Synthesis, spectral characterization, DFT and in vitro antibacterial activity of Zn(II), Cd(II) and Hg(II) complexes derived from a new thiosemicarbazide

Abstract

A new series of mono-nuclear complexes, Cd 2+ , Zn 2+ and Hg 2+ derived from 4,4-dimethyl-2,6-dioxo-Nphenylcyclohexanecarbothioamide (HDDPT) have been prepared and characterized. The complexes adopted the molecular formulae; [Hg(DDPT)Cl(H 2 O)], [Cd (HDDPT) 2 Cl 2 ] and [Zn (HDDPT) 2 Cl 2 ], respectively. IR data showed that HDDPT ligand acts as OS bidentate either in neutral form as in Cd 2+ , Zn 2+ complexes or mononegative chelate in Hg 2+ complex. An octahedral environment was suggested for Zn 2+ and Cd 2+ complexes and a tetrahedral arrangement for Hg 2+ complex. DFT method we used to confirm the geometries of title compounds and evaluate other energetic parameters such as HOMO, LUMO, hardness, softness and electronegativity. Also, the thermal stability was examined by TGA and DrTGA and the associated thermodynamic parameters of activation were determined using Coats-Redfern and Horowitz-Metzger methods. Also, all compounds were screened for antibacterial activity using ciprofloxacin and gentamicin drugs by inhibition zone diameter method technique.