Series of Stable Anionic Lanthanide Metal-Organic Frameworks as a Platform for Pollutant Separation and Efficient Nanoparticle Catalysis.

Eight new stable porous lanthanide metal-organic frameworks (Ln-OFs), namely, [Ln(BPTC)][(CH)NH] [Ln = Ho (), Eu (), Gd (), Dy (), Er (), Tm (), Yb (), Lu ()], were prepared by 3,3',5,5'-biphenyltetracarboxylic acid (HBPTC) and lanthanide ions by solvothermal reactions. Complexes - show a three-dimensional (3D) 6,6-connected network {4·6}·{4·6·8} topology based on binuclear (Ln) clusters and feature a one-dimensional curving porous channel occupied by exchangeable dimethylamine cations ([(CH)NH]) in the 3D anionic frameworks. The occupied [(CH)NH] in the anionic channels exhibited excellent ion-exchange ability, which is favorable to Pd and cationic dye adsorption. Consequently, - were used to load Pd nanoparticles to catalyze the reduction of nitrophenols and adsorb and desorb methyl blue (MB). The catalytic reaction efficiencies of Pd@- were higher than that of Pd/C (5 wt %) in the hydrogenation reaction of -nitrophenol (-NP). Moreover, Pd@ exhibited good cycle stability and achieved nearly 100% -NP conversion after eight cycles. Meanwhile, compound also exhibited a high adsorption ability of MB, possessing an adsorption capacity of 1.41 g·g (second only to 1.49 g·g reported in the literature) selectively over rhodamine B (RhB) and methyl orange (MO) in aqueous solutions. Remarkably, the skeleton of remained stable after four adsorption-desorption cycles of MB in aqueous solution.