Hydrothermal synthesis of two 2D uranyl coordination polymers: structure, luminescence, and photocatalytic degradation of rhodamine B

Two novel two-dimensional (2D) uranyl coordination polymers, namely [(UO2)(bpda)](n) (1) and [(UO2)(bpda)(nmp)](n) (2) (bpda = [1,1'-biphenyl]-2,4'-dicarboxylic acid, nmp = N-methyl pyrrolidone), were synthesized by a hydrothermal method. Single-crystal structural analyses reveal that both polymers were constructed by the packing of 2D uranyl coordination networks via supramolecular interactions. The 2D network of 1 was constructed from distorted pentagonal bipyramid uranyl chains, while which was dual uranyl pentagonal bipyramid for 2. Topological simplification obtained 2D topological symbol of {4(2).8(4)}{4(6)} for 1 and 4-c {4(4).6(2)} for 2. Both polymers exhibit the emblematic charge-transfer green emission of uranyl-bearing complexes. The UV-vis absorption spectra reveal distinct light absorption both on the ultraviolet and visible regions for 1 and 2. Excellent activities of the photocatalytic degradation of rhodamine B (RhB) in aqueous solutions using polymers 1 and 2 were studied, 84.0% of the RhB was degraded in only 30 min under the photocatalysis of 1 and almost all of the RhB (99.7%) was degraded in 90 min by the photocatalysis of 2. These two new 2D uranyl coordination polymers represented effective RhB photocatalytic degradation materials in aqueous solution.