Synthesis, Crystal Structures and Fluorescence Properties of Two Bis(8-Hydroxyquinolinate)-based Coordination Polymers

A bis(8-hydroxyquinoline)-based organic ligand H₂L was synthesized, and its structure was characterized by ¹H-NMR, ¹³C-NMR and ESI-MS. Reacting the ligand H₂L with Cd(Ⅱ) and Zn(Ⅱ)ions, respectively two metalorganic complexes Cd₄L₃I₂·4DMF(1) and Zn₂LI₂·2DMSO(2) were obtained. Herein, the precise structures of two as-synthesized complexes as well as their fluorescent properties were explored by single-crystal X ray diffraction (SXRD), powder X ray diffraction (PXRD) and fluorescence spectrometer. The results show that metal complexes 1 and 2 are coordination polymers with chain-like structures. Interestingly, they possess two different binuclear building units and chain arrangement structures, and both exhibit high phase purities. Upon excitation at 380 nm, complexes 1 and 2 display maximum emission peaks at 580 and 568 nm respectively. Compared with the free ligand H₂L, the emission peaks of two complexes have an obvious red shift.