Homochiral metal-organic frameworks for asymmetric heterogeneous catalysis

Modified Cellulose with BINAP-Supported Rh as an Efficient Heterogeneous Catalyst for Asymmetric Hydrogenation

Asymmetric catalysis is the preferred method for the synthesis of pure chiral molecules in the fine chemical industry. Cellulose has long been sought as a support in enantioselective catalysis. Dialdehyde cellulose (DAC) is produced by the selective oxidation of cellulose and is used to bind 5,5′-diamino Binap by forming a Schiff base. Here, we report the synthesis of modified cellulose-supported Rh as a novel biomass-supported catalyst and the characterization of its morphology, composition, and thermal stability. DAC-BINAP-Rh was a very effective catalyst in the asymmetric hydrogenation of enamides and could be easily recycled. This work provides a novel supported catalyst that broadens the applications of cellulose in asymmetric catalysis.

Design of coordination polymers based on combinations of 1,2-diphenylethane-1,2-diyl diisonicotinate with Cu(ii), Zn(ii), Cd(ii) and Co(ii)

Five new supramolecular coordination polymers of different dimensionalities (L-Cu(acac)2, L-Cu(hfac)2, L-ZnCl2, L-CdI2 and L-CoCl2) based on the use of the flexible organic ligand L (1,2-diphenylethane-1,2-diyl diisonicotinate) are reported.

Novel ditopic 2-mercaptothiazoles and their sodium salts: synthesis, structural diversity and luminescence

A set of novel ditopic 2-mercaptothiazoles has been synthesized. Depending on the nature of the bisthiazoles their sodium salts can form coordination compounds or 2D polymers.

Selective luminescent sensing of metal ions and nitroaromatics over a porous mixed-linker cadmium(ii) based metal–organic framework

A potential luminescent sensor based on porous metal organic framework for the detection of metal ions (Al3+, Fe3+ or Cr3+) and nitro-explosive, 2,4,6-tri-nitrophenol has been discovered. MOF is capable of detecting aqueous phase analyte through luminescent sensing.

Strategies for induced defects in metal-organic frameworks for enhancing adsorption and catalytic performance

Metal-organic frameworks (MOFs) have emerged among porous materials. The designable structure and specific functionality make them stand out for diverse applications. In conceptual MOF, the metal ions/clusters and organic ligands...

One-pot enantioselective construction of 3,4-dihydro-2H-1,4-oxazines over Ru/Au relay catalysis and its mechanistic serendipity

One-pot enantioselective construction of 3,4-dihydro-2H-1,4-oxazines have been developed through the transfer hydrogenation/cyclization enantio-relay process using Ru and Au bimetallic catalysts.

Construction of Stable Metal-Organic Framework Platforms Embedding N-Heterocyclic Carbene Metal Complexes for Selective Catalysis

We report a bottom-up approach to immobilize catalysts into MOFs, including copper halides and gold chloride in a predictable manner. Interestingly, the structures of MOFs bearing NHC metal complexes maintained a similar 4-fold interpenetrated cube. They exhibited exceptionally high porosity despite the interpenetrated structure and showed good stability in various solvents. Moreover, these MOFs possess high size activity depending on the size of the substrates in various reactions, compared to homogeneous catalysis. Also, the high catalytic activity of MOFs can be preserved 4 times without significant loss of crystallinity. Incorporation of the various metal complexes into MOFs allows for the preparation of functional MOFs for practical applications.

Anisotropic nanomaterials for asymmetric synthesis

The production of enantiopure chemicals is an essential part of modern chemical industry. Hence, the emergence of asymmetric catalysis led to dramatic changes in the procedures of chemical synthesis, and now it provides the most advantageous and economically executable solution for large-scale production of chiral chemicals. In recent years, nanostructures have emerged as potential materials for asymmetric synthesis. Indeed, on the one hand, nanomaterials offer great opportunities as catalysts in asymmetric catalysis, due to their tunable absorption, chirality, and unique energy transfer properties; on the other hand, the advantages of the larger surface area, increased number of unsaturated coordination centres, and more accessible active sites open prospects for catalyst encapsulation, partial or complete, in a nanoscale cavity, pore, pocket, or channel leading to alteration of the chemical reactivity through spatial confinement. This review focuses on anisotropic nanomaterials and considers the state-of-the-art progress in asymmetric synthesis catalysed by 1D, 2D and 3D nanostructures. The discussion comprises three main sections according to the nanostructure dimensionality. We analyze recent advances in materials and structure development, discuss the functional role of the nanomaterials in asymmetric synthesis, chirality, confinement effects, and reported enantioselectivity. Finally, the new opportunities and challenges of anisotropic 1D, 2D, and 3D nanomaterials in asymmetric synthesis, as well as the future prospects and current trends of the design and applications of these materials are analyzed in the Conclusions and outlook section.

Exploiting the Chiral Ligands of Bis(imidazolinyl)- and Bis(oxazolinyl)thiophenes-Synthesis and Application in Cu-Catalyzed Friedel-Crafts Asymmetric Alkylation

Five new C₂-symmetric chiral ligands of 2,5-bis(imidazolinyl)thiophene (L1–L3) and 2,5-bis(oxazolinyl)thiophene (L4 and L5) were synthesized from thiophene-2,5-dicarboxylic acid (1) with enantiopure amino alcohols (4a–c) in excellent optical purity and chemical yield. The utility of these new chiral ligands for Friedel–Crafts asymmetric alkylation was explored. Subsequently, the optimized tridentate ligand L5 and Cu(OTf)₂ catalyst (15 mol%) in toluene for 48 h promoted Friedel–Crafts asymmetric alkylation in moderate to good yields (up to 76%) and with good enantioselectivity (up to 81% ee). The bis(oxazolinyl)thiophene ligands were more potent than bis(imidazolinyl)thiophene analogues for the asymmetric induction of the Friedel–Crafts asymmetric alkylation.

Advances and Prospects in Metal-Organic Frameworks as Key Nexus for Chemocatalytic Hydrogen Production

Hydrogen is a clean and sustainable energy carrier, which is considered a promising alternative for fossil fuels to solve the global energy crisis and respond to climate change. Social concerns on its safe storage promote continuous exploration of alternatives to traditional storage methods. In this case, chemical hydrogen storage materials initiate plentiful research with special attention to the design of heterogeneous catalysts that can enhance efficient and highly selective hydrogen production. Metal-organic frameworks (MOFs), a kind of unique crystalline porous materials featuring highly ordered porosities and tailorable structures, can provide various active sites (i.e., metal nodes, functional linkers, and defects) for heterogeneous catalysis. Furthermore, the easy construction of active sites in highly ordered MOFs, which can work as plate for the delicate active site engineering, make them ideal candidates for a variety of heterogeneous catalysts including chemocatalytic hydrogen production. This review concentrates on the application of MOFs as heterogeneous catalysts or catalyst supports in chemocatalytic hydrogen production. Recent progresses of MOFs as catalysts for chemocatalytic hydrogen production are comprehensively summarized. The research methods, mechanism analyses, and prospects of MOFs in this field are discussed. The challenges in future industrial applications of MOFs as catalysts for hydrogen production are proposed.

DNAzyme-Functionalized Nanomaterials: Recent Preparation, Current Applications, and Future Challenges

DNAzyme-nanomaterial bioconjugates are a popular hybrid and have received major attention for diverse biomedical applications, such as bioimaging, biosensor development, cancer therapy, and drug delivery. Therefore, significant efforts are made to develop different strategies for the preparation of inorganic and organic nanoparticles (NPs) with specific morphologies and properties. DNAzymes functionalized with metal-organic frameworks (MOFs), gold nanoparticles (AuNPs), graphene oxide (GO), and molybdenum disulfide (MoS₂ ) are introduced and summarized in detail in this review. Moreover, the focus is on representative examples of applications of DNAzyme-nanomaterials over recent years, especially in bioimaging, biosensing, phototherapy, and stimulation response delivery in living systems, with their several advantages and drawbacks. Finally, the perspective regarding the future directions of research addressing these challenges is also discussed and highlighted.

Amino-functionalized Cu metal-organic framework nanosheets as fluorescent probes for detecting TNP

Here, we report a simple and benign method to successfully fabricate amino-functionalized Cu metal-organic framework (NH₂-Cu-MOF) nanosheets. After synthesizing Cu₂O nanocubes, they were mixed with organic ligand 2-aminoterephthalic acid (NH₂BDC) solution at room temperature for 4 hours to form NH₂-Cu-MOF nanosheets. Interestingly, the prepared NH₂-Cu-MOF nanosheets have ultra-thin thickness, directional growth characteristics and excellent crystallinity. Moreover, such nanosheets showed high-intensity and high-stability fluorescence emission under excitation. As TNP in water can quench the fluorescence emission of the fluorescent probe, the NH₂-Cu-MOF nanosheet fluorescent probe was established for detecting TNP in water with high sensitivity and selectivity, which is very useful for assessing the environmental quality and safety of water bodies. Finally, the probe was used to detect TNP in actual samples with good recovery rate.

Advanced strategies in Metal-Organic Frameworks for CO2 Capture and Separation

The continuous carbon dioxide (CO₂ ) gas emissions associated with fossil fuel production, valorization, and utilization are serious challenges to the global environment. Therefore, several developments of CO₂ capture, separation, transportation, storage, and valorization have been explored. Consequently, we documented a comprehensive review of the most advanced strategies adopted in metal-organic frameworks (MOFs) for CO₂ capture and separation. The enhancements in CO₂ capture and separation are generally achieved due to the chemistry of MOFs by controlling pore window, pore size, open-metal sites, acidity, chemical doping, post or pre-synthetic modifications. The chemistry of defects engineering, breathing in MOFs, functionalization in MOFs, hydrophobicity, and topology are the salient advanced strategies, recently reported in MOFs for CO₂ capture and separation. Therefore, this review summarizes MOF materials' advancement explaining different strategies and their role in the CO₂ mitigations. The study also provided useful insights into key areas for further investigations.

Surviving Under Pressure: The Role of Solvent, Crystal Size, and Morphology During Pelletization of Metal-Organic Frameworks

As metal-organic frameworks (MOFs) gain traction for applications, such as hydrogen storage, it is essential to form the as-synthesized powder materials into shaped bodies with high packing densities to maximize their volumetric performance. Mechanical compaction, which involves compressing the materials at high pressure, has been reported to yield high monolith density but often results in a significant loss in accessible porosity. Herein, we sought to systematically control (1) crystal size, (2) solvation, and (3) compacting pressure in the pelletization process to achieve high packing density without compromising the porosity that makes MOFs functional. It was determined that solvation is the most critical factor among the three factors examined. Solvation that exceeds the pore volume prevents the framework from collapsing, allowing for porosity to be maintained through pelletization. Higher pelletization pressure results in higher packing density, with extensive loss of porosity being observed at a higher pressure if the solvation is below the pore volume. Lastly, we observed that the morphology and size of the MOF particles result in variation in the highest achievable packing efficiency, but these numbers (75%) are still greater than many existing techniques used to form MOFs. We concluded that the application of pressure through pelletization is a suitable and widely applicable technique for forming high-density MOF-monoliths.

Enantioselective Gel Phase Synthesis of Metal-Organic Materials

We report the asymmetric synthesis of homochiral metal-organic materials (MOMs) in chiral gels from achiral components. The enantioselectivity of MOMs depends on the chirality of the gel, whereas the synthesis performed in solution phase and achiral gels resulted in conglomerates.

Heterogenizing a Homogeneous Nickel Catalyst Using Nanoconfined Strategy for Selective Synthesis of Mono- and 1,2-Disubstituted Benzimidazoles

A homogeneous Ni-phenanthroline catalyst was successfully immobilized into the cavities of a metal-organic framework, ZIF-8. The as-synthesized heterogeneous catalyst, Ni-Phen@ZIF, represents the first MOF based catalyst that enables dehydrogenative coupling of alcohols with aromatic diamines for selective synthesis of both mono- and 1,2-disubstituted benzimidazoles. The catalyst survived under harsh basic conditions, characterized by SEM, TEM, BET, PXRD, and EDX elemental mappings. The presence of the nanoconfined Ni-phenanthroline complex and the formation of extra Lewis acid sites during catalysis in the Ni-Phen@ZIF structure, confirmed by TPD analysis and kinetic experiments, might be responsible for higher activity and selectivity.

A new three-dimensional twofold interpenetrated cadmium(II) metal-organic framework: synthesis, structure and photoluminescence properties

The design and synthesis of metal-organic frameworks (MOFs) have attracted much interest due to the aesthetics of their crystalline architectures and their potential applications as new functional materials. A new twofold interpenetrated three-dimensional (3D) MOF, namely, poly[[triaqua(μ₄-(2R,2'R)-2,2'-{[1,4-phenylenebis(carbonyl)]bis(azanediyl)}dipropionato-κ⁷O¹:O¹,O^1':O⁴:O⁴,O^4',O^4'')(μ₃-(2R,2'R)-2,2'-{[1,4-phenylenebis(carbonyl)]bis(azanediyl)}dipropionato-κ³O¹:O⁴:O⁴)dicadmium(II)] dihydrate], {[Cd₂(C₁₄H₁₄N₂O₆)₂(H₂O)₃]·2H₂O}_n, (I), has been synthesized by the reaction of Cd(CH₃COO)₂·2H₂O with the synthesized ligand (2R,2'R)-2,2'-{[1,4-phenylenebis(carbonyl)]bis(azanediyl)}dipropionic acid (H₂L). Single-crystal X-ray diffraction analysis reveals that the carboxylate groups from two crystallographically independent L^2- dianions link the cadmium cations into a one-dimensional helical secondary building unit (SBU). The resulting SBUs are extended into a 3D metal-organic framework via the terephthalamide moiety of the ligand as a spacer. In the crystal, two independent MOFs interpenetrate each other, thus producing a twofold interpenetrated 3D architecture, which shows an unprecedented 2-nodal (7,9)-connected net with the point (Schläfli) symbol (3⁷·4⁶·5⁸)(3⁸·4¹¹·5¹⁶·6). MOF (I) was further characterized by elemental analysis, IR spectroscopy, powder X-ray diffraction and thermogravimetric analysis. The photoluminescence properties and UV-Vis absorption spectrum of (I) have also been investigated. The MOF exhibits enhanced fluorescence emission with a high photoluminescence quantum yield of 31.55% and a longer lifetime compared with free H₂L.

MOF-derived CoNi,CoO,NiO@N-C bifunctional oxygen electrocatalysts for liquid and all-solid-state Zn-air batteries

Metal-organic framework (MOF)-derived carbon composites with embedded metal alloy/metal oxides have attracted much attention due to their low-cost and excellent electrochemical reactivity. However, the drawback of this concept is the severe carbon evaporation during their synthesis, resulting in a reduction of active sites and catalytic durability. To solve this problem, this study proposes the possibility of using Ketjen black (KB) to replenish the carbon content. Impressively, MOF-derived bimetal and oxide N-doped porous carbon (CoNi-CoO-NiO@NC-800) exhibits extremely high catalytic activity with an oxygen reduction reaction (half-wave potential: 0.83 V) and oxygen evolution reaction (overpotential: 352 mV @ 10 mA cm^-2) potential gap of 0.75 V due to the virtue of the hierarchically porous structure and sufficient active sites. By combining theoretical studies, a strong synergetic coupling of the CoNi dual metal is proposed in decreasing the overall reaction barriers and promoting the reversible oxygen reactions. Moreover, the assembled liquid- and all-solid-state Zn-air batteries (ZABs) with the bifunctional catalyst as the air cathode demonstrate superior discharging (223 mW cm^-2 at 310 mA cm^-2) and charging-discharging performance and long lifetime (450 cycles, 75 h). This work will provide guidance for the rational design of metal/carbon hybrid catalysts and cut-price reproducible energy systems.

Artificial Metal-Peptide Assemblies: Bioinspired Assembly of Peptides and Metals through Space and across Length Scales

The exploration of chiral crystalline porous materials, such as metal-organic complexes (MOCs) or metal-organic frameworks (MOFs), has been one of the most exciting recent developments in materials science owing to their widespread applications in enantiospecific processes. However, achieving specific tight-affinity binding and remarkable enantioselectivity toward important biomolecules is still challenging. Perhaps most critically, the lack of adaptability, compatibility, and processability in these materials severely impedes practical applications in chemical engineering and biological technology. In this Perspective, artificial metal-peptide assemblies (MPAs), which are achieved by the assembly of peptides and metals with nanometer-sized cavities or pores, is a new development that could address the current bottlenecks of chiral porous materials. Bioinspired assembly of pore-forming MPAs is not foreign to biological systems and has granted scientists an unprecedented level of control over the chiral recognition sites, conformational flexibility, cavity sizes, and hydrophilic segments through ultrafine-tuning of peptide-derived linkers. We will specifically discuss exemplary MPAs including structurally well-defined metal-peptide complexes and highly crystalline metal-peptide frameworks. With insights from these structures, the peptide assembly and folding by the closer cooperation of metal coordination and noncovalent interactions can create adaptable protein-like nanocavities undergoing a myriad of conformational variations that is reminiscent of enzymatic pockets. We also consider challenges to advancing the field, where the deployment of side-chain groups and manipulation of amino acid sequences are more likely to access the programmable, genetically encodable peptide-mediated porous materials, thus contributing to the enhanced enantioselective recognition as well as enabling key biochemical processes in next-generation versatile biomimetic materials.

Atomically precise metal nanoclusters meet metal-organic frameworks

Significant progress has been made in both fields of atomically precise metal nanoclusters (NCs) and metal-organic frameworks (MOFs) in recent years. A promising direction is to integrate these two classes of materials for creating unique composites with improved properties for catalysis and other applications. NCs incorporated with MOFs exhibit an optimized catalytic performance in many catalytic reactions, in which MOFs play a vital supporting role or as cocatalysts. In this Perspective, we first provide a brief summary of the methods that have been developed for the preparation of NCs/MOF composites and the characteristics of these strategies are analyzed. Following that, some recent works are highlighted to demonstrate the crucial role of MOF matrices in the enhancement of NCs catalytic properties. Finally, we outline some potentially important aspects for future work. This Perspective is in hopes of stimulating more interest in the research on the integration of NCs with MOFs toward functional materials.

Chiral and robust Zr(IV)-based metal-organic frameworks built from spiro skeletons

Chiral metal-organic frameworks (CMOFs) have emerged as an important subclass of chiral materials; however, their development is hindered substantially by limited enantiopure functional linkers and poor chemical stabilities. Here we report the design and synthesis of a total of five enantiopure spiro-based tetracarboxylate linkers with diverse functionalities and their use in connecting Zr₆ clusters to form an array of highly robust and porous CMOFs. X-ray crystallographic analysis and structure examination unambiguously revealed that the resulting CMOFs possess multifarious three-dimensional networks with novel topologies and pore systems, highlighting the great potential of chiral spiro skeletons in the fabrication of intriguing structures. PXRD and N₂ adsorption experiments validated their exceptional chemical stability towards boiling water as well as aqueous acid and base solutions. Moreover, their potential applications in enantioselective catalysis and separation are also presented.

Bifunctional Metal-Organic Layers for Tandem Catalytic Transformations Using Molecular Oxygen and Carbon Dioxide

Tandem catalytic reactions improve atom- and step-economy over traditional synthesis but are limited by the incompatibility of the required catalysts. Herein, we report the design of bifunctional metal-organic layers (MOLs), HfOTf-Fe and HfOTf-Mn, consisting of triflate (OTf)-capped Hf₆ secondary building units (SBUs) as strong Lewis acidic centers and metalated TPY ligands as metal active sites for tandem catalytic transformations using O₂ and CO₂ as coreactants. HfOTf-Fe effectively transforms hydrocarbons into cyanohydrins via tandem oxidation with O₂ and silylcyanation whereas HfOTf-Mn converts styrenes into styrene carbonates via tandem epoxidation and CO₂ insertion. Density functional theory calculations revealed the involvement of a high-spin Fe^IV (S = 2) center in the challenging oxidation of the sp³ C-H bond. This work highlights the potential of MOLs as a tunable platform to incorporate multiple catalysts for tandem transformations.

Strain-Controlled Spin Transition in Heterostructured Metal-Organic Framework Thin Film

Metal-organic framework (MOF) thin films have recently attracted much attention as a new platform for surface/interface research, where unconventional structural and physical properties emerge. Among the many MOFs as candidates for fabrication of thin films, Hofmann-type MOFs {Fe(pz)[M(CN)₄]} [pz = pyrazine; M = Ni (Nipz), M = Pt (Ptpz)] are attractive, because they undergo spin transitions with concomitant structural changes. Here, we demonstrate the first example of a strain-controlled spin transition in heterostructured MOF thin films. The spin transition temperature of Ptpz can be controlled in the temperature range of 300-380 K by fabricating a nanometer-sized heterostructured thin film with a Nipz buffer layer, where the smaller lattice of Nipz causes epitaxial compressive strain to the Ptpz layer. The fabricated heterostructured thin film exhibited a remarkable increase in spin transition temperature with a dynamic structural transformation, confirmed by variable-temperature (VT) X-ray diffraction and VT Raman spectroscopy. By verifying interfacial strain in a heterostructured thin film, we can rationally control the characteristics of MOFs-not only spin transition but also various physical properties such as gas storage, catalysis, sensing, proton conductivity, and electrical properties, among others.

Slow Magnetic Relaxation in {[CoCxAPy)] 2.15 H2O}n MOF Built from Ladder-Structured 2D Layers with Dimeric SMM Rungs

We present the magnetic properties of the metal-organic framework {[CoCxAPy]·2.15 H2O}n (Cx = bis(carboxypropyl)tetramethyldisiloxane; APy = 4,4`-azopyridine) (1) that builds up from the stacking of 2D coordination polymers. The 2D-coordination polymer in the bc plane is formed by the adjacent bonding of [CoCxAPy] 1D two-leg ladders with Co dimer rungs, running parallel to the c-axis. The crystal packing of 2D layers shows the presence of infinite channels running along the c crystallographic axis, which accommodate the disordered solvate molecules. The Co(II) is six-coordinated in a distorted octahedral geometry, where the equatorial plane is occupied by four carboxylate oxygen atoms. Two nitrogen atoms from APy ligands are coordinated in apical positions. The single-ion magnetic anisotropy has been determined by low temperature EPR and magnetization measurements on an isostructural compound {[Zn0.8Co0.2CxAPy]·1.5 CH3OH}n (2). The results show that the Co(II) ion has orthorhombic anisotropy with the hard-axis direction in the C2V main axis, lying the easy axis in the distorted octahedron equatorial plane, as predicted by the ab initio calculations of the g-tensor. Magnetic and heat capacity properties at very low temperatures are rationalized within a S* = 1/2 magnetic dimer model with anisotropic antiferromagnetic interaction. The magnetic dimer exhibits slow relaxation of the magnetization (SMM) below 6 K in applied field, with a tlf ≈ 2 s direct process at low frequencies, and an Orbach process at higher frequencies with U/kB = 6.7 ± 0.5 K. This compound represents a singular SMM MOF built-up of Co-dimers with an anisotropic exchange interaction.

Pillararenes: fascinating planar chiral macrocyclic arenes

Chiral macrocycles possess significant value in chiral science and supramolecular chemistry. Pillararenes, as a class of relatively young supramolecular macrocyclic hosts, have been widely used for host-guest recognition and self-assembly. Since the position of substituents on the benzene rings breaks the molecular symmetry (symmetric plane and symmetric center), pillararenes possess planar chirality. However, it is a great challenge to synthesize stable and resolvable enantiomers because of the easy rotation of the phenylene group. In this review, we summarize the construction methods of resolvable chiral pillararenes. We also focus on their applications in enantioselective recognition, chiral switches, chirality sensing, asymmetric catalysis, circularly polarized luminescence, metal-organic frameworks, and highly permeable membranes. Finally, we discuss the future research perspectives in this field of pillararene-based planar chiral materials. We hope that this review will encourage more researchers to work in this exciting field.

Chiral Yolk-Shell MOF as an Efficient Nanoreactor for Asymmetric Catalysis in Organic-Aqueous Two-Phase System

It remains a great challenge to introduce large and efficient homogeneous asymmetric catalysts into MOFs and other microporous materials as well as retain their degrees of freedom. Herein, a new heterogeneous strategy of homogeneous chiral catalysts is proposed, that is, to construct a yolk-shell MOFs-confined, large-size, and highly efficient homogeneous chiral catalyst, which can be used as a nanoreactor for asymmetric catalytic reactions.

Electron-Conductive Metal-Organic Framework, Fe(dhbq)(dhbq = 2,5-Dihydroxy-1,4-benzoquinone): Coexistence of Microporosity and Solid-State Redox Activity

Redox-active metal-organic frameworks (MOFs) have great potential for use as cathode materials in lithium-ion batteries (LIBs) with large capacities because the organic ligands can undergo multiple-electron redox processes. However, most MOFs are electrical insulators, limiting their application as electrode materials. Here, we report an electron-conductive MOF with a 2,5-dihydroxy-1,4-benzoquinone (dhbq) ligand, Fe(dhbq). This compound had an electrical conductivity of 5 × 10^-6 S cm^-1 at room temperature due to d-π interactions between the Fe ion and the ligand and the permanent microporosity. Fe(dhbq) had an initial discharge capacity of 264 mA h g^-1, corresponding to the two-electron redox process of dhbq.

The influence of piperazine diamine templates on the synthesis, structures and properties of uranyl oxalate complex

As an important nuclear material, uranium is one of the most concerned elements in the nuclear fuel cycle, which could interact with many inorganic and organic ligands. Amine templates have a significant structural-oriented effect on the construction of uranyl oxalate complex. In this work, the piperazine diamine templates were used to synthesize uranyl oxalate complex and their crystal structures were resolved by single crystal diffraction, and their spectra were studied by IR, Raman, UV–vis, fluorescence, and EPR techniques. The final results show that crystal structures, properties and applications of uranyl oxalate complex have a close correlation with polyamine templates. The single crystal structure results show that the structural-oriented effect of piperazine diamine template is greatly affected by the proportion and concentration of solute in the surrounding environment. And the alkyl substituents on N atoms of amine templates are related to the tight of structures. Interestingly, 5# has a potential application as the original material for multiple reuse of fluorescent sensor materials. At present, there is no clear and in-depth study on the internal mechanism of such phenomena in solid uranyl complexes, and the specific mechanism needs to be further explored.