An efficient one-pot synthesis of pyrazole complexes formed in situ: synthesis, crystal structure, Hirshfeld surface analysis and in vitro biological properties

The molecular crystals of monomeric and dimeric pyrazole complexes were prepared via one-pot syntheses. These are dichloridobis(3,5-dimethyl-1H-pyrazole-kappa N-1)cobalt/zinc(0.2/0.8), [Co0.20Zn0.80Cl2(C5H8N2)(2)] or [Co0.2Zn0.8-Cl-2(3,5-dmp)(2)] (1), and bis(mu-3,5-dimethyl-1H-pyrazole)-kappa N-2(1):N-2;kappa(2) N2:N-1-bis[bromido/chlorido(0.7/0.3)bis(3,5-dimethyl-1H-pyrazole-kappa N-1)cobalt/zinc(0.1/0.9)], [Co0.20Zn1.80Br1.40Cl0.60(C5H7N2)(2)(C5H8N2)(2)] or [Co0.1Zn0.9Br0.7Cl0.3(mu-3,5-dmp)(3,5-dmp)](2) (2). The isolated complexes contain 3,5-dimethylpyrazole (3,5-dmp) ligands formed in situ from the decomposition of 1-hydroxymethyl-3,5-dimethylpyrazole. In both isolated complexes, some positional disorder is observed at the metal ions and halogen ligands. The molecular crystals of 1 and 2 are centrosymmetric, with the space groups C2/c and P (1) over bar, respectively. Additionally, in the dinuclear complex, the pyrazole ring has a bridging coordination function with respect to the metal ions. Both complexes have good biological activities against cancer cells. The results of an in vitro cytotoxicity study indicated that compounds 1 and 2 showed significant cytotoxicity for cancer cell lines, including hepatic (HepG2 cells), lung (A549 cells) and colon cancer cells (SW 480 and SW 620). Based on the calculated IC50 values against human cancer cell lines, it was found that both complexes demonstrated potent anti-proliferative activity combined with great selectivity towards cancer cells. Complex 2 was a more effective cytotoxic agent which, at the same time, exhibited high cytocompatibility. The obtained data are very encouraging and could be useful for anticancer drug discovery.

Automated summary

Molecular crystals of monomeric and dimeric pyrazole complexes with good biological activities against cancer cells were prepared via one-pot syntheses. These complexes exhibited significant cytotoxicity for different cancer cell lines and showed potent anti-proliferative activity with great selectivity towards cancer cells. These findings are important for anticancer drug discovery.