New Vanadium(V) Complexes with Salicylaldehyde Semicarbazone Derivatives: Synthesis, Characterization, and in vitro Insulin-Mimetic Activity - Crystal Structure of [V~vO_2(salicylaldehyde semicarbazone)]

摘要

The new dioxo(semicarbazone)vanadium(V) complexes cis-VO2L, where L = salicylaldehyde semicarbazone (L~1), salicylaldehyde 4-n-butylsemicarbazone (L~2), or salicylaldehyde 4-(2-naphthyl)semicarbazone (L~3), have been synthesized, characterized by 1H and ~(13)C NMR and FTIR spectroscopy and tested for bioactivity as potential insulin-mimetic agents. All dioxovanadium(V) complexes exhibited essentially no in vitro insulin-mimetic activity, but the VO_2L_2 complex developed activity in the presence of ascorbic acid, similar to that of vanadyl sulfate. The molecular structure of the novel complex VO_2L~1 has been solved by X-ray diffraction methods. It crystallizes in the tetragonal space group P4_2 with a = 12.7674(7), c = 11.5308(5) A, and Z = 8. The vanadium atom is in a distorted square-pyramidal coordination, with L~1 acting as a tridentate ligand through its azomethyne nitrogen atom, carbonyl oxygen atom and deprotonated phenol oxygen atom. The coordination sphere is completed by two oxo ligands at cis positions.