Synthesis via microwave irradiation, structural characterization, and antibacterial activities of new complexes of bismuth(III) with thiosemicarbazones

Five derivatives of thiosemicarbazide, classified as thiosemicarbazone type ligands (L1-L5), were synthesized along with their respective bismuth(III) complexes (1–5), the latter using microwave irradiation. The ligands and complexes were characterized using various spectroscopic techniques, including IR, Raman, UV–Vis, ¹H NMR, ¹³C NMR, EA, and ESI-mass. X-ray diffraction was also conducted to determine the crystal structures of ligands L1, L2, L4, and L5 and bismuth complexes LBi1 and LBi4. All complexes displayed an octahedral geometry, with a single bismuth atom coordinating with the ligands via the sulfide atoms. Ligands L1-L5 and their complexes were evaluated against the Gram-negative species Salmonella spp. and the Gram-positive species Staphylococcus aureus using the Inhibition Zone (IZ) method to assess their antimicrobial potential. The results indicated that the synthesized bismuth(III) complexes exhibited promising inhibitory effects on the growth of Salmonella spp.