Syntheses, Characterization, And Biological Activities Of Transition Metal Complexes With Schiff Bases With Hydrazide

Schiff bases with hydrazide are a kind of very important ligand containing N atoms which are easy prepared by simple self-condensation of aldehydes or ketones with hydrazide. Many ligands generally have been designed to contain additiona donor groups (0, S, P, etc.) and it makes them good candidates for agents and metal ion complexation. A number of Schiff bases with hydrazide have been claimed to possess good antibacterial, anticancer, antifungal, anticonvulsant, antinflammatory, antimalarial and antituberculosis activities. However, relationship between the structures and biological activities is dimness up to date.In order to investigate relationships between the structures and biological activities, this dissertation investigates the synthesis, characterization and biological activities of 65 Schiff base with hydrazide and their transition metal complexes as potential agents for therapeutic purpose. 24 Schiff base with hydrazide (3a-4d, 4h-4o) were prepared by the reaction of aldehyde with hydrazide and their structures were determined by element analysis, ¹H-NMR and MS. 5 Schiff bases with hydrazide(4c-4g) were characterized by X-ray diffraction. A series of Schiff base ligands were reacted with transitional metal salt (i.e., Ni(OAc)₂·4H₂O, Zn(Ac)₂·4H₂O) to yield a series of transition metal complexes. In most cases, reaction with two equival of ligand in mixture of ethanol and pyridinium yielded mononuclear, dinuclear or trinuclear complexes and formed octahedral or pyramid coordination polyhedron. In this article, 26 complexes (5a-9d) were first sythesised and their elemental analyses, crystal structure, IR spectra and biological activities have been investigated. It should be emphasized that crystal structures of eighteen Schiff base compounds were obtained for the first time. From the analytiacl data, it has been concluded that all the compounds of the hydrazide derivatives showed potent cytotoxic activities and its complex is more ative than the ligand. To the best of our knoeledge, the increased lipophilicity may be responsible for this increased cytotoxic activity. The cytotoxic activity of copper complex is most active among five transion metal complexes. Little is understood up to date about the reason and many efforts need to do. At the same time, some novel chalcone analogys have been sythesised and their reation mechanism and biological activities have been proposed. In a word, chalcone derivations possess weak antimicrobial activity. Thus, it is not suitable for the nitrochalcones to be antimicrobial agents.