VIVO]2+ complexes: Structure, unusual magnetic properties and cytotoxic effect

Abstract

The present investigation was carried out with the aim of synthesizing and characterizing five vanadium coordination compounds (6–10) with different Schiff bases (1 = N,N′-bis(salicylidene)-o-phenylenediamine, 2 = N,N′-bis(4-hydroxysalicylidene)-o-phenylenediamine, 3 = N,N′-bis(4-methoxysalicylidene)-o-phenylenediamine, 4 = N,N′-bis(3-hydroxysalicylidene)-o-phenylenediamine, 5 = N,N′-bis(3-methoxysalicylidene)-o-phenylenediamine) and studying their cytotoxic properties. Based on their physical (magnetic susceptibility), spectral (X-ray, electronic, IR, 1H NMR, 13C NMR, EPR and mass) and analytical (elemental analysis) results, the structures of these Schiff bases and their respective oxidovanadium(IV) complexes were established. Crystal structures of compounds 6 (Monoclinic, C 2/c, Z = 16) and 7–8 (Triclinic, P-1, Z = 2) had been determined by X-ray diffraction and confirmed pentacoordination of vanadium(IV) with a slightly distorted square-pyramidal geometry. Vanadium coordination compounds displayed low effective magnetic moments (0.85–0.89 BM) that maybe due to the intermolecular hydrogen bonding and π-stacking interactions in the crystal arrangements. Cytotoxic activity was evaluated on human tumor cell lines: 6–9 (HeLa = 0.443–1.502 μM) and 6–10 (HCT-15 = 0.373–1.415 μM), with exception of 7. Cell growth inhibition revealed that regardless of the cancer cell line type compounds 6 and 8 showed similar activity -possible effect due to the complex per se- giving new insights into the structure–activity relationship for these complexes.