Synthesis and characterization of cyclic Schiff base ligands and metal complexes

In this study, 5-amino-3-(2,4-dihydroxybenzylidenamino)-4-(4-bromophenylazo)-1H-pyrazol (L1) and 4-[5-amino-3-(2,4-dihydroxybenzylidenamino)-1H-4-pyrazolilazo]benzoic acid (L2 ) ligands and their Cu(II), Ni(II), Zn(II) complexes were synthesized.5-amino-3-(2,4-dihydroxybenzylidenamino)-4-(4-bromophenylazo)-1H-pyrazol ligandı (L1) was synthesized by the condensation reactions of 3,5-diamin-4-(4-bromo-phenylazo)-1H-pirazol with 2,4-dihydroxy benzaldehyde. 4-[5-amino-3-(2,4-dihydroxybenzylidenamino)-1H-4-pyrzolilazo]benzoic acid (L2) was synthesized by the condensation reactions of 4-[3,5-diamine-4H-pyrazol-4-yl)diazenil]benzoic acid with 2,4-dihydroxy benzaldehyde. Complexes of this ligands were prepared with CuCl2.2H2O, NiCl2.6H2O, ZnCl2.2H2O.Structure of complexes of 5-amino-3-(2,4-dihydroxybenzylidenamino)-4-(4-bromophenylazo)-1H-pyrazol ligand (L1) are [Cu (L1)(Cl)2].H2O], [Ni(L1)2(Cl)2].5H2O and [Zn(L1)2(Cl)2].4H2O, respectively. Structure of complexes of 4-[5-amino-3-(2,4-dihydroxybenzylidenamino)-1H-4-pyrazolilazo]benzoic acid (L2) are [Cu(L2 )2(Cl)2].6H2O, [Ni(L2)(Cl)2].DMF.2H2O ve [Zn(L2)(Cl)2].2H2O, respectively.Structure of the ligands and complexes were investigated by 1H-NMR, 13C-NMR, IR, UV-VIS, DTA-TG, Elemental analysis, Magnetic susceptibility techniques.Key Words: Cyclic Schiff Base, Diazo, Aminopyrazol