Studies On Hydrolytic Reaction Kinetics Of Phosphate And Carboxylate Catalyzed By Metallomicelle Mimicking Hydrolytic Metalloenzymes

Metallomicellar catalysis is a new challenging field that is quickly developing. The metallomicellar system can mimic the structure of the active center and the hydrophobic microenvironment of metalloenzymes, so a series of noticeable and creative results have been obtained in studies on mimic hydrolytic metalloenzymes. In this dissertation, kinetics and mechanism of the hydrolysis of carboxylate and phosphate catalyzed by the metallomicellar systems are investigated spectrephotometerically. The catalytic reaction kinetic models of the metallomicellar systems have been proposed. The experimental results have been treated with the kinetic model, the relative kinetic and thermodynamic parameters of the hydrolytic reactions have been obtained. The rationality of the kinetic models has been proved. Four types of ligands containing hydroxyl ,imidazole and pyridine group have been designed and synthesized, respectively. The mononuclear or binuclear complexes have been formed from these ligands and bivalent transition metal ions in micellar solutions.The catalytic hydrolysis of carboxylate (PNPP) by the Cu(II),Zn(II),Ni(II) and Co(II) complexes with bridge-connecting ethoxyl-diamine ligands have been investigated in the cationic surfactant CTAB micellar solution and nonionic surfactant Brij35 micellar solution, respectively. The results indicate the microenvironment of the reaction has affected the formation of kinetic active species, their catalytic activities are related to the structure of the bridged ligands, the polarizing power of metal ion and the microenvironment of the reaction.The catalytic hydrolysis of phosphate (BNPP) by the Cu(II),Zn(II) and Ni(II) complexes of lipophilic imidazole-containg alkanol ligands has been investigated in the CTAB micellar solution. On account of co-metallomicelle formation, the complex with a long alkanol ligand has a stronger catalytic effect than that with a short alkanol ligand .The catalytic hydrolysis of phosphodiester (BNPP) and phosphomonoester (NPP) by Cu(II),Zn(II),Ni(II) and Co(II) complexes with two hydrophobic alkanol-pyridyl ligands has been studied in the CTAB micellar solution, respectively. The experimental results indicate that 2:1 ligand:metal ion complexes in CTAB micellar solution are the active species for the catalytic hydrolysis of BNPP and NPP. The apparent rate constants for hydrolysis of NPP catalyzed by Cu(II) and Co(II) metallomicellar systems are greater than that of BNPP, but the apparent rate constants of NPP are less than that of BNPP catalyzed by Zn(II) and Ni(II) metallomicellar systems.The catalytic hydrolysis of phosphodiester (BNPP) and phosphomonoester (NPP) by Cu(II) and Zn(II) complexes with bridge-connecting alkanol-pyridyl ligands has been studied in the CTAB micellar solution, respectively. The kinetic results show that the catalytic activity of mononuclear and binuclear complexes is related to the structure of ligand. The catalytic effect depends on the rigidity and flexibility of the structure of ligands. The hydrolysis of phosphate experiences a bifunctional catalytic mechanism including double Lewis acid activation and intramolecular nucleophilic attack.The hydrolysis of plasmid DNA(PBin19) catalyzed by Cu(II) complexes of bridge-connecting ethoxyl-diamine ligands as the model of chemical nucleases has been investigated. The condition and the mechanism of the catalytic hydrolysis of plasmid DNA(PBinl9) are investigated preliminarily.