Synthesis, Crystal Structure and Fluorescent Properties of Transition Metal Complexes Constructed with 2-(3′-Carboxyphenoxy) benzoic Acid and N-Donor Ligands

Taking 2-(3'-carboxyphenoxy) benzoic acid (2, 3'-H(2)oba), 1, 3-bis (4-pyridyl)-propane (DPP) and 1, 4-bis (1, 2, 4- triazole-1-) butane (BTB) as ligands, two transition metal complexes Cd (2, 3'-oba) (DPP) (1) and Zn (2, 3'-oba) (BTB)(0.5) (2) were obtained by hydrothermal method. Complex 1 is a two-dimensional network structure, the coordination environment of the central Cd2+ is {CdO4N2}, the 2, 3'-oba ligand and the DPP ligand link Cd2+ into Cd2+-2, 3'-oba-Cd2+-DPP helical chains by bidentate chelating and monodentate bridging modes, respectively. Complex 1 is linked by intermolecular hydrogen bonding and self-assembled into a three-dimensional supramolecular structure. Complex 2 is a three-dimensional framework structure, and the central Zn2+ adopts a five. coordinated distortion quadrilateral cone configuration {ZnO4N}. The 2, 3'-oba ligand links the adjacent Zn2+ as a bidentate chelate and a bidentate bridge to form a two-dimensional network layer. The BTB molecule bridges the Zn2+ and connects adjacent network layers to form a three-dimensional structure. Fluorescence spectroscopy indicates that complexes 1 and 2 have maximum emission at 437 nm and 359 nm, respectively, both are derived from the pi*-pi transition of the ligand. The broad-spectrum pesticide mesotrione has a significant quenching effect on the fluorescence intensity of complex 2, thus complex 2 can be used as a chemical sensor for detecting mesotrione.