Bismuth(III) halide complexes of aromatic thiosemicarbazones: Synthesis, structural characterization and biological evaluation

Abstract

Four new bismuth(III) thiosemicarbazone complexes, {BiCl3(η1-S-Hacptsc)3} (1), {[BiBr3(η1-S-Hacptsc)3]·CH3OH} (2), {[BiI2(µ2-I](η1-S-Hacptsc)]2} (3) and {[BiCl2(µ2-Cl)(η1-S-Hbztsc)2]2} (4), were prepared with the ligands acetophenone thiosemicarbazone (Hacptsc) and benzaldehyde thiosemicarbazone (Hbztsc). The complexes were characterized by a series of spectroscopic techniques. The crystal structures of 1–4 were also determined by X-ray diffraction. To the best of our knowledge, complexes 1–4 are the first examples of bismuth(III) halide aromatic thiosemicarbazones. Hirshfeld surface analysis studies show that H…H and X…H/H…X interactions of complexes 1–4 play an important role in the formation of supramolecular aggregation. Complexes 1–4 have been tested for their in vitro cytotoxic activity against human breast adenocarcinoma (MCF-7) cells. The toxicity of 1–4 has been evaluated on normal human fetal lung fibroblast cells (MRC-5). Complexes 1–4 appeared to show low cytotoxic activity and low toxicity. The antibacterial activity of 1–4 and their ligands was evaluated against the Gram negative species Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli) and Gram positive ones Staphylococcus epidermidis (S. epidermidis) and Staphylococcus aureus (S. aureus) by the Inhibition Zone (IZ) method. The influence of 1–4 on the catalytic peroxidation of linoleic acid by the enzyme lipoxygenase (LOX) has been determined experimentally. The IC50 values reveal that the synthesized bismuth(III) aromatic thiosemicarbazone complexes have good potential to inhibit lipoxygenase, with values better than the free aromatic thiosemicarbazone ligands and cisplatin.