Synthesis, Charactericterization And Properties Of Water-soluble Schiff Base Metal Complexes

Schiff base complexes have long been attracted attentions in the case of their catalytic properties, biological activities and other physical properties. Copper containing Schiff base complexes have also been widely studied as the models of varies of oxidases, such as galactose oxidase, dopamine p-hydroxylase, amine oxidase and so on, in the field of biomimetic catalysis. However, with lower solubility in aqueous solutions, these applications were limited to some extent in biomimetic research areas. While water soluble Schiff base complexes not only can reduce contamination without using organic solvent especially in the biochemistry reactions, but also may display high catalytic activities via increasing the interface between the catalysts and the substrates.In this thesis, series of water-soluble Schiff base complexes have been synthesized, and the electrochemical properties of the complexes have been studied. Furthermore, the catalytic properties of the complexes towards the oxidation of ascorbic acid in the air as well as the interactions of the complexes with DNAhave been investigated. The major contents are as follows:1. Synthesis and characterization of water-soluble Schiff base complexes derived from substituted anilineWith excellent redox potential, Schiff base Copper complexes have been studied widely as catalysts or enzyme models. Otherwise, with sophisticated ligands of the general modeling complexes, the mechanism of the mimetic reaction was remain unclear, In this article, series of water-soluble Schiff base complexes have been synthesized and characterized by elemental analysis, UV-vis, IR, 1H-NMR spectroscopy, and electrochemical analysis. The results clearly indicated the structures of metal centers and can be used to investigate catalytic mechanism as the models of the enzymes.2. Synthesis and Structure of the Water-soluble Schiff base Complexesderived from Amino acid and di-peptideAmino acid and peptides have high compatibilities with the living body. Water-soluble Schiff base compounds containing amino acid or peptide may not only have high bioactivities but also have minimal toxicity. In this article, some water-soluble Schiff base complexes containing dipeptide have been synthesized. The single structure of the complex also has been detected.3. Electrochemical properties of the Schiff base complexesMost of the enzymes display reversible cyclic voltammetry. In this article, electron-transfer properties of the complexes were studied by cyclic voltammetry and differential pulse voltammetric techniques. Cu-L2 and Cu-L3 displayed two cathodic potentials and two anidic potentials, while Cu-Ll has no cathodic current. Comparing the anidic potentials of the Schiff base complexes, it was also found that the complexes with electron-drawing substituent might display high anidic potentials, which may have high oxidation activity.Many metal complexes may display interactions with biomacromolecule (such as DNA or peptides), which can be used extensively as molecular probe to detect the structure of the DNA, and diagnose the mechanism of the diseases. In this article, the interactions of the Schiff base complexes with DNA have been studied by electrochemical methods.4. Kinetic studies of oxidation of Ascorbic acid (Vc )Ascorbic acid is an active species existing in biological bodies, which is related with scurvy and its concentration in human body is an important indicator in diagnosing scurvy. In this article, the oxidation reaction of Vc catalyzed with Schiff base complexes synthesized have been studied. The conclusion indicated that the oxidation reaction was first-order, and Schiff base complexes with electron-drawing substituent might result in higher reaction activity, which were in accordance with the electrochemical properties of the complexes.