The importance of heterolepticity in improving the antibacterial activity of bismuth(III) thiolates

Ahmad Luqman, Victoria L Blair, Rajini Brammananth, Paul K Crellin, Ross L Coppel, Philip C Andrews

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Five mixed thiolatobismuth(III) complexes [BiPh(5-MMTD)2{4-MMT(H)}] (1), [Bi(1-MMTZ)2{(PYM)(PYM(H))2}] (2), [Bi(MBT)2(5-MMTD)] (3), [Bi(4-BrMTD)3{2-MMI(H)}] (4) and [Bi(1-MMTZ)2{1-MMTZ(H)}(2-MMI){2-MMI(H)2}] (5) were synthesised from imidazole-, thiazole-, thiadiazole-, triazole-, tetrazole- and pyrimidine-based heterocyclic thiones. Four of these complexes 1–4 were synthesized from BiPh3, while complex 5 was obtained from Bi[4-(MeO)Ph]3. Complexes 1–5 were structurally characterised by XRD. Evaluation of the antibacterial properties against Mycobacterium smegmatis, Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), Vancomycin-resistant Enterococcus (VRE), Enterococcus faecalis and Escherichia coli showed that mixed thiolato complexes containing the anionic thiazole-based ligands MBT and 4-BrMTD are most effective. The mixed thiolato complexes [Bi(MBT)2(5-MMTD)] (3) having thiazole- and thiadiazole- and [Bi(4-BrMBT)3{2-MMI(H)}] (4) containing thiazole- and imidazole-based ligands proved to be more efficient, with low minimum inhibitory concentrations of 1.73 and 3.45 µm for 3 against VRE and E. faecalis, respectively, and 2.20 µm for 4 against M. smegmatis and E. faecalis. All complexes showed little or no toxicity towards mammalian COS-7 cell lines at 20 µg mL–1.

Original languageEnglish
Pages (from-to)2738-2749
Number of pages12
JournalEuropean Journal of Inorganic Chemistry
Issue number17
Publication statusPublished - 2016


  • Antibiotics
  • Bismuth
  • Drug design
  • Heteroleptic complexes
  • Medicinal chemistry
  • S ligands

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