Dimethyltin (IV) complexes of new thiosemicarbazone ligand with piperazine-1-yimethylene moiety: Synthesis, spectral characterization and antibacterial activity

Three new thiosemicarbazone ligands and their dimethyltin (IV) complexes are reported. The condensation of piperazine-1-carbaldehyde with thiosemicarbazide, 4-methyl-3-thiosemicarbazide, and 4-ethyl-3-thiosemicarbazide was carried out in an ethanol medium using HBr as a catalyst, resulting in the isolation of the ligands (E)-2-(piperazin-1-ylmethylene) hydrazine-1-carbothioamide (HL1), (E)-N-methyl-2-(piperazin-1-ylmethylene) hydrazine-1-carbothioamide (HL2), and (E)-N-ethyl-2-(piperazin-1-ylmethylene) hydrazine-1-carbothioamide (HL3), respectively. The reaction of ligands HL1 - HL3 with dimethyltin (IV) dichloride in ethanol yielded complexes of the general formula [Me2Sn(HLn)Cl2] (n = 1 for 1C, n = 2 for 2C, and n = 3 for 3C). Analytical and spectroscopic analyses confirmed the formation of six-coordinate tin(IV) complexes. Antibacterial studies against six marine pathogenic bacteria and eight human pathogenic bacteria microorganisms belonging to both gram-positive and gram-negative types, using disc diffusion techniques at a concentration of 10 mg/mL with ampicillin as a control, showed that complex 3C possesses enhanced inhibition activity compared to the free ligand HL3.