Helicity-induced two-layered Cd(II) coordination polymers built with different kinked dicarboxylates and an organodiimidazole

A new ligand bis-(4-imidazol-1-yl-phenyl)-diazene (azim), incorporating an azo moiety at the center and two imidazole groups at the terminals has been designed and synthesized. Under solvothermal conditions, this ligand reacts with Cd(NO3)2·6H2O and different angular aromatic dicarboxylates to form layered coordination polymers: [Cd(azim)(bcp)]n (1) and {[Cd(azim)(oba)](H2O)}n (2) [bcpH2 = 1,3-bis-(4′-carboxy phenoxy)benzene; oba = 4,4′-oxybis(benzoate)]. Both 1 and 2 have been characterized by single-crystal X-ray diffraction technique, elemental analysis, PXRD and IR spectroscopy. The structure of each polymer looks like 2D grid where two layers are interpenetrated in a “cloth-like” topology. Both the structures contain single- and double-stranded helical coils where the pitches as well as the width are controlled by the carboxylate co-ligands. The hydrogen-bonding interactions between adjacent layers extend these structures to overall 3D supramolecular architectures.

Graphical abstractTwo new self-catenated two-layered Cd(II) coordination networks have been constructed from two different kinked dicarboxylates and an organodiimidazole ligand under solvothermal conditions. Each of the coordination polymers comprises of both single and double-stranded helices.Figure optionsDownload full-size imageDownload as PowerPoint slide