Solvent‐Dependent Synthesis of Porous Anionic Uranyl–Organic Frameworks Featuring a Highly Symmetrical (3,4)‐Connected ctn or bor Topology for Selective Dye Adsorption

Abstract

Two highly symmetrical (3,4)-connected uranyl-organic frameworks (UOFs) were synthesized by a judicious combination of D -symmetrical triangular [UO (COO) ] and T symmetrical tetrahedral tetrakis(4-carboxyphenyl)methane (H MTB). These two as-synthesized UOFs possess similar structural units and coordination modes but totally different topological structures, namely ctn net and bor net. Solvent-induced interpenetration and a morphology change are observed. The two compounds exhibit crystal transformation via a dissolution-crystallization process. Adsorption experiments in CH OH solution indicate that both of them can selectively remove positively charged dyes over negatively charged and neutral dyes. Moreover, the electronic structural and bonding properties of the two compounds were systematically explored by density functional theory (DFT) calculations.

Structural Consequences of 1,4-Cyclohexanedicarboxylate Cis/Trans Isomerism in Uranyl Ion Complexes: From Molecular Species to 2D and 3D Entangled Nets

“…Although they are not extremely common, the list of entangled nets [20][21][22][23][24][25] in uranyl coordination chemistry is steadily growing and covers a very diverse set of topologies. 8,14,19,[26][27][28][29][30][31][32][33][34][35][36][37][38][39][40]…”

Uranyl Ion Complexes of Polycarboxylates: Steps towards Isolated Photoactive Cavities

“…Many other "nanotubular" species (not all based on carboxylates) have since been characterised [47,[67][68][69][70][71][72][73][74][75][76], their significance lying not only in their possible suitability as reaction vessels for the synthesis or oxidation of long, linear molecules but also, relating to the focus of the present discussion, as channels which might be used to link and provide access to capsular reaction vessels. The objective here would be the creation of uranyl ion-based structures analogous to those of zeolites and mesoporous silicas, an objective, which despite an early success [77] (discussed ahead), has been attained in but a few instances [42][43][44]. An intriguing comparative consideration here is that of the relationships between graphite, fullerenes, and carbon nanotubes, since a common feature of the crystal structures of anionic uranyl ion complexes of dicarboxylates is the presence of diperiodic honeycomb layers with a hexagonal form similar to that of graphite [42,[47][48][49]78].…”

“…The objective here would be the creation of uranyl ion-based structures analogous to those of zeolites and mesoporous silicas, an objective, which despite an early success [77] (discussed ahead), has been attained in but a few instances [42][43][44]. An intriguing comparative consideration here is that of the relationships between graphite, fullerenes, and carbon nanotubes, since a common feature of the crystal structures of anionic uranyl ion complexes of dicarboxylates is the presence of diperiodic honeycomb layers with a hexagonal form similar to that of graphite [42,[47][48][49]78]. While the appropriate choice of ligand has certainly enabled this tendency to be overcome, the actual outcome has proved difficult to predict, as is well illustrated by various investigations of the dianion of camphoric acid as a ligand for uranyl ion [79][80][81][82].…”

“…Thus, the structure of the complex [H 3 O] 2 [(UO 2 ) 5 (cbtc) 3 (H 2 O) 6 ], (R, CSD refcode GOJFAN), contains octanuclear boxes (Figure 9), where each uranyl centre is bound by three κ 2 O,O' carboxylate units, linked by tetranuclear metallacycles where each uranyl centre is bound to two κ 2 O,O' carboxylate units and two water molecules (in trans positions). Neither the luminescence nor porosity of complex R, nor of the more recently isolated framework complex [H 2 NMe 2 ] 4 [(UO 2 ) 4 (cbtc) 3 ] (similar but of a different topological type, CSD refcode TOJJAG) [100], have yet been studied but certainly the porosity of the uranyl ion complexes of tetrakis(4-carboxyphenyl)methane, where a single atom is the source of the tetrahedral orientation, has been demonstrated [42]. It is of course not essential that dicarboxylate units be orthogonally directed in order to generate triperiodic structures of linked cavities, as is seen in the formation of such structures with cis,trans,cis-cyclobutanetetracarboxylate [77] and in the more recently studied structures of uranyl ion complexes of porphyrin-derived tetracarboxylates [39] (where photoreactivity is associated with the porphyrin centres).…”

“…Selectivity of these reactions has not been a major focus and in some early instances [34] would be expected to have been determined by the nature of the preformed support upon which uranyl centres were immobilised. Given that the use of a radioactive material would pose problems in any large-scale application for environmental remediation or water splitting, an alternative, more appealing prospect is that of selective photochemical synthesis within cavities of a porous uranyl complex crystal, a prospect which parallels what has already been realised for synthesis in general with other metal ion derivatives [2,[36][37][38] and which is rendered worthy of wider investigation by the observation of selective incorporation of various materials into the cavities of some known uranyl ion coordination polymers [39][40][41][42][43][44][45].…”