Synthesis, characterization and neurotoxicity of multidentate azomethine series and their Cu(II) and Ni(II) Complexes

Two novel azomethine ligands L1 and L2 are synthesized from guanidine where L1 is (1E,3E)-1,3-bis(2,4-dihydroxybenzylidene)guanidine and L2 is (1E,3E)-1,3-bis(1-(2,4-dihydroxyphenyl)ethylidene)guanidine. The ligands are reacted with Cu(II) and Ni(II) to produce complexes CuL1, CuL2, NiL1 and NiL2. All the compounds are characterized by Fourier Transform Infrared (FTIR) spectroscopy, CHN elemental analysis, Proton Nuclear Magnetic Resonance spectroscopy and magnetic susceptibility measurements. The shift of ν(C=N) peaks upon complexation indicates that the azomethine nitrogens are involved in the chelation to the metal centres. The magnetic susceptibility measurements show that copper(II) complexes are paramagnetic with 1 unpaired electron while nickel(II) complexes are diamagnetic. An investigation for neurotoxicity against treated neuroblastoma SH-SY5Y cell lines showed non-toxic effect for the range of concentrations investigated.