Hydrothermal synthesis, structures, and luminescent properties of zinc(ii) and cadmium(ii) phosphonates with a 3D framework structure using terephthalate as second linkers

摘要

By introduction of 1,4-benzenedicarboxylic acid as a second organic ligand, two new divalent metal(ii) phosphonates with a 3D framework structure, namely, [Zn(HL1)(bdc)_(0.5)] (1) and [Cd_(1.5)(HL_2)(bdc)_(0.5)] (2) (H_2L1 = H_2O_3PCH(NH_2)C _6H_5, H_3L_2 = H_2O_3PCH _2-NC_5H9-COOH, H_2bdc = HOOCC _6H_4COOH), have been synthesized under hydrothermal conditions. The two compounds show three-dimensional (3D) framework structure with infinite two-dimensional (2D) networks pillared by H2bdc. For compound 1, the {ZnO4} polyhedra are interconnected by phosphonate groups into a 2D layer, and the adjacent layers are further cross-linked via the bdc2- anions to generate a three-dimensional framework structure with two types of channel system along the c-axis. A notable feature of compound 1 is the presence of alternate left- and right-handed helical chains in the structure. In compound 2, the inorganic chains, composed of {Cd(1)O 7}, {Cd(2)O4} and {CPO3} polyhedra, are linked by HL22- ligands to form a double layer structure in the ab plane, and the adjacent layers are further linked by the bdc2- anions to form a 3D framework structure with one-dimensional channel systems along the a-axis. Luminescence properties of compounds 1 and 2 have also been studied.