Defect-engineered indium-organic framework displays the higher CO2 adsorption and more excellent catalytic performance on the cycloaddition of CO2 with epoxides under mild conditions.

In order to achieve the high adsorption and catalytic performance of CO2, the direct self-assembly of robust defect-engineered MOFs is a scarcely reported and challenging proposition. Herein, a highly robust nanoporous indium(III)-organic framework of {[In2(CPPDA)(H2O)3](NO3)·2DMF·3H2O}n (NUC-107) consisting of two kinds of inorganic units of chain-shaped [In(COO)2(H2O)]n and watery binuclear [In2(COO)4(H2O)8] was generated by regulating the growth environment. It is worth mentioning that [In2(COO)4(H2O)8] is very rare in terms of its richer associated water molecules, implying that defect-enriched metal ions in the activated host framework can serve as strong Lewis acid. Compared to reported skeleton of [In4(CPPDA)2(µ3-OH)2(DMF)(H2O)2]n (NUC-66) with tetranuclear clusters of [In4(µ3-OH)2(COO)10(DMF)(H2O)2] as nodes, the void volume of NUC-107 (50.7%) is slightly lower than the one of NUC-66 (52.8%). However, each In3+ ion in NUC-107 has an average of 1.5 coordinated small molecules (H2O), which far exceeds the average of 0.75 in NUC-66 (H2O and DMF). After thermal activation, NUC-107a characterizes the merits of unsaturated In3+ sites, free pyridine moieties, solvent-free nanochannels (10.2 × 15.7 Å2). Adsorption tests prove that the host framework of NUC-107a has a higher CO2 adsorption (113.2 cm3/g at 273 K and 64.8 cm3/g at 298 K) than NUC-66 (91.2 cm3/g at 273 K and 53.0 cm3/g at 298 K). Catalytic experiments confirmed that activated NUC-107a with the aid of n-Bu4NBr was capable of efficiently catalyzing the cycloaddition of CO2 with epoxides into corresponding cyclic carbonates under the mild conditions. Under the similar conditions of 0.10 mol% MOFs, 0.5 mol% n-Bu4NBr, 0.5 MP CO2, 60 °C and 3 h, compared with NUC-66a, the conversion of SO to SC catalyzed by NUC-107a increased by 21%. Hence, this work offers a valuable perspective that the in situ creation of robust defect-engineered MOFs can be realized by regulating the growth environment.

Trimetallic Ni-CuCoN0.6 Ohmic junction for the enhanced oxidation of methanol and urea.

Methanol oxidation reaction (MOR) and urea oxidation reaction (UOR) can be utilized as effective alternatives to the anodic oxygen evolution reaction (OER) in overall water-splitting. Nevertheless, the development of cost-effective, highly efficient and durable electrocatalysts for MOR and UOR remains a significant challenge. Herein, the Ohmic junction (Ni-CuCoN0.6@CC) comprising CuCoN0.6 nanosheets and Ni nanoparticles anchored on carbon cloth (CC) was successfully synthesized via a two-step hydrothermal process followed by pyrolysis. The Ni-CuCoN0.6@CC demonstrates exceptional performance in both MOR (1.334 V@10 mA cm-2) and UOR (1.335 V@10 mA cm-2), coupled with outstanding durability, maintaining 88.70 % current density for MOR and 88.92 % for UOR after a rigorous 50-h stability test. Furthermore, the Ni-CuCoN0.6@CC demonstrates a high selectivity for oxidizing methanol to formic acid, achieving Faraday efficiencies exceeding 90 % at various current densities in the context of MOR. The outstanding performance of Ni-CuCoN0.6@CC in terms of MOR and UOR either surpasses or closely approaches the levels reported in previous literature, primarily due to the synergistic effect resulting from the Ohmic junction: in this system, Ni serves as the principal active component, Co augments catalytic activity and diminishes onset potential, while Cu enhances long-term durability. Moreover, CuCoN0.6 nanosheets effectively modulate electronic structure and optimize the morphology of Ni, leading to the exposure of numerous defects that provide a wealth of active sites for the reaction. Additionally, the exceptional hydrophilic and aerophobic surface promotes enhanced mass transfer. Density functional theory (DFT) calculations show that Ni-CuCoN0.6@CC enhances reactant adsorption and product desorption, reducing energy barriers and expediting MOR and UOR kinetics.

Robust {Pb10}-Cluster-Based Metal-Organic Framework for Capturing and Converting CO2 into Cyclic Carbonates under Mild Conditions.

Developing a highly active catalyst that can efficiently capture and convert carbon dioxide (CO2) into high-value-added energy materials remains a severe challenge, which inspires us to explore effective metal-organic frameworks (MOFs) with high chemical stability and high-density active sites. Herein, we report a robust 3D lead(II)-organic framework of {(Me2NH2)2[Pb5(PTTPA)2(H2O)3]·2DMF·3H2O}n (NUC-111) with unreported [Pb10(COO)22(H2O)6] clusters (abbreviated as {Pb10}) as nodes (H6PTTPA = 4,4',4″-(pyridine-2,4,6-triyl)triisophthalic acid). After thermal activation, NUC-111a is functionalized by the multifarious symbiotic acid-base active sites of open Pb2+ sites and uncoordinated pyridine groups on the inner surface of the void volume. Gas adsorption tests confirm that NUC-111a displays a higher separation performance for mixed gases of f CO2 and CH4 with the selectivity of CO2/CH4 at 273 K and 101 kPa being 31 (1:99, v/v), 23 (15:85, v/v), and 8 (50:50, v/v), respectively. When the temperature rises to 298 K, the selectivity of CO2/CH4 at 101 kPa is 26 (1:99, v/v), 22 (15:85, v/v), and 11 (50:50, v/v). Moreover, activated NUC-111a exhibited excellent catalytic performance, stability, and recyclability for the cycloaddition of CO2 with epoxides under mild conditions. Hence, this work provides valuable insight into designing MOFs with multifunctionality for CO2 capture, separation, and conversion.

Confining Polymer Electrolyte in MOF for Safe and High-Performance All-Solid-State Sodium Metal Batteries.

Nanoconfined polymer molecules exhibit profound transformations in their properties and behaviors. Here, we present the synthesis of a polymer-in-MOF single ion conducting solid polymer electrolyte, where polymer segments are partially confined within nanopores ZIF-8 particles through Lewis acid-base interactions for solid-state sodium-metal batteries (SSMBs). The unique nanoconfinement effectively weakens Na ion coordination with the anions, facilitating the Na ion dissociation from salt. Simultaneously, the well-defined nanopores within ZIF-8 particles provide oriented and ordered migration channels for Na migration. As a result, this pioneering design allows the solid polymer electrolyte to achieve a Na ion transference number of 0.87, Na ion conductivity of 4.01×10-4 S cm-1, and an extended electrochemical voltage window up to 4.89 V vs. Na/Na+. The assembled SSMBs (with Na3V2(PO4)3 as the cathode) exhibit dendrite-free Na-metal deposition, promising rate capability, and stable cycling performance with 96 % capacity retention over 300 cycles. This innovative polymer-in-MOF design offers a compelling strategy for advancing high-performance and safe solid-state metal battery technologies.

Enhancing CO2/N2 and CH4/N2 separation performance by salt-modified aluminum-based metal-organic frameworks.

The energy-saving separation of CO2/N2 and CH4/N2 in the energy industry facilitates the reduction of greenhouse gas emissions and replenishes energy resources, but is a challenging separation process. The trade-off between adsorption capacity and selectivity of the adsorbents is one of the key bottlenecks in adsorption separation technologies' large-scale application in the above separation task. Herein, we introduced a series of fluoroborate or fluorosilicate salts (Cu(BF4)2, Zn(BF4)2 and ZnSiF6) into the open coordination nitrogen sites of aluminum-based metal-organic frameworks (MOF-253) to create multiple binding sites to simultaneously enhance the adsorption capacity and selectivity for the target gas. By the synergistic adsorption effect of metal ions (Cu2+ or Zn2+) and fluorinated anions (BF4- or (SiF6)2-), the single-component adsorption capacity and selectivity of salt-modified MOF-253 (MOF-253@Cu(BF4)2, MOF-253@Zn(BF4)2 and MOF-253@ZnSiF6) for CO2 and CH4 were effectively improved when compared to pristine MOF-253 at 298 K and 1 bar. In addition, the salt-modified MOF-253 has a moderate adsorption heat (<30 kJ mol-1) which could be rapidly regenerated at low energy by evacuation desorption. As confirmed by the ambient breakthrough experiments of MOF-253 and MOF-253@ZnSiF6, the real separation performance for both CO2/N2 (1/4) and CH4/N2 (1/4) was obviously improved. This work provides a feasible post-modification strategy on uncoordinated sites of the framework to improve adsorption separation performance and promote the development of ideal adsorbents with a view to realizing their application in the energy industry.

Nanoporous {Co3}-Organic framework for efficiently seperating gases and catalyzing cycloaddition of epoxides with CO2 and Knoevenagel condensation.

Enhancing the catalysis of metal-organic frameworks (MOFs) by regulating inherent Lewis acid-base sites to realize the efficient seperation and chemical fixation of inert carbon dioxide (CO2) is crucial but challenging. Herein, the solvothermal self-assembly of Co2+, 5'-(4-carboxy-2-nitrophenyl)-2,2',2'',4',6'-pentanitro-[1,1':3',1''-terphenyl]-4,4''-dicarboxylic acid (H3TNBTB) and 4'-phenyl-4,2':6',4''-terpyridine (PTP) generated a highly robust cobalt-organic framework of {[Co3(TNBTB)2(PTP)]·7DMF·6H2O}n (NUC-82). In NUC-82, the tri-core clusters of {Co3} with linear shape are bridged by TNBTB3- to form two-dimensional structure in ac plane, which is further linked by PTP to generate a three-dimensional framework with two kinds of solvent-accessible channels: rhombic-like (ca. 11.57 × 10.76 Å) along a axis and rectangular-like (ca. 7.32 × 11.56 Å) along b axis. Furthermore, it is worth emphasizing that the confined pore environments are characterized by plentiful Lewis acid-base sites of tricobalt clusters, grafted nitro groups and free pyridinyl, high specific surface area and solvent-free nano-caged windows. Activated NUC-82a owns the ultra-high ethylene (C2H2) separation performance over the mixture of C2H2/CH4 and CO2/CH4 with the selectivity of 223.1 and 44.7. Thanks to the great Lewis-acid sites as well as the large pore volume, activated NUC-82a displays the high catalytic performace on the cycloaddition of CO2 with epoxides under wield condtions such as amibient pressure. Furthermore, because of the rich Lewis base sites, NUC-82a can efficiently catalyze Knoevenagel condensation of aldehydes and malononitrile. In the above organic reactions, NUC-82a not only shows the high catalytic activity, but also exhibits the high selectivity, satifactory recyclability and easy-to-separate heterogeneity, confirming that NUC-82a is a promising catalyst. Hence, this work provides in-depth insight into the construction of multifunctional MOFs by modifying the traditional ligands with as many Lewis acid-base active sites as possible.

Highly stable lanthanide(III) metal-organic frameworks as ratiometric fluorescence sensors for vitamin B6.

Three lanthanide(III)-based metal-organic frameworks, formulated as [(CH3)2NH2]2[Ln6(µ3-OH)8(EBTC)3(H2O)6]·4H2O·2DMF (Ln = Eu (1), Tb (2) and Ce (3)), were synthesized using a rigid tetracarboxylate organic ligand (1,1'-ethynebenzene-3,3',5,5'-tetracarboxylic acid, H4EBTC). Complexes 1-3 possess 12-connected hexanuclear [Ln6(µ3-OH)8(OOC-)12(H2O)6] clusters with the ftw topology, which were stable in water and acid/alkaline aqueous solution. Due to the antenna effect, complexes 1 and 2 presented double fluorescence emission peaks, which are the characteristic emission peaks of Ln3+ ions and the ligand H4EBTC, respectively. The doped bimetallic EuxTb1--x-MOFs were obtained by tuning the Eu(III)/Tb(III) ratio during the reaction, which exhibited a colour change from red, orange, and yellow to green. Furthermore, complexes 1, 2 and Eu2Tb8-MOF as ratiometric fluorescence sensors exhibited excellent sensing ability for vitamin B6 (VB6) in phosphate buffer solution (pH = 7.35) and real samples with high selectivity and reusability. The low detection limit (LOD) values were calculated to be 1.03 µM for complex 1, 0.25 µM for complex 2 and 0.11 µM for Eu2Tb8-MOF in aqueous solution. Finally, a visual film based on Ln-MOF@SA was prepared to detect VB6 with high reusability.

Heterometallic ZnHoMOF as a Dual-Responsive Luminescence Sensor for Efficient Detection of Hippuric Acid Biomarker and Nitrofuran Antibiotics.

Developing efficient and sensitive MOF-based luminescence sensors for bioactive molecule detection is of great significance and remains a challenge. Benefiting from favorable chemical and thermal stability, as well as excellent luminescence performance, a porous Zn(II)Ho(III) heterometallic-organic framework (ZnHoMOF) was selected here as a bifunctional luminescence sensor for the early diagnosis of a toluene exposure biomarker of hippuric acid (HA) through "turn-on" luminescence enhancing response and the daily monitoring of NFT/NFZ antibiotics through "turn-off" quenching effects in aqueous media with high sensitivity, acceptable selectivity, good anti-interference, exceptional recyclability performance, and low detection limits (LODs) of 0.7 ppm for HA, 0.04 ppm for NFT, and 0.05 ppm for NFZ. Moreover, the developed sensor was employed to quantify HA in diluted urine samples and NFT/NFZ in natural river water with satisfactory results. In addition, the sensing mechanisms of ZnHoMOF as a dual-response chemosensor in efficient detection of HA and NFT/NFZ antibiotics were conducted from the view of photo-induced electron transfer (PET), as well as inner filter effects (IFEs), with the help of time-dependent density functional theory (TD-DFT) and spectral overlap experiments.

A disposable and sensitive sensor based on a ZIF-8@graphene modified carbon paper electrode for the quantitative determination of luteolin.

Rapid and accurate determination of luteolin is of great significance for pharmaceutical quality control. Herein, a disposable and sensitive luteolin sensor was fabricated by a hydrothermal method with carbon paper as substrate where ZIF-8 grew on GR in situ. Notably, the large specific surface area of ZIF-8 provided active sites on the electrode surface and the ability of GR to promote electron transfer greatly improved the sensitivity towards the oxidation of luteolin. Under the optimum conditions, the ZIF-8@GR/CP showed excellent detection performance for luteolin with a linear detection range of 0.04-3.2 µM and 3.2-120 µM, with LOD of 12 nM (S/N = 3). Furthermore, this disposable and sensitive sensor was successfully applied for the quantitative detection of luteolin in a capsule of Lamiophlomis rotata.

Heterostructured Mo and Co-based phosphides as high-performance bifunctional electrocatalysts for overall water splitting.

Transitional metal phosphides are efficient and durable electrocatalysts for water splitting. In this work, Mo-CoP/Co2P/NF heterostructures are reported to exhibit bifunctional electrocatalyst properties in various electrolytes. The Co phosphides were found to be possessing a hydrogenase-like structure in these heterostructures with P as the proton-acceptor site and Co as the hydride-acceptor site, making them highly active during the HER process. Moreover, the electronic structure of Co ions could be modified, or the transfer of electrons could be accelerated due to the different valence states of Mo. Additionally, the Mo centers possessed superior adsorption properties toward hydrogen. Consequently, excellent performance for the electrocatalytic HER was exhibited by the Mo-CoP/Co2P/NF-300 heterostructure with small overpotentials of 86.6 mV and 48 mV at a current density of 10 mA cm-2 in 1.0 M KOH and 0.5 M H2SO4 solutions, respectively. Furthermore, it also exhibited efficient OER activity in an alkaline solution with a low overpotential of 245 mV at 30 mA cm-2. Post-analysis revealed the changes in the surface and the formation of Co oxyhydroxide during the OER process, and the formation of Co-P-O during the HER process. The high HER and OER performances are attributed to these transformations of morphologies and compositions. Consequently, a two-electrode electrolyzer based on Mo-CoP/Co2P/NF-300 required voltages of 1.59 V and 1.703 V at 20 mA cm-2 and 100 mA cm-2, respectively, and maintained long-term stability.

Efficient separation of CO2 from CH4 and N2 in an ultra-stable microporous metal-organic framework.

The efficient separation of CO2 from CH4 and N2 is essential for the upgrading of biogas and reducing carbon emissions in flue gas, but is challenging in the energy industry. Developing ultra-stable adsorbents with high CO2 adsorption performance in adsorption separation technology is deemed an effective solution for the separation of CO2/CH4 and CO2/N2. Herein, we report an ultra-stable yttrium-based microporous metal-organic framework (Y-bptc) used for the efficient separation of CO2/CH4 and CO2/N2. The single-component equilibrium adsorption capacity of CO2 reached 55.1 cm3 g-1 at 1 bar and 298 K, while the adsorption capacity of CH4 and N2 was almost negligible and thus resulted in a high adsorption ratio for CO2/CH4 (45.5) and CO2/N2 (18.1). GCMC simulations revealed that the µ3-OH- functional groups distributed in the pore cage of Y-bptc provide stronger adsorption sites for CO2via hydrogen-bonding interactions. The relatively lower heat of adsorption of CO2 (24 kJ mol-1) further reduces the desorption regeneration energy consumption. Dynamic breakthrough experiments using Y-bptc for the separation of CO2/CH4 (1/1) and CO2/N2 (1/4) mixtures could obtain high purity (>99%) CH4 and N2, and the CO2 dynamic adsorption capacities reached 52 and 31 cm3 g-1, respectively. More importantly, the structure of Y-bptc remained intact under hydrothermal conditions. The high adsorption ratio, low heat of adsorption, great dynamic separation performance, and ultra-stable structure of Y-bptc make it one of the candidate adsorbents suitable for the separation of CO2/CH4 and CO2/N2 in real-world applications.

In situ construction of WNiM-WNi LDH (M = Se, S, or P) with heterostructure as highly efficient electrocatalyst for overall water splitting and urea oxidation reaction.

Electrochemical water splitting as an important means of obtaining high purity hydrogen fuel has attracted great interest. In this study, the structural engineering of complex WNiM-WNi LDH (M = Se, S, or P) was firstly developed by in situ growth on Ni foam for use in overall water splitting and the urea oxidation reaction. These WNiM-WNi LDH (M = Se, S, or P) catalysts exhibit outstanding electrocatalytic performance in the hydrogen evolution reaction (HER), oxygen evolution reaction (OER) and urea oxidation reaction (UOR), respectively. An overpotential of only 64 mV of OER is required for WNiS-WNi LDH and 126 mV of HER is required for WNiP-WNi LDH to achieve 10 mA cm-2. The WNiSe-WNi LDH materials display a particularly outstanding performance for UOR, requiring a potential of 1.25 V to drive 10 mA cm-2. Moreover, the optimized WNiS-WNi LDH as an anode and WNiP-WNi LDH as a cathode can achieve 10 mA cm-2 at a low cell voltage of 1.45 V in 1 M KOH solution for overall water splitting. The density functional theory calculations show that the introduction of the NiP2 and WP material greatly reduces the Gibbs free energy of the hydrogen adsorption of the material.

A highly robust cluster-based indium(III)-organic framework with efficient catalytic activity in cycloaddition of CO2 and Knoevenagel condensation.

The efficient catalytic performance displayed by MOFs is decided by an appropriate charge/radius ratio of defect metal sites, large enough solvent-accessible channels and Lewis base sites capable of polarizing substrate molecules. Herein, the solvothermal self-assembly led to a highly robust nanochannel-based framework of {[In4(CPDD)2(µ3-OH)2(DMF)(H2O)2]·2DMF·5H2O}n (NUC-66) with a 56.8% void volume, which is a combination of a tetranuclear cluster [In4(µ3-OH)2(COO)10(DMF)(H2O)2] (abbreviated as {In4}) and a conjugated tetracyclic pentacarboxylic acid ligand of 4,4'-(4-(4-carboxyphenyl)pyridine-2,6-diyl)diisophthalic acid (H5CPDD). To the best of our knowledge, NUC-66 is a rarely reported {In4}-based 3D framework with embedded hierarchical triangular-microporous (2.9 Å) and hexagonal-nanoporous (12.0 Å) channels, which are shaped by six rows of {In4} clusters. After solvent exchange and vacuum drying, the surface of nanochannels in desolvated NUC-66a is modified by unsaturated In3+ ions, Npyridine atoms and µ3-OH groups, all of which display polarization ability towards polar molecules due to their Lewis acidity or basicity. The catalytic experiments performed showed that NUC-66a had high catalytic activity in the cycloaddition reactions of epoxides with CO2 under mild conditions, which should be ascribed to its structural advantages including nanoscale channels, rich bifunctional active sites, large surface areas and chemical stability. Moreover, NUC-66a, as a heterogeneous catalyst, could greatly accelerate the Knoevenagel condensation reactions of aldehydes and malononitrile. Hence, this work confirms that the development of rigid nanoporous cluster-based MOFs built on metal ions with a high charge and large radius ratio will be more likely to realize practical applications, such as catalysis, adsorption and separation of gas, etc.

RhB-encapsulated metal-organic cage as a dual-emission fluorescence sensor for detection of malachite green and glycine.

RhB@ZrT-1-OH composite was constructed by introduction of Rhodamine B (RhB) into the cages of zirconium-based metal-organic cage that had two fluorescence emission peaks at 466 and 612 nm upon excitation at 327 nm. The dual-emission fluorescence sensor exhibits ultra-high sensitive detection for malachite green (MG) and glycine (Gly) in phosphate buffer solution (pH = 6.86). RhB@ZrT-1-OH as a ratiometric fluorescence probe was applied to detect MG with a low LOD of 0.2879 µM and presented obvious fluorescence visual changes from orange to purple to blue under 254 nm UV-vis lamp. Moreover, RhB@ZrT-1-OH also can be utilized as a "turn-on" fluorescence sensor to recognize Gly with a low LOD of 0.3747 µM and exhibits fluorescence color changes from orange to pink to purple. Notably, the corresponding test papers for sensing MG and Gly were designed for recognize the concentration of MG and Gly. Furthermore, the dual-emission fluorescence sensor can be used to detect MG and Gly in fish and human serum with high sensitivity and reliable. The possible detecting mechanisms of RhB@ZrT-1-OH for sensing MG and Gly were detailedly explored.

Cd (II) coordination polymer as a strip based fluorescence sensor for sensing Fe3+ ions in aqueous system.

The design and construction of a sensor that can sensitively and conveniently recognize metal ions are essential for the treatment of industrial wastewater. In this work, {[Cd4(HL)2(pyp)2(H2O)2]·2H2O·1.5Diox}n (1) was synthesized under solvothermal condition and presented a 2D 3,5-connected layered network with the point symbol of {3.4.5} {32.4.5.62.74}, which was coated on the surface of polyvinylidene fluoride (PVDF) to construct a novel paper sensor (1@PVDF). Meanwhile, the stability of 1@PVDF was characterized by powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). In addition, fluorescence sensing experiments of 1@PVDF sensor for cations in aqueous system indicated that it has high sensitivity for sensing Fe3+ ions with the detection limit (DL) of 4.0 × 10-8 M. By the characterization of PXRD, UV-vis spectra, ICP, XPS, time-resolved excited-state decay measurements, the sensing mechanisms of 1@PVDF for Fe3+ ions were attributed to the competitive absorption and interaction between 1 and Fe3+. And the sensing process of 1@PVDF for Fe3+ ions was static in the Fe3+ concentration of 0 to 0.05 mM. In addition, the binding energies of Fe3+ and Zn2+ with the framework of 1 were calculated by density functional theory (DFT), which further proved that there was an obvious interaction between Fe3+ and the uncoordinated O atom in 1. Based on the thin film technology, a portable and convenient paper-based probe has been developed for practical applications.

Nanochannel {InZn}-Organic Framework with a High Catalytic Performance on CO2 Chemical Fixation and Deacetalization-Knoevenagel Condensation.

The rare combination of InIII 5p and ZnII 3d in the presence of a structure-oriented TDP6- ligand led to a robust hybrid material of {(Me2NH2)[InZn(TDP)(OH2)]·4DMF·4H2O}n (NUC-42) with the interlaced hierarchical nanochannels (hexagonal and cylindrical) shaped by six rows of undocumented [InZn(CO2)6(OH2)] clusters, which represented the first 5p-3d nanochannel-based heterometallic metal-organic framework. With respect to the multifarious symbiotic Lewis acid-base and Brønsted acid sites in the high porous framework, the catalytic performance of activated NUC-42a upon CO2 cycloaddition with styrene oxide was evaluated under solvent-free conditions with 1 atm of CO2 pressure, which exhibited that the reaction could be well completed at ambient temperature within 48 h or at 60 °C within 4 h with high yield and selectivity. Moreover, because of the acidic function of metal sites and a central free pyridine in the TDP6- ligand, deacetalization-Knoevenagel condensation of acetals and malononitrile could be efficiently facilitated by an activated sample of NUC-42a under lukewarm conditions.

Template-Induced {Mn2}-Organic Framework with Lewis Acid-Base Canals as a Highly Efficient Heterogeneous Catalyst for Chemical Fixation of CO2 and Knoevenagel Condensation.

The target for the self-assembly of functional microporous metal-organic frameworks (MOFs) could be realized by employing ligand-directed and/or template-induced strategies, which prompted us to explore the synthetic technique of d10 secondary-building-unit-based nanoporous frameworks. Here, the exquisite combination of a paddle-wheel [Mn2(CO2)6(OH2)2] cluster and a TDP6- ligand contributes one robust honeycomb framework of {(Me2NH2)2[Mn2(TDP)(H2O)2]·3H2O·3DMF}n (NUC-31; DMF = N,N-dimethylformamide), whose activated state with the removal of associated aqueous molecules characterizes the outstanding physicochemical properties of nanochannels, penta- and tetracoordinated Mn2+ serving as highly open metal sites, rich Lewis base sites (rows of C═O groups and Npyridine atoms), and excellent thermal stability. Moreover, it is worth mentioning that Lewis acid-base sites on the inner surface of the channels in activated NUC-31 successfully form one unprecedented canal-shaped acid-base confined space with evenly distributed open metal sites of Mn2+ and Npyridine atoms as the canal bottom as well as two rows of C═O groups serving as dyke dams. Catalytic experiments displayed that activated NUC-31 could serve as an efficient heterogeneous catalyst for the chemical fixation of CO2 with epoxides into cyclic carbonates under mild conditions. Furthermore, NUC-31 could effectively catalyze the reaction Knoevenagel condensation, which should be ascribed to the synergistic polarization effect aroused from its plentiful Lewis base sites in the confined channel space. Hence, these results demonstrate that the employment of ligand-directed and template-dependent strategies could overcome the self-assembled barriers of functional microporous MOFs and achieve unexpected frameworks.

V═O Functionalized {Tm2}-Organic Framework Designed by Postsynthesis Modification for Catalytic Chemical Fixation of CO2 and Oxidation of Mustard Gas.

In terms of recently documented references, the introduction of V═O units into porous MOF/COF frameworks can greatly improve their original performance and expand their application prospects due to a change in their electronegativity. In this work, by a cation-exchange strategy, a consummate combination of separate 4f [Tm2(CO2)8] SBUs and 3d [VIVO(H2O)2] units generated the functionalized porous metal-organic framework {(Me2NH2)2[VO(H2O)][Tm2(BDCP)2]·3DMF·3H2O}n (NUC-11), in which [Tm2(CO2)8] SBUs constitute the fundamental 3D host framework of {[Tm2](BDCP)2}n along with [VIVO(H2O)2] units being further docked on the inner wall of channels by covalent bonds. Significantly, NUC-11 represents the first example of V═O modified porous MOFs, in which uncoordinated carboxylic groups (-CO2H) further grasp the functional [VIVO(H2O)2] units on the initial basic skeleton along with the formation of covalent bonds as fixed ropes. Furthermore, activated samples of NUC-11 displayed a good catalytic performance for the chemical synthesis of carbonates from related epoxides and CO2 with high conversion rate. Moreover, by employing NUC-11 as a catalyst, a simulator of mustard gas, 2-chloroethyl ethyl sulfide, could be quickly and efficiently oxidized into low-toxicity products of oxidized sulfoxide (CEESO). Thus, this study offers a brand new view for the design and synthesis of functional-units-modified porous MOFs, which could be potentially applied as an excellent candidate in the growing field of efficient catalysis.

6s-3d {Ba3Zn4}-Organic Framework as an Effective Heterogeneous Catalyst for Chemical Fixation of CO2 and Knoevenagel Condensation Reaction.

The exquisite combination of Ba2+ and Zn2+ with the aid of 2,4,6-tri(2,4-dicarboxyphenyl)pyridine (H6TDP) under the condition of solvothermal self-assembly generates one highly robust [Ba3Zn4(CO2)12(HCO2)2(OH2)2]-organic framework of {[Ba3Zn4(TDP)2(HCO2)2(OH2)2]·7DMF·4H2O}n (NUC-27), in which adjacent 2D layers are interlaced via hydrogen-bonding interactions to form a 3D skeleton with peapod-like channels and nano-caged voids. It is worth emphasizing that both Ba2+ and Zn2+ ions in NUC-27 display the extremely low coordination modes: hexa-coordinated [Ba(1)] and tetra-coordinated [Ba(2), Zn(1), and Zn(2)]. Furthermore, to the best our knowledge, NUC-27 is one scarcely reported 2D-based nanomaterial with an unprecedented Z-shaped hepta-nuclear heterometallic cluster of [Ba3Zn4(CO2)12(HCO2)2(OH2)2] as SBUs, which not only has plentiful low-coordinated open metal sites but also has the excellent physicochemical properties including omni-directional opening pores, ultrahigh porosity, larger specific surface area, and the coexistence of Lewis acid-base sites. Just as expected, thanks to its rich active metal sites and pyridine groups as strong Lewis acid-base roles, completely activated NUC-27 displays high catalytic efficiency on the chemical transformation of epoxides with CO2 into cyclic carbonates under mild conditions and effectively accelerates the reaction process of Knoevenagel condensation.

Reversible filtration redox of methylene blue in dimethylsulfoxide by manganese oxide loaded carbonaceous nanofibrous membrane through Fenton-like oxidation.

The reversible redox of methylene blue in organic solvents was highly attractive, yet was rarely reported. In this study, we realized the continuous filtration redox of methylene blue (MB) in dimethylsulfoxide (DMSO) through Fenton-like oxidization by using MnO2 loaded carbonaceous nanofibrous membrane (cPAN-MnO2). The carbonaceous nanofibrous membrane (cPAN) was fabricated through electrospun of polyacrylonitrile and subsequent carbonization. The obtained cPAN nanofibrous membrane showed excellent stability in polar DMSO. MnO2 can be readily coated on cPAN nanofibers through an in situ redox reaction between cPAN and potassium permanganate. The fabricated cPAN-MnO2 membrane exhibited instantaneous reduction property towards MB in DMSO during a gravity-driven continuous filtration process. Interestingly, MB reduction was initiated by a typical Fenton-like oxidization, where hydroxyl radicals were firstly generated from hydrogen peroxide catalyzed by MnO2 in DMSO. Then hydroxyl radicals attacked DMSO to further produce methyl radicals, which resulted in the reduction of MB. In addition, MB reduction process in DMSO was reversible. Our study provides a novel strategy for continuous redox of MB in polar organic solvent and might give new ideas for MB applications.