This work presents a 3D cationic coordination framework, showing ultra-highly selective trapping of perrhenate/pertechnetate in the presence of sulfate 20 000 times in excess.

Metal–organic frameworks (MOFs) are a class of promising sorbents for effective sequestration of radioactive 99 TcO 4 – anions. However, their poor stability and slow sorption kinetics in the industrial condition pose a great challenge. Herein, we demonstrate an optimizing strategy via in situ polymerization of ionic liquids (ILs) encapsulated in the pores of MOFs, forming polyILs@MOFs composites with greatly enhanced TcO 4 – sequestration compared with the pristine MOFs. Notably, the cross-linked polymerization of ILs facilitates the formation of both the inside ionic filler as the active sites and outside coating as the protective layers of MOFs, which is significantly beneficial to obtain the optimized sorption materials of exceptional stability under extreme conditions (e.g., in 6 M HNO 3 ). The final optimized composite shows fast sorption kinetics (<30 s), good regeneration (>30 cycles), and superior uptake performance for TcO 4 – in highly acidic conditions and simulated recycle stream. This strategy opens up a new opportunity to construct the highly stable MOF-based composites and extend their applicability in different fields.

Two series of ten 3D porous coordination polymers (PCPs), [Ag­(L434)]­(BF4)­(DMF)2 (1·BF 4 ·DMF), [Ag­(L434)]­(BF4)­(CH3CN)2 (1·BF 4 ·CH 3 CN), [Ag­(L434)]­(BF4)­(DMA)­(CH3OH) (1·BF 4 ·DMA/CH 3 OH), [Ag­(L434)]­(ClO4)­(DMF)2 (1·ClO 4 ·DMF), [Ag­(L434)]­(CF3SO3)­(DMF) (1·CF 3 SO 3 ·DMF), [Ag­(L434)]­(ClO4)­(CH3CN)2 (1·ClO 4 ·CH 3 CN), [Ag­(L434)]­(PF6)­(CH3CN)2 (1·PF 6 ·CH 3 CN), [Ag­(L434)]­(CH3SO3)­(DMA) (1·CH 3 SO 3 ·DMA), [Ag­(L434)]­(CF3SO3)­(DMA) (1·CF 3 SO 3 ·DMA), and [Ag2(L434)2]­(BF4)2(CH3OH)2 (2·BF 4 ·CH 3 OH), have been prepared via assembling 3,5-bis­(4-pyridyl)-4-(3-pyridyl)-1,2,4-triazole (L434) with Ag­(I) salts in different solvent media. All these PCPs possess 3D porous cationic frameworks, exhibiting irl topology for 2·BF 4 ·CH 3 OH and sra topology for others (1·anion·solvent) with the same point symbol of (42.63.8). Solvent-induced structural transformations between the topo-isomeric 1·BF 4 ·solvent and 2·BF 4 ·CH 3 OH show drastic deformations of the 3D host frameworks and concomitant solvent exchanges. Three cycles of anion-induced structural conversions involving 1·anion·DMF, 1·anion·CH 3 CN, and 1·anion·DMA isoreticular structures are also observed, in which the mother frameworks are almost unchanged during the anion exchanges. These two types of structural transformations occur upon different external stimuli (solvent and anion), which are accompanied by significant changes in the shape of channels and the volume of voids.