Synthesis, characterization, crystal structure and biological activities of the unusual main group 8-coordinate bismuth (III) complex derived from 2-acetylpyrazine N4- pyridylthiosemicarbazone

Main group metal complex [Bi(HL)(NO3)3] (1), where HL = 2-acetylpyrazine N(4)-pyridylthiosemicarbazone, has been synthesized and characterized by elemental analysis, IR, MS and single-crystal X-ray diffraction studies. The interesting monomeric 8-coordinate bismuth(III) complex 1 is depicted with one electron pair (6 s2) of the bismuth(III) atom, one N2S tridentate neutral thiosemicarbazone, two monodentate and one bidentate nitrate ions, respectively. In vitro biological studies have indicated that the bismuth complex 1 has shown effective antibacterial and anticancer activities especially with MIC = 15.6 μg/mL against Gram positive bacteria Bacillus cereus and IC50 = 1.6 μM against K562 leukemia cell lines, respectively, comparable to positive control.

Graphical abstractMain group metal complex [Bi(HL)(NO3)3] (1), where HL = 2-acetylpyrazine N(4)-pyridylthiosemicarbazone, has been synthesized and structurally characterized. Formation of 8-coordinated structure of the bismuth(III) atom is unusual and interesting. Biological studies have indicated that the bismuth(III) complex shown effective antibacterial and anticancer activities, especially with MIC = 15.6 μg/mL against Gram positive bacteria Bacillus cereus and IC50 = 1.6 μM against K562 leukemia cell lines, respectively, comparable to positive control.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Bismuth(III) complex [Bi(HL)(NO3)3] (1) has been synthesized and characterized. ► Formation of 8-coordinated structure of the bismuth(III) atom is unusual. ► The bismuth complex 1 shown effective biological activities. ► These results are encouraging its further screening and evaluation of mechanism.