List of Schemes vii

  iii  

Contents

Acknowledgements i

List of Schemes vii

List of Figures ix

List of Tables xiii

Preface xv

CHAPTER 1 Introduction 1

1.1 Hydroxamic acids: general properties 6 1.1.1 Ionization of hydroxamic acids 7 1.1.2 Metal complexation of hydroxamic acids 9 1.2 Complexation mechanism 9

1.2.1 The “ion pair” 11

1.2.2 The “solvent exchange” 12 1.2.3 Activation mechanisms 13 CHAPTER 2 Materials and methods 17 2.1 Chemicals 17

2.2 Methods 18 2.2.1 UV-VIS Spectrophotometry 18

2.2.2 FTIR Spectrophotometry 18 2.2.3 FAB-Mass Spectrometry 19 2.2.4 Stopped-Flow 19

2.2.5 Calorimetry 20 2.2.6 Ultrafiltration 21

2.2.7 pH measurements 22 CHAPTER 3 Ni(II) complexation by salicylhydroxamic acid in SDS 23

3.1 Surfactants 24

3.2 Micelles 24 3.2.1 Critical micelle concentration 25

3.2.2 Solubilization 26

3.2.3 Micellar Catalysis 27 3.3 Micellar extraction 28

3.3.1 Micellar-Enhanced Ultrafiltration 29 3.4 Determination of the acid dissociation constant of SHA in the presence of SDS 29 3.5 Extraction of SHA and Ni(II)/SHA complex by MEUF 32

3.6 Complex Formation Equilibria 33 3.7 Complex Formation Kinetics 37 3.8 Micellar Catalysis 42

3.9 Discussion 44

CONTENTS

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CHAPTER 4

A route to metallacrowns: Fe(III) and its complexation by salicylhydroxamic

and benzohydroxamic acid 47

4.1 Fe(III) hydrolysis and self-aggregation equilibria 48 4.2 Fe(III) hydrolysis and self-aggregation kinetics 51 4.3 Formation equilibria of the Fe(III)/BHA and Fe(III)/SHA complexes 56

4.3.1 The Fe(III)/BHA system 56

4.3.2 The Fe(III)/SHA system 59

4.4 Fe(III)/BHA and Fe(III)/SHA complexes formation kinetics 60

4.4.1 The Fe(III)/BHA system 61

4.4.2 The Fe(III)/SHA system 63

4.5 FTIR experiments 66

4.6 Discussion 67

4.6.1 Fe(III) hydrolysis and self-aggregtion 67

4.6.2 Complex formation of Fe(III) with BHA and SHA 69

CHAPTER 5

Metallacrowns: mechanism of formation of Cu(II)/(S)α-alaninehydroxamic

acid 12-MC-4 and its interaction with La(III) 71

5.1. 12-MC-4 self-assembly equilibrium 74

5.2. 12-MC-4 self-assembly kinetics 75

5.2.1 Reaction order determination 75

5.2.2 Rate and amplitude dependence on pH 77

5.2.3 Rate dependence on Cu(II) concentration at different ionic strength values 79

5.2.4 Rate dependence on ionic strenght 80

5.2.5 Dimer formation process 82

5.2.6 Reverse reaction kinetics 83

5.3. FAB-MS for the system Cu(II)/(S)-α-Alaha 85

5.4. 12-MC-4 thermal stability 85

5.4.1 UV-vis analysis 85

5.4.2 DSC analysis 86

5.4.3 ITC analysis 88

5.5. 15-MC-5 self-assembly equilibrium 88

5.6. 15-MC-5 self-assembly kinetics 90

5.6.1 Rate dependence on La(III) concentration 90

5.6.2 Rate dependence on (S)-α-Alaha concentration 92

5.6.3 Rate dependence on Cu(II) concentration 93

5.7. Discussion 95

CHAPTER 6

Conclusions 97

APPENDIX I

Determination of the first acid dissociation constant of SHA 101

APPENDIX II

CONTENTS

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Determination of the equilibrium constant for formation of a 1:1 complex 103

APPENDIX III

A. Derivation of the relaxation time equation for a reaction at the equilibrium 105 B. Derivation of the relaxation time equation for a dimerization reaction 107 C. Derivation of the relaxation time equation for coupled reactions at the equilibrium 109

APPENDIX IV

Separation of contributions in aqueous and micellar media for two coupled reactions at

the equilibrium 115

APPENDIX V

Derivation of the equilibrium constants for hydrolysis, dimerization and trimerization of

Iron(III) 121

APPENDIX VI

Derivation of the relaxation times for a system of coupled reactions using the Castellan’s

method 123

APPENDIX VII

Derivation of the relaxation times for the complex formation between Iron(III) and

SHA 127

APPENDIX VIII

Derivation of the relationship between the apparent binding constant, K

, and the

individual constant, K 131

APPENDIX IX

Derivation of the fast relaxation time at [H+]>0.04 M according to reactions

(4.1)-(4.2)-(4.5) of Chapter 4 133

References 135