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)(NO_(3))](Ln=Gd(1),La(2),Y(3),H_(3)hpc=5-hydroxy-1 H-pyrazole-3-carboxyIic 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(2 D)wavy layered structure constructed from inorganic chains,in which equivalent eight coordinated Ln^(3+) 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.