Synthesis, spectroscopic, electrochemical, magnetic properties and super oxide dismutase activity of nickel (II) complexes with unsymmetrical Schiff base ligands

s: Five new mixed-ligand nickel (II) complexes; viz; [Ni (BHM)(PMDT)]1; [Ni(BHM)(dien)] 2; [Ni(BHM)(L 1 )]3; [Ni(BHM)(L 2 )] 4, [Ni(BHM)(L 3 )] 5; where H2BHM= N ’ -(1E)-(5-bromo-2-hydroxyphenyl) methylidene] benzoylhydrazide, PMDT= N,N,N’,N, ” N ” -Pentamethyldiethylenetriamine; dien= diethylenetriamine; L 1 = N,Ndimethyl-N’ (Pyrid-2-yl-methyl) ethylenediamine; L 2 = N-methyl-N’-(pyrid-2ylmethyl)ethylenediamine; L 3 = N,N-dimethyl-N’-(6-methyl)pyrid-2-ylmethyl) ethylenediamine, have been synthesized and characterized by using elemental analyses, FAB (fast atomic bombardment), magnetic measurements, electronic absorption , conductivity measurements, cyclic voltammetry (CV) and IRspectroscopy . All the complexes yielded an irreversible couple that can be assigned to a Ni II → Ni I redox process. Infrared spectra, ligand field spectra and magnetic susceptibility measurements agree with the observed octahedral environment. H2BHM is a diprotic tridentate Schiff base ligand (ONO donor atom) whereas L 1 -L 3 possessing N3 coordination sites. The SOD activities have been measured using alkaline DMSO as a source of superoxide radical (O2 – ) and nitro blue tetrazolium (NBT) as O2 – scavenger.