Synthesis and study of homo- and heterometallic coordination compounds of Cu(II) and Bi(III) with 4-ethylthiosemicarbazones of 2-formyl and 2-acetylpyridine

This paper deals with synthesis and analysis of two series of homo- and heterometallic coordination compounds of Cu(II) and Bi(III) with 4-ethylthiosemicarbazones of 2-formyl and 2-acetylpyridine, with the general formulas: {Cu(HL)}Cu(edta)·nH2O and {Cu(L)}2Cu(edta)·nH2O for Cu(II) homometallic complexes, and {Cu(L)}Bi(edta)·nH2O (n = 1 - 5) for heterometallic compounds. In the synthesized complexes, 4-ethylthiosemicarbazones of 2-formylpyridine (HFoPyTSC-4Et) and 2-acetylpyridine (HAcPyTSC4Et) are in monodeprotonated (L) or nondeprotonated (HL) forms. The antimicrobial and antifungal activities of the obtained homo- and heterometallic compounds have been determined. The results demonstrated that [Cu(AcPyTSC-4Et)Bi(edta)]·5H2O compound has the highest antimicrobial activity, being approximatly 76 and 19 times more active than Furacilin (MIC = 4.67 μg/mL) against Staphylococcus aureus (ATCC 25923) and Bacillus cereus (ATCC 11778) strains, correspondingly. While against Candida albicans strain, the most active antifungal agent, with MIC = 0.98 μg/mL, was {Cu(AcPyTSC-4Et)}2Cu(edta)·H2O complex, being approximately 32 times more active than Nystatin (MIC = 32.0 μg/mL).