Multifunctional Uranyl Hybrid Materials: Structural Diversities as a Function of pH, Luminescence with Potential Nitrobenzene Sensing, and Photoelectric Behavior as p-type Semiconductors

Iodine capture of a two-dimensional layered uranyl-organic framework: a combined DFT and AIMD study

To develop nuclear energy sustainably, it is important to effectively capture radioiodine in nuclear waste. In this study, we used density functional theory (DFT) and ab initio molecular dynamics (AIMD) calculations to investigate how well the uranyl-organic framework (UOF) could capture radioiodine. We found that the uranyl center and C-N ring sites in both cluster and periodic UOF models are very attractive to the I2 molecule. The adsorption energies of the I2 molecule in the periodic UOF models are as high as -1.10 eV, which is much higher than in the cluster model. The interaction characteristics between the I2 molecule and the UOF were revealed by electronic density topological analyses. Our AIMD simulations at 300 and 600 K have confirmed that the UOF has high adsorption kinetics for I2 molecules and can effectively capture them. The UOF has a high adsorption capacity and good adsorption stability for the I2 molecule, making it a promising option for the environmentally friendly removal of radioiodine.

High-Symmetry Co/Ni Triazine Polycarboxylate Diverse Frameworks Constructed by Mx(COO)y Building Blocks: Characterization and Catalytic Performance Evaluation of p-Nitrophenol

Three new triazine compounds [Co_1.5(H₃TDPAT)(H₂O)₃]·6H₂O (1), [Co₂(TCPT)(μ₂-H₂O)₂]·OH (2), and [Ni₃(TCPT)]·3OH (3) were designed and synthesized via the reaction of the symmetrical triazine ligand connected by C-N-C and C-O-C bonds with triazine poly(carboxylic acid)s ligands as the side arms: H₆TDPAT (H₆TDPAT = 2,4,6-tris(3,5-dicarboxylphenylamino)-1,3,5-triazine) and H₃TCPT (H₃TCPT = 2,4,6-tris(4-carboxyphenoxy)-1,3,5-triazine) as well as the corresponding metal salts under the solvothermal condition. Three triazine polycarboxylate frameworks were characterized by elemental analysis, infrared spectroscopy, ultraviolet spectroscopy, thermogravimetric analysis, X-ray powder diffraction, and solid fluorescent spectra in detail. The structural analysis results showed that the three-dimensional porous cage framework of compound 1 was constructed by three different polyhedral cages connected with [Co(COO)₄(H₂O)₂] building blocks. One of the compounds, 2, is formed by twin propeller Co₂(μ₂-H₂O)(COO)₃ building blocks connecting two-dimensional layers and the intermolecular π-π interactions involved the triazine rings between the layers. While the structure of compound 3 is similar to that of 2, assembly is by Ni(COO)₃ building blocks and adjacent layers of the face-to-face π-π interaction between the triazine rings. In order to explore functional properties, the catalytic reduction of p-nitrophenol (PNP) of compounds 1-3 was investigated. They exhibit excellent catalytic activity of more than 95% for reduction of PNP with a dose of 2.5 mg of the compounds.

Progress in solid state and coordination chemistry of actinides in China

In the past decade, the area of solid state chemistry of actinides has witnessed a rapid development in China, based on the significantly increased proportion of the number of actinide containing crystal structures reported by Chinese researchers from only 2% in 2010 to 36% in 2021. In this review article, we comprehensively overview the synthesis, structure, and characterizations of representative actinide solid compounds including oxo-compounds, organometallic compounds, and endohedral metallofullerenes reported by Chinese researchers. In addition, Chinese researchers pioneered several potential applications of actinide solid compounds in terms of adsorption, separation, photoelectric materials, and photo-catalysis, which are also briefly discussed. It is our hope that this contribution not only calls for further development of this area in China, but also arouses new research directions and interests in actinide chemistry and material sciences.

Construction of Large-Scale Conjugated Functionalized Cyclotriphosphazene Lanthanide Framework for Selective Sensing of Volatile Organic Compounds and Assembly of Color-Tunable Dye-Encapsulated Composites

A flexible functionalized cyclotriphosphazene hexacarboxylic acid, hexakis(4-carboxylatephenoxy) cyclotriphosphazene (HCPCP), is used for the synthesis of a family of fluorescent Ln-HCPCP frameworks (Ln = La, Pr, Nd, Gd, and Ho). Structural analysis shows that the compounds exhibit 3D structures with [Ln₃(COO)₁₀], secondary building units formed by Ln-O-C-O-Ln connection. Then the molecules are connected to each other through HCPCP, forming rectangular channels along the c-direction. Interestingly, the fluorescence sensing studies show that compound 1 could be used as a multifunctional fluorescence sensor toward volatile organic compounds via different fluorescence emission behaviors. Moreover, a series of Dye@La-HCPCP composites (Dye = rhodamine B, safranine T, crystal violet, and malachite green) are successfully prepared with different quantum yields by the solvothermal reaction followed by cation exchanges.

3D Uranyl Organic Frameworks Supported by Rigid Octadentate Carboxylate Ligand: Synthesis, Structure Diversity, and Luminescence Properties

Seven three dimensional (3D) uranyl organic frameworks (UOFs), formulated as [NH₄ ][(UO₂ )₃ (HTTDS)(H₂ O)] (1), [(UO₂ )₄ (HTTDS)₂ ](HIM)₆ (2, IM=imidazole), [(UO₂ )₄ (TTDS)(H₂ O)₂ (Phen)₂ ] (3, Phen=1,10-phenanthroline), [Zn(H₂ O)₄ ]_0.5 [(UO₂ )₃ (HTTDS)(H₂ O)₄ ] (4), and {(UO₂ )₂ [Zn(H₂ O)₃ ]₂ (TTDS)} (5), {Zn(UO₂ )₂ (H₂ O)(Dib)_0.5 (HDib)(HTTDS)} (6, Dib=1,4-di(1H-imidazol-1-yl)benzene) and [Na]{(UO₂ )₄ [Cu₃ (u₃ -OH)(H₂ O)₇ ](TTDS)₂ } (7) have been hydrothermally prepared using a rigid octadentate carboxylate ligand, tetrakis(3,5-dicarboxyphenyl)silicon(H₈ TTDS). These UOFs have different 3D self-assembled structures as a function of co-ligands, structure-directing agents and transition metals. The structure of 1 has an infinite ribbon formed by the UO₇ pentagonal bipyramid bridged by carboxylate groups. With further introduction of auxiliary N-donor ligands, different structure of 2 and 3 are formed, in 2 the imidazole serves as space filler, while in 3 the Phen are bound to [UO₂ ]²⁺ units as co-ligands. The second metal centers were introduced in the syntheses of 4-7, and in all cases, they are part of the final structures, either as a counterion (4) or as a component of framework (5-7). Interesting, in 7, a rare polyoxometalate [Cu₃ (μ₃ -OH)O₇ (O₂ CR)₄ ] cluster was found in the structure. It acts as an inorganic building unit together with the dimer [(UO₂ )₂ (O₂ CR)₄ ] unit. Those uranyl carboxylates were sufficiently determined by single crystal X-ray diffraction, and their topological structures and luminescence properties were analyzed in detail.

Ln-MOFs with window-shaped channels based on triazine tricarboxylic acid as a linker for the highly efficient capture of cationic dyes and iodine

Seven isostructural complexes were synthesized under solvothermal condition by the 4,4′,4′′ ((1,3,5-triazine-2,4,6-triyl)tri(azanediyl))tribenzoic acid and rare earth metal ions. It is found that 1 exhibits the adsorption capacity of 758.72 mg g⁻¹ to iodine.

A stable mixed-valent uranium(v,vi) organic framework as a fluorescence thermometer

A stable mixed-valent uranium(v/vi) organic framework with a 3D interpenetrating structure was synthesized, which can be used as a dual-responsive fluorescence temperature sensor based on the fluorescence intensity and fluorescence lifetime.

Rational Design of a Uranyl Metal-Organic Framework for the Capture and Colorimetric Detection of Organic Dyes

A new uranyl containing metal-organic framework, RPL-1: [(UO₂)₂(C₂₈H₁₈O₈)] ^. H₂O (RPL for Radiochemical Processing Laboratory), was prepared, structurally characterized, and the solid-state photoluminescence properties explored. Single crystal X-ray diffraction data reveals the structure of RPL-1 consists of two crystallographically unique three dimensional, interpenetrating nets with a 4,3-connected tbo topology. Each net contains large pores with an average width of 22.8 Å and is formed from monomeric, hexagonal bipyramidal uranyl nodes that are linked via 1,2,4,5-tetrakis(4-carboxyphenyl)benzene (TCPB) ligands. The thermal and photophysical properties of RPL-1 were investigated using thermogravimetric analysis and absorbance, fluorescence, and lifetime spectroscopies. The material displays excellent thermal stability and temperature dependent uranyl and TCPB luminescence. The framework is stable in aqueous media and due to the large void space (constituting 76 % of the unit cell by volume) can sequester organic dyes, the uptake of which induces a visible change to the color of the material.

Dual-Mode Light-Emitting Lanthanide Metal-Organic Frameworks with High Water and Thermal Stability and Their Application in White LEDs

It is well known that the upconversion luminescence from lanthanide metal-organic frameworks (Ln-MOFs) is difficult to achieve, and thus, there are few reports on dual luminescence-based MOFs. Here, dual-mode light-emitting Ln-MOFs are synthesized using a low-cost hydrothermal method. Our results show that the obtained Ln-MOFs not only have high thermal stability (up to 420°) but also are stable in deionized water. The dual-mode up- and downconversion luminescence is simultaneously observed from Er-Eu-MOFs. The temperature-dependent fluorescence decay time is calculated to be ranging from 0.46 to 0.36 ms for temperatures from 100 to 300 K. We suggested that this phenomenon was because the number of phonons participating in the MOF matrix increases with temperature during the luminescence process, and the phonons interact with the electrons in the material. The values of the J-O parameters calculated from the emission spectra indicated that the symmetry around Eu³⁺ ions in Eu-MOF is the highest, which was also higher than that of Er-Eu-MOF. To explore the potential applications of Eu-MOFs in white light-emitting diodes (LEDs), red emission from Eu-MOFs was combined with blue, green, and yellow emissions from metal halide perovskites to achieve white light emission. White light with excellent color quality and vision performance was obtained. These findings demonstrate that Ln-MOFs are potentially successful materials for applications in white LEDs.

State of the art methods and challenges of luminescent metal–organic frameworks for antibiotic detection

This review focuses on recent developments in the design and synthesis of luminescence MOFs for monitoring antibiotics.

Syntheses, Structures, and Characteristics of Three Metal Complexes Constructed Using Hexacarboxylic Acid

In this study, three new 3D coordination polymers (CPs), {[Cd3(L)(H2O)6]·H2O}n (1), {[Cu1.5(L)0.5(bimb)1.5]·5H2O·DMF}n (2), and {[Mn1.5(H3L)(bibp)0.5(H2O)2]·3H2O}n (3) (bimb= 1,3-bis(imidazol-1-yl)benzene, bibp= 1,4-bis((4-imidazol-1-yl)benzyl)piperazine), were prepared under solvothermal or hydrothermal conditions based on a hexadentate ligand (1,3,5-triazine-2,4,6-triamine hexa-acetic acid (H6L)). Structural elucidations were carried out by IR spectra along with single-crystal X-ray diffraction analysis, while thermogravimetric analysis (TGA) (dynamic and isothermal) and XRD techniques were used for property evaluations of the polymers. Furthermore, the fluorescence properties and detection of the Fe3+ ions in 1 were tested at room temperature, and the electrochemical behavior of 2 is also stated in this article.

Structural Diversity of Bipyridinium-Based Uranyl Coordination Polymers: Synthesis, Characterization, and Ion-Exchange Application

As well-known functional groups with excellent electro/photochromic and ion-exchange properties, bipyridinium motifs have been used in functionalized metal-organic coordination polymers, but they are still rarely applied to construct actinide coordination polymers. In this work, we utilized a bipyridinium-based carboxylic acid, 1,1'-bis(4-carboxyphenyl)-4,4'-bipyridinium bis(chloride) ([H₂bcbp]Cl₂), as the organic ligand to assemble with uranyl cations. By the introduction of different kinds of auxiliary ligands and adjustment of the pH, five novel uranyl coordination compounds, 1-5, have been synthesized through hydrothermal reactions. Starting from uranyl ions and terephthalic acid (H₂TP) and H₂bcbp ligands, [(UO₂)₂(bcbp)(TP)₂]·3H₂O (1) has a wave-shaped two-dimensional (2D) structure consisting of dinuclear units connected by terephthalate linkers and further supported by the longer H₂bcbp ligands. [(UO₂)₂(bcbp)(PA)₂]·4H₂O (2) has a zigzag chain of dimeric uranium units, and [(UO₂)₂(bcbp)(bpdc)₂]·5H₂O (3) forms a one-dimensional ribbonlike structure. The 2D structures of [(UO₂)(bcbp)(OH)(H₂O)]·Cl (4) and [(UO₂)(bcbp)Cl]·Cl (5) are similar, both of which are constructed from dinuclear uranyl units and bcbp^2- ligands. Furthermore, the performance for perrhenate removal of compound 4 with a cationic framework is assessed, and we found that compound 4 can efficiently remove ReO₄^- from an aqueous solution in a wide range of pH values. This work extends the library of viologen derivative-based uranyl coordination polymers, provides to some extent broader insights into actinide coordination chemistry of functionalized ligands, and may facilitate the ion-exchange applications of related coordination polymers.

Water adsorption and proton conduction of a cobalt(ii) complex assembled by triazine-based polycarboxylate

A new flexible triazine-based polycarboxylate coordination polymer, {[Co3(H3TTHA)2(4,4'-bipy)5(H2O)8]·12H2O}n (1), where H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, has been synthesized under hydrothermal conditions and structurally characterized by infrared spectroscopy, elemental analysis, TGA, XRD and X-ray single-crystal diffraction. Structural analysis indicates that 1 displays a planar structure with alternate rectangular structures of 22.695 × 11.485 Å2. The investigation of water vapor adsorption shows that the adsorption capacity of 1 is comparable to that of the typical adsorption material of MCM-41 with 73.86% (41.03 mmol g-1) water uptake at 90% relative humidity (RH). Based on the resistance to water and high-density hydrophilic units as well as abundant hydrogen-bonding networks in the complex, the proton conductivities of 1 under different conditions were measured. The results indicate that the proton conductivity values are highly temperature and relative humidity dependent, with the highest conductivity of nearly 10-3 S cm-1 at 353 K and 98% RH. The Arrhenius activation energy derived in the wide temperature range of 293-353 K is 0.32 eV, corresponding to a typical Grotthuss mechanism.

Three-in-one is really better: exploring the sensing and adsorption properties in a newly designed metal-organic system incorporating a copper(ii) ion

A 2-D copper(ii)-based coordination polymer, [Cu(SCN)(hmp)]_n CP (1), was crystallized via the slow evaporation method after the reaction of CuSO₄·5H₂O, 2-pyridinemethanol (hmpH), sodium thiocyanate and sodium hydroxide in water for functional applications. CP (1) was characterized via elemental analysis, FTIR, PXRD, magnetic, EPR, crystallographic and TGA studies. The crystal structure and EPR data confirmed a square pyramidal geometry around the Cu(ii) ions. The topological analysis revealed that CP 1 has a {6^{^}3} point symbol with a [6.6.6] extended point symbol and 3-c net, uninodal net having hcb and Shubnikov hexagonal plane net/(6,3) type of uncommon topology. The magnetic studies suggested the strong antiferromagnetic nature of CP (1). The fluorescence sensing property of CP (1) was investigated with different nitro aromatic compounds and hazardous metal ions. CP (1) demonstrated high selectivity and sensitivity towards nitrobenzene, even in the presence of other competitive nitro aromatics. In addition, CP (1) showed excellent selectivity and sensitivity toward Fe³⁺ over other metal ions. The possible detection mechanisms were proposed employing UV-visible and fluorescence spectroscopy and DFT calculations. CP (1) also showed excellent recyclability towards both analytes, and its initial intensity was almost regained after several washings. Moreover, CP (1) acted as an excellent adsorbent material for natural dyes with different charges and sizes, i.e., methylene blue (MB), methyl orange (MO) and Rhodamine-B. Furthermore, CP (1) was utilized repeatedly for the effective adsorption of MB from wastewater without significant loss in its adsorption capacity. Hence, the present CP (1) was designed to relate coordination chemistry with various functional applications of interest.

Enhancement of Intrinsic Proton Conductivity and Aniline Sensitivity by Introducing Dye Molecules into the MOF Channel

The encapsulation of dyes into metal-organic frameworks (MOFs) has generated a variety of platforms for luminescence, but little attention has been paid to their application in proton conduction. Here, a cationic MOF {{[In₃OL_1.5(H₂O)₃](NO₃)}·(DMA)₃·(CH₃CN)₆·(H₂O)₃₀} _n (FJU-10, H₄L = 4,4',4″,4‴-(1,4-phenylenbis(pyridine-4,2,6-triyl))-tetrabenzoic acid, DMA = N, N-dimethylacetamide) was synthesized, and the dye molecule 8-hydroxy-1,3,6-pyrenetrisulfonic acid trisodium salt (HPTS) was further added to the MOF growth solution, but during the reaction, HPTS was nitrated and nitrated HPTS was encapsulated into the FJU-10 to obtain dye@FJU-10. As a result, the intrinsic proton conductivity of dye@FJU-10 is nearly 5 times higher than that of FJU-10 at 90 °C. Dye@FJU-10 exhibits more sensitive fluorescence quenching toward aniline than FJU-10 in DMF solution (the detection limits of FJU-10 and dye@FJU-10 are as low as 0.58 and 0.62 μM, respectively). Here, it is demonstrated for the first time that intrinsic proton conductivity can be effectively improved by encapsulating a nitrated HPTS dye into an MOF.

Multi-colour uranyl emission efficiently tuned by hexacyanidometallates within hybrid coordination frameworks

Hexacyanidometallates of transition metal ions govern the topology and the photoluminescence of bimetallic d–f hybrid coordination networks incorporating uranyl cations.

Hydrothermal synthesis, crystal structure and properties of a two-dimensional uranyl coordination polymer based on a flexible zwitterionic ligand

The interaction between the uranyl cation, (UO₂)²⁺, and organic species is of interest due to the potential applications of the resulting compounds with regard to nuclear waste disposal and nuclear fuel reprocessing. The hydrothermal reaction of various uranyl compounds with flexible zwitterionic 1,1'-[1,4-phenylenebis(methylene)]bis(pyridin-1-ium-4-carboxylate) dihydrochloride (Bpmb·2HCl) in deionized water containing drops of H₂SO₄ resulted in the formation of a novel two-dimensional uranyl coordination polymer, namely poly[tetraoxido{μ₂-1,1'-[1,4-phenylenebis(methylene)]bis(pyridin-1-ium-4-carboxylate)}di-μ₃-sulfato-diuranium(VI)], [(UO₂)₂(SO₄)₂(C₂₀H₁₆N₂O₄)]_n, (1). Single-crystal X-ray diffraction reveals that this coordination polymer exhibits a layered arrangement and the (UO₂)²⁺ centre is coordinated by five equatorial O atoms. The structure was further characterized by FT-IR spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). The polymer shows high thermal stability up to 696 K. Furthermore, the photoluminescence properties of (1) has also been studied, showing it to exhibit a typical uranyl fluorescence.

A luminescent zinc(ii) coordination polymer with unusual (3,4,4)-coordinated self-catenated 3D network for selective detection of nitroaromatics and ferric and chromate ions: a versatile luminescent sensor

A zinc coordination polymer is a sensor for detection of TNP, Fe³⁺, Cr₂O₇²⁻ and CrO₄²⁻.

A ZnII-MOF Assembled by Triazine-Based Polycarboxylate and 4,4′-Bipy: Structure, Fluorescent Properties, and Water Vapour Adsorption

A new flexible triazine-based polycarboxylate metal–organic framework, {[Zn4(TTHA)(4, 4′-bipy)2(OH)2(H2O)]·H2O}n (1), H6TTHA = 1,3,5-triazine-2,4,6-triamine hexaacetic acid, has been synthesised under hydrothermal conditions and structurally characterised by X-ray diffraction, infrared spectroscopy, elemental analysis, and X-ray single-crystal diffraction. Structural studies indicate that 1 exhibits a 3D network with a 4,6-connected topology, formed by the interconnection of tetranuclear units and the ligands. The fluorescence emission properties of 1 and the free ligands were investigated in the solid state at room temperature. Moreover, the fluorescence lifetime (τ) and quantum yield (Φf) were obtained to further characterise the fluorescence properties. In addition, the water vapour adsorption of 1 was first studied for H6TTHA based complexes, which shows a general water adsorption capacity.

Two 2-D multifunctional cobalt(ii) compounds: field-induced single-ion magnetism and catalytic oxidation of benzylic C–H bonds

Two 2-D multifunctional cobalt(ii) compounds were reported with both field-induced single-ion magnetism and catalytic oxidation of benzylic C–H bonds.

A Highly Stable 3D Luminescent Indium-Polycarboxylic Framework for the Turn-off Detection of UO22+, Ru3+, and Biomolecule Thiamines

Hydrothermal reaction of the multidentate organic ligand (H₆TTHA) with indium chloride (InCl₃) produced a highly stable 3D luminescent indium-organic framework [In₂(OH)₂(H₂TTHA)(H₂O)₂]_n (1). Complex 1 exhibits remarkable luminescent properties, especially the multifunction sensitivity and selectivity for detecting Ru³⁺, UO₂²⁺; as well as small biomolecules thiamines (TPP, TMP, and TCl) based on a "turn-off" manner. In particular, the pyrophosphate groups of TPP and the phosphate groups of TMP could further affect the quenching rate, leading to different luminescent responds. In addition, we also discussed and proved the luminescence quenching mechanism in detail through comparative test and PXRD characterization. Therefore, complex 1 could be used as a kind of excellent luminescence sensor to detect Ru³⁺, UO₂²⁺, and thiamines (TPP, TMP, and TCl).

Photoelectric properties and potential nitro derivatives sensing by a highly luminescent of Zn(ii) and Cd(ii) metal–organic frameworks assembled by the flexible hexapodal ligand, 1,3,5-triazine-2,4,6-triamine hexaacetic acid

The luminescent quenching of coordination polymers 1 and 2 were especially obvious with the increasing of the nitro derivatives concentration, indicating 1 and 2 have very high sensitivity sensing properties.

An unusual (4,4)-connected 3D porous cadmium metal–organic framework as a luminescent sensor for detection of nitrobenzene

The MOF 1 shows an unusual (4,4)-connected 3D porous network. The high quenching efficiency of 1 is up to 98.2% at 160 ppm NBZ. 1 displays highly selectivity, sensitivity and recyclability in the detection of nitrobenzene.

Highly sensitive and selective fluorescent probes for Hg2+ in Ag(i)/Cu(ii) 3D supramolecular architectures based on noncovalent interactions

Three novel Ag(i)/Cu(ii) metal–organic assemblies displayed 3D supramolecular architectures with the help of noncovalent interactions. 1 performs as a highly sensitive and selective fluorescent probe for Hg²⁺, and 2 shows a unique semiconductive nature.

A luminescent metal–organic framework for highly selective sensing of nitrobenzene and aniline

A luminescent metal–organic frameworkgea-MOF-1, can act as a fluorescent sensor for sensitive and selective detection of nitrobenzene and aniline. More importantly, the detection limit of nitrobenzene is on the 5–60 ppm scale.