Template synthesis of square-planar Ni(II) complexes with new thiophene appended Schiff base ligands: Characterization, X-ray structure and DFT calculation

New square planar nickel(II) complexes, [Ni(L1)2] (1) and [Ni(L2)2] (2) with thiophene appended Schiff's base ligands have been synthesized and characterized. Geometries of the complexes have been confirmed by single crystal X-ray studies. Absorption and emission properties have been studied. The complexes show quasi-reversible NiII/NiIII oxidation couple along with irreversible NiII/NiI reduction. Electronic structure and spectral properties are well interpreted by DFT and TDDFT calculations.