Platinum group complexes containing salicylaldehyde based thiosemicarbazone ligands: Their synthesis, characterization, bonding modes, antibacterial and antioxidant studies

Herein we report the synthesis, characterization, bonding modes, antibacterial and antioxidant studies of half-sandwich ruthenium, rhodium and iridium complexes containing salicylaldehyde based thiosemicarbazone derivatives. All complexes have been prepared by reacting [(arene)MCl2]2 (M = Ru, Rh, Ir) with thiosemicarbazone derivatives (L1, L2, and L3) in 1:2 (M:L) molar ratio respectively. Three mononuclear and six binuclear cationic complexes have been obtained with either chloride or PF6 or both (in the case of binuclear complexes) as their counter ion. The binding modes of the thiosemicarbazone derivatives to the metal center for complexes 1–3, 6 and 8 have been confirmed by single-crystal X-ray diffraction studies. Further, their in-vitro antibacterial activity against gram-positive Staphylococcus aureus and gram-negative Escherichia coli, Klebsiella pneumoniae strains have been tested. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of these complexes have also been evaluated. Antioxidant activity of these compounds have also been tested. DNA binding studies for complexes 1 and 4 have been assessed owing to their good fluorescence intensity and are presented in supplementary information.