Design, Syntheses And Mimic Bromination Reaction Activity Of Model Molecules Of Vanadium Haloperoxidases

The coordination chemistry of vanadium is a new field in potentially biological applications. Vanadium plays a vital role in the life activities, where it is present in metalloenzymes (e.g. haloperoxidases and nitrogenases) and it can also inhibit ribonuclease and Na-K-ATPase. What functions that vanadium plays in vivo and how to play these functions, these have attracted the attention of scientists. Functional model of vanadium complexes played a crucial role in exploring process of the catalytic mechanism of enzyme, so synthesis and biological activity study of vanadium functional model complexes have received increasing attention.Spatial configuration of vanadium haloperoxidases (V-HPOs) was determined that points out the direction for us designing and synthesizing of functional catalytic activity of vanadium complexes. Model molecules of the V-HPOs were designed and synthesized by mimicking N, O coordination environment of the active center of the V-HPOs and hydrogen-bond interact active center with amino acid residues or water molecule. In the modelling active centres of metalloenzymes, one commonly distinguishes between structural and functional models. Structural models are those which are good 'copies' of the active centre with respect to the nature of the ligand functions, the arrangement of the ligand set and the spectroscopic properties. Functional models, on the other hand, mimic the native reaction catalysed by the enzyme. Functional models may or may not be good replicas of the actual build-up of the active centre. So it is important to choose appropriate ligands in synthesizing vanadium functional and structural complexes. In this thesis, we choose some small molecule carboxylic acids and hydrogen peroxide as the oxygen ligands(mimicking V-O, V=O of the active center of enzymes), and choose imidazole, pyrazole and its derivatives as nitrogen ligands(mimicking V-N of the active center of enzymes), synthesized a series of different valence vanadium structural and functional model complexes of vanadium haloperoxidases.In this paper, in order to studying the valence center-metal of vanadium halide peroxidase model complexes, coordination modes, spatial configuration and hydrogen bond, which are influence on the bromide catalytic of organic substrate, we designed and synthesized 11 complexes. The structures of complexes 1-11 are determined by X-ray single crystal diffraction and characterized by elemental analysis, IR spectra and UV-vis spectroscopy, thermal analysis for complexes 4-10. In addition, bromide catalytic activity of the four types of model complexes was estimated systematically by the catalytic kinetic experiment. (1)...