Investigation Of MEtal Complex And Metallomicelle Mimicking Hydrolytic Metalloenzymes

In this dissertation, the effects of two-valence metal ions extensively used inartificial enzyme models, Cu(II), Zn(II), Co(II) and Ni(II), and two three-valence metal ions, La(III) and Fe(III), on the critical micellization concentrations(CMC) of ionic surfactants CTAB and SDS have been systematically studied by conductivity method. A series of general empirical expressions describing the relationship between the CMC values for ionic surfactants and the concentrations of added metal ions have been derived, which are the bases for quantitative treatments of catalytic reaction kinetics by artificial enzyme system.A substituted long alkyl pyridine ligand and its Cu(II) and Zn(II) complexes have been designed. The mechanisms of the hydrolysis of carboxylate catalyzed by these complexes in the co-micellar solution with cationic surfactant CTAB have been comparatively investigated, and the catalytic reaction kinetic models of micellar system have been proposed respectively. The experimental results indicate that this type of metallomicellar system is especially effective for the hydrolysis of PNPP, and the co-existence of pyridine and hydroxyl plays an important role in the reaction.The Cu(II) and Zn(II) complexes based on 2,2'-dipyridylamine have been designed and synthesized, and the catalytic hydrolysis of phosphodiester by the complexes in nonionic surfactant Brij35 micellar solution has been studied. The kinetic results show that the complex with cis- diaquo structure is an effectivecatalyst for the hydrolysis of phosphodiester, and this structure can assist theintramolecular nucleophilic attack with effect.The macrocyclic homodinuclear (Zn(II)-Zn(II), Cu(II)-Cu(II)) and heterodinuclear (Zn(II)-Cu(II)) metal complexes simulating phosphomonoesterase-promoted hydrolysis of phosphomonoester have been discussed. The kinetic analysis illustrates that the hydrolysis of phosphomonoester experiences a bifunctional catalytic process including double Lewis acid activation and intramolecular nucleophilic attack. The different stereoscopic requirements between metal ions and the different nucleophilicities of the nucleophiles coordinated to metal ions determine the catalytic efficiencies of the complexes. The rigidity and flexibility of the complex and the distance between two metal centers determine the selectivity of the catalyst towards the substrates.The hydrolysis of phosphodiester promoted by dinuclear complexes (Cu(II)-Cu(II) and Co(II)-Co(II)) bearing special functional oxime group has been studied. The results testify the possibility that the phosphodiester not binding with any nucleophile may also hydrolyze through double Lewis acid activation and intramolecular nucleophilic attack by the nucleophile of ligand.