Synthesis, spectral characterization and biological evaluation of copper(II) and nickel(II) complexes with thiosemicarbazones derived from a bidentate Schiff base

Complexes of copper(II) and nickel(II) of general composition M(L)2X2, have been synthesized with the ligand 1-Tetralone thiosemicarbazone (where L = 1-Tetralone thiosemicarbazone and X=Cl-,1/2SO42-). The molar conductance of the complexes in fresh solution of DMSO lies in the range of 10–20 Ω−1 cm2 mol−1 indicating their non-electrolytic behavior. Thus, the complexes may be formulated as [M(L2)X2]. Ligand was characterized by mass, NMR, IR and single crystallographic studies. All the complexes were characterized by elemental analyses, magnetic moments, IR, electronic and EPR spectral studies. The IR spectral data of ligand indicated the involvement of sulfur and azomethine nitrogen in coordination to the central metal ion. The copper(II) and nickel(II) complexes were found to have magnetic moments1.93–1.96 BM and 2.91–2.94 BM corresponding to one and two unpaired electrons respectively. On the basis of molar conductance, EPR, electronic and infrared spectral studies, a tetragonal geometry has been assigned for Cu(II) chloride complex and trigonal bipyramidal to Cu(II) sulfate complex but an octahedral geometry for Ni(II) complexes. Newly synthesized ligand and its Cu(II) and Ni(II) complexes have also been screened against different bacterial and fungal species.

Graphical abstractLigand and its Cu(II) and Ni(II) complexes were successfully synthesized, and characterized in the solid state and in solution. The some of the synthesized Cu(II) and Ni(II) complexes have shown an enhanced antimicrobial activities.Single crystal structure for ligand.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesized ligand was characterized by single crystal study and other methods. ► Synthesized Cu(II) and Ni(II) complexes with ligand were characterized by different spectroscopic methods. ► Synthesized compounds have been screened against bacterial and fungal species in In vitro conditions. ► Ligand was not found to be active against pathogenic bacteria while some of the complexes were found effective. ► All the complexes were found to be more active against fungal pathogens than the parent ligand.