A chiral metal-organic framework{(HQA)(ZnCl_(2))(2.5H_(2)O)}n for the enantioseparation of chiral amino acids and drugs

Chiral metal-organic frameworks(CMOFs)with enantiomeric subunits have been employed in chiral chemistry.In this study,a CMOF formed from 6-methoxyl-(8S,9R)-cinchonan-9-ol-3-carboxylic acid(HQA)and ZnCl_(2),{(HQA)(ZnCl_(2))(2.5H_(2)O)}n,was constructed as a chiral stationary phase(CSP)via an in situ fabrication approach and used for chiral amino acid and drug analyses for the first time.The{(HQA)(ZnCl_(2))(2.5H_(2)O)}n nanocrystal and the corresponding chiral stationary phase were systematically characterised using a series of analytical techniques including scanning electron microscopy,X-ray diffraction,Fourier transform infrared spectroscopy,circular dichroism,X-ray photoelectron spectroscopy,thermogravimetric analysis,and Brunauer-Emmett-Teller surface area measurements.In opentubular capillary electrochromatography(CEC),the novel chiral column exhibited strong and broad enantioselectivity toward a variety of chiral analytes,including 19 racemic dansyl amino acids and several model chiral drugs(both acidic and basic).The chiral CEC conditions were optimised,and the enantioseparation mechanisms are discussed.This study not only introduces a new high-efficiency member of the MOF-type CSP family but also demonstrates the potential of improving the enantioselectivities of traditional chiral recognition reagents by fully using the inherent characteristics of porous organic frameworks.

A Novel TADDOL-based Chiral Metal-organic Framework：Synthesis, Structure and Photoluminescence Study

A new C2-symmetric TADDOL-based ligand H4L was designed and synthesized from readily available tartaric acid and was used to construct a novel TADDOL-based chiral metal-organic framework {[Co2L（DMA）（H2O）5]·2DMA}n 1（DMA = N,N-dimethylacetamide）. It was characterized by single-crystal and powder X-ray diffraction, Fourier-transform infrared spectra（FTIR）, solid-state circular dichroism（CD） and thermal gravimetric analysis（TGA）. 1 crystallizes in the chiral orthorhombic space group P212121 with a = 9.7060（8）, b = 15.5661（1）, c = 44.564（3） , V = 6732.9（9） -3, Z = 4, Mr = 1394.08, Dc = 1.375 g/cm-3, F（000） = 2888, GOOF = 1.032, the final R = 0.0607 and wR = 0.1582 for 21374 observed reflections with I 〉 2σ（I）. Each Co2 cluster in 1 is linked by three ligands and each ligand is coordinated to three Co2 clusters with one free carboxylate group, thus generating a 2D network. These 2D networks are further extended into a 3D supramolecule framework by the hydrogen bonding interactions（O–H…O） in an A-B-A-B stacking mode. Additionally, the photoluminescence of 1 and H4L were also investigated.

A Zeolitic rho-type Chiral Metal-organic Framework Based on L-alanine

One new chiral zeolitic rAo-type metal-organic framework[Cd(L-ala)2]n(l)has been successfully synthesized based on L-alanine chiral ligand,which demonstrates the feasibility of fabricating MOF that integrates the 4-connected zeotype topology by the employment of Z-alanine.To the best of knowledge,it's the first report that metal-organic framework based on amino acid features the chiral zeolitic rho-type structure.Compound 1 was characterized by X-ray powder diffraction,elemental analysis and single-crystal X-ray diffraction.Crystal data:CbH9CdN2O4,Mr=285.55,cubic system,space group/432,a=24.0795(6),V=13961.9(10)A3,Z=48,Dc=1.630 Mg/m3,F(000)=6672,μ(MoKa)=1.865 mm-1,S=1.058,R=0.0271 and wR=0.0312 for 1870 observed reflections with I>2δ(I).The circular dichroism(CD)property of compound 1 was also investigated.

Three Isomeric Chiral Metal-organic Frameworks Determined by Different Halogen Ions

Three isomeric metal-organic frameworks,[Cd2（X）（btc）（DMA）3]n（X = Cl（1）,Br（2）,I（3）,H3btc =1,3,5-benzenetricarboxylic acid and DMA = N,Nˊ-dimethylacetamide）,have been synthesized and characterized by elemental analysis,infrared spectra（IR）,thermogravimetric（TG） analyses and single-crystal X-ray diffraction.Single-crystal X-ray analysis reveals that compounds 1–3 crystallize in the orthorhombic P212121 space group,and feature a three-dimensional（3D） extended framework containing dinuclear [Cd2（COO）3] units as the secondary building units（SBUs）.Topological analysis reveals that compounds 1–3 can be simplified into a 3-connected srs topological network.

Electrochemical Chiral Recognizing Tryptophan Enantiomers Based on Chiral Metal-Organic Framework D-MOF

In this work,an electrochemical chiral sensor of a nanowire-like chiral metal-organic framework/multiwalled carbon nanotube-chitosan/glassy carbon electrode(D-MOF/MWCNTs-CS/GCE)was proposed for the enantiorecognition of L/D-tryptophan(L/D-Trp).The asymmetrical spatial structure of D-MOF provides the feasibility for the enantiorecognition of Trp enantiomers.Moreover,differential pulse voltammetry(DPV)was carried out to be the detection method and the DPV peak potential difference(ΔEp)between L-Trp and D-Trp was referred as the index of the enantiorecognition performance.Several parameters,such as mass ratios and drop-coated volume of MWCNTs-CS,drop-coated volume and concentration of D-MOF,pH and detection temperature of D-MOF/MWCNTs-CS/GCE were optimized for the largestΔEp value.And the molecular dynamics(MD)simulation was used to elucidate the enantiorecognition mechanism.Furthermore,the proportions of D-Trp(D-Trp%)in Trp mixtures were detected in a good linear relationship with the DPV peak potentials(Ep),and the proposed electrochemical chiral sensor exhibited good reproducibility,stability and enantiorecognition ability.Additionally,the proposed electrochemical chiral sensor(D-MOF/MWCNTs-CS/GCE)has a good application prospect in the fields of biomedicine,clinical diagnosis,chemical production,pharmaceuticals safety and so on.

Metal-organic frameworks and their composites for advanced lithium-ion batteries:Synthesis,progress and prospects

Metal-organic frameworks(MOFs)are among the most promising materials for lithium-ion batteries(LIBs)owing to their high surface area,periodic porosity,adjustable pore size,and controllable chemical composition.For instance,their unique porous structures promote electrolyte penetration,ions transport,and make them ideal for battery separators.Regulating the chemical composition of MOF can introduce more active sites for electrochemical reactions.Therefore,MOFs and their related composites have been extensively and thoroughly explored for LIBs.However,the reported reviews solely include the applications of MOFs in the electrode materials of LIBs and rarely involve other aspects.A systematic review of the application of MOFs in LIBs is essential for understanding the mechanism of MOFs and better designing related MOFs battery materials.This review systematically evaluates the latest developments in pristine MOFs and MOF composites for LIB applications,including MOFs as the main materials(anode,cathode,separators,and electrolytes)to auxiliary materials(coating layers and additives for electrodes).Furthermore,the synthesis,modification methods,challenges,and prospects for the application of MOFs in LIBs are discussed.

Synergistic catalysis of the N-hydroxyphthalimide on flower-like bimetallic metal-organic frameworks for boosting oxidative desulfurization

Synergic catalytic effect between active sites and supports greatly determines the catalytic activity for the aerobic oxidative desulfurization of fuel oils.In this work,Ni-doped Co-based bimetallic metal-organic framework(CoNi-MOF)is fabricated to disperse N-hydroxyphthalimide(NHPI),in which the whole catalyst provides plentiful synergic catalytic effect to improve the performance of oxidative desulfurization(ODS).As a bimetallic MOF,the second metal Ni doping results in the flower-like morphology and the modification of electronic properties,which ensure the exposure of NHPI and strengthen the synergistic effect of the overall catalyst.Compared with the monometallic Co-MOF and naked NHPI,the NHPI@CoNi-MOF triggers the efficient activation of molecular oxygen and improves the ODS performance without an initiator.The sulfur removal of dibenzothiophene-based model oil reaches 96.4%over the NHPI@CoNi-MOF catalyst in 8 h of reaction.Furthermore,the catalytic product of this aerobic ODS reaction is sulfone,which is adsorbed on the catalyst surface due to the difference in polarity.This work provides new insight and strategy for the design of a strong synergic catalytic effect between NHPI and bimetallic supports toward high-activity aerobic ODS materials.

Hollow Metal-Organic Framework/MXene/Nanocellulose Composite Films for Giga/Terahertz Electromagnetic Shielding and Photothermal Conversion

With the continuous advancement of communication technology,the escalating demand for electromagnetic shielding interference(EMI)materials with multifunctional and wideband EMI performance has become urgent.Controlling the electrical and magnetic components and designing the EMI material structure have attracted extensive interest,but remain a huge challenge.Herein,we reported the alternating electromagnetic structure composite films composed of hollow metal-organic frameworks/layered MXene/nanocellulose(HMN)by alternating vacuum-assisted filtration process.The HMN composite films exhibit excellent EMI shielding effectiveness performance in the GHz frequency(66.8 dB at Kaband)and THz frequency(114.6 dB at 0.1-4.0 THz).Besides,the HMN composite films also exhibit a high reflection loss of 39.7 dB at 0.7 THz with an effective absorption bandwidth up to 2.1 THz.Moreover,HMN composite films show remarkable photothermal conversion performance,which can reach 104.6℃under 2.0 Sun and 235.4℃under 0.8 W cm^(−2),respectively.The unique micro-and macrostructural design structures will absorb more incident electromagnetic waves via interfacial polarization/multiple scattering and produce more heat energy via the local surface plasmon resonance effect.These features make the HMN composite film a promising candidate for advanced EMI devices for future 6G communication and the protection of electronic equipment in cold environments.

Photophysics of metal-organic frameworks:A brief overview

Metal-organic frameworks(MOFs),which are self-assembled porous coordination materials,have garnered considerable attention in the fields of optoelectronics,photovoltaic,photochemistry,and photocatalysis due to their diverse structures and excellent tunability.However,the performance of MOF-based optoelectronic applications currently falls short of the industry benchmark.To enhance the performance of MOF materials,it is imperative to undertake comprehensive investigations aimed at gaining a deeper understanding of photophysics and sequentially optimizing properties related to photocarrier transport,recombination,interaction,and transfer.By utilizing femtosecond laser pulses to excite MOFs,time-resolved optical spectroscopy offers a means to observe and characterize these ultrafast microscopic processes.This approach adds the time coordinate as a novel dimension for comprehending the interaction between light and MOFs.Accordingly,this review provides a comprehensive overview of the recent advancements in the photophysics of MOFs and additionally outlines potential avenues for exploring the time domain in the investigation of MOFs.

Regulating interfacial behavior of zinc metal anode via metal-organic framework functionalized separator

Aqueous zinc ion batteries(AZIBs)are one of the promising energy storage devices.However,uncontrolled dendrite and side reactions have seriously hindered its further application.In this study,the metal-organic framework(MOF)functionalized glass fiber separator(GF-PFC-31)was used to regulate interfacial behavior of zinc metal anode,enabling the development of high-performance AZIBs.In PFC-31,there areπ-πinteractions between two adjacent benzene rings with a spacing of 3.199 A.This spacing can block the passage of[Zn(H_(2)O)_6]^(2+)(8.6 A in diameter)through the GF-PFC-31 separator to a certain extent,which promotes the deposition process of Zn ions.In addition,the sulfonic acid group(-S03H)contained in GF-PFC-31 can form a hydrogen bonding network with H_(2)O,which can provide a desolvation effect and reduce the side reaction.Consequently,GF-PFC-31 separator achieves uniform deposition of Zn ions.The Zn‖GF-PFC-31‖Zn symmetric cell exhibits stable cycle life(3000 h at 1.2 mA cm^(-2),2000 h at 0.3 mA cm^(-2),and 2000 h at 5.0 mA cm^(-2)),and Zn‖GF-PFC-31‖MnO_(2) full cell with GF-PFC-31 separator can cycle for 1000 cycles at 1.2 A g^(-1)with capacity retention rate of 82.5%.This work provides a promising method to achieve high-performance AZIBs.

Accelerating Oxygen Electrocatalysis Kinetics on Metal-Organic Frameworks via Bond Length Optimization

Metal-organic frameworks(MOFs)have been developed as an ideal platform for exploration of the relationship between intrinsic structure and catalytic activity,but the limited catalytic activity and stability has hampered their practical use in water splitting.Herein,we develop a bond length adjustment strategy for optimizing naphthalene-based MOFs that synthesized by acid etching Co-naphthalenedicarboxylic acid-based MOFs(donated as AE-CoNDA)to serve as efficient catalyst for water splitting.AE-CoNDA exhibits a low overpotential of 260 mV to reach 10 mA cm^(−2)and a small Tafel slope of 62 mV dec^(−1)with excellent stability over 100 h.After integrated AE-CoNDA onto BiVO_(4),photocurrent density of 4.3 mA cm^(−2)is achieved at 1.23 V.Experimental investigations demonstrate that the stretched Co-O bond length was found to optimize the orbitals hybridization of Co 3d and O 2p,which accounts for the fast kinetics and high activity.Theoretical calculations reveal that the stretched Co-O bond length strengthens the adsorption of oxygen-contained intermediates at the Co active sites for highly efficient water splitting.

Breaking Mirror Circularly Polarized Luminescence of Chiral Metal-Organic Frameworks by High-Pressure Stimulation

Understanding high-pressure-stimulated circularly polarized luminescence(CPL)of enantiomers remains a challenging but significant task in fundamental research and optical applications.Here,we combined in situ high-pressure photoluminescence with circularly polarized light to study how high pressure stimulated the CPL of crystalline enantiomers.Chiral lanthanide(Ln)-tartrate(Tar)metal-organic frameworks(MOFs;Ln=Eu,Tb)were synthesized to study their CPL from atmospheric pressure to 10 GPa.Under atmospheric pressure,D-and L-Eu(Tar)showed strong andmirror CPL.CPL intensity changes,emission wavelength shifts,and signal inversions were induced by increasing pressure.Note that the D-Eu(Tar)enantiomer showed strong CPL with a maximal dissymmetric factor(g_(lum))of 0.69 under 3 GPa,which is much higher than that under atmospheric pressure and of other reported MOF-based CPL materials.More interestingly,D-and L-Ln(Tar)enantiomers display obvious asymmetric CPL signals with increasing pressure,demonstrating that high pressure can break the mirror CPL of the MOF enantiomers.Our findings provide a critical understanding on in situ high-pressure CPL of chiral materials and establish a new optical phenomenon where high pressure can break the mirror CPL of enantiomers.

Synthesis,Structure and Characterization of a 3D Chiral Indium Carboxylate Metal-organic Framework Based on 1,1'-Biphenol Ligand

A novel indium-based chiral metal organic-framework 1 {In2L（μ2-O）（H2O）3}n was synthesized from C2-symmetric 1,1？-biphenol-based ligand H4 L and structurally characterized by single-crystal and powder X-ray diffraction, Fourier-transform infrared spectra（FTIR）, solid-state circular dichroism（CD） and thermal gravimetric analysis（TGA）. 1 crystallizes in monoclinic space group P21 with a = 10.1861（5）, b = 18.5632（9）, c = 16.5153（8） A^°, V = 3077.1（3） A^°^3, Z = 2, Mr = 944.29 g/mol, Dc = 1.019 g/cm^3, F（000） = 944, GOOF = 0.932, the final R = 0.0577 and w R = 0.1091 for 22090 observed reflections with I 〉 2σ（I）. Each In2 cluster in 1 is linked by four ligands and each ligand is coordinated to four In2 clusters to generate a 3D network. Additionally, the photoluminescence of 1 and H4 L were also investigated.

Engineering Spin States of Isolated Copper Species in a Metal-Organic Framework Improves Urea Electrosynthesis

The catalytic activities are generally believed to be relevant to the electronic states of their active center, but understanding this relationship is usually difficult. Here, we design two types of catalysts for electrocatalytic urea via a coordination strategy in a metal–organic frameworks: Cu^(Ⅲ)-HHTP and Cu^(Ⅱ)-HHTP. Cu^(Ⅲ)-HHTP exhibits an improved urea production rate of 7.78 mmol h^(−1)g^(−1) and an enhanced Faradaic efficiency of 23.09% at-0.6 V vs. reversible hydrogen electrode, in sharp contrast to Cu^(Ⅱ)-HHTP.Isolated CuⅢspecies with S = 0 spin ground state are demonstrated as the active center in Cu^(Ⅲ)-HHTP, different from Cu^(Ⅱ) with S = 1/2 in Cu^(Ⅱ)-HHTP. We further demonstrate that isolated Cu^(Ⅲ)with an empty dx2-y20orbital in Cu^(Ⅲ)-HHTP experiences a single-electron migration path with a lower energy barrier in the C–N coupling process, while Cu^(Ⅱ)with a single-spin state( d_(x2-y2)^(1)) in Cu^(Ⅱ)-HHTP undergoes a two-electron migration pathway.

Research progress on the substrate for metal-organic framework(MOF) membrane growth for separation

During the last decade, metal-organic frameworks(MOFs) have been applied in various fields due to their unique chemical and functional advantages. One of the widespread research hotspots is MOF-based membranes for separations, specifically continuous defect-free MOF membranes, which are usually grown on porous substrates. The substrate not only serves as the MOF layer support but also has a great influence on the membrane fabrication process and the final separation performance of the resultant membrane. In this review, we mainly introduce the progress focused on the substrates for MOF membranes fabrication. The substrate modifications and seeding methods aimed at synthesizing highquality MOF membranes are also summarized systematically.

Dual-conductive metal-organic framework@MXene heterogeneity stabilizes lithium-ion storage

Although a few pristine metal-organic frameworks(MOFs) of graphene analogue topology exhibit high intrinsic electrical conductivity, their use in lithium-ion batteries(LIBs) is still hampered by unfavorable Li+adsorption energy(ΔEa). In this paper, an electroconductive ferrocene-based MOF@MXene heterostructure is built to provide stable anodes for Li+storage. Charge density difference and planar average potential charge density show substantial redistribution of charges at the interfaces, transferring from MXene to MOF layers. Moreover, density functional theory(DFT) calculations reveal that the interaction between MXene and MOF significantly increases the ΔEa. As a result, the heterostructure anode exhibits high capacities and outstanding cycling stability with a capacity retention of 80% after 5000 cycles at 5 A g^(-1), outperforming mono-component MXene and MOF. Furthermore, the heterostructure anode is built into a full cell with a commercial NCM 532 cathode, delivering a high energy density of 611 Wh kg^(-1)and power density of 7600 W kg^(-1). The developed conductive MOF@MXene heterogeneity for improved LIB offers valuable insights into the design of advanced electrode materials for energy storage.

Structural survey of metal-covalent organic frameworks and covalent metal-organic frameworks

This review offers an overview of the latest developments in metal-covalent organic framework(MCOF)and covalent metal-organic framework(CMOF)materials,whose construction entails a combination of reversible coordination and covalent bonding adapted from metal-organic frameworks(MOFs)and covalent organic frameworks(COFs),respectively.With an emphasis on the MCOF and CMOF structures,this review surveys their building blocks and topologies.Specifically,the frameworks are classified based on the dimensions of their components(building blocks),namely,discrete building blocks and one-dimensional infinite building blocks.For the first category,the materials are further divided into collections of two-and three-dimensional networks based on their topologies.For the second category,the recently emerging MCOFs with woven structures are covered.Finally,the state-of-the-art in MCOF and CMOF chemistry has been laid out for promising avenues in future developments.

Novel in-capsule synthesis of metal-organic framework for innovative carbon dioxide capture system

Metal-Organic Frameworks(MOFs)have been developed as solid sorbents for CO_(2) capture applications and their properties can be controlled by tuning the chemical blocks of their crystalline units.A number of MOFs(e.g.,HKUST-1)have been developed but the question remains how to deploy them for gas-solid contact.Unfortunately,the direct use of MOFs as nanocrystals would lead to serious problems and risks.Here,for the first time,we report a novel MOF-based hybrid sorbent that is produced via an innovative in-situ microencapsulated synthesis.Using a custom-made double capillary microfluidic assembly,double emulsions of the MOF precursor solutions and UV-curable silicone shell fluid are produced.Subsequently,HKUST-1 MOF is successfully synthesized within the droplets enclosed in the gas permeable microcapsules.The developed MOF-bearing microcapsules uniquely allow the deployment of functional nanocrystals without the challenge of handling ultrafine particles,and further,can selectively reject undesired compounds to protect encapsulated MOFs.

Tuning the electronic structure of a metal-organic framework for an efficient oxygen evolution reaction by introducing minor atomically dispersed ruthenium

The establishment of efficient oxygen evolution electrocatalysts is of great value but also challenging.Herein,a durable metal–organic framework(MOF)with minor atomically dispersed ruthenium and an optimized electronic structure is constructed as an efficient electrocatalyst.Significantly,the obtained NiRu_(0.08)-MOF with doping Ru only needs an overpotential of 187 mV at 10 mA cm^(-2) with a Tafel slop of 40 mV dec^(-1) in 0.1M KOH for the oxygen evolution reaction,and can work continuously for more than 300 h.Ultrahigh Ru mass activity is achieved,reaching 56.7 Ag^(-1)_(Ru) at an overpotential of 200 mV,which is 36 times higher than that of commercial RuO_(2).X-ray adsorption spectroscopy and density function theory calculations reveal that atomically dispersed ruthenium on metal sites in MOFs is expected to optimize the electronic structure of nickel sites,thus improving the conductivity of the catalyst and optimizing the adsorption energy of intermediates,resulting in significant optimization of electrocatalytic performance.This study could provide a new avenue for the design of efficient and stable MOF electrocatalysts.

One-step ethylene separation from ternary C_(2) hydrocarbon mixture with a robust zirconium metal-organic framework

One-step separation of high-purity ethylene(C_(2)H_(4))from C_(2) hydrocarbon mixture is critical but challenging because of the very similar molecular sizes and physical properties of C_(2)H_(4),ethane(C_(2)H_(6)),and acetylene(C_(2)H_(2)).Herein,we report a robust zirconium metal-organic framework(MOF)Zr-TCA(H3TCA=4,4',4"-tricarboxytriphenylamine)with suitable pore size(0.6 nm×0.7 nm)and pore environment for direct C_(2)H_(4) purification from C_(2)H_(4)/C_(2)H_(2)/C_(2)H_(6) gas-mixture.Computational studies indicate that the abundant oxygen atoms and non-polar phenyl rings created favorable pore environments for the preferential binding of C_(2)H_(2) and C_(2)H_(6) over C_(2)H_(4).As a result,Zr-TCA exhibits not only high C_(2)H_(6)(2.28 mmol·g^(-1))and C_(2)H_(2)(2.78 mmol·g^(-1))adsorption capacity but also excellent C_(2)H_(6)/C_(2)H_(4)(2.72)and C_(2)H_(2)/C_(2)H_(4)(5.64)selectivity,surpassing most of one-step C_(2)H_(4) purification MOF materials.Dynamic breakthrough experiments confirm that Zr-TCA can produce high-purity C_(2)H_(4)(>99.9%)from a ternary gas mixture(1/9/90 C_(2)H_(2)/C_(2)H_(6)/C_(2)H_(4))in a single step with a high C_(2)H_(4) productivity of 5.61 L·kg^(-1).