List of Figures

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ix

List of Figures

1.1 Ultrasound spectrum of MgSO4 in aqueous solution……… 10

1.2 Ultrasound spectrum of some divalent metal sulphates in aqueous solution.……….. 10

1.3 Dependence of the rate constant of the H2O exchange process on the number of d electrons in different cations.………..………..……….. 13

2.1 IR radiation path into a cristal and a sample during a FTIR-ATR experiment………. 19

2.2 Internal scheme of a stopped flow apparatus.………..………. 20

2.3 Schematic view of an ultrafiltration cell.………..……… 22

3.1 Structure of a generic surfactant..………..………... 24

3.2 Structure of a spherical micelle..………..………. 25

3.3 Changes in some physical properties for an aqueous solution of SDS close to the CMC……… 26

3.4 Effect of surfactants on reaction rates………... 27

3.5 Dissociation equilibria of SHA……….……… 30

3.6 Analysis of a spectrophotometric titration for the determination of pKA1 of SHA in SDS……... 31

3.7 Spectral changes recorded during a spectrophotometric titration of SHA with Ni(II)………….. 33

3.8 Binding isotherm deriving from a spectrophotometric titration of SHA with Ni(II). Inset: analysis of the titration by means of equation (3.8)………... 34

3.9

€

K

app SDS dependence on [H+_{] and [SDS] for the Ni(II)/SHA system……… 36}

3.10 Kinetic relaxation curves for the complexation reaction of Ni(II)/SHA system in [SDS]. Insets: time constant values dependences on Ni(II) concentration………... 38

3.11 Kinetic behavior for the fast effect of the Ni(II)/SHA reaction in SDS……… 40

3.12 Micellar catalysis for the system Ni(II)/SHA.………..………. 43

4.1 (A) UV-visible spectra of Fe(ClO4)3; (B) Absorbance dependence on CM at λ=240 nm.

[H+]=1 M………..………..………..

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LIST OF FIGURES

x

4.2 (A) UV-visible spectra of Fe(ClO4)3; (B) Absorbance dependence on CM at λ=240 nm.

[H+]=1.2×10-2 _{M..………..………} ₄₉

4.3 Stopped-flow experiments showing the kinetic behavior of Fe(ClO4)3 solutions upon dilution

jumps. Inset: plot of the kinetic data according to equation (4.4).……… 52 4.4 Dependence 1/τf + 1/τs (A) and 1/τf × 1/τs (B) on CM……….. 54

4.5 Dependence of the rate constant of trimer decomposition on the hydrogen ion concentration… 55 4.6 Kinetic trace recorded by spectrophotometric measurements for Fe(III)………. 56 4.7 Binding isotherm for the interaction of Fe(III) with BHA. Inset shows the spectral change

induced by complex formation.………. 57 4.8 Dependence of the apparent binding constant, K1app, for the Fe(III)/BHA system on [H+]. Inset:

dependence of K1app on αFeOH, the molar fraction of FeOH2+ ion………... 57

4.9 Binding isotherms for the interaction of Fe(III) with SHA. Inset shows the spectral change induced by complex formation.………..………... 59 4.10 Dependence of the apparent binding constants, K1app and K2app, for the Fe(III)/SHA system on

[H+_{]. Insets: dependence of K}

1app and [H+]×K2app on αFeOH.………..… 60

4.11 Stopped-flow traces recorded at λ = 520 nm upon mixing BHA Fe(ClO4)3………. 61

4.12 Dependence of 1/τ on CM at different [H+] values for the Fe(III)/BHA system. The inset

represents the dependence of 1/τ on [FeOH2+_{]………...…………...} ₆₂

4.13 Stopped-flow traces recorded at λ = 532 nm upon mixing SHA and Fe(ClO4)3. The inset

shows the slowest of the two effects on a magnified scale………... 63 4.14 Dependence of the relaxation time on [FeOH2+_{] for the Fe(III)/SHA system under different}

acidity conditions………... 64 4.15 Dependence of the rate dissociation, 1/τdiss, on the hydrogen ion concentration for the

Fe(III)/SHA system.……….. 66 4.16 FTIR spectra of the investigated systems.……….... 67

5.1 Representation of the 12-MC-4 metallamacrocycle of Cu(II) and α-aminohydroxamic acids…. 73 5.2 Binding isotherm for the reaction between Cu(II) and (S)-α-Alaha……….……… 74 5.3 Representative distribution diagram of the Cu(II)/(S)-α-Alaha system in aqueous solution…....

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xi

5.4 Logarithmic dependence of the initial rate, v°, on ligand concentration, CL, for the Cu(II)/HL

system……… 76

5.5 pH dependence of the initial rate values for the Cu(II)/(S)-α-Alaha system……… 78

5.6 pH dependence of the amplitude values for the Cu(II)/(S)-α-Alaha system.……… 79

5.7 Kinetic relaxation curves for the reaction of Cu(II))/(S)-α-Alaha system.………... 79

5.8 Dependence of the initial rate on metal ion concentration for the Cu(II)/(S)-α-Alaha system…. 80 5.9 Dependence of the logarithm of the initial rate on ionic strength, according to equation (5.8), for the Cu(II)/(S)-α-Alaha system.………...………... 81

5.10 Kinetic relaxation curve for the dissociation reaction of the Cu(II))/(S)-α-Alaha 12-MC-4 metallacrown………...………...………... 84

5.11 (A) Amplitudes, Adiss, and (B) rate constants, 1/τdiss, dependence on [H+] for the reverse reaction of Cu(II)/(S)-α-Alaha 12-MC-4 self assembly.………... 84

5.12 Absorbance dependence on temperature for the Cu(II)/(S)-α-Alaha 12MC4.……….. 86

5.13 DSC curves for the 12-MC-4.………...………...…… 86

5.14 ITC curve for the system Cu(II)/(S)-α-Alaha.…………...………...……… 88

5.15 Binding isotherm (A) and data plot obtained from equation 5.2 (B) for the reaction between 12-MC-4 and La(III).…………...………...………... 89

5.16 Biphasic kinetic curve for the reaction of 12-MC-4 with La(III)……….. 90

5.17 Time constant dependence on La(III) concentration for the fast and slow kinetic effect observed for the 12-MC-4/La(III) reaction………... 91

5.18 Time constant dependence on (S)-α-Alaha concentration for the fast and slow kinetic effect observed for the 12-MC-4/La(III) reaction………... 92

5.19 Monophasic kinetic curve for the reaction of 12-MC-4 with La(III) and excess Cu(II)………... 93

5.20 Rate constants dependence on La(III) concentration for the fast kinetic effect observed for the 12-MC-4/La(III) reaction with different excess Cu(II) concentrations………. 94

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