Uranyl Organic Framework Research Articles

A Uranyl-Organic Framework Featuring Two-Dimensional Graphene-like Layered Topology for Efficient Iodine and Dyes Capture.

A novel uranyl-organic framework [(CH3)2NH2][UO2(TATAB)]·2DMF·4H2O (U-TATAB) was assembled through the solvothermal synthesis of UO2(CH3COO)2·2H2O and triazine tricarboxylate linker H3TATAB (H3TATAB = 4,4',4″-s-triazine-1,3,5-triyltri- p-aminobenzoate). It was characterized by single-crystal X-ray diffraction, elemental analysis, IR, powder X-ray diffraction, and thermogravimetric microanalysis. It is worth mentioning that U-TATAB exhibits an original arrangement of structures with interesting topology. Structural analysis confirmed that U-TATAB displays an interesting two-dimensional graphene-like layered topology. In order to broaden its functional characteristics, we first investigated the functional adsorbent U-TATAB for iodine capture in cyclohexane solution and for the removal of dye in aqueous solution. Large porosity, unique structure character, and the π-electron walls made of TATAB make the material a promising functional absorbent exhibiting excellent adsorption performance for iodine and dye molecules. Most notably, this is the first case of a uranyl-organic framework built by secondary building unit (SBU) [UO2(RCOO)3]- and extended trigonal triazine tricarboxylate ligand H3TATAB with amino functional groups.

Emergence of Uranium as a Distinct Metal Center for Building Intrinsic X‐ray Scintillators

AbstractThe combination of high atomic number and high oxidation state in UVI materials gives rise to both high X‐ray attenuation efficiency and intense green luminescence originating from ligand‐to‐metal charge transfer. These two features suggest that UVI materials might act as superior X‐ray scintillators, but this postulate has remained substantially untested. Now the first observation of intense X‐ray scintillation in a uranyl–organic framework (SCU‐9) that is observable by the naked eye is reported. Combining the advantage in minimizing the non‐radiative relaxation during the X‐ray excitation process over those of inorganic salts of uranium, SCU‐9 exhibits a very efficient X‐ray to green light luminescence conversion. The luminescence intensity shows an essentially linear correlation with the received X‐ray intensity, and is comparable with that of commercially available CsI:Tl. SCU‐9 possesses an improved X‐ray attenuation efficiency (E>20 keV) as well as enhanced radiation resistance and decreased hygroscopy compared to CsI:Tl.

Emergence of Uranium as a Distinct Metal Center for Building Intrinsic X-ray Scintillators.

The combination of high atomic number and high oxidation state in UVI materials gives rise to both high X-ray attenuation efficiency and intense green luminescence originating from ligand-to-metal charge transfer. These two features suggest that UVI materials might act as superior X-ray scintillators, but this postulate has remained substantially untested. Now the first observation of intense X-ray scintillation in a uranyl-organic framework (SCU-9) that is observable by the naked eye is reported. Combining the advantage in minimizing the non-radiative relaxation during the X-ray excitation process over those of inorganic salts of uranium, SCU-9 exhibits a very efficient X-ray to green light luminescence conversion. The luminescence intensity shows an essentially linear correlation with the received X-ray intensity, and is comparable with that of commercially available CsI:Tl. SCU-9 possesses an improved X-ray attenuation efficiency (E>20 keV) as well as enhanced radiation resistance and decreased hygroscopy compared to CsI:Tl.

Phase transition triggered aggregation-induced emission in a photoluminescent uranyl-organic framework.

When exposed to water, the two-dimensional uranyl-organic layered compound [(CH3)2NH2][(UO2)(BCPBA)]·2DMF·H2O (H3BCPBA = 3,5-bis (4'-carboxylphenoxy) benzoic acid) gradually undergoes a complete single-crystal-to-single-crystal phase transition to [(CH3)2NH2][(UO2)(BCPBA)]·3.4H2O, resulting in an enhanced ligand-ligand interaction between the adjacent layers. This process gives rise to initial quenching of the uranyl photoluminescence followed by subsequent recovery of the photoluminescence with a much elevated intensity, as a unique case of aggregation-induced emission in an extended solid system, further confirmed by DFT analysis on bonding.

A hydrolytically stable uranyl organic framework for highly sensitive and selective detection of Fe3+ in aqueous media.

We present a depleted uranium-based metal organic framework, UO2(C8H3O6N)·DMF, that exhibits highly sensitive and selective detection towards Fe3+ ions in aqueous media with an extremely low detection limit of 6.3 ppb. This work offers insight into exploring the potential applications of actinide-based metal organic frameworks in the area of chemical sensing with intrinsic advantages of high selectivity and sensitivity.

Highly Sensitive Detection of Ionizing Radiations by a Photoluminescent Uranyl Organic Framework.

Precise detection of low-dose X- and γ-radiations remains a challenge and is particularly important for studying biological effects under low-dose ionizing radiation, safety control in medical radiation treatment, survey of environmental radiation background, and monitoring cosmic radiations. We report here a photoluminescent uranium organic framework, whose photoluminescence intensity can be accurately correlated with the exposure dose of X- or γ-radiations. This allows for precise and instant detection of ionizing radiations down to the level of 10-4 Gy, representing a significant improvement on the detection limit of approximately two orders of magnitude, compared to other chemical dosimeters reported up to now. The electron paramagnetic resonance analysis suggests that with the exposure to radiations, the carbonyl double bonds break affording oxo-radicals that can be stabilized within the conjugated uranium oxalate-carboxylate sheet. This gives rise to a substantially enhanced equatorial bonding of the uranyl(VI) ions as elucidated by the single-crystal structure of the γ-ray irradiated material, and subsequently leads to a very effective photoluminescence quenching through phonon-assisted relaxation. The quenched sample can be easily recovered by heating, enabling recycled detection for multiple runs.

Highly Sensitive Detection of Ionizing Radiations by a Photoluminescent Uranyl Organic Framework

AbstractPrecise detection of low‐dose X‐ and γ‐radiations remains a challenge and is particularly important for studying biological effects under low‐dose ionizing radiation, safety control in medical radiation treatment, survey of environmental radiation background, and monitoring cosmic radiations. We report here a photoluminescent uranium organic framework, whose photoluminescence intensity can be accurately correlated with the exposure dose of X‐ or γ‐radiations. This allows for precise and instant detection of ionizing radiations down to the level of 10−4 Gy, representing a significant improvement on the detection limit of approximately two orders of magnitude, compared to other chemical dosimeters reported up to now. The electron paramagnetic resonance analysis suggests that with the exposure to radiations, the carbonyl double bonds break affording oxo‐radicals that can be stabilized within the conjugated uranium oxalate‐carboxylate sheet. This gives rise to a substantially enhanced equatorial bonding of the uranyl(VI) ions as elucidated by the single‐crystal structure of the γ‐ray irradiated material, and subsequently leads to a very effective photoluminescence quenching through phonon‐assisted relaxation. The quenched sample can be easily recovered by heating, enabling recycled detection for multiple runs.

First Cationic Uranyl-Organic Framework with Anion-Exchange Capabilities.

By controlling the extent of hydrolysis during the self-assembly process of a zwitterionic-based ligand with uranyl cations, we observed a structural evolution from the neutral uranyl-organic framework [(UO2)2(TTTPC)(OH)O(COOH)]·1.5DMF·7H2O (SCU-6) to the first cationic uranyl-organic framework with the formula of [(UO2)(HTTTPC)(OH)]Br·1.5DMF·4H2O (SCU-7). The crystal structures of SCU-6 and SCU-7 are layers built with tetranuclear and dinuclear uranyl clusters, respectively. Exchangeable halide anions are present in the interlaminar spaces balancing the positive charge of layers in SCU-7. Therefore, SCU-7 is able to effectively remove perrhenate anions from aqueous solution. Meanwhile, the H2PO4(-)-exchanged SCU-7 material exhibits a moderate proton conductivity of 8.70 × 10(-5) S cm(-1) at 50 °C and 90% relative humidity, representing nearly 80 times enhancement compared to the original material.

The templated synthesis of a unique type of tetra-nuclear uranyl-mediated two-fold interpenetrating uranyl-organic framework.

Two novel tetra-nuclear uranyl-mediated two-fold interpenetrating networks, [U4O10(dbsf)3]2[H2bpp]2 and [U4O10(dbsf)3][H2bpp], have been hydrothermally synthesized from a semi-rigid carboxylic acid, H2dbsf, with the organic base, bpp, as the charge balancing agent and stacking template (H2dbsf = 4,4'-dicarboxybiphenyl sulfone, bpp = 1,3-di(4-pyridyl)propane).

Layered and three-dimensional uranyl–organic assemblies with 4,4′-oxidiphthalic acid

Abstract Hydrothermal reactions of uranyl nitrate and 4,4′-oxidiphthalic acid (H 4 L) resulted in the formation of three new uranyl–organic framework materials, namely (NH 4 ) 2 [(UO 2 ) 3 (L) 2 ]·5H 2 O ( 1 ), (NEt 4 )[(UO 2 ) 3 (H 2 O)(L)(HL)] ( 2 ) and (UO 2 ) 7 (H 2 O) 2 (phen) 4 (L) 2 (HL) 2 ( 3 ) (NEt 4 = tetraethylammonium, phen = 1,10-phenanthroline). These three structures all comprise common uranyl pentagonal bipyramids. In 1 , UO 7 polyhedra are linked by hexadentate ligands to form a 3D framework with 1D channels, in which are located NH 4 + ions and water molecules. While in 2 , the organic ligands adopt pentadentate and hexadentate coordination modes, ligating UO 7 units to create a layered structure with channels filled by NEt 4 + ions. For 3 , uranyl square bipyramids are also accommodated together with pentagonal bipyramids, which are linked by tetradentate carboxylate ligands to produce the layered assembly. Phen molecules also coordinate to the uranyl centers to build up the structure. Luminescent studies indicate that 2 and 3 exhibit the characteristic uranyl emission.

Silver Ion-Mediated Heterometallic Three-Fold Interpenetrating Uranyl-Organic Framework.

A unique case of a uranyl-silver heterometallic 3-fold interpenetrating network (U-Ag-2,6-DCPCA) from a multifunctionalized organic ligand, 2,6-dichloroisonicotinic acid, in the presence of uranyl and silver ions is reported. It is the first report of a heterometallic uranyl-organic interpenetrating network or framework. Notably, a (4,4)-connected uranyl building unit in U-Ag-2,6-DCPCA, which is available through combined influences of structural halogenation and silver ion additive on uranyl coordination, plays a vital role in the formation of a 3-fold interpenetrating network. Halogen substitution effectively changes structural features and coordination behaviors of isonicotinate ligand and contributes to the control of uranyl coordination. Meanwhile, it exerts influence on the stabilization of 3-fold interpenetrating networks by halogen-halogen interactions. Theoretical calculation suggests that the silver ion should mainly serve as an inductive factor of uranyl species through strong Ag-N binding affinity, directly leading to the formation of a (4,4)-connected uranyl building unit and finally a heterometallic 3-fold interpenetrating network. Related experimental results, especially an interesting postsynthetic metalation, afford further evidence of this induction effect.

Umbellate Distortions of the Uranyl Coordination Environment Result in a Stable and Porous Polycatenated Framework That Can Effectively Remove Cesium from Aqueous Solutions

Searching for new chemically durable and radiation-resistant absorbent materials for actinides and their fission products generated in the nuclear fuel cycle remain highly desirable, for both waste management and contamination remediation. Here we present a rare case of 3D uranyl organic framework material built through polycatenating of three sets of graphene-like layers, which exhibits significant umbellate distortions in the uranyl equatorial planes studied thoroughly by linear transit calculations. This unique structural arrangement leads to high β and γ radiation-resistance and chemical stability in aqueous solutions within a wide pH range from 3 to 12. Being equipped with the highest surface area among all actinide compounds known to date and completely exchangeable [(CH3)2NH2](+) cations in the structure, this material is able to selectively remove cesium from aqueous solutions while retaining the polycatenated framework structure.

New three-fold interpenetrated uranyl organic framework constructed by terephthalic acid and imidazole derivative.

A new 3-fold interpenetrated uranyl organic framework, UO2(bdc)(dmpi), was hydrothermally synthesized using 1,4-benzenedicarboxylic acid (H2bdc) and 1-(4-(1H-imidazol-1-yl)-2,5-dimethylphenyl)-1H-imidazole (dmpi). This framework, which was determined by synchrotron radiation X-ray, exhibited a new 3-fold interpenetrated (2,4)-connected topology with the Schläfli symbol of (12(6))(12)2. Additionally, large incurvation happened to the bond angle of [O=U=O](2+), which was always arranged in a rigorous line. Computational results based on density functional theory (DFT) indicated that the bent geometry of uranyl in UO2(bdc)(dmpi) was mainly due to the higher charge populations in the valence 6d shells of uranium, rendered by the electronegative imidazoles.

Halogen Bonded Three-Dimensional Uranyl–Organic Compounds with Unprecedented Halogen–Halogen Interactions and Structure Diversity upon Variation of Halogen Substitution

Actinide-based metal–organic materials have drawn much attention due to their intriguing 5f bonding properties and promising applications in nuclear fuels and other fields. Introduction of weak interactions, such as halogen bonds, into actinide–organic hybrid materials will provide them with more flexibility and dynamics. The first case of halogen bonded three-dimensional (3D) uranyl–organic supramolecular frameworks with regular nanoscale channels has been obtained from multifunctional halogen-substituted isonicotinic acids. Distinct from conventional halogen bonded uranyl–organic frameworks, the supramolecular networks obtained here consist of three-component cocrystals and have been assemblied by intensive supramolecular networks to obtain an extended 3D geometry. Moreover, secondary “X3” and “X6” halogen–halogen interactions resulting from the driving forces of primary hydrogen bonds have been found and analyzed by quantum chemical calculation, indicating their feature of weak bonding and special geometry. It is notable that this unprecedented type of “X6” synthon, especially for “Br6”, represents a new pattern of halogen–halogen interaction. When halogen substitution of the organic precursor is changed, another type of halogen bonded and hydrogen bonded 3D uranyl–organic framework with two-dimensional layered networks and cross-linking agents formed in situ was acquired. Finally, reversible transformation of 3D uranyl–organic supramolecular frameworks is available through loss and regain of water involving in hydrogen bonding networks and thus affords them structural dynamics.

Copper(I) and copper(II) uranyl heterometallic hybrid materials.

Two copper-uranium heterometallic compounds, [(UO2)3Cu(II)O2(C6NO2)5] (1) and [(UO2)Cu(I)(C6NO2)3] (2), have been synthesized by the reaction of uranyl acetate with copper salts in the presence of isonicotinic acid. Both compounds have been characterized by single-crystal X-ray diffraction, IR, Raman, and UV-vis spectroscopy. In compound 1, interactions between copper and uranium centers occur and result in a three-dimensional pillar layered structure. Compound 1 is also the first example of a heterometallic uranyl organic framework with a trinuclear U3O18 building block. Compound 2 is the first uranyl organic framework that contains monovalent copper, which arises from the reaction of Cu(II) chloride and is assumed to be due to the oxidation of chloride at low pH.

Synthesis, crystal structure and spectroscopic studies of some organic/inorganic hybrid materials containing isostructural monomeric uranyl complexes bridged by bipyridyl typed ligands

Three uranyl complexes [UO2(TPC)2(NO3)](4,4BIPY)0.5(H-4,4BIPY)0.5 (1), [UO2(5-TPC)3]2 (H-1,4PYPI)(H2O)2 (2), [UO2(NO3)2(4NBPY)2.(H2O)]0.5(H2O) (3) (where TPC=thiophene-2-carboxylate, 5-TPC=5-chlorothiophene-2-carboxylate, 4,4BIPY=4,4′-bipyridine, H-4,4BIPY=4,4′-bipyridinium, H-1,4PYPI=1,4-pyridyl piperazinium and 4NBPY=-4,4-dipyridyl N,N′-dioxide) have been synthesized and characterised using single crystal X-ray diffraction studies. The common structural feature of complexes (1, 2) is the presence of [UO2X3]− anionic unit (X=TPC and NO3 in 1, 5-TPC in 2 respectively). In both of these complexes the (UO22+) uranyl cation is chelated by different thiophene carboxylates. The back bone that transforms these structures into organic/inorganic hybrid materials are the presence of bipyridyl typed ligands. The coordination polymer UO2(NO3)2(4NBPY)2·(H2O)]0.5(H2O) (3) is quite different from that of (1,2) was obtained unexpectedly while trying to synthesize a similar typed. In all the three complexes the space filling, structure direction as well as charge neutralisation roles are played by the organic ligand. Further, the two of the similar typed complexes reported by us with the similar typed [UO2X3]- anionic unit; [UO2(5-TPC)2(NO3)](H-4,4BIPY)0.5.(H2O)=(U44B), and [UO2(5-TPC)2(NO3)](H-1,2BIPY)0.5.(H2O)=(U12B) [where H-1,2BIPY=1,2-bis(4-pyridinium)ethane cation] have also been compared with these present structures. This family of uranyl organic framework materials (UOFs) show a similar type of primary building unit (PBU) which is the [UO2X3]- unit despite of different type of carboxylate or heterocyclic ligands.