1.5 Thermal studies of [Cu(tmen)(o-ClBA)2] (5a) 95

4.3.1.6 Thermal studies of [Cu(tmen)(cinn)2]. H2O (6a) 95

4.3.1.7 Thermal studies of [Cu(tmen)(phtH)2] (7a) 98

4.3.1.8 Thermal studies of [Cu(tmen)(tpht)(H2O)2]n 8a 98

xiv

4.3.1.9 Thermal studies of [Cu(tmen)(succin)] .4H2O}n 9a 101

4.3.1.10 Thermal studies of {[Cu2(tmen)2(tart)2]·2H2O}n (10a) 101

4.3.2 Thermal studies of complexes 1b-2b 104

4.3.2.1 Thermal studies of [Cu(bipy)(cinn)2H2O] (1b) 104

4.3.2.2 Thermal studies of [Cu2(bipy)2(pABA)3(pABAH)]. Cl. S3H2O (2b) 105

4.3.3 Thermal studies of complexes 1c-2c 108

4.3.3.1 Thermal studies of [Cu(phen)(benzoate)2] (1c) 108

4.3.3.2 Thermal studies of Cu(phen)(m-amb)Cl·½H2O (2c) 108

4.4 X-ray Structure Description of Complexes 111

4.4.1 X-ray Structure Description of Complexes 1a-11a 111

4.4.1.1 X-ray Structure Description of complex (1a) 111











4.4.2 X-ray Structure Description of Complexes 1b-2b 145

4.4.2.1 X-ray Structure Description of complex (1b) 145

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4.4.2.2 X-ray Structure Description of complex (2b) 149

4.4.3 X-ray Structure Description of Complexes 1c-2c 154

4.4.3.1 X-ray Structure Description of complex (1c) 154

4.4.3.2 X-ray Structure Description of complex (2c) 157

4.5 Antimicrobial activity of complexes 160

4.5.1 Antimicrobial activity of complexes 1a-11a 160

4.5.2 Antimicrobial activity of complexes 1b-2b 161

4.5.3 Antimicrobial activity of complexes 1c-2c 161

CONCLUSIONS 164

FUTURE RESEACH WORKS 169

REFERENCES 170

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LIST OF TABLES

Table Title Page

1.1 Common oxidation states of copper with their coordination geometries 2

3.1 Structure refinement parameters of complexes 1a-2a 29





3.6 Structure refinement parameters of complex 11a 34

3.7 Structure refinement details for complexes 1b and 2b 35

3.8 Structure refinement parameters of the complexes 1c and 2c 37

4.1 Selected bond lengths (A˚) and angles (˚) for complex (1a) 114

4.2 Bond separations (Å) and bond angles (˚) in the complex (1a) 114

4.3 Selected bond lengths (Å) and angles (˚) for complex (2a) 116


4.5 Selected geometric parameters (A˚, ˚) for (3a) 119



4.8 Selected geometric parameters (A˚, ˚) for{[Cu(tmen)(Clba)2]·(5a) 125




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4.14 Selected geometric parameters (A˚, ˚) for complex (8a) 133




4.18 Selected geometric parameters (A˚, ˚) for {[Cu2(tmen)2(tart)2]·2H2O}n (10a) 140

4.19 Selected geometric parameters (A˚, ˚) for [Cu(en)(salH)Cl]n(11a) 143


4.21 Selected bond lengths (A˚) and angles (˚) for complex (1b) 148

4.22 Bond separations (Å) and bond angles (˚) in the complex (1b) 148

4.23 Selected bond lengths (Å) and angles (˚) for complex (2b) 152

4.24 Bond separations (Å) and bond angles (˚) in the complex (2b) 153

4.25 Selected bond distances (Å) and bond angles (o) for compounds (1c) 155

4.26 Selected bond lengths (Å) and angles (˚) for complex (2c) 158

4.27 Bond separations (Å) and bond angles (˚) in the complex (2c) 158

4.28 The antimicrobial activity data of complexes with inhibition zones (mm) against the

bacterial strains 162

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LIST OF FIGURES

Figure Title Page

1.1. Different coordination modes of metal carboxylates 6

1.2 Different lone pairs of metal carboxylates 6

1.3 Various bridging modes in metal carboxylates 7

1.4 Four-coordinate copper(II) complexes 8

1.5 Copper(II) complexes with square pyramidal geometry 9

1.6 Examples of complexes with octahedral geometry around copper(II) ion 10

1.7 X-ray structures of binuclear copper(II) carboxylates 11

1.8 X-ray structure of trinuclear complex [Cu3(dns)2(dnsH)2(H2O)4].4H2O 12

1.9 X-ray structures of polymeric copper(II) carboxylates 13

2.1 Copper(II) complexes of tmen with monocarboxylates 19

2.2 Copper(II) complexes of tmen with dicarboxylates 20

2.3 Copper(II) complexes of tmen with carboxylates 21

2.4 Structures of ternary copper(II)-bipy-carboxylates 24

2.5 Copper(II) complexes of phen with benzoate and 2-fluorobenzoate 25

4.1 FT-IR spectrum of copper(II)-tmen complex (1) 51

4.2 FT-IR spectrum of [Cu(tmen)(BA)2(H2O)2] (1a) 54

4.3 FT-IR spectrum of [Cu(tmen)(salH)2H2O] (2a) 56

4.4 FT-IR spectrum of [Cu(tmen)(mef)2] (3a) 58

4.5 FT-IR spectrum of [Cu(tmen)(pABA)2].1/2 MeOH) (4a) 60

4.6 FT-IR spectrum of [Cu(tmen)(o-ClBA)2] (5a) 62

4.7 FT-IR spectrum of [Cu(tmen)(cinn)2]. H2O (6a) 64

xix

4.8 FTIR spectrum of [Cu(tmen)(phtH)2] (7a) 66

4.9 FT-IR spectrum of [Cu(tmen)(tpht)(H2O)2]n (8a) 68

4.10 FT-IR spectrum of [Cu(tmen)(succin)] .4H2O}n (9a) 70

4.11 FT-IR spectrum of {[Cu(tmen)(tart)]·2H2O}n (10a) 72

4.12 FT-IR spectrum of [Cu(en)(salH)Cl]n (11a) 74

4.13 FT-IR spectrum of Cu(II)-2,2′-bipyridine complex (2) 78

4.14 FT-IR spectrum of [Cu(bipy)(cinn)2H2O] (1b) 79

4.15 FT-IR spectrum of [Cu2(bipy)2(pABA)3(pABAH)]. Cl. 3H2O (2b) 80

4.16 FT-IR spectrum of [Cu(phen)(benzoate)2] (1c) 82

4.17 FT-IR spectrum of [Cu(phen)(m-ABA)Cl[.·½H2O (2c) 84

4.18 Thermogram of [Cu(tmen)(BA)2(H2O)2] (1a) 89

4.19 Thermogram of [Cu(tmen)(salH)2 H2O] (2a) 90

4.20 Thermogram of [Cu(tmen)(mef)2] (3a) in N2 92

4.21 Thermogram of [Cu(tmen)(mef)2] (3a) in static air 93

4.22 Thermogram of [Cu(tmen)(pABA)2]. 1/2 MeOH) (4a) in N2 94

4.23 Thermogram of [Cu(tmen)(o-ClBA)2] (5a) in N2 96

4.24 Thermogram of [Cu(tmen)(cinn)2]. (H2O) (6a) 97

4.25 Thermogram of [Cu(tmen)(phtH)2] (7a) 99

4.26 Thermogram of [Cu(tmen)(tpht)(H2O)2]n (8a) 100

4.27 Thermogram of [Cu(tmen)(succin)]. 4H2O}n (9a) 102

4.28 Thermogram of {[Cu(tmen)(tart)]·2H2O}n (10a) 103

4.29 Thermogram of [Cu(bipy)2(cinn)(H2O)] (1b) 106

4.30 Thermogram of [Cu2(bipy)2(pABA)3(H-pABA)]. Cl. 3H2O (2b) 107

xx

4.31 Thermogram of [Cu(phen)(benzoate)2] (1c) 109

4.32 Thermogram of Thermogram of [Cu(phen)(m-ABA)Cl].·½H2O (2c) 110

4.33 ORTEP diagram (25 % ellipsoid probability) of the molecular structure of 1a 114

4.34 Selected part of the 1D chains of 1a 114

4.35 ORTEP diagram (50 % ellipsoid probability) of 2a 117

4.36 Packing diagram of 2a with hydrogen bonding interactions 117

4.37 ORTEP diagram (50 % ellipsoid probability) of 3a 120

4.38 ORTEP diagram (25 % ellipsoid probability) of the molecular structure of (4a) 122

4.39 Graphical illustration of the repetitive element of the 3D network formed by 4a 122


4.41 Packing diagram of complex 5a 124





4.46 Packing diagram of 8a 134





4.51 The building units in 11a showing 50 % displacement ellipsoids. 144

4.52 ORTEP diagram (50 % ellipsoid probability) of the molecular structure of 1b 147

4.53 ORTEP diagram (25 % ellipsoid probability) of the molecular structure of 2b 151

xxi

4.54 The molecular structure of 1c (50% displacement ellipsoids) 156

4.55 Fragment of a [001] hydrogen-bonded chain of 1c molecules 157

4.56 The molecular structure of 2c showing 50% displacement ellipsoids 159

4.57 Fragment of a [101] polymeric chain in the structure of 2c 159

xxii

LIST OF SCHEMES

Scheme Title Page

1.1 The NᴖN-chelating diamines used in research work 15

2.1 Ligands used in research work for 1b and 2b 23

2.2 Ligands used in research work for 1c and 2c 25

3.1 Schematic sketch of synthetic procedure for complex 4a 43

3.2 Schematic sketch of synthetic procedure for complexes 3a and 5a 43

3.3 Schematic sketch of synthetic procedure for complexes 6a and 7a 44

3.4 Schematic sketch of synthetic procedure for complexes 8a, 9a and 10a 46

3.5 Schematic sketch of synthetic procedure for complexes (1b) and (2b) 48

xxiii

LIST OF ABBREVIATIONS AND SYMBOLS

Abbreviations Description

Δ change in

° degrees

°C degree centigrade

> greater than

< less than

λ max wavelength of maximum absorption

ѵ wavenumber cm-1 (FT-IR)

en ethylenediamine

phen 1, 10-phenanthroline

bipy 2,2'-bipyridine

salH2 salicylic acid

Hcinn cinnamic acid

cinn1- cinnamate

pABA1- 4-aminobenzoate

mABA1- 3-aminobenzoate

phtH2 phthalic acid

tphtH2 terephthalic acid

succH2 succinic acid

EtOH ethanol

MeOH methanol

NSAIDs non-steroidal anti-inflammatory drugs

% percent

1D one-dimensional

2D two-dimensional

3D three-dimensional

Å angstrom

aq aqueous phase

m.p. melting point

xxiv

cm-1 wavenumber (IR)

e. g. for example

FTIR Fourier Transform Infrared

i.e., that is

IR infrared

mmol millimole

pH -log10[H+]

UV-Vis Ultraviolet-Visible

XRD X-Ray Diffraction

DMSO Dimethyl sulfoxide

CSD Cambridge structural database

1

CHAPTER 1

INTRODUCTION

1.1 Chemistry of Copper

Copper is a reddish colored, malleable, ductile and corrosion resistant metal. Copper, is the

29th element of the periodic table, and along with its heavier congeners-the other two coinage

metals i.e, silver (Ag) and gold (Au), it belongs to group 11 of the periodic table. The

electronic configuration of copper is [Ar] 3d10, 4s1 [1]. Although it has a relative abundance

of 68 ppm in the earth's crust, it is still the earth's 25th most abundant transition metal [2, 3].

Copper with its high electrical conductivity-which is second only to that of silver, is used in

making electrical wires [4]. Copper has three different oxidation states including, Cu1+, Cu2+,

and Cu3+. More commonly copper exists in +2 oxidation state. Copper(III) complexes are

mostly available in mixed-valent polynuclear copper complexes and have important role in

homogeneous catalysis [5].

The oxidation potential for Cu+/Cu+2 (Eo=-0.15) is less negative than that for the

Cu/Cu1+ (Eo= -0.52). Any oxidizing agent that can oxidize Cu/Cu+, can even more easily

convert Cu+ to Cu+2 , which justifies why Cu+2 is the most common oxidation state of copper.

The properties of copper in coordination chemistry are due to the almost noble metal

character, the intermediate stability, the reactivity of the d10 electron configuration in Cu(I),

and the relative small radius of the Cu(II) ion, which contributes to the high energy of

hydration and thus to the higher stability of Cu(II) (aq) over Cu(I) (aq) [6]. Cu (I) ions need

to be stabilized by chelating ligands.

Cu1+ has a d10 configuration and is associated with regular, cubic coordination

geometries. The preferred coordination geometries of such complexes are four-coordinated

tetrahedral or trigonal pyramidal structures, but three- and two- coordinate complexes have

also been reported. Furthermore, five-coordinated Cu(I) complexes are well known for

adopting either a square pyramidal or a trigonal bipyramidal geometry [7, 8].

2

Table 1.1: Common oxidation states of copper with their coordination geometries

Oxidation

state

Coordination

Number Shape Examples

Cu(I), d10 2 Linear CuCl21-, CuBr21-

3 Planar K[Cu(CN)2], [Cu(SPMe3)3]ClO4

4 Tetrahedron [Cu(MeCN)4]+,CuI,[Cu(CN)4]-3

4 Distorted square

planar CuBr

5 Square pyramidal [CuBrCO]

CuII, d9 3 Trigonal planar Cu2(µ-Br)2Br2

4 Square planar CuO, [Cu(py)4]

5 Square pyramidal [Cu(pht)(phen)2]

6 Distorted

octahedron

[Cu(SO4)(C2H8N2)2]n,

K2[Cu(EDTA)]

6 Octahedron K2Pb[Cu(NO2)6]

3

1.2 Chemistry of copper (II)

Copper(II) is the most common oxidation state of copper, as Cu(I) has a great tendency to be

oxidized to Cu(II), while Cu(II) shows little tendency for further oxidization to Cu(III). The

electronic configuration of copper (II) is [Ar] 3d94So. Cu2+ has a d9 configuration and in an

environment of cubic symmetry, can manifest Jahn-Teller distortions. Copper (II) complexes

possess a variety of coordination geometries and usually form tetrahedral, square planar,

square pyramidal, tetragonal and octahedral complexes.

1.2.1 General metabolic functions of copper

Copper is a biologically essential trace micronutrient and is found in all living organisms. Its

importance is also evident from the fact that, after iron and zinc, copper comes third in

abundance in the human body. Most of the copper is stored in liver, though its total amount

in the body is from 75 mg to 100 mg, it is found in every cell, especially in major organs like

brain, kidney, muscles and heart [9]. Copper also plays a pivotal role in our metabolism, as

many critical enzymes are copper dependent like oxidases and oxygenases [10].

Copper is required for the function of over 30 proteins It is acts as a cofactor and is

responsible for structural and catalytic properties of many metallo-enzymes. These enzymes

perform an array of biological processes. Some examples of cuproenzymes, together with

their biological role may include, cytochrome-c oxidase (electron transport, mitochondrial

oxidative phosphorylation, energy production and synthesis of phospholipids found in myelin

sheaths) [11], ceruloplasmin (feroxidase I) and feroxidase II (oxidation of Fe2+ to Fe3+,

transportation of Fe3+ to the red blood cells and blood formation), lysyl oxidase (synthesis of

collagen and elastin-which form connective tissue, and bone formation), tyrosinase (melanin

synthesis-pigmentation of hair, skin and eyes) [12], dopamine ß-hydroxylase (catecholamine

production, conversion of the neurotransmitter dopamine into norepinephrine) [13],

monoamine oxidase (oxidation of monoamines, metabolism of the neurotransmitters,

breakdown of the serotonin) [14], catechol oxidase (synthesis of melanin, conversion of

ortho-diphenols to the corresponding o-quinones accompanied by the reduction of oxygen to

water [15], copper/zinc superoxide dismutase (antioxidant), ceruloplasmin (anti-

inflammatory activity), iron metabolism, and copper transport in living organism [16, 17].

4

1.3 Biological activities of copper (II) complexes

Copper (II) complexes have been found to be excellent SOD-mimetic agents. Copper/zinc

superoxide dismutase (Cu-Zn-SOD) is an antioxidant enzyme that contains an active site, in

which zinc (II) and copper (II) are bridged by deprotonated imidazole. It converts/ dismutates

superoxide ion into less harmful species i.e., H2O2 [18] in biological systems.

2O2−. + 2H+ → O2 + H2O2

This detoxification is proton assisted and is dependent on the ease of Cu(I)/Cu(II)

redox inter conversions [18]. Copper is also necessary for the synthesis of thyroxine, while

many Cu-containing proteins are involved in the electron transfer processes. Being a free

radical scavenger, copper acts as an antioxidant and prevents cell from damage [19].

Although, antioxidant enzymes like Cu-Zn-SOD, can be regarded as the organism’s

first line of antioxidant defense, their supplementation in treating such disorders, like

Alzheimer’s disease, and Parkinson’s disease however, is restricted. The reason is that

because of their high molecular weights, these cannot cross the cell membranes [20] and are

also rapidly degraded in biological systems [21]. A recent approach involves synthesis of low

molecular weight complexes that can mimic the enzyme activity. An important class of such

materials constitutes copper(II) complexes of N- and O-donor ligands. Many such copper(II)

complexes are considered as antimicrobial, antiviral, anti-inflammatory agents [22, 23].

These copper(II) complexes have also been found effective in the treatment of a

number of diseases including cancer and tumors due to their superoxide scavenging ability

[24, 25]. Low molecular weight copper complexes are important owing to their potential use

as catalysts in selective oxidation reactions [26]. Catalysis of oxygenation reaction in nature

occurs through metalloproteins having copper containing active sites [27].

Synthetic biomimetic copper complexes which can act as model systems for the study

of O2-activation chemistry are investigated [5, 28]. Such systems are synthetic analogues of

naturally occurring copper proteins like hemocyanin-a respiratory protein in arthropods and

mollusks that reversibly binds O2, and other enzymes [5].

5

1.4 Metal carboxylate chemistry and their coordination modes

Metal carboxylates are extensively studied in various fields of chemistry including; inorganic

chemistry, coordination chemistry, bioinorganic chemistry, magnetochemistry, and

supramolecular chemistry. Being versatile ligands, they can assume different coordination

modes and can also have different nuclearities. Copper as a central metal atom, also has the

ability to coordinate with a great number of ligands to form coordinate complexes of varying

structural geometries, nuclearities and dimensions [29, 30].

The ubiquitous metal-carboxylate complexes are well known for their extensive

applications. From the coordination chemistry point of view, the bonding, structures, and

properties of metal carboxylates have inspired much interest of researchers. The coordination

between the carboxylate ligand and the metal can be classified into four different categories.

(i) Metal carboxylates having ionic nature

Ionic carboxylates have little cation-anion interaction [31, 32], as there are only coulombic

forces of attraction between positively charged metal ion and the negatively charged

carboxylates. The ionic carboxylates of all alkali metals, with the exception of lithium have

been reported, for example in sodium formate, the electrons are delocalised in the

carboxylate group and both C-O bonds are equal with the bond length of 1.27A [33].

(ii) Metal carboxylates with monodentate coordination mode

In lithium acetate (Li(CH3COO). 2H2O) the carboxylate moiety of acetate ion coordinates in

a monodentate fashion [34], as a result, one of the C-O bond distance involving the

carboxylate oxygen directly coordinated to lithium is longer (1.33 A) than the other O atom

which is doubly bonded to carboxylate carbon atom (1.22A).

(iii) Metal carboxylates with bidentate (chelating) coordination mode

In this mode, the carboxylate ion acts as a bidentate ligand, and coordinates to a metal centre

through its two carboxylate-O atoms, and forms a four-membered ring containing the metal

ion. This coordination can be either symmetrical bidentate chelating, having same C-O bond

6

lengths or asymmetrical bidentate chelating, having different C-O bond lengths. An example

of such complexes is Zn(CH3COO)2. 2H2O [35].

(i) (ii) (iii) (iv)

Figure 1.1: Different coordination modes of metal carboxylates; (i) Ionic, (ii) monodentate, (iii) bidentate (sym), (iv) bidentate (asym)

(iv) Metal carboxylates with bridging coordination modes

The bridging modes can be classified into four basic types, depending on which electron

pairs (whether syn or anti), of carboxylate oxygens are used to coordinate with the metal

centre. These include syn-syn, syn-anti, anti-anti, and monodentate terminal bridging or

monoatomic bridging coordination modes (figure 1.3). The examples of each type include

Cu(O2CMe)2. 2H2O [36], Cu(O2CH)2 [37], Cu(O2CH)2. 4H2O [38], and

Hg(O2CMe)2(C6H11)3P) [39], respectively.

O

O

R

:

:

::

syn

anti

anti

Figure 1.2: Different lone pairs of metal carboxylates

The syn- electron pairs are more basic and geometry of the syn-syn bridge can bring

the metal centers close enough for magnetic interactions, which may lead to unusual

magnetic properties [40, 41]. The syn-syn mode is observed in dinulear complexes like

7

copper(II) acetate dihydrate. In this Cu(II) carboxylate complex, the two copper centers are

connected through four syn-syn bridges, formed by four carboxylate groups, giving it a

paddle wheel or lantern shape. The anti-anti mode is observed in many carboxylate

complexes of ruthenium [42]. Monodentate terminal bridging (monoatomic bridging) mode

is quite rare and is actually an intermediate between other bridging modes. One such

complex is [Mn2(sal)4(H2O)4] [43].

A B C D

Figure 1.3: Various bridging modes in metal carboxylates: A= syn-syn, B= syn-anti,

C= anti-anti, D= monoatomic bridging

1.5 Structures and molecular geometries of copper (II)-carboxylate complexes

In the synthesis of copper(II) carboxylates, the copper(II) center acts as a lewis acid of

intermediate strength, which accepts electron pairs from caboxylate-O donor atoms. As

discussed above, these copper(II) caboxylate complexes may be tetra, penta, or hexa

coordinate and can possess versatile geometries and coordination modes. Their most

commonly encountered geometries are tetrahedral, square-planar, square-pyramidal, and

octahedral. Similarly, on the basis of nuclearity, these copper(II) carboxylates can be

classified as mononuclear, dinuclear to polynuclear.

1.5.1 Geometries of mononuclear copper(II) carboxylates

Mononuclear complexes can assume a variety of coordination geometries. The tetrahedral,

square planar, square pyramidal, trigonal bipyramidal, and octahedral geometries are

discussed as follows.

8

1.5.1.1 Four-coordinate complexes:

Most of the copper(II) carboxylate complexes tend to assume geometries with higher

coordination numbers. This can be attributed to the oxophilicity of copper(II), due to which,

copper(II) exhibits the tendency to expand its coordination sphere and forms dimeric to

polymeric complexes [44]. Though tetrahedrally coordinated, homoleptic copper(II)

carboxylates are not known. However, the ternary copper(II) carboxylate complexes having

tetrahedral geometry have been reported.

A B

Figure 1.4: Four-coordinate copper(II) complexes; A= with distorted tetrahedral geometry

[Cu(neocuproine)(salH)2], B= having square planar geometry [Cu(O2CMe)2(bipy)]

One example of a tetrahedral complex is [Cu(neocuproine)(salH)2], which is a

copper(II) complex of neocuproine (2,9-dimethyl-1,10-phenanthroline), and salicylic acid.

The complex has two asymmetric units. Each Cu(II) ion is four-coordinated by two N atoms

from chelating neocuproine, and two O atoms from two salicylate (salH1-) anions. The

CuO2N2 unit adopts a distorted tetrahedral geometry (figure 1.4A) [45]. The example of

square planar complex is [Cu(O2CMe)2(bipy)](figure 1.4B) [46].

Out of the two tetra-coordinate geometries, square planar geometry is more stable

than the tetrahedral one and hence, is more frequently encountered [45-48]. The reason for

the non expansion of coordination number may be attributed to the stability of the square

planar geometry due to the steric interactions of the attached ligands, which prevent other

incoming groups from approaching closer to the central metal ion. All these complexes show

9

π-π stacking interactions between aromatic rings, and an extensive O-H…O and N-H…O

hydrogen-bonding network, which stabilize crystal lattice.

1.5.1.2 Five-coordinate copper(II) complexes

Both square pyramidal and trigonal bipyramidal geometries most frequently occur in five-

coordinate copper(II) complexes. EPR studies of penta-coordinated Cu(II) complexes have

shown that these two geometries are interconvertible. This change is temperature-dependent

and involves shifting of the unpaired d electron on copper(II) ion from the dz2 (in trigonal

bipyramidal geometry) to the dx2-y2 orbital (in square pyramidal geometry) [49].

A B

Figure 1.5: Copper(II) complexes with square pyramidal geometry; A =

[Cu(neocuproine)(5-chloro-2-hydroxybenzoate)2], B= [CuCl(neocuproine)(benzoate)]

Ternary mononuclear copper(II) complexes of neocuproine (2,9-dimethyl-1,10-

phenanthroline) with 5-chloro-2-hydroxybenzoate (figure 1.5A) [50], benzoate (figure 1.5B)

[51], 2-hydroxybenzoate [45] and 4-hydroxybenzoate [52] can be quoted as examples in

which the coordination environment around the central copper atom is square pyramidal.

Trigonal bipyramidal geometry is exemplified in (figure 1.7 C) [53] in dimeric complexes.

1.5.1.3 Six-coordinate copper(II) complexes

Hexa-coordinate copper(II) complexes assume octahedral coordination geometry. A number

of mononuclear copper(II) carboxylate complexes are known to possess octahedral

10

coordination geometry. In the complex [Cu(C7H6N2)2(C7H5O3)2], (where C7H6N2

=benzimidazole, C7H5O3 = 4-hydroxy-benzoate anion), the CuN2O4 chromophore assumes

distorted octahedral geometry by two benzimidazole ligands and two chelating 4-

hydroxy-benzoate anions. Neighboring benzimidazole groups are also interlinked through

π-π stacking interations [54].

A B

Figure 1.6: Copper(II) complexes with octahedral geometry around copper(II) ion.

A = [Cu(ndmen)2(salH)2].H2O, B = [Cu(C12H8N2)(C9H9O4)2]

The X-ray crystal structure of [Cu(salH)2(ndmen)2].·H2O (where ndmen=N,N-

dimethylethylenediamine) (figure 1.6 A) shows that the CuN4O2 chromophore in the complex

is coordinated by two chelating ndmen ligands in trans disposition and two monodentate

salicylate ions leading to distorted trans-octahedral geometry [55]. The monomeric complex

[Cu(C12H8N2)(C9H9O4)2] (where C12H8N2 = 1,10-phenanthroline, C9H9O41- = 3,4-

dimethoxybenzoate1-) also has octahedral geometry (figure 1.6 B) [56].

1.5.2 Bi-nuclear copper(II) carboxylate complexes

Dimeric copper(II) carboxylate derivatives are frequently encountered among copper(II)

complexes. Depending on whether syn or anti electron pairs are involved in coordination,

bridging carboxylates can assume syn-syn, syn-anti, or anti-anti orientations.

Many dinuclear copper(II) carboxylates possess the classical paddlewheel (lantern)

type structure. This familiar motif is present in [Cu(salH)4(EtOH)(H2O)] (figure 1.7 A), in

11

which the two copper centers are linked by four carboxylato oxygens from four salH1- anions

in a syn-syn fashion, while apical positions are occupied by ethanol (EtOH) and water

molecules [57].

In dimeric complex [Cu2(bipy)2(salH)(sal)]. ClO4, the cationic moiety

[Cu2(bipy)2(salH)(sal)]1+ has two copper(II) centers, each Cu(II) is coordinated by a

chelating 2,2ʹ-bipyridine and by a monodentate carboxylate-O atom and phenolate-O atom of

salicylate ion. This complex is of interest because, one salicylate ligand, still has its

carboxylic H-atom in an undissociated form [58].

A B C

Figure 1.7: X-ray structures of binuclear copper(II) carboxylates; A= [Cu(salH)4(EtOH)(H2O)], B= [Cu2(bipy)2(OAc)3], C= [{Cu(phen)2}2(μ-CH3COO)][PF6]3

The structure of dinuclear copper(II) complex, [{Cu(phen)2}2(μ-CH3COO)][PF6]3, is

interesting as two independent Cu(II) centers show two different geometries with a trigonal

bipyramidal geometry for the Cu1 center and a distorted square-based pyramidal geometry

for the Cu2 center, each copper center is bridged by an acetate anion and shows a syn–anti

coordination mode (figure 1.7 C) [53].

Another complex [Cu2(bipy)2(OAc)3], is dimeric, consisting of two copper(II)

centres, each coordinated by a cheating bipy, and bridged by three acetate1- anions, two in

bridging chelating mode and the third OAc1- in the rare mono-atomic bridging mode (figure

1.7 B) [59]. The crystal structure of dimeric complex [Cu(Neo)(sal)]2 shows that the

coordination geometry of Cu(II) ions is a distorted square pyramid [50].

12

1.5.3 Trinuclear copper(II) carboxylate complexes

Valigura et al (2004) reported a trinuclear complex [Cu3(dns)2(Hdns)2(H2O)4]. 4H2O (where

dnsH2 = 3,5-dinitrosalicylic acid). In this centrosymmetric complex, Cu1 centre is square

planar, whereas the outer Cu2 and Cu3 centres exhibit square pyramidal geometries. Each

outer copper(II) is coordinated by a phenoxy-O and a carboxylate-O from dnsH1- ligands,

while the inner Cu(II) is coordinated by two bridging chelating dns2- groups and hence is

connected to both outer Cu(II) ions (figure 1.8) [60].

Figure 1.8: X-ray structure of trinuclear complex [Cu3(dns)2(dnsH)2(H2O)4].4H2O

1.5.4 Polynuclear copper(II) complexes

Copper(II) carboxylates with more than three copper(II) centers are also frequent. A

hexanuclear complex [Cu6(tmen)6(µ-N3)2(µ-C2O4)3(H2O)2][ClO4]4. 2H2O (where tmen =

Me2NCH2CH2NMe2, N31-= azido1- , C2O42- = oxalate2-) [61] has been reported. Adducts of

copper(II) benzimidazole with malonate2- (figure 1.9 A) and salicylate1- (figure 1.9 B) anions

lead to two polynuclear complexes including catena-((μ2-malonato)-aqua-(1H-

benzimidazole)copper(II)) [62], and Catena-((μ2-salicylato)-bis(1H-benzimidazole)-

(salicylato)-copper(II)) [63], respectively.

13

A B C

Figure 1.9: X-ray structures of polymeric copper(II) carboxyates; A = catena-((μ2-

malonato)-aqua-(1H-benzimidazole) copper(II)), B = Catena-((μ2-salicylato)-bis(1H-

benzimidazole)-(salicylato)-copper(II)), C = [Cu(ipt)(dap)H2O]n. nH2O

The complex [Cu(ipt)(dap)H2O]n. nH2O (where ipt2- = 1,3-benzenedicarboxylate

dianion, dap = 1,3-diaminopropane) shows a distorted square pyramidal structure in which

two O atoms, one each from bridging ipt2- units, and the two N atoms of the chelating bonded

dap ligand form the basal square plane, while the aqua-O atom occupies axial position (figure

1.9 C) [64].

1.6 Supra-molecular architechtures based on copper(II) carboxylates

The design and construction of metal-organic frameworks is important in the fields of supra-

molecular chemistry and crystal engineering. Both covalent and non covalent interactions

play an important role in the self-assembly of supramolecules and in molecular recognition.

Non-covalent interactions (also called van der Waals interactions) can be categorized in to

following main types including; halogen-halogen and C-H…X interactions (where X= O, N,

F, Cl or Br etc.), hydrogen bonding interactions for example of O-H…O, N-H…O type, and

π···π interactions especially among aromatic systems.

Among these, hydrogen bonding and π···π interactions play a crucial role in

establishing structure-activity relationship in various biological processes [65, 66]. Cation…π

14

interactions play an important role in the selectivity process of potassium channels, while

anion…π type interactions are under study for their potential applications as anion receptors

in molecular recognition [67-70].

The metal-organic frameworks with 1-D, 2-D, and 3-D spatial arrangements can be

designed with organic molecules having hydroxyl, floro, amino and carboxylate functional

groups.

In our research work, some of the synthesized mixed ligand copper(II) carboxylates

contain hydroxyl, chloro and amino groups in addition to carboxylate group as a major

functionality. In almost all complexes, the carboxylate moiety is in deprotonated form and

because of the absence of carboxylate-H atom, the COO1- moiety can only form hydrogen

bonds with aqua-H atoms of either coordinated and/or lattice water molecules which serve to

keep the complex molecules together via extensive H-bonding.

1.7 The diamine ligands

In order to synthesize metallopharmaceuticals which have less toxicity, more selectivity

and and can bind through non covalent interactions, the diamine adducts of copper(II)

carboxylates were selected. In this respect both open chain diamines like N,N,N′,N′-

tetramethylethylenediamine and ethylenediamine as well as NᴖN heterocyclic diamines like

bipyridine, and 1,10-phenanthroline have been used in our work. These diamines-׳2,2

although exhibit invariably bidentate (chelating) coordination mode, but their synthesized

ternay complexes with carboxylate ligands manifest great structural diversity and showed a

variety of coordination modes and geometries. Most of these diamines have been reported to

possess antimicrobial effects.

Onawumi O. O. E.et al (2013) reported two complexes, [Cu(en)(phen)2]·2Br1-.

2Phen.·8H2O and [Cu(en)(phen)2]ClO4, having [Cu(en)(phen)2]2+ cation with antimicrobial

activities similar to the known standard drugs including amplicilline, chloramphenicol,

15

ciprofloxacin and norfloxacin [71]. Both 1,10–phenanthroline and 2,2ʹ–bipyridine are

bidentate chelating ligands that form very stable complexes with copper(II) ion.

NNCH3

CH3

CH3

CH3 NH2NH2

N,N,N′,N′-tetramethylethylenediamine ethylenediamine

N N N N

bipyridine 1,10-phenanthroline-׳2,2

Scheme 1.1: The NᴖN-chelating diamines used in research work

Agwara, M.O. et al (2010) studied antimicrobial activities of the complex

[Cu(bipy)(phen)(H2O)2]Cl2 .2H2O together with cobalt (II) and Zinc (II) mixed-ligand

complexes containing 1,10-phenanthroline and 2,2ʹ–bipyridine. This complex was found to

be biologically active [72].

Prasad, R. et al (2002), synthesized two mixed ligand copper(II) complexes

[Cu(dien)(phen)](ClO4)2 and [Cu(dien)(bipy)](BF4)2 and tested their antimicrobial activity. It

was found that antimicrobial activity of the copper(II)-bipy complex was higher than the

coordinated copper(II)-phen complex [73]. Puglisi, A., et al (2003), have studied the

application of pure phenanthroline or bipyridine containing macrocycles in asymmetric

catalysis [74].

16

1.8 Aims and Objectives

The main goal of this study is to understand the coordination environment and

molecular geometry of ternary copper(II) complexes of diamines and carboxylates.

To attain this goal the present study was carried out with the following objectives

a. Synthesis of copper(II) complexes with carboxylates incorporating diamines

b. Characterization of the complexes by elemental analysis (CHNS), Uv-visible and

FTIR, spectroscopic methods

c Characterization of the complexes by thermal (TGA/DTG) analyses

d Structural characterization of the synthesized complexes by single crystal X-ray

diffraction analysis

e To study the biological activity of some of the complexes

17

CHAPTER 2

LITERATURE REVIEW

Ternary metal-based carboxylates incorporating diamines as ligands are important for their

biological significance as well as for their formative role in the design and synthesis of

metal-organic hybrids. A brief literature survey regarding the properties of various ligands

utilized in the research work and their complexes that have been reported, is presented as

follows.

Benzoic acid has been utilized as a food preservative, and due to its antifungal

properties, it is an important constituent of ointments like Whitfields, and bensal for the

treatment of fungal infections of skin [75]. Similarly, p-aminobenzoic acid (pABAH), also

known as vitamin B10 or factor R is a naturally occurring substance that acts as a precursor

in biosynthesis of folic acid by bacteria, plants, and fungi. P-aminobenzoic acid has been

used as a protective drug against solar insolation, as a part of sun-screen lotions and in

diagnostic tests for the state of the gastrointestinal tract in medicine. It is an antioxidant, an

interferon inducer and immuno-modulator and has antithrombotic, fibrinolytic, antiherpetic

effects. "Actipol" is a drug that contains p-aminobenzoic acid [76-83].

Succinate acts as a bis-bidentate bridging ligand. The carboxylate moieties of each

succinate coordinate with their respective copper(II) centers in a bidentate manner. Hence,

each succinate acts as a tetradentate ligand [84]. Another complex with bis-bidentate

coordination of succinate2- is [Cu2(succ)(bipy)4](NO3)2. 10.5H2O [85], while the complex

[Cu2(succ)(bipy)4]. (succ). 12H2O has succinate2- anion linked to copper(II) ions in a bis-

monodentate mode [86]. Since most of the reported complexes are dimeric to polymeric,

some examples of these complexes are discussed here. The complex

[(phen)2Cu(succ)Cu(phen)2]succ. 12.5H2O (succ2- = doubly deprotonated anion of succinic

acid) represents a dimeric complex [84]. 1D chain forming complexes are exemplified by

[Cu2(μ-OH2)2(succ)(bipy)2(NO3)2]n and [Cu2(μ-OH2)2(succ)(phen)2(NO3)2]n [87].

The complex [Mn(H2O)2(bipy)(succ)]. H2O forms a polymeric 1D helical chain [88],

while a 2-D grid is formed by the complex {[Cu4(succ)2(bipy)4(H2O)2](ClO4)4(H2O)}n [87].

18

A discrete octanuclear complex [Cu8(succ)4(phen)12]. (BF4)8. 8H2O [87], and a polymeric

hexanuclear complex [Cu6(phen)6(succ)4]. 2NO3. 5O [89] is also reported.

Ternary copper(II) phthalate complex [Cu(pht)(phen)2] has been investigated for its

pharmacological potential, owing to its DNA binding properties. It also acts as a chemical

nuclease with high antitumour activity. The complex [Cu(pht)(phen)2] is mononuclear and

contains the pht2- dianion bound to the metal through one of its carboxylate groups in a

monodentate coordination mode.

Another monomeric complex is [Cu(phtH)2(1-CH3Im)2], in which phtH1- anion is

present [91]. The [Cu2(phen)2(phtH)2(NO3)(H2O)]1+ cationic moiety present inthe dinuclear

complex [Cu2(phen)2(phtH)2(NO3)(H2O)]. NO3. 2H2O, contains two Hpht1-ions. Each Hpht1-

has one singly deprotonated carboxylate group and an undissociated carboxylic acid group.

The later does not take part in coordination. The two O atoms of each deprotonated

carboxylate moiety form syn–syn carboxylato bridges which coordinate with the two

copper(II) centers [92].

Mefenamic acid (mefH = 2-(2,3-dimethylphenyl)aminobenzoic acid) is a derivative

of N-phenylanthranilic acid. It is a widely used non-steroidal anti-inflammatory drug

(NSAID) that is chemically similar to other tolfenamates such as tolfenamic and flufenamic

acids. Like other NSAIDs, it is a potent analgesic, anti-inflammatory and antipyretic agent,

and its use is prevalent for the treatment of diseases like osteoarthritis, and nonarticular

rheumatism [93-94]. Similarly, in the polymeric square pyramidal complexes

{[Cu(pht)(Phen)(H2O)].·H2O}n [95], and [Cu(pht)(H2O)(phen)]. 0.5H2O [96], pht2- anion

bridges two adjacent Cu2+ ions with its two oxygen atoms from two carboxylato moieties to

form one-dimensional chains.

A small description of some of the reported copper(II) complexes of tmen is given

now. Estes, E.D. (1975) et al have reported crystal structure of the distorted square pyramidal

complex [Cu(tmen)Cl2]2. The structure is similar to its bromo analogue [97].

Geetha K, and coworkers (1996), have described synthesis, and single crystal

analyses of two ferromagnetically coupled dinuclear cationic complexes of the type [Cu2(μ-

OR)(μ-O2CPh)2(tmen)2]+ (R = H, Me) (figure 2.1 A). The ferromagnetic character is

19

attributed to the pyramidal geometry at the oxygen of the hydroxo/methoxo bridging ligand.

The coordination environment around Cu1 and Cu2 centres is square pyramidal [98].

A B

Figure 2.1: Copper(II) complexes of tmen with monocarboxylates;

A= [Cu2(μ-OH)(μ-O2CPh)2(tmen)2]+, B= [Cu(tmen)(BA)2].pyridine

J. Chris Slootweg et al (2008) have reported a complex [Cu(tmen)(acetate)2], the

Cu(II) ion is coordinated by two N atoms from the chelating tmen and two O atoms from two

acetate anions forming a distorted square-planar coordination environment. In addition, there

are longer contacts between Cu and the second O atom of each acetate ligand [Cu—O =

2.509 (2), 2.531 (2) Å], due to which an alternative description can be a distorted octahedron

[99].

L. Parkanyi et al (1995) have described synthesis, and crystal structure of a complex

[Cu(tmen)(BA)2].pyridine (figure 2.1 B). The coordination geometry around the copper(II)

centre of the centrosymmetric mononuclear complex is distorted square planar, by two

monodentate benzoate-O atoms and two N atoms of chelating tmen, while pyridine is present

as an outer sphere ligand [100].

J. Ferjani et al (2005) have reported an octahedral polymeric complex

{[Cu(C2O4)(tmen)] 4H2O}n (figure 2.2 A), in which each Cu(II) centre is coordinated by two

20

N atoms of bidentate tmen and by four O atoms of two bridging oxalate dianions forming

infnite chains. The structure is supported by hydrogen-bonding leading to a three-

dimensional network [101].

A B

Figure 2.2: Copper(II) complexes of tmen with dicarboxylates; A =

{[Cu(C2O4)(tmen)]4H2O}n, B= [Cu2(pht)(tmen)2(H2O)2]

A. Taha et al (2014), have synthesized a new dimeric ternary copper(II) complex

[Cu2(pht)(tmen)2(H2O)2(NO3)2] H2O (figure 2.2 B) complex and characterized it by spectral,

magnetic, molar conductivity and TGA analyses [102].

H. Muhonen et al (1978), have prepared the complex [Cu(tmen)(salicylate)2] (figure

2.3 A). The Cu(II) centre in the CuN2O4 chromophore is coordinated by four carboxylate-O

atoms from two chelating salicylate ligands and two N atoms of bidentately coordinated

tmen, resulting in a distorted octahedral geometry [103].

A. Saini and coworkers (2015), have reported two mononuclear ternary copper(II)

complexes of tmen including [Cu(tmen)(4-chloro-2-nitrobenzoate)2] (figure 2.3 B) and

[Cu(tmen)(5-chloro-2-nitrobenzoate)2] (figure 2.3 C). Characterization is done through

elemental analyses, spectroscopic techniques (UV–Vis, FT-IR, EPR), TGA analysis,

magnetic moment determination, and single crystal analyses. Both the complexes are

monomeric with distorted square planar coordination geometry around Cu(II) centers in a

CuN2O2 chromophore, defined by two N atoms from a chelating tmen and two carboxylate-O

21

atoms. The two structures are stabilized by various non covalent interactions, leading to a 3-

dimensional framework [104].

A B C

Figure 2.3: Copper(II) complexes of tmen with carboxylates A =

[Cu(tmen)(salicylate)2], B = [Cu(tmen)(4-chloro-2-nitrobenzoate)2] and C =

[Cu(tmen)(5-chloro-2-nitrobenzoate)2]

Copper is a biologically essential trace mineral for all living things including

microorganisms, animals and plants. In biological systems, it acts as a catalytic cofactor for

numerous metallo-enzymes (tyrosinase, cytochrome C oxidase, ceruloplasmin, dopamine

hydroxylase, etc.) and hence, controls many metabolic pathways for example, mitochondrial

oxidative phosphorylation, iron metabolism, transport of O2, cell growth, detoxification of

ROS (reactive free radical species) etc. The characteristic feature that enables copper to

manifest biological properties, is its ability to undergo copper(I)-copper(II) redox

interconversions in many metallo-enzymes like catechol oxidase [105], dopamine

monoxygenase [106], methane monoxygenase [107], and tyrosinase [108]. One important

copper containing metalloenzyme is Cu-Zn superoxide dismutase (Cu-Zn SOD) that is a

natural antioxidant and dismutates reactive and toxic superoxide O2- into less toxic hydrogen

peroxide (H2O2) and O2 [109].

Complexation of biologically active compounds like carboxylates, and NᴖN

heterocyclic chelators with the metals which themselves possess biological properties, may

22

lead to pharmacologically important ternary complexes. One such ligand, p-aminobenzoic

acid, is an important intermediate in the synthesis of folic acid, which is a constituent of the

vitamin B complex. It is a growth factor in plants, in certain micro-organisms with especially

Enterococci and Lactobacilli, and in animal and plant tissues [110-111].

Besides its applications as a good growth factor for many microbes, p-aminobenzoic

acid, also known as vitamin H, is well known for its potent natural antimutagenic activity

[38]. Cinnamic acid and its derivatives are dietary phenolic compounds that occur naturally

in fruits, vegetables, and flowers are well reputed for their biological properties. Their

antioxidant [113-114], antimicrobial [115-116], anti-inflammatory [117], cytotoxic [118],

anticancer [119], antitumor [120-122], antiviral [123], antifungal [124] activities have been

reported.

There is an increasing surge to design and synthesize ternary copper(II) complexes

incorporating bio-ligands like carboxylic acids, with NᴖN-heterocyclic ligands like

phenanthrolines and bipyridines, as most of them are good antioxidants and possess anti-

infective, antifungal, and antibacterial activities [125-127]. The other biological properties of

these copper-based metallo-drugs include their biomimetic action like Cu-Zn SOD enzyme,

and their DNA binding ability, leading to their applications as chemical nucleases, DNA

probes, and chemo-preventive, anticancer, antitumor agents [128-133].

Another reason for the selection of copper(II) ion for complex formation is its

peculiarity to display a variety of coordination shapes. Similarly, in addition to the biological

activity, multifunctional aromatic carboxylates such as phthalic acid, terephthalic acids, o-,

m-, and p-aminobenzoic acids provide more than one potential binding sites around the

aromatic ring. Ternary copper(II) carboxylates have been reported to exhibit rich structural

diversity in their coordination modes, molecular geometries, and their various nuclearities.

The study of diversity in coordination modes of carboxylate moiety is especially important

for the synthesis of metal-organic frameworks (MOFs).

Many ternary copper(II) carboxylates with Nᴖ

N-heterocyclic ligands such as

bipyridines have been reported which exhibit a variety in coordination geometries. These

complexes contain carboxylate moieties that assume versatile coordination motifs, leading to

23

complexes with different nuclearities including mononuclear [134], binuclear [135-137],

trinuclear [138], or tetranuclear [139-140], hexanuclear [141] and polynuclear [142]

complexes.

The various coordination modes adopted by carboxylate moiety in mixed ligand

copper (II)-carboxylates of 2,2′-bipyridine (C10H8N2) include monodentate, bidentate

(chelating), and bridging modes. In the mononuclear complexes [Cu(C8H5O3)2(C10H8N2)]

and [Cu(C7H4IO2)2(C10H8N2)(H2O)], 4-formylbenzoate and (C8H5O31-) 4-iodobenzoate

anions (C7H4IO21-) coordinate to Cu(II) ion in a monodentate manner [143-144].

NH2

O

OH

O

OH

N

N

P-aminobenzoic acid, 2,2′-bipyridine cinnamic acid

Scheme 2.1: Ligands used in research work for 1b and 2b

The complexes [Cu(C4H4O4)(C10H8N2)(H2O)]. 2H2O and [Cu(C8H7O3)2(C10H8N2)].

H2O can be quoted as examples of bidentate chelating mode, in which 2-methylmalonate

(C4H4O42-) [145], and 3-methoxybenzoate (C8H7O31-) [148] anions assume bidentate or

chelating modes. Bridging coordination mode is more frequent in carboxylic acids having

more than one carboxylate moieties. The different modes of coordination of carboxylate

oxygen atoms to Cu(II) may include any of the syn-syn, syn-anti and anti-anti configurations.

This fact further increases the structural versatility of copper(II) carboxylates. In some

interesting complexes, more than one such configuration is reported [147-148].

Introduction of a chelating 2,2′-bipyridine into a copper(II)-carboxylate with paddle

wheel structure like [Cu2(O2CCH3)4. 2H2O] involves serious structural perturbations that

might lead to a polymer such as [-Cu2(O2CCH3)2(2,2′-bipy)2-O2CCH3-Cu2(O2CCH3)4-

O2CCH3-]n that consists of 1-D polymeric chains, containing alternate Cu2(O2CCH3)4 and

[Cu2(O2CCH3)2(2,2′-bipy)2]2+ units, interlinked by bridging acetato oxygen atoms in syn-anti

mode. The Cu2(O2CCH3)4 unit has four chelating bridging acetates connecting the two

24

copper(II) centres in syn-syn configuration, and two axial ones exhibiting syn-anti mode. The

cationic unit [Cu2(O2CCH3)2(2,2′-bipy)2]2+ however has two acetate groups in monoatomic

bridging mode which is quite rare [147]. The complex [Cu2(O2CCH3)4(2,2′-bipy)2]. 2H2O can

be quoted as another example of a complex possessing the dimeric structure with acetate

(O2CCH3)1- anions connecting the two Cu(II) centers in a bridging chelating fashion but

possess syn-anti configuration [147]. Similarly, the anti-anti configuration of malonate (mal)

in complex {[Cu(bipy)(H2O)][Cu(bipy)(mal)(H2O)]}(ClO4)2 leads to antiferromagnetic

coupling interactions through OCCCO bonds of malonate [74]. [Cu(O2CCH3)2(2,2′-bipy)],

on the other hand is the complex in which the paddle wheel arrangement is completely lost

and a monomer is obtained [149].

Self-assembly of the these monomeric and dimeric units leads to multi-dimensional

supramolecular networks, interwoven by non-covalent interactions like π-π stacking, and

hydrogen bonding interactions [143-148].

Copper containing enzymes perform many functions and take part in a large number

of biochemical processes such as growth, cell differentiation, mitochondrial oxidative

phosphorylation, catecholamine production, antioxidant protection, anti-inflammatory

activity iron metabolism etc [150-160].

A B C

Figure 2.4: Structures of ternary copper(II)-bipy-carboxylates; A=

[Cu(bipy)(BA)2(H2O)], B= [Cu(bipy)(pABAH)(pABA)]2. (NO3)2. (H2O)3/2, C=

[Cu(bipy)(ClBA)2]2

Literature is replete with the copper(II) complexes of 1,10-phenanthroline and

carboxylic acids that are known to exhibit a wide range of pharmacological applications due

to their antiviral [161], antimicrobial [162-164], anti-mycobacterial [165-166], anti-

25

inflammatory, and anti-candida [167], antitumor and anti-mutagenic activities [165-173].

Their relatively low molecular weights make their use attractive as drugs [168].

O

OH

N

N

NH2

O

OH

Scheme 2.2: Ligands used in research work for 1c and 2c

There has been an increasing surge in research related to the synthesis and study of

copper(II) complexes of 2,2′-bipyridine or 1,10-phenanthroline and carboxylates [169-170,

172-190]. These complexes exhibit structural diversity, and form mononuclear, binuclear, or

even polynuclear supramolecular complexes. Although 1,10-phenanthroline is almost

invariably chelating, meta aminobenzoate is a multifunctional ligand, with two potential sites

of attachment with the copper(II) ion, one through its amino group and other through its

carboxylate group.

A B C

Figure 2.5: Copper(II) complexes of phen with benzoate and 2-fluorobenzoate A=

[Cu(phen)(C9H9O4)2], B= [Cu(phen)2(C7H5O2)]. 2(C7H6O2). Cl1-, C= [Cu(phen)(C7H5O2F)2]

26

Due to their variable ligation, carboxylate ions might involve; monodentate [169,

172-183] bidentate (chelating), including both symmetrical and asymmetrical, and chelating

bridging coordination modes [170, 183-189]. Dicarboxylates usually form binuclear, or

polymeric complexes exhibiting bis-monodentate or chelating bridging modes [170, 172-173,

, 189]. Weak interactions like hydrogen bonding of different types like O-H…O, O-H…N,

C-H…O etc, and π–π stacking interactions between different phenantroline moieties and with

aromatic carboxylates, play a very important role in the formation of supramolecular

architectures [169, 172, 173, 178, 181]. The unique ability of copper to manifest biological

copper(I)—copper(II) redox interconversions makes it an attractive candidate for its function

as a catalytic cofactor. Figure 4.1 shows monodentae (figure 4.1 B, and C), and bidentate

(figure 4.1 A) [150] coordination modes of carboxylate moieties.

A considerable number of copper(II) complexes of 1,10-phenanthroline and

monocarboxylic acids (acetic, benzoic, 2-fluorobenzoic, formic, lactic, and propionic) have

been reported [170, 179, 184, 185, 188, 190]. Except acetate and propionate complexes, the

carboxylate ligand in these complexes coordinates in a monodentate terminal mode. The

acetate and propionate ions behave as bridging ligands [170, 179].

In conclusion, the literature is replete with mixed ligand copper(II) complexes of

diamines incorporating carboxylates. These complexes exhibit a great structural variety and a

wide range of applications in various fields of science.

27

CHAPTER 3

EXPERIMENTAL

3.1 Materials and methods

CuCl2.2H2O,1,10-phenanthroline and 2,2′-bipyridine were purchased from Merck chemical

company Germany, while N,N,N′,N′-tetramethylethylenediamine, benzoic acid, cinnamic

acid, acetylsalicylic acid, phthalic acid, o-chlorobenzoic acid, mefenamic acid, p-amino

benzoic acid, terephthalic acid succinic acid, tartaric acid, salicylic acid, methanol and NaOH

were purchased from Sigma-Aldrich, chemical company, and are used in the same condition

as received. Distilled water used was singly distilled. The melting points were obtained in a

capillary tube using a Gallenkamp, serial number C040281, U.K, electro–thermal melting

point apparatus. Elemental analyses for C, H and N were carried out using a Perkin–Elmer

2400 II elemental analyzer. TGA was performed on TGA instrument Q500, USA, in N2

atmosphere at the rate 10 ºC per minute. A few samples were done in static air , and it is

mentioned in their figures. Infrared absorption spectra were recorded as KBr pellets with

Avatar 360 E.S.P. Nicolet FT/IR spectrometer in the range of 4000–400 cm-1. Uv-visible

spectra in DMSO were taken using Mega-2100 Double Beam Uv-Visible spectrophotometer.

3.2 Single crystal X–ray structure determination of complexes

Since the reaction products were good quality crystals, so single crystal analysis was carried

out for all the complexes including 1a-11a, 1b-2b, 1c-2c.

28

3.2.1 Single crystal X–ray structure determination of complexes 1a-11a

The X-ray data forcomplexes 1a-11a are collected on Bruker SMART APEX-II CCD

diffractometer at 296 K, by using graphite monochromated MoKα radiation (λ = 0.71073 Å).

Data were collected and reduced by SAINT software [177]; data reduction: SAINT;

program(s) used to solve structure: SHELXS-97 (Sheldrick, 2008); program(s) used to refine

structure: SHELXL-97 (Sheldrick, 2008); [178] molecular graphics: ORTEP-3 for Windows

(Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare material for

publication: WinGX (Farrugia, 2012) and PLATON [179-180]. The positions of oxygen

bonded hydrogen atoms were taken from difference Fourier maps and these hydrogen atoms

were refined isotropically with accompanying DFIX/DANG commands. Details concerning

data collection and analysis are reported in tables 3.1-3.6.

29

Table 3.1: Structure refinement parameters of complexes 1a-2a

1a 2a

Formula C20H30CuN2O6 C20H28CuN2O7

Formula Weight(g mol1-) 458.00 471.98

Temperature (K) 296(2) 296(2)

Wavelength (Å) 0.71073 0.71073

Radiation type MoKα MoKα

Crystal system Monoclinic Orthorhombic

Space Group C 2/c P b c a

a (Å) 22.8512(10) 16.8070(7)

b (Å) 8.4249(3) 11.6652(6)

c (Å) 11.6074(5) 22.8878(12)

α (deg) 90 90

β (deg) 95.659 (2) 90

γ (deg) 90 90

V (Å3) 2223.75(16) 4487.3(4)

Z 4 8

ρcalc (g cm–3) 1.368 1.397

F(000) 964 1976

µ (mm–1) 1.299 1.015

Limiting indices; h, k, l −27 ≤h≤ 26 -21≤h≤12

−9≤k≤9 -14≤k≤14

−9≤l≤13 -29≤l≤-27

Reflections: collected. 7819 20729

Reflectionsuniq 1941 4875

Data/restraints/parameters 1941 /11/ 152 4875/6/284

R1, wR2 0.0305, 0.0805 0.0424, 0.1058

30


3a 4a

Formula C36H42CuN2O4 C41H60Cu2N8O9



Wavelength (Å) 0.71073 0.71073


Crystal system monoclinic Monoclinic

Space Group C 2/c C 2/c

a (Å) 8.5257(9) 22.4722(18)

b (Å) 13.3557(15) 7.5639(6)

c (Å) 30.039(3) 16.5090(15)

α (deg) 90 90

β (deg) 91.644(6) 124.950(3)

γ (deg) 90 90

V (Å3) 3419.0(6) 2300.1(3)

Z 4 2

ρcalc (g cm–3) 1.224 1.352

F(000) 1388 984

µ (mm–1) 0.682 0.984

θ range () 2.835 -27.000 2.211-24.997

Limiting indices; h, k, l -10≤h≤10 -26≤h≤26

-16≤k≤13 -6≤k≤8

-38≤l≤38 -19≤l≤19


Reflections uniq 3648 1881

Data/restraints/parameters 3648/0/207 1988/6/157

R1, wR2 0.0779, 0.1876 0.0370, 0.1037

31


5a 6a

Formula C20H24Cl2CuN2O4 C24H31.39CuN2O4.70



Wavelength(Å) 0.71073 0.71073


Crystal system Monoclinic Monoclinic


a (Å) 26.070(3) 8.5877(2)

b (Å) 7.4943(7) 11.1546(3)

c (Å) 33.390(3) 13.0772(4)

α (deg) 90 90

β (deg) 100.181(3) 104.955(2)

γ (deg) 90 90

V (Å3) 6421.1(11) 1210.27(6)

Z 12 2

ρcalc (g cm–3) 1.523 1.335

F(000) 3036 512

µ (mm–1) 1.299 1.035


-9≤k≤ 7 -14≤k≤12

-42≤l≤ 42 -16≤l≤16




R1, wR2 0.0500, 0.1105 0.0255.0.0611

min,max(eÅ–3) 0.583, +-0.794 0.28 +0.18

32


7a 8a




Wavelength(Å) 0.71073 0.71073




a (Å) 23.046(2) 19.5429(16)

b (Å) 7.8138(7) 8.4215(6)

c (Å) 12.3343(12) 11.5209(10)

α (deg) 90 90

β (deg) 90.351(5) 119.567(3)

γ (deg) 90 90

V (Å3) 2221.1(4) 1649.2 (2)

Z 4 4

ρcalc (g cm–3) 1.525 1.530

F(000) 1060 796

µ (mm–1) 1.035 1.356


-10≤k≤10 -10≤k≤10

-15≤l≤15 -12≤l≤14




R1, wR2 0.0525, 0.1340 0.0525, 0.1340

min,max(eÅ–3) 0.583, +-0.794 -0.794- 0.583

33


9a 10a




Wavelength(Å) 0.71073 0.71073


Crystal system Monoclinic Orthorhombic

Space Group P 21/n P c c n

a (Å) 7.1368 (4) 6.6538(8)

b (Å) 12.3417 (6) 15.2032(18)

c (Å) 19.9037 (9) 15.274(2)

α (deg) 90 90

β (deg) 91.049 (2) 90

γ (deg) 90 90

V (Å3) 1752.83 (15) 1545.1(3)

Z 4 4

ρcalc (g cm–3) 1.394 1.564

F(000) 1.281 1.452

µ (mm–1) 780 764

Limiting indices; h, k, l 9≤h≤-15 -7≤h≤8

15≤k≤15 -12≤k≤19

-25≤l≤25 -19≤l≤18




R1, wR2 0.0369, 0.0948 0.0400, 0.0998

34

Table 3.6: Structure refinement parameters of complex 11a

Complex 11a

Empirical formula C9H13ClCuN2O3

Formula weight 296.20

Temperature 296(2)

Wavelength 0.71073

Radiation type MoKα

Crystal system Monoclinic

Space group P21/c

a(Å) 13.9179 (10)

b(Å) 10.4900 (8)

c(Å) 8.5181 (6)

α() 90

() 105.518 (4)

γ() 90

Volume (Å3) 1198.30 (15)

Z 4

calc (g cm–3) 1.642

(mm–1) 2.038

F(000) 604

hkl ranges -17≤h≤17

-13≤k≤13

-8≤l≤10

Reflections collected 8951

Independent Reflections 2351

Data/ restraints/parameters 2612/0/149

R[F2> 2σ(F2)] 0.026

wR(F2) 0.069

35

3.2.2 Single crystal X–ray structure determination for 1b and 2b

Intensity data were collected for the single crystals of (1b) and (2b), at 296 K, on a Bruker

SMART APEX-II CCD diffractometer using graphite monochromatedMoKα radiation (λ =

0.71073 Å). SAINT was used to refine the unit-cell and for data reduction [177]; data

reduction: SAINT; program(s) used to solve structure: SHELXS-97 (Sheldrick, 2008);

program(s) used to refine structure: SHELXL-97 (Sheldrick, 2008); [178]. Molecular

graphics were performed using programs: ORTEP-3 for Windows (Farrugia, 2012) and

PLATON (Spek, 2009); software used to prepare material for publication: WinGX (Farrugia,

2012) and PLATON [189-180]. Crystallographic data as well as details of data collection and

refinement for complexes 1b and 2b are presented in table 3.7.

Table 3.7: Structure refinement details for complexes 1b and 2b

Compound 1b 2b

Empirical Formula C28H24CuN2O5 C48H47ClCu2N8O11

Formula weight 532.03 1074.47

Crystal system Triclinic Orthorhombic

Space group 𝑃1̅ (No. 2) P212121(No. 19)

a (Å) 12.0357 (7) 13.5061 (10)

b (Å) 13.8799 (8) 18.1441 (11)

c (Å) 16.3225 (9) 18.9671 (13)

(°) 84.916 (3) 90

(°) 88.551 (3) 90

(°) 67.877 (3) 90

V (Å3) 2516.0 (2) 4648.1 (5)

Z 4 4

calc (g cm–3) 1.405 1.535

(mm–1) 0.909 1.044

Data collected 35228 21605

Unique data 10388 8839

RInt 0.044 0.039

R(F) [I> 2(I)] 0.060 0.039

wR(F2) [all data] 0.199 0.083

36

3.2.3 Single crystal X–ray structure determinationfor 1c and 2c

Single crystal data collection for 1c and 2c was performed on a Bruker SMART APEX-II

CCD diffractometer using graphite monochromatedMoKα radiation (λ = 0.71073 Å) at 293

K. SAINT was used for the unit cell refinement and data reduction [177]. The structure was

solved by direct methods using SHELXS-97 and refined by full matrix least-squares against

|F|2 using SHELXL-97 [178]. Molecular graphics were performed using programs: ORTEP-

3 for Windows (Farrugia, 2012) and PLATON (Spek, 2009); software used to prepare

material for publication: WinGX (Farrugia, 2012) and PLATON [179-180]. The hydrogen

atoms were geometrically placed (C–H = 0.93 Å) and refined as riding atoms with Uiso(H) =

1.2Ueq(C). Crystal data and details of the data collection are given in Table 3.8. In the

complex 2c, the O3 atom of the water molecule of crystallization was found to be statistically

disordered over two adjacent sites related by inversion symmetry (O3⋯

C-bound H atoms were geometrically placed (C—H = 0.93 Å) and refined as riding atoms.

The N- and O-bound H atoms were located in difference maps: the positions of the N-bonded

H atoms were freely refined and the O-bonded H atoms were refined as riding atoms in their

as-found relative positions. The constraint Uiso(H) = 1.2Ueq(carrier) was applied in all

cases.

37

Table 3.8: Structure refinement parameters of the complexes 1c and 2c

Compound 1c 2c

Empirical formula C26H18CuN2O4 C19H15ClCuN3O2½

Formula weight 485.90 424.33


Wavelength (Å) 0.71073 0.71073


Space group C2/c P21/n (No. 14)

a (Å) 21.2662(7) 9.8200(5)

b (Å) 9.9266(3) 10.9291 (7)

c (Å) 10.9599(3) 16.3803(9)

() 115.575(1) 105.293(3)

V (Å3) 2086.96(11) 1695.74 (17)

Z 4 4

calc (g cm–3) 1.547 1.662

(mm–1) 1.085 1.469

F(000) 996 864

2range () for data collection 2.77–28.30 5.56–53.0

hkl ranges –28 → 27, –13 → 12, –12 9; –13 13;

–14 → 14 –19 20

Reflections scanned 9910 12658

Independent reflections 2601 3493 (RInt = 0.047)

Data / restraints / parameters 2346 3493 / 0 / 259

R(F) [I> 2(I)] 0.026 0.043

wR(F2) 0.076 0.122

Min., max. (e Å3) –0.26, +0.33 –0.60, + 0.37

38

3.3 Antimicrobial activity measurement (Agar well diffusion method)

3.3.1 Antimicrobial activity of complexes 1a-11a

The in-vitro antimicrobial activities of synthesized complexes [Cu(tmen)(BA)2(H2O)2], (1a)

[Cu(tmen)(salH)2(H2O)] (2a), {[Cu(tmen)(mef)2] (3a), [Cu(tmen)(pABA)2]. 1/2 MeOH(4a),

[Cu(tmen)(o-ClBA)2] (5a), [Cu(tmen)(cinn)2]. H2O (6a), [Cu(tmen)(phtH)2] (7a),

[Cu(tmen)(tpht)(H2O)2]n (8a), {[Cu(tmen)(succin)].4H2O}n (9a), {[Cu(tmen)(tart)]·2H2O}n

(10a)[Cu(en)(salH)Cl]n (11a) were tested by well diffusion method. The chosen strains were:

Bacillus spizizenii, Escherichia coli, Klebsiella pneumonia and Staphylococcus aureus.

Nutrient agar medium (Merck) was prepared by dissolving 25 g of nutrient agar powder in

one litre of distilled water in a conical flask. Its pH was adjusted to 7.00. The conical flasks

were plugged with cotton wool and were covered with aluminum foil. These were then

sterilized in an auto-clave for 15 minutes at 121°C. The fresh sterile nutrient broths (Merck)

were separately inoculated with bacterial strains, with the help of an inoculate wire loop from

slant cultures of respective microbes (Bacillus spizizenii, Escherichia coli, Klebsiella

pneumonia and Staphylococcus aureus). After incubation at 3

synthesis and structural characterization of mixed ligand...

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