Synthesis, hydrolysis and fluorescence of Schiff base derivatives of (±) trans-1,2-diaminocyclohexane (DACH) in Co(II), Zn(II), Ni(II) and Cu(II) Complexes

The Schiff base ligands trans-N,N′-bis[benzylidene]cyclohexane-1,2-diamine (L1) and trans-N,N′-bis [cinnamalidene]cyclohexane-1,2-diamine (L2) were synthesized. The reaction of L1 with MCl2.xH2O (M = Co, Zn, Ni, Cu) in ethanol, undergoes partial hydrolysis of the imino bond and results bidentate ligand (L1 ′ ) which immediately formed the complexes [ML1 ′ Cl2] with N2 coordination sphere. L2 reacts with MCl2.xH2O (M = Co, Zn) in ethanol and gives complexes [MLCl2]. The reaction of L2 with MCl2.xH2O (M = Ni, Cu) in ethanol undergoes hydrolysis of the imino bond and [M (DACH)Cl2] complexes are formed. The ligands and complexes were analyzed by elemental analysis, UV-VIS, FT-IR, 1H NMR, GC/MS and luminescence properties. The ligands and complexes display intra-ligand (π–π*) fluorescence in the solid state at room temperature.