Search

The synthesis of cyclic carbonates through cycloaddition reactions between epoxides and carbon dioxide (CO2) is an important industrial process. Metal-Organic Frameworks (MOFs) have functional and ordered pore structures, making them attractive catalysts for converting gas molecules into valuable products. One approach to enhance the catalytic activity of MOFs in CO2 cycloaddition reactions is to create open metal sites within MOFs. In this study, the amino-functionalized rare earth Gd-MOF (Gd-TPTC-NH2) and its ionic liquid composite catalysts (Gd-TPTC-NH-[BMIM]Br) were synthesized using 2'-amino-[1,1':4',1"-terphenyl]-3,3",5,5"-tetracarboxylic acid (H4TPTC-NH2) as the ligand. The catalytic performance of these two catalysts was observed in the cycloaddition reaction of CO2 and epoxides. Under the optimized reaction conditions, Gd-TPTC-NH-[BMIM]Br can effectively catalyze the cycloaddition reaction of a variety of epoxide substrates with good to excellent yields of cyclic carbonate products. Comparatively, epichlorohydrin and epibromohydrin, which possess halogen substituents, promote higher yields of cyclic carbonates due to the electron-withdrawing nature of Cl and Br substituents. Additionally, the Gd-TPTC-NH- [BMIM]Br catalyst demonstrated good recyclability and reproducibility, maintaining its catalytic activity without any changes in its structure or properties after five reuse cycles. [ABSTRACT FROM AUTHOR]

Selective CO2 adsorption and catalysis conversion of CO2 to high value-added chemicals not only gives an effective way to reduce the concentration of CO2 but also provides the precursors for industrial manufacturing of chemicals and fuels. With well-defined frameworks, flexible modifiability, and permanent porosity, metal–organic frameworks (MOFs) can be the ideal platforms for CO2 utilization applications. In this work, a copper functionalized-zirconium MOF, denoted Zr-CPB-Cu (CPB = 1,2,3,4,5,6-hexakis(4-carboxyphenyl)-benzene), was successfully produced via post-metalation of copper(II) ions into a presynthesized Zr-CPB MOF. The bimetallic Zr-CPB-Cu containing two open metal sites (Zr4+ and Cu2+), polarized groups (e.g., uncoordinated –COOH, monodentate carboxylates, and acetate anions), accessible triangular channels, and permanent porosity (SBET = 420 m2 g−1) revealed outstanding selective CO2 adsorption and catalytic activity for the oxidative carboxylation of CO2 and olefins. As a proof of concept, the Zr-CPB-Cu showed higher low-pressure capacities of CO2, CH4, and N2 at room temperature and larger CO2 selectivities over N2 and CH4 than those of the parent Zr-CPB. As for catalysis of CO2 conversion, the Zr-CPB-Cu catalyst exhibited exceptional performance in direct synthesis of styrene carbonate from styrene and CO2 with 97% conversion of styrene, and 92% yield of styrene carbonate in the presence of anhydrous TBHP oxidant and under mild conditions (1 atm of CO2, 80 °C, and 12 h). Notably, the catalytic activity of Zr-CPB-Cu outperformed that of the parent Zr-CPB and other MOFs, and the recovered Zr-CPB-Cu can be reused up to six times without considerable reduction in catalytic activity. Our result envisaged an effective approach for the elaboration of MOFs as efficient heterogeneous catalysts for CO2 separation and catalytic conversion of CO2. [ABSTRACT FROM AUTHOR]

Flexible metal–organic frameworks (MOFs) have been attracting increasing attention in stimuli-responsive applications. However, the effects of the MOF's structural transition on catalysis have been largely unexplored. Herein, the dynamic behaviors and catalytic ability of a flexible bimetallic MOF (i.e., MIL-88B(Fe/Co)) were systematically investigated through density functional theory calculations, which suggested rotary metal nodes and twisted ligands upon lattice contraction, subsequently leading to variable performances in the oxygen evolution reaction as confirmed by the differences in the free energy diagrams. To correlate the catalytic performance with the structural dynamics of the MOFs, partial pair distribution function analysis was carried out, which demonstrated that the short-range order of MIL-88B(Fe/Co) is unaffected by the lattice expansion/contraction, suggesting the intact bond connectivity during the structural transition. The bonding nature of the bimetallic MOF was further investigated through electron localization function analysis, which revealed that structural modulation poses negligible impacts on the bonding interactions in the metal nodes while the contracted structures can cause a closely packed framework. The dependence of the catalytic performance on the dynamic structures demonstrated in this work suggests that the structural transition of the flexible MOFs can be exploited to alter the energy barriers of the elementary steps during the catalysis processes, offering potential avenues to achieving better control over the catalytic pathways for enhanced efficiency. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) show excellent catalytic activity and have been widely applied in diagnosis of diseases and tumors. However, current assay methods usually involve cumbersome configurations and complicated procedures, which inhibit their practical applications. Hence, a Cu–Ni MOF/carbon printed electrode (CPE)-based integrated electrochemical immunosensor was constructed for highly sensitive and efficient determination of carcinoembryonic antigen (CEA). First, highly conductive carbon ink was screen-printed onto a polyethylene terephthalate substrate to manufacture a CPE. Afterward, an aminated Cu-Ni MOF was prepared by a typical solvothermal strategy and modified on the CPE. Owing to its excellent peroxidase activity, the Cu–Ni MOF can catalytically oxidize hydroquinone using hydrogen peroxide, which greatly amplifies the peak current signal. Then the formation of an immune complex inhibited the catalytic activity of the MOF, thus enabling the quantitative determination of CEA content with a wide linear range of 0.5 pg mL−1–500 ng mL−1 and a low detection limit of 0.16 pg mL−1. Furthermore, the Cu–Ni MOF/CPE-based integrated portable electrochemical immunosensor also showed satisfactory performance in the detection of CEA in clinical serum samples with excellent accuracy, showing great potential for application in point-of-care disease diagnosis. [ABSTRACT FROM AUTHOR]

The acylamide functionalized tetra-carboxylic acid (H4CDA) has been successfully employed for the formation of two robust 3D-MOFs, Cd-CDA-MOF and Cu-CDA-MOF, having open metal sites with two distinct and diverse network topologies namely diamondoid and PCU. The Cd-CDA-MOF is shown to act as an efficient heterogeneous catalyst for the Knoevenagel condensation reaction under mild and ambient conditions. The Cu-CDA-MOF demonstrates excellent catalytic activity for the Chan–Lam coupling reaction with a considerably high turnover number. The heterogeneous catalytic activity of the MOFs can be attributed to the coordinatively unsaturated open metal sites of the activated frameworks. The MOFs are found to be recyclable with almost uniform catalytic activity. [ABSTRACT FROM AUTHOR]

A non-porous version of SU-101 (herein n-SU-101) was evaluated for the CO2 cycloaddition reaction. The findings revealed that open metal sites (Bi3+) are necessary for the reaction. n-SU-101 displays a high styrene oxide conversion of 96.6% under mild conditions (3 bar and 80 °C). The catalytic activity of n-SU-101 demonstrated its potential application for the cycloaddition of CO2 using styrene oxide. [ABSTRACT FROM AUTHOR]

Transition-metal-based metal–organic frameworks (MOFs) have received great interest for the development of low cost, platinum-free, non-precious water splitting electrocatalysts for hydrogen generation to resolve the energy crisis. Recent studies are mainly concerned with the use of MOFs as a self-sacrificing template for the synthesis of carbon-based electrocatalysts encapsulating metallic sites. However, the process often produces undesired metal nanoparticles, lowering the catalytic activity of the materials. This report explores a novel strategy to improve the intrinsic electrocatalytic activity of MOFs by a ligand substitution method. Ligands with different electron donating capacity have been used for the substitution process and the hydrogen evolution activity has been found to be greatly affected by the presence of different donor ligands. The MOF used in this work is designed with Ni as a metal center with 5-azido isophthalic acid as the primary linker. Subsequently, the MOF is functionalized with different organic moieties, i.e., N,N-dimethylethylenediamine (DMEDA) and 4-aminotetrafluoropyridine (4-ATFP) with rich non-metal catalytic active sites by means of post synthetic modification. A comparative study has been performed which shows the 4-ATFP functionalized MOF to have the best electrocatalytic activity among the three with significant performance in all three media, i.e. neutral, acidic and alkaline. Furthermore, theoretical approaches have been employed for the analysis of these experimental observations. [ABSTRACT FROM AUTHOR]

Because of their large specific surface area, high porosity, changeable pore size, and ordered pore arrangement, metal–organic frameworks (MOFs) are emerging as electrocatalysts in various fields of energy resources and bio-sensors. In this work, we report a one-pot synthesis of trimetallic MOFs (Co–Ni–Al-MOFs), as well as bimetallic MOFs (Co–Ni-MOFs, Co–Al-MOFs, and Ni–Al-MOFs) using Co, Ni, and Al metal salts and BTC and 4,4′-bipyridine as linkers, their characterization for surface morphology, functional group and elemental analysis using various analytical techniques and explored them as tri-modal catalysts for thiophene electrooxidation, water splitting and chemical reduction of 4-nitrophenol (4-NP). Electrochemical studies using linear sweep voltammetry (LSV) and electrochemical impedance spectroscopy (EIS) on Co–Ni–Al-MOFs showed the lowest onset potential of 1.36 V with a lower Tafel slope of 181 mV dec−1 and charge transfer resistance value (Rct) of 447 Ω for the effective electrooxidation of thiophene. Further catalytic activity studies towards water splitting revealed that Co–Ni–Al-MOFs displayed superior catalytic activity towards the HER and the OER at lower overpotentials of 174 and 220 mV with Tafel slopes of 108 and 97 mV dec−1 respectively, compared to other bimetallic MOFs with excellent long-term stability, as revealed by chronoamperometry (CA). The high catalytic activity of Co–Ni–Al-MOFs may be associated with their larger surface area and higher pore volume than those of the other bi-metallic MOFs, as studied by BET analysis, leading to innumerable redox-active sites towards electrochemical processes. Moreover, the catalytic activity of the as prepared catalysts was assessed towards the reduction of 4-NP to 4-aminophenol (4-AP), where Co–Ni–Al-MOFs exhibited exceptional activity with a minimum reduction time of 8 min bearing a high rate constant value. [ABSTRACT FROM AUTHOR]

A 2D Dy(III) metal–organic layer (MOL 1) was synthesized under solvothermal conditions. Structural analysis suggests that the Dy(III) ions in each one-dimensional (1D) arrangement are evenly arranged in the form of broken lines. The 1D chains are linked to one another via ligands to form a 2D layer that generates a 2D surface with elongated apertures. The photocatalytic activity study suggests that MOL 1 exhibits good catalytic activity in flavonoids by the formation of an O2˙− radical as an intermediate. This is the first reported method of synthesizing flavonoids using chalcones. [ABSTRACT FROM AUTHOR]

A palladium diphosphine pincer complex H3(PNNNP-PdI) has been encapsulated in the benzotriazolate metal-organic framework MFU-4l-OH ([Zn5(OH)4(btdd)3], btdd2− = bis(1,2,3-triazolo)dibenzodioxin), and the resulting materials were investigated as Lewis acid catalysts for cyclization of citronellal to isopulegol. Rapid catalyst immobilization is facilitated by a Brønsted acid–base reaction between the H3(PNNNP-PdI) benzoic acid substituents and Zn–OH groups at the framework nodes. Catalyst loading can be controlled up to a maximum of 0.5 pincer complexes per formula unit [ PdI-x , Zn5(OH)4−nx(btdd)3(H3−nPNNNP-PdI)xx = 0.06–0.5, n ≈ 2.75]. Oxidative ligand exchange was used to replace I− with weakly coordinating BF4− anions at the Pd–I sites, generating the activated PdBF4-x catalysts (x = 0.06, 0.10, 0.18, 0.40). The Lewis acid catalytic activity of the PdBF4-x series decreases with increasing catalyst density as a result of the appearance of mass transport limitations. Initial catalytic rates show that the activity of PdBF4-0.06 approaches the intrinsic activity of a homogeneous PNNNP-PdBF4 catalyst analogue. In addition, PdBF4-0.06 exhibits better catalytic activity than the metallolinker-based MOF Zr-PdBF4 and was not subject to leaching or catalyst degradation processes observed for the homogeneous analogue. [ABSTRACT FROM AUTHOR]

Direct synthesis of 2,1-benzisoxazole and its related N-heterocyclic compounds via a chemoselective reductive heterocyclization route, which involves hydrogenation and subsequent intramolecular cyclodehydration steps, is a viable and attractive approach. However, the efficient transformation of the feedstocks using hydrogen as a hydrogen source at ambient temperature and atmospheric hydrogen pressure remains a great challenge. Herein, we reported a MgO-incorporated porous carbon composite (MgO@C) stabilized subnanometric Pt cluster (Pt/MgO@C) catalyst prepared by annealing a Mg-containing metal–organic framework, Mg-MOF-74, followed by impregnation of a Pt precursor and further reduction treatment strategy. The as-prepared Pt/MgO@C with ultralow Pt loading (0.078 wt%) exhibited superior catalytic performance for synthesizing 2,1-benzisoxazole derivatives by the reductive heterocyclization methodology. Excellent catalytic activity (conversion ≥ 99%), high chemoselectivity (≥92%), good stability (8 cycles), and broad functional group tolerance (10 substrates) were achieved under very mild conditions (1 bar hydrogen pressure at 303 K) over the developed Pt/MgO@C. Control experiments indicated that a proper amount of basic sites, subnanometric Pt clusters, and a close contact between them synergistically contributed to the extraordinary performance of Pt/MgO@C. Density functional theory calculations showed that the high activity and chemoselectivity of Pt/MgO@C stemmed from the active interfacial sites of Pt/MgO@C simultaneously activating the H2 and substrate, where the formed stable hydroxyl groups contributed to the enhancement of activity. The combined experimental and theoretical approach identified the formation of the –NO and –NHOH groups during the hydrogenation process, and the former corresponds to the rate-determining step. [ABSTRACT FROM AUTHOR]

Building metal–organic frameworks (MOFs) covalently modified by onium halides is a promising approach to develop efficient MOF-based heterogeneous catalysts for the cycloaddition of CO2 to epoxides (CCE) into cyclic carbonates. Herein, we report a novel zirconium-based MOF covalently modified by methyl pyridinium bromide, Zr6O4(OH)4(MPTDC)2.2(N-CH3-MPTDC)3.8Br3.8 ((Br−)CH3-Pyridinium-MOF-1), where MPTDC denotes 3-methyl-4-pyridin-4-yl-thieno[2,3-b] thiophene-2,5-dicarboxylate. The structure and composition of this complex were fully characterized with PXRD, NMR, XPS, TEM and so on. CO2 adsorption experiments show that (Br−)CH3-Pyridinium-MOF-1 has a higher affinity for CO2 than its electrically neutral precursor, which should be attributed to the fact that charging frameworks containing pyridinium salt have stronger polarization to CO2. (Br−)CH3-Pyridinium-MOF-1 integrated reactive Lewis acid sites and Br− nucleophilic anions and exhibited efficient catalytic activity for CCE under ambient pressure in the absence of co-catalysts and solvents. Furthermore, (Br−)CH3-Pyridinium-MOF-1 was recycled after five successive cycles without substantial loss in catalytic activity. The corresponding reaction mechanism also was speculated. [ABSTRACT FROM AUTHOR]

The template-directed strategy is a facile and universal method to synthesize novel and useful functional materials that are difficult to achieve by traditional methods. Herein, a ternary hybrid Cu2O/Cu/Au with a hollow structure is synthesized via a two-step template-directed strategy. Hollow Cu-MOF-74 is selected as a self-sacrificial template and calcined under an Ar atmosphere to obtain hollow Cu2O/Cu with the preservation of the original hollow structure and rod-like shape. Then, hollow Cu2O/Cu acts as a self-sacrificial template as well as a reducing agent. The metal precursors are adsorbed on the surface of Cu2O/Cu and in situ reduced to Au nanoparticles, decorating the surface uniformly and forming the hollow ternary hybrid Cu2O/Cu/Au. More importantly, hollow Cu2O/Cu/Au is equipped with enhanced electrochemical catalytic activity toward the reduction of H2O2, which is ascribed to the introduction of Au nanoparticles facilitating electron transfer in the catalytic reaction, and it can be used as a candidate for an H2O2 sensor with high sensitivity, wide detection range and low limit of detection. Selecting suitable templates provides a new opportunity for constructing hybrids with novel structures. [ABSTRACT FROM AUTHOR]

The extensive use of sulfasalazine (SSZ) antibiotics has brought potential threats to aquatic ecosystems and human health. Thus, necessary measures for the removal of SSZ must be taken to prevent arbitrary antibiotic exposure to the aquatic environment. However, not all the recent photocatalysts that have been used for the degradation of SSZ could not achieve the controlled release of SSZ and hence are losing their medicinal values. Herein, by utilizing an Eosin Y moiety as an efficient light-harvesting and emission site, an Eosin Y-based visible-light-responsive metal–organic framework has been synthesized and characterized, which exhibits high selectivity for detecting the antibiotic SSZ in water and simulated physiological conditions, with a detection limit of below 1 μM (0.4 μg mL−1). It also represents the first example of a MOF-based photocatalyst for the controllable degradation of SSZ into 5-aminosalicylic acid with excellent catalytic activity and recyclability. [ABSTRACT FROM AUTHOR]

Three mixed porphyrins, icpp (1–3), were synthesized via the reactions of 4-formylbenzoic acid and 4-imidazolecarboxaldehyde, and then five amorphous or crystalline Zr-MOFs—SPUZ (1–5) were obtained from icpp (1–3), timp and tcpp, respectively. The catalytic activities of the synthesized porphyrins and MOFs were studied on the Knoevenagel condensation of aldehydes and malononitrile under solvent-free conditions. Among them, amorphous MOF SPUZ-1 showed the highest catalytic activity. Further studies on various aldehydes demonstrated that most reactions were completed with a low catalyst loading (1 mol%) in a short reaction time (5–30 min), and the best result was obtained with the yield of 99.9% within 5 min. Moreover, SPUZ-1 could be recycled 7 times without significant loss of activity. [ABSTRACT FROM AUTHOR]

It is of pivotal significance to probe highly efficient, cost-effective and low-cost catalysts for the hydrogen evolution reaction. Herein, a closely packed carbon-encapsulated CuO/Cu2O heterohedron with a heterojunction structure is reported that combines chemical etching and thermal oxidation processes. CuO/Cu2O@C-10 has remarkable catalytic activity for HER with an overpotential of 121 mV at a current density of 10 mA cm−2 and a Tafel slope of 81.58 mV dec−1, along with excellent stability in alkaline media under optimal conditions. Benefiting from CuO/Cu2O nanoparticles embedded in a carbon matrix, it forms a porous heterohedron structure by a close packing mode, owing to the unique CuO/Cu2O heterostructure with an ultrathin coated carbon layer and an interconnected conductive carbon network structure. These characteristics make a great contribution to the massive number of active interfacial sites, alleviating the aggregation of active substances, enhancing ion diffusion and the conductivity of the materials. This facile strategy sheds new light on a rational synthesis for a highly efficient hydrogen evolution catalyst with a heterostructure. [ABSTRACT FROM AUTHOR]

The oxygen evolution reaction is a kinetically sluggish half-cell reaction which plays an important role in tuning the efficiency of various electrochemical energy conversion systems. However, this process can be facilitated by manipulating the composition and morphology of the electrocatalyst. Here, by tuning the annealing temperature, a series of cobalt borides (CoB@300, CoB@450, CoB@550 and CoB@650) were synthesized from a metal–organic framework Prussian blue analogue (PBA) following boronization. The resulting borides were characterized systematically and we explored their electrocatalytic activity towards the oxygen evolution reaction (OER). In an alkaline electrolyte, the in situ surface transformation of the boride working electrode to the corresponding metaborite and cobalt oxyhydroxide took place which thereafter acted as the active catalytic sites for the OER. Interestingly, the amorphous form of cobalt boride (i.e., CoB@300) shows many fold increased catalytic activity compared to those of crystalline CoB and commercial RuO2 requiring only 290 mV overpotential to reach the benchmarked 10 mA cm−2 current density and the trend follows the order as CoB@300 > CoB@450 > CoB@550 > CoB@650 > PBA. The dominant catalytic activity of the amorphous cobalt boride nanostructure is attributed particularly to its amorphous nature and synergy between the in situ formed catalytically active centres (meta-borites and cobalt oxyhydroxide). [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) as nanozymes have been widely used in biosensing. However, MOFs have inherent defects of easy agglomeration, leading to the stacking of active surfaces. In addition, the low conductivity of MOFs is not conducive to the electron migration in the Fenton-like reaction, which leads to a further decrease in catalytic activity and severely restricts their application. In response to the above problems, it makes sense to develop a method to improve both the dispersion and conductivity of MOFs. Here, a simple ligand exchange method with polydopamine (PDA) was used to synthesize MOF PDA-MIL-88B. PDA-MIL-88B shows stronger peroxidase-like activity than MIL-88B. One reason is the good dispersibility of PDA-MIL-88B, which is conducive to exposing the active surface. In addition, the reduced electrochemical impedance of PDA-MIL-88B increases its electrical conductivity, which is favorable for electron migration in the Fenton-like reaction. As a result, PDA-MIL-88B can better catalyze 3,3′,5,5′-tetramethylbenzidine to achieve redoximorphic color changes. PDA-MIL-88B can be used to detect glucose in human serum with good sensitivity and selectivity. This work can provide a strategy for MOFs to enhance the enzyme-like activity. [ABSTRACT FROM AUTHOR]

Currently, rapidly increasing consumption of fossil resources has propelled the upgrading of biomass as an alternative and sustainable technology to produce important chemicals and bio-oils. In this regard, the rational design of low-cost and robust supported metal-based catalysts that exhibit excellent catalytic hydrodeoxygenation (HDO) performance for the conversion of biomass is quite necessary. Herein, we developed hierarchical flower-like nitrogen-doped carbon layer-coated bimetallic Ni–Co nanoparticles, which were distributed over the carbonaceous matrix (NixCo@NC@C), via a metal–organic framework (MOF) ZIF-67 precursor approach, assisted by the etching of Ni2+ ions, hydrothermal treatment together with glucose, and following carbonization processes. The as-fabricated Ni3Co@NC@C catalyst bearing a 3 : 1 Ni/Co molar ratio showed a superior catalytic HDO activity towards aqueous phase HDO of vanillin to other bimetallic NiCo catalysts with different Ni/Co molar ratios under mild reaction conditions, along with a 100% selectivity to 2-methoxy-4-methylphenol at a full vanillin conversion, despite its smaller number of exposed metallic sites. It was revealed that over the Ni3Co@NC@C catalyst, the surface abundant defective oxygen vacancies and electron-rich Co0 species were conducive to the adsorption and activation of vanillin and the reaction intermediate, thereby giving rise to the outstanding catalytic activity. Moreover, for Ni3Co@NC@C, the adequate protection effect of surface carbon layers, as well as the unique hierarchical flower-like microstructure, could significantly inhibit the leaching of active metal species in the reaction medium, thereby leading to high structural stability. The present findings afford a promising strategy for constructing low-cost and robust carbon-supported bimetallic catalysts for the HDO of lignin-derived derivatives. [ABSTRACT FROM AUTHOR]

Organic and inorganic building blocks are used to construct a class of metal–organic frameworks (MOFs) that exhibit tremendous chemical tunability. In this study, a novel zirconium-based MOF UiO-66-(alkyne)2 with a di-alkyne tag was obtained through solvothermal pre-synthesis, which provides a potential covalent binding site for post-synthesis modification. On this basis, a gentle post-synthesis modification strategy based on covalency was expanded for introducing diverse metals, and a family of isostructural tailored materials (UiO-66-alkyne-Co, UiO-66-(alkyne-Co)2 and UiO-66-(alkyne-Ni)2) with base metals Ni or Co were designed and synthesized successfully. Among them, di-alkyne tagged UiO-66-(alkyne-Co)2 has shown unprecedented remarkable performance as a heterogeneous catalyst for the Knoevenagel reaction, completely converting benzaldehyde in just 5 min at room temperature, to our knowledge, faster than the reported MOF catalysts. Moreover, UiO-66-(alkyne-Co)2 maintains high stability and functionality after five cycles, and the catalytic activity is also preserved in the gram level scale-up experiment, indicating that UiO-66-(alkyne-Co)2 has great potential for practical application in the formation of C–C bonds. In a sense, this research provides an ideal platform for anchoring the required functional groups on alkyne-modified MOFs, which lays a foundation for finding more potential applications of MOF materials in the future. [ABSTRACT FROM AUTHOR]

Black TiO2 and metal–organic frameworks (MOF) are great materials with light-harvesting ability, redox power and consequently catalytic activity. Here, the integration of MIL-100(Fe) with TiO2(B) composite was designed for photocatalytic application, which greatly promoted light-harvesting and charge transfer. As expected, the integrated TiO2(B)/MIL-100(Fe) composite showed high photocatalytic activity due to unique Fe–O–Ti bonds that were constructed, which acted as an electronic tunnel to reduce electronic transfer resistance between MIL-100(Fe) and TiO2(B). In addition, the presence of Fe–O clusters in MIL-100(Fe) can also promote the charge dissociation and improve catalytic activity via the Fe3+/Fe2+ redox cycle. This achievement would help us to understand and design charge transfer pathways in the integration of MOF/semiconductor photocatalysts. [ABSTRACT FROM AUTHOR]

The development of efficient and sustainable strategies that evade the utilization of petroleum reserves is highly challenging yet inevitable today. In this regard, the conversion of pine tree-derived β-pinene to highly recognized nopol is particularly attractive owing to its widespread applications. Herein, we describe an approach that enables the selective synthesis of nopol based on the extraordinary activity of MIL-101(Cr). This remarkable activity of MIL-101(Cr) is attributed to its high specific surface area (SSA), accessible active sites in the mesopore architecture and unsaturated Cr3+ Lewis acid sites. We have established a good correlation between the superior catalytic performance and textural properties of the materials, which can be tuned by using different mineralizing agents. To realize the unprecedented catalytic activity, the influence of reaction parameters, solvent properties, and mineralizing agents has been investigated systematically. MIL-101(AA) (AA-acetic acid) showed the highest catalytic activity, which is superior to most of the reported materials for this transformation to date. The results of catalyst recycling and hot filtration experiments have emphasized that the catalyst is resistant towards leaching of active sites and retained its original catalytic activity beyond four recycles. An Eley–Rideal based model was used to study the reaction kinetics and establish a plausible reaction mechanism. The activation energy of the reaction was found to be 102 kJ mol−1 and the enthalpy of formaldehyde adsorption was −86.88 kJ mol−1. This approach opens up new avenues for the valorization of biomass-based molecules into useful chemicals. [ABSTRACT FROM AUTHOR]

Considering the outstanding characteristics of metal organic frameworks (MOFs) and magnetic nanoparticles, herein we report a facile approach for the synthesis of a magnetic zeolitic-imidazolate-framework-supported palladium(II) catalyst. In brief, zeolitic imidazolate framework-67 (ZIF-67) was successfully incorporated onto the surface of titania-coated magnetic nanoparticles using ethane-1,2-diamine as a linker, and then Pd(II) was immobilized onto this. The resulting Pd@ZIF-67–Fe3O4–TiO2 catalyst possesses a high surface area (205 m2 g−1), a large pore volume (0.10 cm3 g−1), good magnetic responsivity (10.71 emu g−1), and high stability. A comparative analysis of Pd@ZIF-67–Fe3O4–TiO2 and Pd@Fe3O4–TiO2 catalysts for the oxidation, reduction, and oxidative deprotection of oximes was done to investigate the effects of ZIF-67 on the catalytic performance of Pd species. Substantial differences in activity and stability were observed in the presence of ZIF-67, suggesting that ZIF-67 plays an important role in enhancing the activity of Pd(II). This superior catalytic activity and stability arises due to a synergistic effect between well-dispersed palladium species and highly porous ZIF-67, which was confirmed via XPS analysis. Moreover, the catalyst retains its structure, chemical environment, and good magnetic response even after five catalytic runs, as confirmed via FTIR, XRD, XPS, and VSM studies of reused catalyst samples. [ABSTRACT FROM AUTHOR]

A ferrocene carboxylic acid (Fc)-doped copper–p-phthalic acid metal–organic framework material (Fc–Cu PTA) exhibited remarkably high peroxidase-mimicking activity, while Cu PTA showed nearly no peroxidase-mimicking activity. Under the enzymatic catalysis of Fc–Cu PTA as a peroxidase-mimicking nanozyme, the tested organic dyes were rapidly degraded by peroxymonosulfate. Fc–Cu PTA could be an effective catalyst for the degradation treatment of dye-polluted water and soil sources, and potentially for other peroxidase-related applications as well. [ABSTRACT FROM AUTHOR]

Incorporating catalytic units into a crystalline porous matrix represents a facile way to build high-efficiency heterogeneous catalysts, and by rational design of the porous skeleton with appropriate building blocks the catalytic performance can be significantly enhanced for a series of organic transformations owing to the synergistic effect from the multicomponent and confined porous microenvironment around catalytically active sites. Herein, we demonstrate that the design and synthesis of a porous polyoxometalate-based metal–organic framework YL2(H2O)2[CrMo6O18(PET)2]·4H2O (POMOF-1) constructed from Anderson-type [CrMo6O18(PET)2] (PET = pentaerythritol), which can be employed as a multifunctional platform for synthesis of N-containing compounds via selective oxidative coupling with amines. POMOF-1 features microporous 1D channels defined by Y3+ and L, with [CrMo6O18(PET)2] arranged orderly between adjacent Lvia electrostatic interactions. Upon using POMOF-1 as a catalyst and H2O2 as an oxidant, a variety of amines could be effectively converted to value-added amides, imines and azobenzenes via the oxidative cross-coupling with alcohols or homo-coupling. In particular, POMOF-1 showed dramatically improved activity for the N-formylation reaction owing to the synergistic and confinement effect, with the yield of amides up to 95% and 4 times higher than that of homogeneous [CrMo6O18(PET)2]. Meanwhile, the oxidative homo-coupling of arylmethylamines and arylamines can be facilely tuned by adjustment of the amount of oxidant, solvent and additive, affording imines and azobenzenes in high selectivity and yield, respectively. POMOF-1 is robust and can be reused for 5 cycles with little loss of catalytic activity and structural integrity. The work demonstrates that the combination of catalytically active POMs with crystalline porous MOFs holds great potential to build robust and recyclable heterogeneous systems with enhanced activity and selectivity for multifunctional catalysis. [ABSTRACT FROM AUTHOR]

Five novel metal–organic frameworks (MOFs) with the formula [MII(dcpbpy)(sol)x]n (MII = CoII, sol = H2O, x = 1, 1; MII = NiII, sol = H2O, x = 1, 2; MII = MnII, sol = DMAc, x = 1, 3; MII = MnII, sol = DMF, x = 1, 4; MII = MnII, sol = H2O, x = 2, 5; dcpbpy = 4-(2,4-dicarboxylphenyl)-4,2′:6′,4′′-terpyridine) having various dimensions were prepared with different solvents and transition-metal ions (CoII, NiII and MnII). Single-crystal X-ray diffraction showed that 1–5 resulted in the grid layer stacked 3D (1 and 2), 2D (3 and 4) and 1D (5) frame structures due to their different coordination modes. Electrochemical analyses showed that 1–5 displayed efficient catalytic activity towards oxygen evolution reactions (OERs) under alkaline conditions. Besides, 1–2 with the stacked 3D framework could present a large interaction and result in a low overpotential of their OER behaviour, compared to the 2D (3 and 4) and 1D (5) frameworks. MOF 2 with a 3D frame structure and NiII as the active central ion gave the lowest required overpotential (130 mV) to generate a current density of 1 mA cm−2. [ABSTRACT FROM AUTHOR]

Two model porphyrin metal–organic frameworks were used for the incorporation of Rh(I) species by a post-synthetic metallation under mild conditions. As a result, new rhodium MOFs (Rh/MOFs), Rh/PCN-222 and Rh/NU-1102, were synthesized and structurally characterized. To illustrate the potential of this catalytic platform, we use Rh/MOFs as phosphine-free heterogeneous catalysts in the hydrogenation of unsaturated hydrocarbons under mild reaction conditions (30 °C and 1 atm H2). We found that for our Rh/MOFs an activation step is required during the first run of the catalytic process. The presence of Rh–CO moieties allowed us to monitor the activation pathway of the catalyst under a H2 atmosphere, by in situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). After activation, the catalyst remains highly active during the subsequent catalytic cycles. This simple post-synthetic modification approach presents new possibilities for the utilization of Rh-based catalytic systems with robust porphyrin-based MOFs as supports. [ABSTRACT FROM AUTHOR]

For electrochemical energy conversion, highly efficient and stable electrocatalysts are required, which are principally designed and synthesized by virtue of structural regulation. Two-dimensional cluster-based metal–organic layers (CMOLs) would have good performance in oxygen evolution reaction (OER) because of their stable and layered structure. Here, we first report the synthesis of CoNi bimetal two-dimensional CMOLs directly grown on Ni foam, which show excellent catalytic activity for the OER under alkaline conditions. Co0.6Ni0.4-CMOLs exhibited the best OER performance, compared with Co-CMOLs and Ni-CMOLs. The findings are expected to help understand the fundamental concept of enhanced electrochemical activity based on pristine metal–organic frameworks with high stability. [ABSTRACT FROM AUTHOR]

The Ti-based metal–organic framework (Ti-MOF) MIL-125 with tunable crystalline size in the range of ca. 50 nm to 1500 nm was synthesized by the coordination modulation method using trans-cinnamic acid (CA) as a modulator. The coordination modulation also induced hierarchical porosity and structure defects on the nanocrystals. A significant size-dependent catalytic activity towards the oxidative desulfurization (ODS) reaction was observed for these MIL-125 nanocrystals. In particular, the MIL-125 nanocrystals with a mean size of ca. 50 nm exhibit dramatically enhanced catalytic performance for the bulky sulfur compound 4,6-dimethyldibenzothiophene (4,6-DMDBT) compared to the microcrystals. It is demonstrated that the size modulation of MIL-125 is an effective approach to promote its performance for the catalysis of bulky molecules. [ABSTRACT FROM AUTHOR]

The development of non-platinum catalysts for the oxygen reduction reaction (ORR) in fuel cells is an urgent challenge given the limited reserves of platinum. The Fe–Nx/C electrocatalyst possessing isolated atomic metal active sites on N-doped carbon matrices is one of the most promising candidates for platinum-based catalyst alternatives because of its high efficiency and durability. Here carbon-supported porphyrin-encapsulated and -functionalized metal–organic frameworks (MOFs) have been synthesized to afford an Fe-implanted nitrogen-doped porous carbon electrocatalyst via pyrolysis. The fabricated electrocatalyst exhibited outstanding oxygen reduction catalytic activity with a half-wave potential of 0.916 V (vs. RHE), surpassing state-of-the-art Pt/C (0.891 V). Durability tests revealed that the half-wave potential decreased by only 15 mV after 30 000 cycles. Abundant and well-separated atomic Fe–Nx/C active sites in the catalyst play an essential role in the superior ORR activity. [ABSTRACT FROM AUTHOR]

The field of metal–organic framework (MOF)-based biomimetic catalysts has achieved great progress but is still in its infancy. The systematic investigation of the tailored construction of MOF-based biomimetic catalysts is required for further development. Herein, two iron-based MOFs, namely, [(Fe3O)2(H2O)4(HCOO)(L)2]n (HUST-5: H6L = hexakis(4-formylphenoxy) cyclotriphosphazene; HUST = Huazhong University of Science and Technology) and [(Fe3O)(H2O)3(L)]n (HUST-7) have been fabricated through the assembly of different iron clusters and hexa-carboxylate ligand under the control of the added acid species. The two MOFs exhibit distinct secondary building units (SBUs) and topological structures, which could be used as biomimetic catalysts for the systematic comparisons of structural characteristics and the catalytic activity. Both MOFs possess catalytic activity similar to that of natural peroxidases towards the catalysis of the oxidation of a variety of substrates. Significantly, HUST-5 and HUST-7 can effectively catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) by H2O2 accompanied by significant colorimetric biosensing. With same compositions, different catalytic performances were obtained due to differences in the porous structures and characteristics of SBUs in two Fe-MOFs, which was also validated by theoretical calculation results. Furthermore, the phenomenon of colorimetric biosensing could be significantly suppressed by the addition of ascorbic acid (AA) during the oxidation process of TMB. It was observed from these findings that a facile colorimetric biosensing platform for detecting H2O2 and ascorbic acid has been successfully explored. Therefore, this work provides another unique perspective for the tailor-made preparation of stable MOF-based peroxidase mimics with excellent catalytic performance and colorimetric biosensing. [ABSTRACT FROM AUTHOR]

MOF-74-type frameworks are considered one of the most promising metal–organic frameworks owing to their remarkable structural features and properties such as a high density of open metal sites, hexagonal channels along the c-axis, and high porosity. Diverse strategies have been adopted to prepare bimetallic MOF-74 frameworks, in the pursuit of synergistic effects and enhanced properties originating from different metal sites that serve as Lewis acidic sites. Moreover, extended versions of the MOF-74-type structure have been demonstrated in terms of ligand extension, featuring enhanced pore size and surface area. The extended variants of MOF-74 are beneficial for the incorporation of additional functional groups due to the relatively larger pore size. Pre- or post-synthetic modification approaches have been applied to introduce functionalities into the framework, resulting in desirable and superior properties such as chemical stability, binding affinity, and catalytic activity. This review addresses the significant progress made in the development of MOF-74-type frameworks with respect to synthetic strategies and modification approaches. [ABSTRACT FROM AUTHOR]

Two new three-dimensional (3D) metal–organic frameworks (MOFs), namely {[Cu2(L)(4,4′-bipy)(OH)]·H2O}n (1) and {[Mn3(L)2(4,4′-bipy)(DMA)2]·H2O}n (2), were constructed by a newly synthesized thioether carboxylic acid ligand 5-((formic acid-3-sulfur)methyl)isophthalic acid (H3L) and 4,4′-bipyridine (4,4′-bipy). Thioether bonds in H3L can rotate freely in space, which are conducive in constructing MOFs with rich and stable structures. Simultaneously, the uncoordinated sulfur atoms affect the polarity of the framework and play an important role in adsorption. Gas adsorption results indicated that 1 can selectively adsorb CO2 from the mixture of CH4/CO2. Moreover, due to the high catalytic activity of [Cu4(COO)6N4O2] clusters, 1 is also an excellent recyclable catalyst that can chemically fix CO2 into cyclic carbonate under mild solvent-free conditions. Therefore, 1 may be explored as a dual-functional material for industrial adsorption and catalysis. [ABSTRACT FROM AUTHOR]

Two isostructural lanthanide metal–organic frameworks (Ln-MOF-589, Ln = La3+, Ce3+), constructed from a tetratopic linker, benzoimidephenanthroline tetracarboxylic acid (H4BIPA-TC), have been solvothermally synthesized and characterized. These Ln-MOF-589 materials consist of Lewis acid [Ln2(-COO)6(-COOH)2(H2O)6] units and a naphthalene diimide core, which exhibited promising catalytic activity for the oxidation of olefins. Among them, Ce-MOF-589 exhibited outstanding performance with high conversions of styrene and cyclohexene (94 and 90%, respectively), and good selectivities towards styrene oxide and 2-cyclohexen-1-one (85, and 95%, respectively). Notably, the catalytic activity of Ce-MOF-589 outperformed that of homogeneous and heterogeneous catalysts, and representative MOFs. Also, Ce-MOF-589 can be recycled for at least up to six cycles with no significant loss of catalytic performance. [ABSTRACT FROM AUTHOR]

The phosphate content in water is crucial to all forms of life. Excessive phosphate in water can cause the excessive growth of algae and lower the oxygen content in water, which is a danger to our environment. However, most conventional methods for phosphate detection are time-consuming and instrument-dependent. In this work, three Cu-based metal–organic framework nanomaterials (Cu-MOF(1), Cu-MOF(2), Cu-MOF(3)) were synthesized. And it was found that the obtained three nanomaterials all exhibited peroxidase-like activities. Cu-MOF catalyzed color reaction can be inhibited in the presence of phosphate, and a colorimetric assay is constructed for the determination of phosphate by taking Cu-MOF(3) as an example. Good linearity existed between the absorbance of the Cu–MOF/TMB–H2O2 system at 652 nm and phosphate concentration from 0.05 μM to 5 μM, with the limit of detection down to 20 nM according to the S/N = 3 rule. Besides, the practicality of our assay was also certified by sensing PO43− in local river water samples. [ABSTRACT FROM AUTHOR]

Insights into the relationship between the crystal structure and activity of metal–organic frameworks (MOFs) are meaningful to investigate the potential properties of pristine MOFs for targeted catalytic reactions. Herein, we develop a high-efficiency method for boosting the oxidative desulfurization (ODS) activity of Ti-MOF in the presence of H+. The ODS activity of pristine Ti-MOF prepared via a solvothermal approach is very poor at a low reaction temperature but can be enhanced in the presence of H+. Ti-MOF in the presence of H+ shows ultrahigh ODS activity that can eliminate 1000 ppm sulfur after 7 min at 30 °C with no catalytic activity loss after recycling 11 times. The turnover frequency value reaches 12.4 h−1 at 30 °C, surpassing all the previously reported Ti-MOFs as ODS catalysts even at high temperatures. Characterization and quenching experimental results indicate that more uncoordinated Ti sites can be formed from slight damage to the structure of Ti-MOF during the catalytic reaction, and such exposed Ti sites can easily react with H+ and H2O2 to form Ti–hydroperoxo active species that determine the upgradation of ODS activity. This work provides a significant way to upgrade the catalytic activity of pristine Ti-MOFs for future application. [ABSTRACT FROM AUTHOR]

A novel polyoxovanadate-based copper(I)–organic framework, [CuI(bib)]4{VV4O12} (V–Cu–MOF, bib = 1,4-bis(1H-imidazoly-1-yl)benzene), is facilely synthesized under mild hydrothermal conditions. The structure of the V–Cu–MOF is constructed from a cyclic {V4O12}4− polyanion cluster and a 1D chain Cu(I)–MOF ([CuI(bib)]+). The presence of the {V4O12}4− cluster stabilizes the Cu(I)–MOF with Cu(I) as the center, thereby improving the stability of the V–Cu–MOF and enabling it to stably exist in various solvents and pH = 2–12 solutions. Additionally, the V–Cu–MOF as a heterogeneous catalyst can catalyze the carboxylative cyclization of CO2 and propargylic alcohols to high value-added α-alkylidene cyclic carbonates at room temperature, and the conversion and selectivity are almost 100%. More importantly, no obvious decrease in the yield of the α-alkylidene cyclic carbonate is observed after ten cycles. These results indicate the excellent catalytic activity and sustainability of the V–Cu–MOF. Research on the mechanism of the catalytic reaction suggests that the high-density Cu(I) sites in the V–Cu–MOF are the catalytically active centers for activating the C≡C bonds of propargylic alcohols. To the best of our knowledge, this is the first example of polyoxometalate-based metal–organic framework catalyst for catalyzing the conversion of CO2 to value-added α-alkylidene cyclic carbonates at room temperature. [ABSTRACT FROM AUTHOR]

Three zirconium–porphyrin based MOFs with different linker connectivity, PCN-222, PCN-223 and PCN-224, and their Zn(II) ion metalated analogues, were prepared and used as catalysts for the photoreduction of CO2 under visible-light irradiation. Before metalation with Zn2+ in the porphyrin linkers, the lowest linker-connected PCN-224 (6-fold) exhibited a higher formate yield rate of 45.2 μmol g−1 h−1 compared to PCN-222 and PCN-223. However, after the incorporation of Zn2+ into the porphyrin, PCN-222-Zn showed the highest formate yield rate of 120.2 μmol g−1 h−1. The density functional theory (DFT) computational results revealed that the catalytic activity correlated with the CO2 adsorption affinity. The CO2 adsorption energy on PCN-222-Zn (294.4 kJ mol−1) was the highest among all of the samples. The overall catalytic performance was affected by the Zr6-oxo cluster connectivity and the introduced dual reaction sites when the porphyrin linkers were metalated with Zn(II) ions. [ABSTRACT FROM AUTHOR]

Nanoscale MIL-125 crystals with truncated octahedral shape were synthesized through the coordination modulation method using butyric acid as the modulator. Compared to the traditional MIL-125 crystals with dominant {001} facets, the truncated octahedral crystals are dominated by {101} facets as the exposed crystal facets. The MIL-125 crystals with different morphology exhibit significant facet-dependent catalytic activity for the oxidative desulfurization (ODS) reaction. The truncated octahedral MIL-125 crystals show remarkably enhanced catalytic performance towards oxidative desulfurization of the most refractory sulfur compound 4,6-dimethyldibenzothiophene (4,6-DMDBT). It is demonstrated that the shape-controlled synthesis of nanoscale MIL-125 is a promising way to promote its catalytic performance towards the reaction involving bulky molecules. [ABSTRACT FROM AUTHOR]

The design of highly stable, effective, and selective electrocatalysts is essential for electrochemical reduction of carbon dioxide (CO2). Here, on the basis of density functional theory (DFT) computations, the reaction mechanisms of the reduction of CO2 over a series of bis(iminothiolato)metal (TMIT, TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, and Pd) were studied. It is found that the CO2RR activity of TMIT depends on the choice of the central metal atom. Our results demonstrated that HCOOH is the main product for TMIT (TM = Mn, Fe, Co, Ni, Cu, Pd). Among them, MnIT and FeIT are promising CO2RR catalysts for the HCOOH production due to the good selectivity and catalytic activity with the low overpotential of 0.34 V and 0.35 V, respectively. For RuIT and RhIT, the main product is CO, and the strong adsorption of CO on the catalyst surfaces would poison the catalysts. This makes RhIT and RuIT not good CO2RR catalysts. We anticipate that this work may shed new light on the development of high-performance metal organic framework (MOF)-based electrocatalysts. [ABSTRACT FROM AUTHOR]

Solvothermal reactions between a pyridine based amide functionalized dicarboxylic acid, 4,4′-{(pyridine-2,6-dicarbonyl)bis(azanediyl)}dibenzoic acid (H2L), and zinc(II) nitrate in the absence and presence of a base produced the binuclear metallomacrocyclic compound [Zn2(L)2(H2O)4]·2(H2O)·6(DMF) (1) and the metallomacrocyclic based two dimensional MOF [Zn5(L)4(OH)2(H2O)4]n·8n(DMF)·4n(H2O) (2), respectively. Compound 1 bears two tetrahedral Zn(II) centres, whereas the 2D framework 2 includes a penta-nuclear Zn(II) cluster as a secondary building block unit, with two of the metal cations assuming a tetrahedral type geometry and the remaining three an octahedral type geometry. The topological analyses reveal that compound 1 has a 2-connected uninodal net and framework 2 has a 2, 8-connected binodal net. These compounds heterogeneously catalyse the tandem deacetalization-Knoevenagel condensation reactions carried out under conventional heating, microwave irradiation or ultrasonic irradiation. Comparative studies show that ultrasonic irradiation (final product yield of 99% after 2 h of reaction time) provides the most favourable method (e.g., microwave irradiation leads to a final product yield of 91% after 3 h of reaction time). Moreover, the catalysts can be reused at least for five consecutive cycles without losing activity significantly. [ABSTRACT FROM AUTHOR]

The efficient and selective aerobic oxidation of alcohols has been investigated with judicious combinations of europium-incorporated and/or TEMPO ((2,2,6,6-tetramethylpiperidin-1-yl)oxyl)-functionalized zirconium-based porous metal–organic frameworks (MOFs). Although MOFs are well-known catalytic platforms for the aerobic oxidation with radical-functionalities and metal nanoparticles, these systematic approaches involving metal cations and/or radical species introduce numerous interesting aspects for cooperation between metals and TEMPO for the aerobic oxidation of alcohols. The role of TEMPO as the oxidant in the heterogeneous catalytic aerobic oxidation of alcohols was revealed through a series of comparisons between metal-anchored, TEMPO-anchored, and metal and TEMPO-anchored MOF catalysis. The fine tunability of the MOF allowed the homogeneously and doubly functionalized catalysts to undergo organic reactions in the heterogeneous media. In addition, the well-defined and carefully designed heterogeneous molecular catalysts displayed reusability along with better catalytic performance than the homogeneous systems using identical coordinating ligands. The role of metal-cation fixation should be carefully revised to control their coordination and maximize their catalytic activity. Lastly, the metal cation-fixed MOF displayed better substrate tolerance and reaction efficiencies than the TEMPO-anchored MOF or mixture MOF systems. [ABSTRACT FROM AUTHOR]

By utilizing a flexible fluorinated bis(triazole) ligand 1,4-bis(1,2,4-triazole-1-ylmethyl)-2,3,5,6-tetrafluorobenzene (Fbtx), a thermally and chemically stable cobalt(II)-containing tungstovanadate-based metal–organic framework (MOF) {[Co3(Fbtx)5(V2W18O62)(H2O)2]·26H2O}n (denoted as CZU-5) was synthesized and structurally characterized. The X-ray structural analysis revealed that CZU-5 features a three-dimensional (3-D) self-penetrated α-polonium cubic structure, which results from a 3-D 4-fold interpenetrated diamondoid [Co(Fbtx)]n network connected by the Wells–Dawson-type tungstovanadate clusters. Unexpectedly, the introduction of vanadium atoms as heteroatoms into the Dawson-type anion in polyoxometalate (POM)-based coordination polymers has not been reported to date. For the first time, the POM-based material was demonstrated to be an effective catalyst for the solvent-free ring-opening polymerization of ε-caprolactone. Moreover, the CZU-5 catalyst could be recycled up to five times with the retention of both catalytic activity and crystal structure. [ABSTRACT FROM AUTHOR]

A major challenge in the field of photocatalytic carbon dioxide (CO2) reduction is to design catalyst systems featuring high selectivity for CO production, long-term stability and a composition of Earth-abundant elements. Here, we present a metal–organic framework (MOF) based catalyst to mitigate the technical problems associated with the above-mentioned features. We report a carbon-coated CuNi alloy nanocatalyst obtained by high temperature vacuum treatment of a MOF material (CuNiBTC). The resulting carbon encapsulated CuNi (denoted as CuNi/C) nanoparticles possess a well-designed core–shell composite structure with graphene shells. Meanwhile, we investigated the reaction mechanism of CO2 on the surface of the CuNi/C photocatalyst in an aqueous solution containing triethanolamine. The experimental results show that the activity and catalytic yield of CuNi/C are much higher than those of Cu/C and Ni/C alone. At the same time, the catalytic activity of CuNi/C is also affected by changing the reaction temperature in the preparation process. As a result, the CuNi/C samples can achieve nearly 90% selectivity for NIR-light-driven CO2 reduction to CO. Our approach demonstrates the potential of non-semiconductor materials as catalysts for efficient and selective reduction of CO2 to CO. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have attracted great attention as enzyme mimic materials in colorimetric hydrogen peroxide (H2O2) detection. At present, it is highly desirable but remains challenging to prepare MOFs with high stability and dispersity to further improve their peroxidase-mimicking catalytic activity. In this work, we developed a new and facile method for the synthesis of a sub-100 nm peroxidase-mimicking zirconium porphyrin metal–organic framework (Zr-PorMOF) via a solvothermal method. The experimental results indicated that compared with the micron-sized crystals obtained using a classical synthesis method, the catalytic activity, stability and dispersity in water of the colloidal Zr-PorMOF were obviously enhanced. The as-synthesized colloidal Zr-PorMOF was further successfully applied in colorimetric H2O2 detection, and satisfactory detection performance was obtained. Furthermore, the colloidal Zr-PorMOF was also successfully employed in the construction of a peroxidase-based tandem catalysis system. Taking glucose oxidase as an example, this system was successfully applied for glucose sensing in real human serum samples, which proved its practical feasibility in diabetes diagnosis and indicates its high potential feasibility in peroxidase-related applications in complex biomatrix. [ABSTRACT FROM AUTHOR]

In the present work, a new 3D metal–organic framework (MOF) has been synthesized and characterized. The MOF exhibits good chemical stability in aqueous solutions with the pH scale ranging from 3 to 11. Interestingly, the MOF shows high catalytic activities for the degradation of azo dyes (MO, CR and CBR) under visible light without H2O2. The Ea values of the MOF for MO, CR and CBR degradation are obtained to be 23.49, 52.68 and 15.19 kJ mol−1, respectively. In addition, the MOF can be reused in the catalytic process without the catalytic activity decreasing obviously. [ABSTRACT FROM AUTHOR]

Flower-like mesoporous sulfated zirconia nanosheets (SZNs) were developed by thermal decomposition of in situ sulfated Zr-MOFs for the first time. The sulfated Zr-MOFs act as both a morphological template and zirconium and sulfate sources. The amounts of SO42− in the synthesis system of UiO-66 greatly affected the morphology of sulfated Zr-MOFs via a coordination modulation method. The flower-like sulfated Zr-MOF nanosheets were obtained as the S/Zr ratio increased to 0.5. The calcination temperature has a great influence on the structural properties and catalytic performances of sulfated zirconia nanosheets other than morphology. Sulfated zirconia nanosheets (SZN-500) obtained by calcination at 500 °C had a large surface area (186.1 m2 g−1) and strong bonding between sulfate and zirconia atoms and exhibited a good catalytic activity and reusability for the transesterification of tributyrin with methanol. This viable synthetic strategy can offer an alternative way to prepare functionalized metallic oxides with a specific morphology. [ABSTRACT FROM AUTHOR]

Subphthalocyanine has been incorporated into a robust metal–organic framework having amino groups as binding sites. The resulting SubPc@MIL-101(Cr)-NH2 composite has a loading of 2 wt%. Adsorption of subphthalocyanine does not deteriorate host crystallinity, but decreases the surface area and porosity of MIL-101(Cr)-NH2. The resulting SubPc@MIL-101(Cr)-NH2 composite exhibits a 575 nm absorption band responsible for the observed photoredox catalytic activity under simulated sunlight irradiation for hydrogenative dehalogenation of α-haloacetophenones and for the coupling of α-bromoacetophenone and styrene. The material undergoes a slight deactivation upon reuse. In comparison to the case of phthalocyanines the present study is one of the few cases showing the use of subphthalocyanine as a photoredox catalyst, with its activity derived from site isolation within the MOF cavities. [ABSTRACT FROM AUTHOR]

In this work, we report a simple and versatile method for the modification of a metal–organic framework (NH2-MIL53(Al)) in a step-wise manner. To characterize the synthesized nanostructured catalyst, a variety of spectroscopic and microscopic techniques including FT-IR, XRD, BET, TEM, FE-SEM, EDX, EDX-mapping, TGA, XPS, VSM, ICP-OES and CHN have been employed. Fe3O4@AMCA-MIL53(Al)-NH2-CoII NPs, which benefit from small nanocrystalline size (10–30 nm, according to the XRD and TEM data) in combination with the coexistence of magnetic nanoparticles, a metal–organic framework, and cobalt species, were found to be an excellent environment catalyst to promote the C–N and C–S cross coupling reactions. A wide range of functional substrates including electron-withdrawing and electron-donating aryl halides underwent the coupling reaction with aromatic/heteroaromatic/benzylic and aliphatic amines and sulfides. The results demonstrated that the yields of the target products were good to excellent and the catalyst can be recycled for at least seven recycling runs without a discernible decrease in its catalytic activity. Furthermore, the heterogeneity studies (such as hot filtration and poisoning tests) efficiently confirmed that the as-synthesized nanostructured catalyst is heterogeneous and completely stable under the reaction conditions. We hope that our study inspires more interest in designing novel catalysts based on using low-cost metal ions (such as cobalt) in the field of cross coupling reactions. [ABSTRACT FROM AUTHOR]