Structural and biological features of bismuth(III) halide complexes with heterocyclic thioamides

Ten novel bismuth(III) halide complexes of [Bi(L)X-3](n), [Bi(L)(2x3)](2), and [Bi(L)(3X3)] structural types were synthesized, in which L: 5-ethoxy-2-mercaptobenzimidazole, 5-methoxy-2-mercaptobenzimidazole and N-methylbenzothiazole. Bismuth(III) halide complexes 1-10 were characterized by melting point, elemental analysis, molar conductivity, FT-IR, FT-Raman, UV-Visible, H-1 and C-13 NMR spectroscopic techniques, as well as by the Thermogravimetric-Differential Thermal Analysis (TG-DTA). The crystal structures of complexes 1-10 were determined by using single crystal X-ray diffraction study. The results show that the bismuth(III) complexes exist as monomer (4), doubly-bridged dimer (1-3 and 5-9), and edge-sharing polymer (10), in which the central bismuth atom is a six-coordinated and adopts distorted octahedral geometries. We report here, for the first time, cis-sulfur, cis-halide arrangement of the doubly-bridged dimer bismuth(III) complexes. The intermolecular interactions in bismuth(III) complexes play a very important role in the supramolecular architecture. A detailed analysis of the intermolecular interactions has been performed as based on the Hirshfeld surfaces and their associated two-dimensional fingerprint plots. Bismuth(III) halide complexes 1-10 and their free ligands have been screened for antimicrobial activity against two Gram negative bacteria (Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853) and two Gram positive bacteria (Staphylococcus aureus ATCC 25923 and Enterococcus faecalis ATCC 29212). The influence of complexes 1-10 and the free ligands on the catalytic peroxidation of the linoleic acid by the enzyme lipoxygenase (LOX) has been determined experimentally and theoretically. (C) 2020 Elsevier B.V. All rights reserved.