Synthesis, crystal structure and properties of a new 3D supramolecular unsymmetrical tetradentate Schiff bases copper (II) framework with stable tunnels

Flexible unsymmetrical Schiff base ligand (L) which is derived from the half unit Y=C6H5COCH2C(N=CH2C6H4NH2)CH3 (obtained from the reaction of benzoylacetone and 2-aminobenzylamine) and 2-quinolinecarboxaldehyde have been successfully co-assembled with Cu(ClO4)(2) to give out the [Cu(L)]ClO4 complex. The complex crystallizes in two different space groups; P21/n and P-1. The crystal structure of the P-1 phase indicates the presence of tunnels; the volume of these tunnels is 157 angstrom(3) which is big enough to accommodate solvent molecules. The X-ray data indicates that these tunnels are most probably filled by highly disordered solvent molecules or solvent molecules with partial occupancy. The tunneled structure is stabilized via pi-pi stacking interactions to give a supramolecular MOF with 1D rhomboidal tunnels array. The copper(II) atom assumes a distorted-square pyrimidal coordination geometry where the perchlorate is located on the apex of the pyramide. In addition, this work presents and discusses the spectroscopic (IR, UV/vis), electro-chemical (cyclic voltammetry) behavior of the Cu(II) complexes. The Cu(II) oxidation state is stabilized by the novel tetradentate ligands, showing Cu(I/II) couple around 0.1 vs. Cp2Fe/Cp2Fe+. (C) 2016 Elsevier B.V. All rights reserved.