Synthesis, Structure, and Luminescence Properties of Coordination Polymers Containing Conjugated Triene Pyridine Ligands

Solvothermal reactions of the conjugated triene pyridine ligand 1,6-bis(4-pyridyl)-1,3,5-hexatriene (bphte) and Cd(II) salts in the presence of auxiliary carboxylic acid ligands (2,5-furandicarboxylic acid (2,5-H2FDC) and 1,3, 5-trimesic acid (1,3,5-H3BTC)) gave rise to two coordination polymers [Cd(2,5-FDC)(bphte)(H2O)](n) (1) and [Cd(1,3,5-HBTC)(bphte)](n) (2), respectively. Both complexes were characterized by elemental analysis, IR, single-crystal X-ray diffraction, powder X-ray diffraction, and thermogravimetric analysis. Complex 1 has a 3D framework with an spl topological structure, while complex 2 holds another 3D architecture formed by bridging 1D [Cd-2(1,3,5-HBTC)(2)](n) chains via bphte ligands. Both complexes exhibited luminescence emission in the solid state. Complex 2 showed an emission quenching phenomenon in Fe3+ aqueous solution, and thus was used as an excellent fluorescence probe to selectively detect Fe3+ in water with a low detection limit of 0.013 mu mol center dot L-1. The above emission quenching mechanism is likely due to the overlap between the absorption band of the Fe3+ ion and the excitation band of 2. CCDC: 2168533, 1; 2168532, 2.