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 (L^1′) which immediately formed the complexes [ML^1′Cl₂] with N₂ coordination sphere. L² reacts with MCl₂.xH₂O (M = Co, Zn) in ethanol and gives complexes [ML²Cl₂]. 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.