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: [VOL 1 (NCS) 2 ] (1) and [VOL 1 (NCS) 2 ]·C 6 H 5 CH 3 (2) where L 1 -bis(3,5dimethylpyrazol-1-ylmethyl)amine have been reported.The products, isolated in one-pot synthesis, contain multipodal pincer ligand L 1 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 biological activity of complex 2 was investigated. The complex 2 exhibited anti-proliferative activity towards 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. * AbstractExperimental and theoretical studies on the structure and spectroscopic properties of two complexes: [VOL 1 (NCS) 2 ] (1) and [VOL 1 (NCS) 2 ]·C 6 H 5 CH 3 (2) where L 1 -bis(3,5dimethylpyrazol-1-ylmethyl)amine have been reported.The products, isolated in one-pot synthesis, contain multipodal princer ligand L 1 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 biological activity of complex 2 was investigated. The complex 2 exhibited anti-proliferative activity towards 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. Fig.2. Normalized Hirshfeld surface around the [VOL 1 (NCS) 2 ] molecules (a) in 1 and (b) in 2. Chain patterns created (c) by hydrogen bonds in 1 and (d) by C-H···π interactions in 2.

Selective Cytotoxicity of Complexes with N,N,N-Donor Dipodal Ligand in Tumor Cells

“…This multipodal, tridentate organic ligand formed in situ can be called an "impaired" scorpionate, an analogue of poly(pyrazolyl)borate ligands, containing only two, instead of three, pyrazole groups. Generally, complexes with an N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)amine (L D ) ligand are much less numerous than those with tripodal teradentate ligands [16,18,19,22]. Only nine complexes with N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)amine have been reported in CCDC, and therein six complexes were synthesised by us [16,18,19,21,22].…”

“…Generally, complexes with an N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)amine (L D ) ligand are much less numerous than those with tripodal teradentate ligands [ 16 , 18 , 19 , 22 ]. Only nine complexes with N,N-bis(3,5-dimethylpyrazol-1-ylmethyl)amine have been reported in CCDC, and therein six complexes were synthesised by us [ 16 , 18 , 19 , 21 , 22 ]. Here, we have tested three selected complexes, containing the same ligand (L D ), and formed anionic and neutral complexes with different geometries.…”

“…In all complexes, the order of M-N bond lengths is: M-N (amine) > M-N (pyrazole) > M-N (NCS) . The M-N-donor distance and the N-donor–Co–N-donor angles creates the optimal rigid structure, which determines the formation of a stable complex [ 18 , 19 , 22 ].…”

“…In line with this, 1 and 3 also inhibited growth on noncancerous cells ( Figure 2 A). Indeed, we have previously found that vanadium complex 3 may express antiproliferative potency also towards normal cells [ 22 ].…”

“…Results are arithmetic mean values and standard deviation (M; ±SD), n = 3. Data adapted from previous study [15,22]…”