Nickel(II) complexes of novel thiosemicarbazone compounds: Synthesis, characterization, molecular modeling and in vitro antimicrobial activity

Abstract

A series of novel thiosemicarbazone compounds, HL 1 , 2-(1-(2-phenyl-hydrazono)-propan-2-ylidene)hydrazine-carbothioamide (TPHP), HL 2 , N -methyl-2-(1-(2-phenyl-hydrazono)-propan-2-ylidene)hydrazinecarbothioamide (MTPHP) and, HL 3 , N -phenyl-2-(1-(2-phenyl-hydrazono)-propan-2-ylidene)hydrazinecarbothioamide (PTPHP) and their Ni(II) complexes have been synthesized and characterized using elemental analysis, magnetic susceptibility, molar conductance and spectral measurements. IR spectra indicate that the free ligands exist in the thione form rather than thiol form in the solid state. In all the studied complexes, all ligands behave as a tridenate anion with coordination involving the two azomethine nitrogens and the thiolate sulfur after deprotonation. The magnetic and spectral data indicates a square planar geometry for Ni(II) complexes. The structures of the free thiosemicarbazone ligands and their Ni(II) complexes have been modelled using parameterized PM3 semiempirical method. The free ligands and their Ni(II) chelates have been screened for their antimicrobial activities.