Solvent-dependent synthesis and mono-hydrolysis of di-Schiff base of (+/-)trans-1,2-cyclohexanediamine and 2-pyridinecarboxaldehyde in Cu(II), Co(II) and Zn(II) complexes

The Schiff base ligand trans-N,N′-bis[2-pyridinecarboxylidene] cyclohexane-1,2-diamine (L) was synthesized. This ligand when stirred with 1 equiv of MCl2.xH2O (M = Cu, Co, Zn) in ethanol, undergoes partial hydrolysis of the imino bond and the result tridentate ligand (L') and immediately forms the complexes with N3 coordination sphere. The reactions of L with MCl2.xH2O (M = Cu, Co, Zn) in THF give complexes [ML]Cl2. The ligand (L), complexes [M(L')Cl]Cl and [ML]Cl2 were characterized by elemental analysis, UV-Vis, FT-IR, 1H NMR, GC/MS and luminescence properties. The 1H NMR spectra of the ligand and its diamagnetic complexes were recorded in CDCl3 and DMSO solvents, respectively. Obtained data confirm that the donor atoms N in ligand coordinated to the metal ions. The luminescence studies show ligands and their complexes display intraligand (π-

Copper(II) complex of (±)trans-1,2-cyclohexanediamine azo-linked Schiff base ligand encapsulated in nanocavity of zeolite-Y for the catalytic oxidation of olefins

A Schiff base ligand derived from 4-(benzeneazo) salicylaldehyde and (±)trans-1,2-cyclohexanediamine (H2L) and its corresponding Cu(II) complex (CuL) has been synthesized and characterized by FT-IR, UV-VIS and 1H NMR. The copper Schiff base complex encapsulated in the nanopores of zeolite-Y (CuL-Y) by flexible ligand method and its encapsulation have been ensured by different studies. The homogeneous and its corresponding heterogeneous catalysts have been used for oxidation of different alkenes with tert-butyl hydroperoxide. Under the optimized reaction conditions, the oxidation of cyclooctene, cyclohexene, styrene and norbornene catalyzed by CuL gave 89, 63, 46 and 13% conversion, respectively. These olefins were oxidized efficiently with 50, 96, 96 and 92% conversion in the presence of CuL-Y, respectively. Comparison of the catalytic behavior of CuL and CuL-Y showed the higher catalytic activity and selectivity of the heterogeneous catalyst with respect to the homogenous one