Antibacterial properties of binuclear Zn(II)-azomethine complexes derived from diaminodiphenylsulphide bridged spacer

Antimicrobial resistance of microbes against treatment that once could  cure, has inspired an urgent need for new drugs development. Accordingly, three binuclear Zn(II)-Schiff bases complexes ZnLa - ZnLc were  prepared by direct reaction of the ligands La-Lc with Zn(II) ions in equimolar ratios bearing salicyldehydes with OH, NO2 and Cl functional groups. The synthesized compounds ZnLa - ZnLc were evaulated against Gram positive  (Enterococcus faecalis NCIMB 13280, Streptococcus mutant ATCC 25175™ and Staphylococcus aureus ATCC 6538™) and gram negative (Escheria coli NCTC 12900,  Salmonella typhi and Pseudomonas aeruginosa ATCC 15442) bacterial strains, respectively, by agar well diffusion and broth microdilution techniques. The minimum inhibitory concentration (MIC90) values were calculated by microplate reader at 550 nm to optimum result. It was found that  all the synthesized compounds showed promising antibacterial activity against the genus Streptococcus mutant followed Staphylococcus aureus and Escheria coli. Binuclear Zn(II) complexes had a superior antibacterial activity compared to their parent Schiff base ligands. In general, 3,4-dihydroxy derived Schiff bases  alongwith their relevant complexes exhibited magnificent antibacterial activity and hence merits to be established as promising keystone for subsequent antimicrobial drug advancement.