Zinc(II) Mixed Ligand Complexes of Acesulfame and Thiones: Structural Characterization and Biological Activity

Acesulfame, with its oxathiazinone ring and potential coordination sites, acts as a ligand in forming complexes with various metal ions. According to this point, this study includes the synthesis and characterization of novel zinc(II) complexes incorporating acesulfame (acs) with various thione-containing ligands: 2-mercaptobenzothiazole (bztSH), 2-mercapto-benzimidazole (bizmSH), 2-mercaptobenzoxazole (bzoxSH), 1,3-dihydro-2H-imidazole-2-thione (imSH), and 5-( p -tolyl)oxazole-2(3H)-thione (mphtSH). The synthesized complexes, identified as [Zn(acs)₂(bztSH)₂] (1), [Zn(acs)₂(bizmSH)₂] (2), [Zn(acs)₂(bzoxSH)]₂ (3), [Zn(acs)₂(imSH)₂] (4), and [Zn(mphtS)₂] (5), were structurally elucidated using CHN analysis, nuclear magnetic resonance (NMR) spectroscopy, infrared (IR) spectroscopy, and molar conductivity measurements. Results indicate that the acesulfame ligand coordinates as a monodentate ligand via its nitrogen atom in complexes (1-4). In complex (1), the bztSH ligand coordinates in a monodentate mode through the nitrogen atom of its heterocyclic ring. Conversely, in complexes (2) and (4), bizmSH and imSH coordinate as monodentate ligands via their sulfur atoms. Complex (3) is a binuclear species where bzoxSH coordinates as a bidentate ligand through both its nitrogen and sulfur atoms. Notably, in complex (5) , the mphtSH ligand displaces acesulfame, coordinating as a bidentate ligand through its nitrogen and sulfur atoms. Furthermore, the antibacterial activities of these complexes were evaluated against Staphylococcus aureus and Escherichia coli . Complexes (4) and (1) demonstrated the highest efficacy. The [Zn(acs)₂(imSH)₂] (4) exhibited inhibition efficiencies of 74% and 79% with inhibition zones of 20 mm and 23 mm against S. aureus and E. coli , respectively. Similarly, [Zn(acs)₂(bztSH)₂] (1) showed inhibition efficiencies of 70% and 76% with inhibition zones of 19 mm and 22 mm against S. aureus and E. coli , respectively.