New oxovanadium(iv) complexes with pincer ligand obtained in situ: experimental and theoretical studies on the structure, spectroscopic properties and antitumour activity

Abstract

Experimental and theoretical studies on the structure and spectroscopic properties of two complexes: [VOL¹(NCS)₂] (1) and [VOL¹(NCS)₂]·C₆H₅CH₃ (2) where L¹-N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)amine have been reported. The products, isolated in a one-pot synthesis, contain a multipodal pincer ligand L¹ obtained in situ from the system containing 1-hydroxymethyl-3,5-dimethylpyrazole (L) as one of the substrates. The crystal structure, electronic (UV-VIS) and infrared (IR) spectra of the complexes have been analyzed. The combined use of experiments and computations allowed a firm assignment of the majority of the observed electronic and vibrational transitions. Theoretical (DFT) calculations have been carried out at the B3LYP/LanL2DZ level to investigate the geometry of 1 and 2. They were found to be in a good agreement with the experimental results. Additionally the biological activity of complex 2 was investigated. Complex 2 exhibited anti-proliferative activity towards a panel of human cancer cells (hepatocellular carcinoma Hep G2, lung carcinoma A549, colorectal adenocarcinomas SW 480 and SW 620). The anti-proliferative potency of complex 2 and its higher selectivity towards cancer cells than those of the vanadium salt tested, makes it an interesting candidate for further investigation of its anti-cancer properties.