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

•[Cu(L)]ClO4 crystallizes in two different space groups; P21/n and P-1.•P-1 polymorph has tunnels with a volume of 157 Å3.•The tunneled structure is stabilized via π–π stacking interactions to give MOF.•[Cu(L)]ClO4 has a distorted-square pyrimidal coordination geometry.•The complex has Cu(I/II) couple around 0.1 vs. Cp2Fe/Cp2Fe+.

Flexible unsymmetrical Schiff base ligand (L) which is derived from the half unit Y = C6H5COCH2C(NCH2C6H4NH2)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 Å3 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 π–π 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+.

Graphical abstractThe reported complex in this paper 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 Å3 which is big enough to accommodate solvent molecules.Figure optionsDownload full-size imageDownload as PowerPoint slide