Hydrothermal Syntheses and Crystal Structures of Three Zn(II) Coordination Compounds Constructed with 3,5-Pyrazoledicarboxylic Acid

Abstract

Three novel metal–organic coordination compounds, [Zn(Hdcp)(H2O)4]·1.5H2O (1), [Zn(Hdcp)(H2O)2]∞ (2) and [Zn3(dcp)2(H2O)5]∞ (3) with the ligand 3,5-pyrazoledicarboxylic acid were prepared by the hydrothermal method. The complexes were structurally characterized by elemental analysis, IR spectroscopy and X-ray single-crystal diffraction. Compound 1 is a mononuclear molecule that is linked into a 3D supramolecular framework via N–H···O and O–H···O hydrogen bonds. In 2, two types of carboxylic bridges were found between ZnII ions to form a 1D double-chain. The 1D chains were further construct into a 3D structure by hydrogen bonds. Trinuclear 3 consists of 1D bi-infinite parallelogram chains of [Zn3(dcp)2(H2O)3] trimers. In the basic trinuclear unit a further bridging mode of the ligand is seen where two dcp3− ligands chelate three ZnII ions by utilizing five donors of the dcp3− ligand. The photoluminescent properties of 1, 2 and 3 were investigated.