JOURNAL OF COORDINATION CHEMISTRY, cilt.75, sa.15-16, ss.2258-2274, 2022 (SCI-Expanded)
Three new Schiff bases (1a-3a) were synthesized as the starting compounds with the reaction of 5-(2-nitrophenyl)-2-furfural and 2-hydroxy-5-X aniline (X: H, Cl, Me, respectively). Afterwards, the asymmetric diimine ligands (1b-3b) were obtained by a two-step method as follows: nitro group of the starting Schiff bases was reduced into their amino derivative in solution and were reacted with 2-hydroxy-1-naphthaldehyde. Ni(II) complexes of the diimines (1c-3c) were then synthesized. The starting Schiff bases, asymmetric diimines and their complexes were characterized by elemental analyses, IR, LC-MS, TGA, UV-vis, H-1 and C-13-NMR, conductivity and magnetic measurements. Square planar geometry was proposed for the complexes. The protonation constants of all the Schiff bases and the stability constants of the complexes were determined potentiometrically in 50% ethanol-water solution (1:1, v/v) at 25 degrees C and 0.5 M KCl ionic strength.