Abstract: | Chalcone-derived 3-phenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCTPh) (1), 3-(4-chlorophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4ClPh) (2), 3-(4-bromophenyl)-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4BrPh) (3), and 3-(4-nitrophenyl-1-pyridin-2-ylprop-2-en-1-one thiosemicarbazone (HPyCT4NO2Ph) (4) were obtained as well as their gallium(III) and zinc(II) complexes Ga(PyCTPh)2]NO3 (Ga1), Ga(PyCT4ClPh)2]NO3 (Ga2), Ga(PyCT4BrPh)2]NO3 (Ga3), Ga(PyCT4NO2Ph)2]NO3 (Ga4), Zn(PyCTPh)2] (Zn1), Zn(PyCT4ClPh)2] (Zn2), Zn(PyCT4BrPh)2] (Zn3), and Zn(PyCT4NO2Ph)2] (Zn4). The chalcones, thiosemicarbazones, and zinc(II) complexes were not active against Pseudomonas aeruginosa. The thiosemicarbazones proved to be more active than the parent chalcones against Staphylococcus aureus and Candida albicans. Coordination to zinc(II) resulted in activity improvement of most thiosemicarbazones against S. aureus. Coordination to gallium(III) significantly improved the antimicrobial activity of all thiosemicarbazones against the studied micro-organisms, suggesting this to be an effective strategy for antimicrobial activity enhancement. |