The Zn(II)-organic coordination polymers based on 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylate ligands: Crystal structures and luminescent properties

Two novel compounds, [Zn(H2PIDC)2(H2O)2] (1) and [Zn4(PIDC)2(SO4)(H2O)5]·(2.5H2O) (2) (H3PIDC = 2-(pyridin-4-yl)-1H-imidazole-4,5-dicarboxylic acid) have been synthesized under hydrothermal condition, and characterized by thermal analyses (TGA), powder X-ray diffractions (PXRD), and single-crystal X-ray diffractions, respectively. Compound 1 is constructed from mononuclear molecules which form the 2D square networks and further extend to 3D supermolecular framework through the π–π stacking and strong hydrogen bonding interactions. Compound 2 exhibits a 3D framework and generates the 1D open rhombic channels filled with the coordinated water molecules, sulfate anions and free water molecules. The structure of 2 can be rationalized as a (4,4,4)-connected net and shown as a unique (4.53.6.7)4(42.52.72)2(52.62.72) topology. The different luminescent nature for 1 and 2 may be due to their various delocalization environments.