Two Zn(II) and Co(II) compounds with dicarboxylates and curved 4,4′-azopyridine ligands: Syntheses, crystal structures and gas sorption properties

Abstract

Two new compounds Zn(PDA)(AZPY)·4H2O (1) and [Co(NDC)(AZPY)]2·2H2O·DMF (2) (H2PDA=pyridine-2,6-dicarboxylic acid, AZPY=4,4′-azopyridine, H2NDC=2,6-naphthalenedicarboxylic acid) were prepared through solvothermal reactions and characterized. Single crystal X-ray diffraction analysis indicates that compound 1 exhibits a one-dimensional chain structure, while compound 2 features a three-dimensional framework. Notably the bridged AZPY ligands involved in both compounds exhibit rare bent configurations. The thermal stability and gas sorption properties of compound 2 have also been studied. A normal amount (2.8mmolg−1) of hydrogen uptake at 1atm and −196°C for compound 2 were observed, which can be attributed to the presence of micropores.