Series Of Vanadium Hydrazone Complexes Of Single-crystal Synthesis And Biological Activity Study

Vanadium is a metal element existing in organism with tiny concentration. Its compounds are related to some important physiological processes for their similarity with phosphates and their special redox properties. The physiological activities mainly include inhibiting Na⁺,K⁺-ATPases and phosphorylases, the potential as insulin-enhancing or insulin- mimetic agents, their model character for vanadate-dependent nitrogenases and haloperoxidases and, in relation to the latter, their use in oxo-transfer catalysis and oxidative halogenation. These activities are attracting increasing interests of correlating investigators.In this work, the series of hydrazone ligands with typical structures were synthesized, their reactions with vanadium compounds (VO(acac)₂, V₂O₅, VOSO₄, NH₄VO₃ etc.) at some different conditions were performed and the single crystals of a series of complexes were obtained. They were characterized by IR, UV/vis, ¹H NMR spectra and TG. Analyses and the X-ray crystal structures were determined. These complexes are all monomeric cw-dioxovanadium(V) species, coordination centers all adopt pseud-square pyramidal coordination geometry with the hydrazone ligands in their enol form losing two hydrogens and coordinating by tridentate mode, and amines' cations act as counter ions. Moreover, the electronic absorption spectra of the complexes upon titration with calf thymus DNA showed certain interaction between them, which is confirmed by the fluorescence measurements of interactional solutions of the DNA and ethidium bromide affected by our complexes, probably by the mode of partial insertion of the moiety of the hydrazone ligands between the base pairs of the DNA which results in the stacking interaction between bases and the aromatic chromophores of the ligands. Lastly, the effect of the typical compound, complex 1, on rats with diabetes mellitus and ordinary rats was investigated. This kind of complexes obtained showed some insulin-mimetic activities.