Uranyl Ion Complexes Research Articles

Decoration of phosphoric acid groups onto Ti3C2Tx MXene for enhanced uranium removal

The construction of novel MXene-based composites with superb abilities through functionalization is an effective strategy to enhance the potential of this emerging inorganic lamellar material for environmental adsorption applications. The present work systematically investigated the adsorption performance of Ti3C2Tx MXene modified with phosphate functional groups that facilitate the capture of uranyl ions. After introducing phosphate groups via a two-step modification of 3-aminopropyltriethoxysilane (APTES) and phytic acid (PA), the synthesized Ti3C2-APTES-PA is significantly superior to pristine Ti3C2Tx nanosheets in terms of adsorption capacity, adsorption selectivity and reusability for uranium. The maximum uptake capacity of Ti3C2-APTES-PA at pH = 5 reaches 323 mg/g, which is 2.5 times higher than that of unmodified MXene. Furthermore, the large selectivity coefficient (SU/M > 16.2) declares that Ti3C2-APTES-PA preferentially adsorbs uranium among substantial competing ions. Ti3C2-APTES-PA also shows good cycling performance that its adsorption capacity remained 92.3 % after 6 cycles. When it comes to treating simulated uranium tailings pond leachate and radioactive wastewater from mines, high U(VI) removal rates of 88.9 % and 96.8 % can be achieved by our ternary composite at a dosage of 0.05 g/L. The underlying adsorption mechanism was unraveled by spectroscopic analysis to be the formation of coordination complexes of uranyl ions with phosphate groups on PA and hydroxyl groups on Ti3C2Tx substrate, as well as the reduction of a small amount of adsorbed U(VI) to U(IV) by MXene. The overall results imply that Ti3C2-APTES-PA is an effective uranium chelating scavenger for the treatment of environmental radioactive wastewater.

Understanding the Interaction of Uranyl Cation with Two C-Pivot Tripodal Amides: Synthesis, Complexation, Microcalorimetry, and DFT Studies.

Complexation of uranyl ions with two structurally related C-pivotal tripodal amides with varying spacer lengths, synthesized for the first time, was studied by optical spectroscopy. In the tripodal amides, the coordination was through the carbonyl O atoms where the carbonyl groups were away from the central C-atom by three spacer atoms (LI) and four spacer atoms (LII), respectively. Increasing the spacer atoms going from LI to LII favors the complexation with the linear uranyl cations and results in stronger complex formation. The complexation heat between the uranyl cations and the two amide ligands was directly measured by microcalorimetric titrations. The complexation with both the ligands was driven by exothermic enthalpy and positive entropy changes. Formation of the complex proceeded by the replacement of water molecules from the primary coordination sphere of the uranyl cation. Both ligands formed bisolvated (ML2-type) complexes in which one unit of the ligand binds in a monodentate manner and the other in a bidentate mode. Density functional theory calculations further supported our experimental observations.

1,1ʹ-Dimethyl-4,4ʹ-bipyridinium as a multivalent structure-directing counterion to anionic uranyl ion polycarboxylate complexes

Seven uranyl ion complexes with polycarboxylates have been synthesized under solvo-hydrothermal conditions and in the presence of 1,1ʹ-dimethyl-4,4ʹ-bipyridinium (Me2bipy2+) as structure-directing counterion. Two complexes were obtained with phthalate (pht2–), [Me2bipy]2[(UO2)4(pht)4(O)2] (1), which is a discrete, bis(μ3-oxo-bridged) tetranuclear species, and {[Me2bipy][(UO2)3(pht)4(H2O)]}n (2), which crystallizes as a monoperiodic coordination polymer. The complex obtained with citric acid (H4cit), {[Me2bipy][UO2(Hcit)]2·H2O}n (3), assumes a well-known monoperiodic form. {[Me2bipy][(UO2)2(Hthftc)2]}n (4), obtained from tetrahydrofurantetracarboxylic acid (H4thftc), is also a monoperiodic polymer further assembled into layers through hydrogen bonding, the packing defining channels containing columns of stacked counterions. The previously reported {[Me2bipy][(UO2)2(tdc)3]}n (5), where tdc2– is 2,5-thiophenedicarboxylate, is a diperiodic hcb network, with the counterions crossing the hexanuclear rings. One experiment with pimelate (pim2–) gave the two complexes {[Me2bipy][(UO2)2(pim)3]}n (6) and {[Me2bipy][(UO2)4(pim)5(DMA)2]}n (7) (DMA = N,N-dimethylacetamide). Both 6 and 7 are diperiodic assemblies, but while 6 has the KIa topology previously found in other uranyl ion complexes with elongated dicarboxylate ligands, 7 is a very intricate and thick assembly with a packing displaying interdigitation. The weak interactions formed by the counterions are discussed through examination of Hirshfeld surfaces.

Uranyl ion coordination polymers with the dibenzobarrelene-based rac- and (R,R)-trans-9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboxylate ligands

Uranyl ion complexes of a dibenzobarrelene-based dicarboxylate have oligomeric or mono- to triperiodic polymeric arrangements displaying the influence of the interactions of the hydrophobic part of the ligand on the structures formed.

Facile synthesis of robust polyethyleneimine incorporated chitosan composite hydrogel for efficient enrichment of uranium(VI) in aqueous solution

The development of polymer hydrogel with abundant ion diffusion paths is needed to address sustainable energy supply and ecological security. Herein, a robust chitosan-based polymer hydrogel with superior structural stability and sufficient active sites was fabricated by incorporating polyethyleneimine into chitosan for efficient enrichment of uranium(VI). The as-prepared chitosan-based polymer hydrogel has a maximum uranium adsorption capacity of 291.75 mg-U/g at pH= 6, together with relatively good selectivity to uranium(VI). The adsorption process was described well with the pseudo-second-order kinetic model and Langmuir isotherm model. The main adsorption mechanism was related to the complexation of uranyl ions with the amino and hydroxyl groups. The chitosan-based polymer hydrogel, with the merits of facile preparation, easy solid-liquid separation, eco-friendliness and cyclic utilization highlights its promising application in uranium removal and recovery from uranium-containing wastewater.

Woven, Polycatenated, or Cage Structures: Effect of Modulation of Ligand Curvature in Heteroleptic Uranyl Ion Complexes

Combining the flexible zwitterionic dicarboxylate 4,4'-bis(2-carboxylatoethyl)-4,4'-bipyridinium (L) and the anionic dicarboxylate ligands isophthalate (ipht2-) and 1,2-, 1,3-, or 1,4-phenylenediacetate (1,2-, 1,3-, and 1,4-pda2-), of varying shape and curvature, has allowed isolation of five uranyl ion complexes by synthesis under solvo-hydrothermal conditions. [(UO2)2(L)(ipht)2] (1) and [(UO2)2(L)(1,2-pda)2]·2H2O (2) have the same stoichiometry, and both crystallize as monoperiodic coordination polymers containing two uranyl-(anionic carboxylate) strands united by L linkers into a wide ribbon, all ligands being in the divergent conformation. Complex 3, [(UO2)2(L)(1,3-pda)2]·0.5CH3CN, with the same stoichiometry but ligands in a convergent conformation, is a discrete, binuclear species which is the first example of a heteroleptic uranyl carboxylate coordination cage. With all ligands in a divergent conformation, [(UO2)2(L)(1,4-pda)(1,4-pdaH)2] (4) crystallizes as a sinuous and thread-like monoperiodic polymer; two families of chains run along different directions and are woven into diperiodic layers. Modification of the synthetic conditions leads to [(UO2)4(LH)2(1,4-pda)5]·H2O·2CH3CN (5), a monoperiodic polymer based on tetranuclear (UO2)4(1,4-pda)4 rings; intrachain hydrogen bonding of the terminal LH+ ligands results in diperiodic network formation through parallel polycatenation involving the tetranuclear rings and the LH+ rods. Complexes 1-3 and 5 are emissive, with complex 2 having the highest photoluminescence quantum yield (19%), and their spectra show the maxima positions usual for tris-κ2O,O'-chelated uranyl cations.

Inorganic polyphosphate accumulation protects a marine, filamentous cyanobacterium, Anabaena torulosa against uranium toxicity

The intricate dynamics of inorganic polyphosphate (polyP) in response to phosphorus (P) limitation and metal exposure typical of contaminated aquatic environments is poorly understood. Cyanobacteria are important primary producers in aquatic environments that are exposed to P stringency as well as metal contamination. There is a growing concern regarding migration of uranium, generated as a result of anthropogenic activities, into the aquatic environments owing to high mobility and solubility of stable aqueous complexes of uranyl ions. The polyP metabolism in cyanobacteria in context of uranium (U) exposure under P limitation has hardly been explored. In this study, we analyzed the polyP dynamics in a marine, filamentous cyanobacterium Anabaena torulosa under combination of variable phosphate concentrations (overplus and deficient) and uranyl exposure conditions typical of marine environments. Polyphosphate accumulation (polyP+) or deficient (polyP−) conditions were physiologically synthesized in the A. torulosa cultures and were ascertained by (a) toulidine blue staining followed by their visualization using bright field microscopy and (b) scanning electron microscopy in combination with energy dispersive X-ray spectroscopy (SEM/EDX). On exposure to 100 μM of uranyl carbonate at pH 7.8, it was observed that the growth of polyP+ cells under phosphate limitation was hardly affected and these cells exhibited larger amounts of uranium binding as compared to polyP− cells of A. torulosa. In contrast, the polyP− cells displayed extensive lysis when exposed to similar U exposure. Our findings suggest that polyP accumulation played an important role in conferring uranium tolerance in the marine cyanobacterium, A. torulosa. The polyP-mediated uranium tolerance and binding could serve as a suitable strategy for remediation of uranium contamination in aquatic environments.

Triple-armed aliphatic tricarboxylic acids as sources of ligands for uranyl ion: influence of bridgehead functionalization

Seven uranyl ion complexes with two tripodal, tricarboxylic acids with nitromethane or phosphine oxide bridgeheads display various diperiodic and triperiodic arrangements, depending on the bridgehead and the structure-directing species present.

Ligand competition on uranyl ion: further examples of zwitterionic vs. anionic carboxylate coordination

Four mixed-ligand uranyl ion complexes with anionic and zwitterionic carboxylates illustrate different modes of association of these ligands and give some clues about their respective donor strength.

Zwitterionic and Anionic Polycarboxylates as Coligands in Uranyl Ion Complexes, and Their Influence on Periodicity and Topology.

The three zwitterionic di- and tricarboxylate ligands 1,1'-[(2,3,5,6-tetramethylbenzene-1,4-diyl)bis(methylene)]bis(pyridin-1-ium-4-carboxylate) (pL1), 1,1'-[(2,3,5,6-tetramethylbenzene-1,4-diyl)bis(methylene)]bis(pyridin-1-ium-3-carboxylate) (mL1), and 1,1',1″-[(2,4,6-trimethylbenzene-1,3,5-triyl)tris(methylene)]tris(pyridin-1-ium-4-carboxylate) (L2) have been used as ligands to synthesize a series of 15 uranyl ion complexes involving various anionic coligands, in most cases polycarboxylates. [(UO2)2(pL1)2(cbtc)(H2O)2]·10H2O (1, cbtc4- = cis,trans,cis-1,2,3,4-cyclobutanetetracarboxylate) is a discrete, dinuclear ring-shaped complex with a central cbtc4- pillar. While [UO2(pL1)(NO3)2] (2), [UO2(pL1)(OAc)2] (3), and [UO2(pL1)(HCOO)2] (4) are simple chains, [(UO2)2(mL1)(1,3-pda)2] (5, 1,3-pda2- = 1,3-phenylenediacetate) is a daisy chain and [UO2(pL1)(pdda)]3·10H2O (6, pdda2- = 1,2-phenylenedioxydiacetate) is a double-stranded, ribbon-like chain. Both [UO2(pL1)(pht)]·5H2O (7, pht2- = phthalate) and [(UO2)3(mL1)(pht)2(OH)2] (8) crystallize as diperiodic networks with the sql topology, the latter involving hydroxo-bridged trinuclear nodes. [(UO2)2(pL1)(c/t-1,3-chdc)2] (9, c/t-1,3-chdc2- = cis/trans-1,3-cyclohexanedicarboxylate) and [UO2(pL1)(t-1,4-chdc)]·1.5H2O (10, t-1,4-chdc2- = trans-1,4-cyclohexanedicarboxylate) are also diperiodic, with the V2O5 and sql topologies, respectively. Both [(UO2)2(mL1)(c/t-1,4-chdc)2] (11) and [(UO2)2(pL1)(1,2-pda)2] (12, 1,2-pda2- = 1,2-phenylenediacetate) crystallize as diperiodic networks with hcb topology, and they display threefold parallel interpenetration. [HL2][(UO2)3(L2)(adc)3]Br (13, adc2- = 1,3-adamantanedicarboxylate) contains a very corrugated hcb network with two different kinds of cells, and the uncoordinated HL2+ molecule associates with the coordinated L2 to form a capsule containing the bromide anion. [(UO2)2(pL1)(kpim)2] (14, kpim2- = 4-ketopimelate) is a three-periodic framework with pL1 molecules pillaring fes diperiodic subunits, whereas [(UO2)2(L2)2(t-1,4-chdc)](NO3)1.7Br0.3·6H2O (15), the only cationic complex in the series, is a triperiodic framework with dmc topology and t-1,4-chdc2- anions pillaring fes diperiodic subunits. Solid-state emission spectra and photoluminescence quantum yields are reported for all complexes.

Anionic uranyl ion complexes with pyrazinetetracarboxylate: Influence of structure-directing cations

Pyrazine-2,3,5,6-tetracarboxylic acid (H4PZTC) has been used to synthesize three uranyl ion complexes under solvo-hydrothermal conditions and in the presence of additional cations as structure-directing agents. The complex [C(NH2)3]2[UO2(PZTC)]⋅2H2O (1) displays double ONO-chelation of uranyl, resulting in the formation of a monoperiodic coordination polymer, further association being provided by guanidinium and water hydrogen bonding. The PZTC4– ligand in [Co(en)3][UO2(PZTC)](NO3)⋅H2O (2) is bound to three uranyl cations, one of them ONO-chelated and the others bound to monodentate carboxylate donors, and the polymer formed is triperiodic with the ths topology. The ONO sites in the heterometallic complex [UO2Ag2(PZTC)] (3) are occupied by Ag+ cations, further carboxylate bonding to uranyl and Ag+ cations, as well as oxo bonding of uranyl to Ag+, resulting in the formation of an intricate triperiodic framework in which uranyl cations and PZTC4– alone give a triperiodic polymer with the lvt topology displaying double interpenetration, the Ag+ cations connecting the two networks into a single assembly.

Polyethyleneimine incorporated chitosan/α-MnO2 nanorod honeycomb-like composite foams with remarkable elasticity and ultralight property for the effective removal of U(VI) from aqueous solution

The development of new adsorbents is needed to address the environmental challenges of radioactive wastewater treatment. Herein we reported a novel polyethyleneimine incorporated chitosan/α-MnO2 nanorod honeycomb-like composite (PCM) foam with remarkable elasticity and ultralight property for U(VI) removal. Among different PCM sorbents, PCM-40 possessed the highest sorption capacity for U(VI) due to its highly developed macroporous structure and high content of amine/imine groups. The kinetics were well-simulated by the pseudo-second-order model, indicating chemisorption as the rate-controlling step. The isotherms could be described by the Langmuir model, suggesting mono-layer homogeneous sorption of U(VI). The maximum sorption U(VI) capacity for PCM-40 reaches up to 301.9 mg/g at pH 4.5 and 298 K. The thermodynamic parameters revealed the spontaneous and endothermic nature of the adsorption process. The main sorption mechanism is related to the complexation of uranyl ions with the amine/imine and hydroxyl groups. The high sorption capacity, fast kinetic rate and relatively good selectivity of PCM-40 highlights its promising application in radioactive pollution cleanup.

Ni(2,2′:6′,2″-Terpyridine-4′-carboxylate)2 Zwitterions and Carboxylate Polyanions in Mixed-Ligand Uranyl Ion Complexes with a Wide Range of Topologies

The zwitterionic complex formed by NiII and 2,2':6',2″-terpyridine-4'-carboxylate, Ni(tpyc)2, has been used as a coligand with a diverse group of polycarboxylates in uranyl ion complexes synthesized under solvo-hydrothermal conditions, thus giving a series of 14 mixed ligand, heterometallic compounds. Both [(UO2)2(c-1,2-chdc)Ni(tpyc)2(NO3)2]2·4CH3CN (1) and [(UO2)2(tdc)Ni(tpyc)2(NO3)2]2 (2), where c-1,2-chdc2- is cis-1,2-cyclohexanedicarboxylate and tdc2- is 2,5-thiophenedicarboxylate, display discrete U4Ni2 dinickelatetrauranacycles, a motif which is also found as part of a daisychain coordination polymer in [(UO2)4(bdc)3Ni2(tpyc)4(NO3)2]·2CH3CN·2H2O (3), where bdc2- is 1,4-benzenedicarboxylate. Similar U4Ni2 rings associate to form a nanotubular polymer in [(UO2)2(tca)Ni(tpyc)2(NO3)]·2CH3CN·2H2O (4), where tca3- is tricarballylate. [(UO2)2(1,2-pda) (1,2-pdaH)Ni(tpyc)2(NO3)]·CH3CN (5), where 1,2-pda2- is 1,2-phenylenediacetate, crystallizes as a meander-like chain in which each bent section can be seen as an open, semi-U4Ni2 ring. Oxalate (ox2-) gives [(UO2)2(ox)2Ni(tpyc)2] (6), a monoperiodic polymer containing smaller U4Ni rings, while 1,2,3-benzenetricarboxylate (1,2,3-btc3-) and citrate (citH3-) give [Ni(tpycH)(H2O)3][UO2(1,2,3-btc)]2·2H2O (7) and [UO2Ni2(tpyc)4][UO2(citH)]2 (8), two complexes with charge separation, the latter displaying one-periodic + two-periodic semi-interpenetration. [(UO2)2(btcH)Ni(tpyc)2(NO3)] (9) and [(UO2)2(cbtcH)Ni(tpyc)2(NO3)] (10), where btc4- and cbtc4- are 1,2,3,4-butanetetracarboxylate and cis,trans,cis-1,2,3,4-cyclobutanetetracarboxylate, respectively, are diperiodic networks with hcb topology, and [(UO2)2(ndc)Ni(tpyc)2(OH)(NO3)] (11), where ndc2- is 2,6-naphthalenedicarboxylate, is a sql network containing dinuclear nodes and involving 100-membered U10Ni4 metallacyclic units. U4Ni2 rings are found in the diperiodic polymer formed in [(UO2)4(t-R-1,2-chdc)4Ni2(tpyc)4] (12), where t-R-1,2-chdc2- is trans-R,R-1,2-cyclohexanedicarboxylate, the heavily puckered sheets being interlocked. 1,3-Phenylenediacetate (1,3-pda2-) gives a very thick diperiodic polymer with KIa topology, [(UO2)4(1,3-pda)4Ni2(tpyc)4]·CH3CN·2H2O (13). A triperiodic framework is formed with nitrilotriacetate (nta3-) in [(UO2)2(nta)2Ni2(tpyc)2] (14), where NiII is found in Ni(tpyc)2 units as well as in Ni(nta)24- moieties which both act as 4-coordinated nodes.

Varying Structure‐Directing Anions in Uranyl Ion Complexes with Ni(2,2′ : 6′,2′′‐terpyridine‐4′‐carboxylate)2

Abstract2,2′ : 6′,2“‐Terpyridine‐4′‐carboxylic acid (tpycH) reacts with uranyl cations under solvo‐hydrothermal conditions to give [UO2(tpyc)2] ⋅ 2H2O (1), a monoperiodic polymer different from that previously reported. In the additional presence of NiII cations, the Ni(tpyc)2 “expanded ligand” is formed and the structure of its complexes with the uranyl cation depends on the additional anions present. [(UO2)2F4(H2O)2Ni(tpyc)2] ⋅ 2H2O (2) and [UO2(mds)(H2O)Ni(tpyc)2] (3), where mds2− is methanedisulfonate, are monoperiodic polymers in which the fluoride anions are bridging and the mds2− anions chelating. [(UO2)4(NO3)2(H2O)4Ni5(tpyc)10](CF3SO3)4(NO3)2 ⋅ 7H2O (4) crystallizes as a wide and nearly planar monoperiodic ribbon. [(UO2)2(NO3)2(chdc)Ni(tpyc)2] ⋅ chdcH2 ⋅ 2CH3CN (5), where chdc2− is trans‐1,4‐cyclohexanedicarboxylate, is a monoperiodic chain including both bridging Ni(tpyc)2 and chdc2− ligands, the chains being further assembled into layers through hydrogen bonding to bridging chdcH2 molecules. Finally, [UO2Ni2(tpyc)4](I3)2 (6) crystallizes as a diperiodic network with sql topology. These results point to the possibility of modulating the structure of cationic uranyl ion complexes with Ni(tpyc)2 through addition of a wide range of bonding or non‐bonding anions.

Contrasting Networks and Entanglements in Uranyl Ion Complexes with Adipic and trans,trans-Muconic Acids.

Adipic (hexane-1,6-dicarboxylic, adpH2) and trans,trans-muconic (trans,trans-hexa-2,4-diene-1,6-dicarboxylic, mucH2) acids have been reacted with uranyl cations under solvo-hydrothermal conditions, yielding nine homo- or heterometallic complexes displaying in their crystal structure the effects of the different flexibility of the ligands. The complexes [PPh4]2[(UO2)2(adp)3] (1) and [Ni(bipy)3][(UO2)2(muc)3]·5H2O (2), where bipy is 2,2'-bipyridine, crystallize as diperiodic networks with the hcb topology, the layers being strongly puckered or quasiplanar, respectively. Whereas [(UO2)2(adp)3Ni(cyclam)]·2H2O (3), where cyclam is 1,4,8,11-tetraazacyclotetradecane, crystallizes as a diperiodic network, [(UO2)2(muc)3Ni(cyclam)]·2H2O (4) is a triperiodic framework in which the NiII cations are introduced as pillars within a uranyl-muc2- framework with the mog topology. [UO2(adp)(HCOO)2Cu(R,S-Me6cyclam)]·2H2O (5), where R,S-Me6cyclam is 7(R),14(S)-5,5,7,12,12,14-hexamethylcyclam, is a diperiodic assembly with the sql topology, and it crystallizes together with [H2NMe2]2[(UO2)2(adp)3] (6), a highly corrugated hcb network with a square-wave profile, which displays 3-fold parallel interpenetration. In contrast, [(UO2)3(muc)2(O)2Cu(R,S-Me6cyclam)] (7) is a diperiodic assembly containing hexanuclear, μ3-oxido-bridged secondary building units which are the nodes of a network with the hxl topology. The two related complexes [PPh3Me]2[(UO2)2(adp)3]·4H2O (8) and [PPh3Me]2[(UO2)2(muc)3]·H2O (9) crystallize as hcb networks, but their different shapes, undulated or quasiplanar, respectively, result in different entanglements, 2-fold parallel interpenetration in 8 and 2-fold inclined 2D → 3D polycatenation in 9.

Plumbing the uncertainties of solvothermal synthesis involving uranyl ion carboxylate complexes

Uranyl ion complexes with long-chain, saturated or unsaturated aliphatic dicarboxylate ligands illustrate how solvo-hydrothermal synthetic conditions sometimes result in the formation of species different from those hoped for.

Varied role of organic carboxylate dizwitterions and anionic donors in mixed-ligand uranyl ion coordination polymers

Two organic dizwitterions were combined with various anionic donors to generate a series of five uranyl ion complexes crystallizing as mono- or diperiodic coordination polymers, with separation into two distinct networks in one case.

Uranyl Ion Coordination by Benzene‐1,2,3‐tricarboxylate: Building Chains and Networks from Binuclear Bricks

AbstractBenzene‐1,2,3‐tricarboxylic acid (123btcH3) was used to synthesize 7 uranyl ion complexes under hydro‐solvothermal conditions, in the presence of different structure‐directing agents. [Zn(phen)3][Zn2(123btc)(phen)4][(UO2)2(123btc)2(OH)(CH3CN)] ⋅ 3H2O (1, phen=1,10‐phenanthroline), the only discrete species in the series, crystallizes as a binuclear, cup‐shaped dimer. Both [PPh3Me][UO2(123btc)] (2) and [C(NH2)3][UO2(123btc)] ⋅ 0.5H2O (3) contain anionic, monoperiodic coordination polymers based on quasi‐planar, binuclear (UO2)2(123btc)22− subunits in which two oxygen atoms of each ligand are uncoordinated. Similar chains are found in [UO2(123btc)K(18C6)] ⋅ H2O (4, 18C6=18‐crown‐6), the potassium cations being decorating groups bound to carboxylato and uranyl oxo donors. An analogous decorating role to monoperiodic polymers is played by UO2(DMF)2(H2O)22+ cations in [(UO2)3(123btc)2(DMF)2(H2O)2] (5), while bridging of chains by UO2(NMP)32+ cations in [(UO2)3(123btc)2(NMP)3] (6) yields a diperiodic network with V2O5 topology. [NH4][UO2(123btc)] (7), which does not contain the dimeric subunit found in the other cases, crystallizes as a diperiodic network with sql topology, the layers being associated through hydrogen bonding interactions with the ammonium counterions.

Chain, Network and Framework Formation in Uranyl Ion Complexes with 1,1′‐Biphenyl‐3,3′,4,4′‐Tetracarboxylate

Abstract1,1′‐Biphenyl‐3,3′,4,4′‐tetracarboxylic acid dianhydride has been reacted with uranyl nitrate under solvo‐hydrothermal conditions and in the presence of different counterions to give three complexes of varying periodicity. [Co(en)3]‐ [UO2(bptc)(HCOO)] ⋅ 2.5H2O (1) crystallizes as a monoperiodic coordination polymer in which the bptc4− ligand is exclusively bound through formation of two 7‐membered chelate rings. The [Co(en)3]3+ counterion is essentially a hydrogen bond donor, forming 15 hydrogen bonds with carboxylate and water oxygen atoms. In [H2NMe2]2[UO2(bptc)] ⋅ 0.5H2O (2), half the ligand forms a 7‐membered chelate ring, and the other half bridges two uranium atoms, resulting in the formation of a diperiodic network with hcb topology, the H2NMe2+ counterions being located between the undulating sheets. [PPh4]4[(UO2)4(bptc)3] ⋅ 6H2O (3) contains a mixture of ligands forming either four 4‐membered or two 7‐membered chelate rings, the latter with further bridging, which gives a triperiodic framework displaying large channels, each of which contains two rows of PPh4+ counterions. These results are compared to those of previous studies with this ligand, and of similar studies of phthalate complexes of uranyl ion, in particular in relation to 7‐membered chelate ring formation.

Inversion of the Deactivation Efficiency of Excited States upon Selective Photoexcitation of the Uranyl Ion Complex with D-Tryptophan in Aqueous and Methanol Solutions

Inversion of the Deactivation Efficiency of Excited States upon Selective Photoexcitation of the Uranyl Ion Complex with D-Tryptophan in Aqueous and Methanol Solutions