Novel lanthanide coordination polymers based on mixed N,O-donor ligands and their visible-light-driven photocatalytic performance

In the present work, we prepared three isostructural lanthanide (Ln) coordination polymers (CPs), namely [Ln (Hhpc) (phen) (NO3)] (Ln = Gd (1), La (2), Y (3), H3hpc = 5-hydroxy-1H-pyrazole-3-carboxylic acid, phen = 1,10-phenanthroline) by hydrothermal method. Their structures were characterized by single crystal X-ray diffraction, Fourier transform infrared spectrum, elemental analysis, powder X-ray diffraction and thermal gravimetric analysis. CPs 1–3 are isostrutural and exhibit two-dimensional (2D) wavy layered structure constructed from inorganic chains, in which equivalent eight coordinated Ln3+ ions are linked through carboxylate groups. The three dimensional supramolecular structure is further formed by hydrogen bonding. The photocatalytic experiments show that CPs 2 and 3 exhibit good photocatalytic performances under visible light in degradation of methylene blue organic dye. The photocatalytic degradation efficiencies in 90 min are about 86.19% and 93.60% for CPs 2 and 3, respectively. The photocatalytic degradation mechanisms have been proposed through photoelectrochemical and trapping radical experiments.