Syntheses, spectroscopic characterization, thermal study, molecular modeling, and biological evaluation of novel Schiff’s base benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) with Ni(II), and Cu(II) metal complexes

•Synthesis, characterization and Molecular modeling of novel Schiff’s base ligand and complexes.•Complexes possessed octahedral, tetragonal, square pyramidal, and tetrahedral geometry.•Thermal data suggested that metal complexes were more stable than free ligand.•In vitro antimicrobial activity of ligand and its complexes were screened.•Complexes were found more biologically sensitive than ligand.

Novel Schiff’s base ligand, benzil bis(5-amino-1,3,4-thiadiazole-2-thiol) was synthesized by the condensation of benzil and 5-amino-1,3,4-thiadiazole-2-thiol in 1:2 ratio. The structure of ligand was determined on the basis of elemental analyses, IR, 1H NMR, mass, and molecular modeling studies. Synthesized ligand behaved as tetradentate and coordinated to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen–sulfur donor (N2S2) ligand. Metal complexes were characterized by elemental analyses, molar conductance, magnetic susceptibility measurements, IR, electronic spectra, EPR, thermal, and molecular modeling studies. All the complexes showed molar conductance corresponding to non-electrolytic nature, expect [Ni(L)](NO3)2 complex, which was 1:2 electrolyte in nature. [Cu(L)(SO4)] complex may possessed square pyramidal geometry, [Ni(L)](NO3)2 complex tetrahedral and rest of the complexes six coordinated octahedral/tetragonal geometry. Newly synthesized ligand and its metal complexes were examined against the opportunistic pathogens. Results suggested that metal complexes were more biological sensitive than free ligand.

Graphical abstractSynthesized ligand behaves as tetradentate and coordinates to metal ion through sulfur atoms of thiol ring and nitrogen atoms of imine group. Ni(II), and Cu(II) complexes were synthesized with this nitrogen–sulfur donor (N2S2) ligand. Geometry optimized structure of [Cu(L)Cl2] complex.Figure optionsDownload full-size imageDownload as PowerPoint slide