Copper(II) and nickel(II) complexes with N′-[(Z)-phenyl(pyridin-2-yl)methylidene]acetohydrazide: Synthesis, crystal structures, DFT calculations and antioxidant effects

Two mononuclear copper(II) and nickel(II) complexes viz., [Cu(HL)(L)]NO3·2H2O 1 and [Ni(L)(Neocup)]ClO4·MeOH 2 (where HL/L− = N′-[(Z)-phenyl(pyridin-2-yl)methylidene]acetohydrazide) complexes were synthesized and characterized by routine physiochemical techniques. Both complexes were structurally characterized using single crystal X-ray diffraction studies and belonging to space group P21/n for 1 and P1¯ for 2 respectively. Complex 1 has hexacoordinated geometry with 1:2 metals to ligand ratio whereas complex 2 has pentacoordinated with two ligand and Schiff base and neocuproine donors sites. The room temperature EPR spectrum of 1 shows two S = 1/2 signals due to the elongated axial symmetry. Time dependent DFT calculations on the optimized structure of 1 and 2 in DMSO solvent allowed for the assignment of specific electronic transitions in the UV–Vis spectrum. The highest occupied molecular orbital (HOMO) was noted to consist of 55% Cu-d and 100% Ni-d character identified as the dx2–y2dx2–y2 orbital. In addition, antioxidant activity showed that both complexes exhibited significant scavenging effect against super oxide anion from radicals.

Two new copper(II) and nickel(II) complexes viz., [Cu(HL)(L)]NO3·2H2O 1 and [Ni(L)(Neocup)]ClO4·MeOH 2 (where HL/L− = N′-[(Z)-phenyl(pyridin-2-yl)methylidene]acetohydrazide) complexes were synthesized and characterized. Both complexes were structurally characterized using single crystal X-ray diffraction studies and belonging to space group P21/n for 1 and P1¯ for 2 respectively. Further, complexes catalyzed the dismutation of superoxide (O2−) at biological pH.Figure optionsDownload as PowerPoint slide