Series of Dual Functional Two-Dimensional RE-OFs for Nitrophenol Reduction and Dye Separation.

The rational design and preparation of stable and multifunctional metal-organic frameworks (MOFs) with excellent catalysis and adsorption properties are desirable but are great challenges. The nitrophenol (NP) reduction to aminophenols (APs) by using the catalyst Pd@MOFs is an effective strategy, which has attracted extensive attention in recent years. Here, we report four stable isostructural two-dimensional (2D) rare earth metal-organic frameworks [RE 4 (AAPA) 6 (DMA) 2 (H 2 O) 4 ][DMA] 3 [H 2 O] 8 (namely LCUH - 101 , RE = Eu, Gd, Tb, Y; AAPA 2- = 5-[(anthracen-9-yl-methyl)-amino]-1,3-isophthalate), which feature a 2D layer structure with sql topology of point symbol {4 4 ·6 2 } and exhibit excellent chemical stability and thermostability. The as-synthesized Pd@ LCUH - 101 was utilized for the catalytic reduction of 2/3/4-nitrophenol, which indicates high catalytic activity and recyclability attributed to the synergistic effect between Pd nanoparticles and the 2D layered structure. Of note, the turnover frequency (TOF), the reaction rate constant ( k ), and the activation energy ( E a ) of Pd@ LCUH - 101 (Eu) in the reduction of 4-NP, respectively, are 1.09 s -1 , 2.17 min -1 , and 50.2 kJ·mol -1 , which show that it has superior catalytic activity. Remarkably, LCUH - 101 ( Eu, Gd, Tb, and Y) are multifunctional MOFs that can effectively absorb and separate mixed dyes. The appropriate interlayer spacing enables them to efficiently adsorb methylene blue (MB) and rhodamine B (RhB) in aqueous solution, with adsorption capacities of 0.97 and 0.41 g·g -1 , respectively, which is one of the highest values among those of the reported MOF-based adsorbers. Meanwhile, LCUH - 101 (Eu) can be used for the separation of the dye mixture MB/MO and RhB/MO, and the excellent reusability enables LCUH - 101 (Eu) to be used as chromatographic column filters to quickly separate and recover dyes. Therefore, this work provides a new strategy for the exploitation of stable and efficient catalysts for NP reduction and adsorbents for dyes.