Synthesis And Biological Activity Research Of Schiff Bases And Its Metal Complexes

Superoxide dismutase,as one kind of metalloenzyme,exists widely in the organism,which has extensive prospects in the application for it plays an important role in protecting the body from the toxic effect of superoxide anion radical.But the disadvantages of lower stability ,macro molecular weight,lower penetrability and immunogenic property restrict it's application.So the researches of SOD have been being paid close attention to by scientists and engineers.In this paper,the new Schiff bases of thiadiazole and its Cu(Ⅱ),Co(Ⅱ),Zn(Ⅱ) complexes were synthesized, and the properties of catalytic activity of the metal complexes in disproportionation of O2― were studied.2-amino-1,3,4-thiadiazole-5-thiol has great coordination capability and good biological activities.We synthesized four new Schiff base ligands by the condensation of 2-amino-1,3,4-thiadiazole-5-thiol and [(2-amino-1,3,4-thiadiazole-5-yl)thio]acetic acid separately with salicylaldehyde and 2,4-dihydroxybenzaldehyde,and got their Cu(Ⅱ),Co(Ⅱ),Zn(Ⅱ) quadridentate complexes.All the compounds were characterized by elemental analysis,IR spectrum,UV-vis spectrum,atomic spectrum and molar conductance measurements.The tests of catalytic activity of all the complexes, determined by NBT method ,indicate that:(1)All the complexes show some inhibitive effects to O2―,and the activities have close correlation with the kinds of metal.(2)In the metal complexes of each ligand, the copper(Ⅱ) complex has the best activity.The possible reasion is that the copper(Ⅱ) itself has some inhibitive effects to the O2― ,and copper(Ⅱ) can carry out the process of being deoxidized to copper(Ⅰ), which simulates the really catalytic process of disproportionation of O2― in Cu/Zn-SOD well;(3)The copper(Ⅱ) complexes have different catalytic mechanism with the cobalt(Ⅱ) and zinc(Ⅱ) complexes in disproportionation of O2―; The activities of copper(Ⅱ) complexes behave logarithmic correlation with the concentration,(4)The activities of all the metal complexes have the direct correction with their concentration,and they all behave the better inhibitive effects than the SOD reported in concerned literature in the same mass concentration.We concluded that the configurations of copper(Ⅱ) complexes are similar to the planar square coordination ofCu/Zn-SOD's. (5)In the effects of compositive factors,the metal complexes behave different activities.In the copper(Ⅱ) complexes of four ligands, the complex 4a has the best activity in lower concentration,but in the higher concentration, complex 2a does. In the cobalt(Ⅱ) complexes of four ligands, the complex 1b has the best activity. In the zinc(Ⅱ) complexes of four ligands, the complex 4c shows the best activity.