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The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. It includes articles on various topics such as the promise of metal-organic frameworks in turning CO2 into treasure, the design and synthesis of functional coordination polymers, and the study of power consumption and heat transfer in silicon crystal growth. The journal is published by The Royal Society of Chemistry, a leading chemistry community that reinvests its profits back into the chemistry community. [Extracted from the article]

Metal organic frameworks (MOFs) are porous crystalline materials that display a wide variety of physical and chemical properties. Their single crystal structure determination is often challenging because in most cases micro- or nano-sized crystals spontaneously form upon MOF synthesis, which cannot be recrystallized. The production of larger single crystals for structure determination involves optimizing, and thus modifying, the conditions of synthesis, in which success cannot be guaranteed. Failure to produce crystals suitable for single-crystal X-ray diffraction leaves the 3D structure of the MOF compound unknown, and scientists must resort to more challenging structure solution methods based on X-ray powder or electron diffraction data. These laborious tasks can be avoided by using serial crystallography techniques which merge data collected on many micro-crystals. Here, we report the application of three synchrotron serial crystallography methods. We call these "mesh", "grid" and "mesh&collect" scans. "Still" images (no rotation) are collected in the mesh scan approach, whereas small rotational wedges are collected in the grid scan method. The third protocol, mesh&collect, combines the acquisition of still images and rotational wedges. Using these means, we determine the ab initio structure of benchmark MOFs, MIL-100(Fe) and ZIF-8, that differ largely in unit cell size. These methods are expected to be widely applicable and facilitate structure determination of many MOF microcrystalline systems. [ABSTRACT FROM AUTHOR]

Five new lanthanide MOFs were prepared by solvothermal synthesis to investigate the effect of ligand and pillar length using the unsymmetrical mixed-donor ligands L1H (4′-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)-[1,1′-biphenyl]-3-carboxylic acid) and L2H (3-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)benzoic acid) and linear pillaring ligands H2BDC (terephthalic acid) and H2BPDC (3,4-dihydro-[1,1′-biphenyl]-4,4′-dicarboxylic acid). Nd-MOF1 and Gd-MOF1, [M(BDC)(L2)]2.5DMA (M = Nd or Gd), were isomorphous. They both presented a 3D pillared framework with bcu topology with a paddlewheel SBU and sinusoidal channels. Nd-MOF2, [Nd(BDC)(L1)]·4DMA, has a pseudo-paddlewheel SBU and formed a 3D pillared pcu framework where 1D double-chains were crosslinked with BDC to provide sinusoidal channels. Gd-MOF2, [Gd2(BPDC)2(L1)2]·9DMA·0.25H2O, has a pseudo-paddlewheel SBU and the 1D double-chains were cross-linked by BPDC to form a regular pcu 3D network which was interpenetrated and has sinusoidal channels. The solvent rich Nd-MOF3, [Nd2(BPDC)(L1)2(DMA)4](OH)2·10DMA, has a pseudo-paddlewheel SBU and formed 1D double-chains which were partially cross linked by BPDC to form a 2D sheet. The bound DMA solvent prevented the extension of these sheets into a 3D framework. Interestingly, the double chains do not interfere with the adoption of a regular topology by the networks. The sinusoidal channels appeared to be a consequence of the unsymmetrical nature of the L1H and L2H ligands. [ABSTRACT FROM AUTHOR]

CO2 is considered the primary contributor to greenhouse gases in the atmosphere and is responsible for several global environmental and energy-related disasters, causing serious concerns because of its adverse impacts on the deterioration of the global ecosystem. Thus, it is now crucial to develop efficient strategies for capturing CO2 and its conversion into desired products. It is anticipated that this will greatly improve the stability of the ecosystem and encourage sustainable expansion in the energy industry. In this case, metal organic frameworks (MOFs) are becoming increasingly popular nowadays as a result of their appealing features including large internal surface area, structural homogeneity, and flexible porosity. This review critically examines the current advancements and real-world applications of metal–organic frameworks for CO2 fixation and its conversion into useful chemical products. Considering this, the contemporary trends and developments in CO2 conversion into cyclic carbonates, formic acid, olefins, methane, carbon monoxide, heterocycles, etc. via cycloaddition, hydrogenation and carboxylation processes are comprehensively deliberated. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. The issue includes various articles and papers on topics such as organic charge transfer complexes, metal organic frameworks, mechanical properties of cocrystals, and scintillation crystals. The journal is published by The Royal Society of Chemistry, a leading chemistry community that reinvests its profits back into the chemistry community. [Extracted from the article]

The crystal structure and electrocatalytic performance of Ni-based MOFs were controlled by the symmetrical engineering of Br functional groups on the terephthalic acid ligand. The asymmetric coordination between metal active sites and the ligand makes Ni-DBC-1Br an excellent OER electrocatalyst with a significantly lower overpotential (247 mV) accompanied by a low Tafel slope of 58.1 mV dec−1 in 1 M KOH (pH = 13.88). [ABSTRACT FROM AUTHOR]

A caged metal–organic framework based on heptanuclear and binuclear copper clusters, namely [Cu9(L)10(H2O)2][Me2NH2+]2 (Cu-MOF) (L = rigid 6-(1H-tetrazol-5-yl)-2-naphthoic acid) was synthesized and structurally characterized by a solvothermal method. Single-crystal X-ray diffraction shows that Cu-MOF displays a three-dimensional porous anionic framework and exhibits a cage-cavity structure. The tri-functional ligand uses two coordination modes to bridge different SBUs to form a dodecahedral cage. Since Cu-MOF possesses both anionic and porous frameworks, it could be used for efficient and selective absorption of cationic organic dyes. Further studies truly showed that both the charge and size of the dye molecules affect the absorption of Cu-MOF. Besides, thanks to the electronic configuration and wide range of visible light absorption properties of the heptanuclear copper clusters, Cu-MOF could be used as a photocatalyst for energy transfer from oxygen molecules to singlet oxygen, and successfully oxidized benzyl alcohol to benzoic acid in air under additive-free mild conditions. Therefore, rationally prepared Cu-MOFs, guided by crystal engineering, demonstrate potential for application as organic dye adsorption separators and photocatalysts, and the feasibility of preparing functionally tailored frameworks using tri-functional ligands consisting of tetrazolium and carboxylate acid is presented. [ABSTRACT FROM AUTHOR]

Designing metal–organic framework (MOF) materials with high conductivity is crucial for their application in energy storage devices. In this study, a simple process, namely, a one-pot hydrothermal method, was used for simultaneously synthesizing the composite of carbon quantum dots (CQDs) and NiCo-MOF, and the effect of various carbon sources for CQDs was compared. The results showed that it was very necessary to choose an appropriate carbon source for obtaining NiCo-MOF with the expected lower Rs and Rct. Carbon sources significantly affected the morphology of NiCo-MOF, and in turn its specific surface area, pore volume and pore size. Particularly, after introducing CQDs derived from citric acid, the electron cloud density around the metal Co atom in the NiCo-MOF composite became higher, improving electron transfer ability, activating the metal center Co and alleviating polarization. As a result, the obtained NiCo-MOF-CA composite exhibited a capacitance of 1826.8 F g−1 at 1 A g−1, significantly higher than that of NiCo-MOF (1060.3 F g−1). An amplifying circuit model was proposed for explaining the phenomenon. Its cyclic performance also became better, but still left to be further improved. The simple synthesis process might be applied to the preparation of other similar composites. In addition, the conductivity of MOFs was improved by introducing specific conductive additives to alter the electronic structure of the metal atom in active materials, providing an effective strategy for other researchers. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. It includes a cover image by Gonzalo Campillo-Alvarado and an inside cover image by Shuai Wang and Xiaoyang Dai. The highlighted articles in this issue include one on multiple synthesis routes for atomically precise noble metal nanoclusters by Lizhong He and Tingting Dong, and another on co-crystal formation versus boron coordination in azopyridines by Jesus Daniel Loya, Sidhaesh A. Agarwal, Nicholas Lutz, Eric W. Reinheimer, and Gonzalo Campillo-Alvarado. The document also mentions professional development opportunities and provides a list of papers featured in the journal. [Extracted from the article]

Among the recent developments in metal–organic frameworks (MOFs), porous two-dimensional (2D) MOFs have garnered attention due to providing key technical supports, important energy-saving measures and precise chemical sensors for the green and sustainable society. Herein, two rare porous 2D Dy3+ MOFs, namely [Dy4L6(DMA)2(H2O)3]·7DMA (1, DMA = N,N-dimethylacetamide) and [Dy2L3(DMF)2]·DMF (2, DMF = N,N-dimethylformamide), have been successfully synthesized from reaction with 4,4′-(1,2-diphenylethene-1,2-diyl) dibenzoic acid (H2L) under different solvent systems. The main distinctions between the crystal structures of 1 and 2 arise from the differing solvent molecules residing within the pores which interact with the surrounding frameworks. These effects lead to different sizes of 1D channels. Importantly, different solvents of coordinated/free DMA molecules in 1 and DMF molecules in 2 induce the conversion of magnetic dynamics. Compound 1 exhibits obvious slow magnetic relaxation behavior under 0 Oe dc field, while zero-field out-of-phase signals of 2 exhibit no peaks in the whole temperature range. Compound 1 was magnetically characterized as a new example that the slow magnetic relaxation process can be observed in a 2D Dy3+ layer with 1D channels. Theoretical analysis based on ab initio calculation provides interpretations of magnetic observation. Additionally, compounds 1 and 2 have been tested as efficient fluorescent sensors for Fe3+ ions with high selectivity and sensitivity. The fluorescence quenching of 1 and 2 was demonstrated by an approximately 90% reduction in the emission intensity upon binding to Fe3+ ions. The emission intensities of 1 and 2 at 464 nm and 443 nm have shown linear responses to Fe3+ ion concentration with detection limits of 4.51 × 106 ppb and 6.90 × 106 ppb. [ABSTRACT FROM AUTHOR]

This work explores the synthesis and DFT study of five tetranuclear Pb(II) complexes and the role of tetrel bonding in their crystal engineering. Three synthesised Pb(II) complexes and two theoretical tetrameric Pb(II) complexes with halogenated thiophene carboxylate and 1,10-phenanthroline ligands are reported here. Their structural configurations, which feature chair-like repeating units connected via oxygen bridges, without Pb–Pb bonds, show two types of packing arrangements. Each Pb atoms form hemidirectional coordination creating space for the formation of tetrel bonds. The close packed arrangements are stabilised and guided by tetrel bonds. The Pb⋯Br tetrel bonds were found to contribute −4.38 kcal mol−1 and Pb⋯Cl −3.37 kcal mol−1 for the stability of the complexes. These tetrel bonds direct the packing arrangements within the crystal lattice. Additionally, open packed arrangements are stabilised by hydrogen bonds. These findings offer new insights into the design of lead-based metal organic frameworks and highlights the critical role of tetrel bonds in the crystal architecture. [ABSTRACT FROM AUTHOR]

The determination of formaldehyde (HCHO) concentration in human exhaled breath can be used as an effective means for the early diagnosis of lung cancer. Lanthanide metal–organic frameworks (LnMOFs) have shown great potential in formaldehyde fluorescence sensing, yet challenges persist in achieving high sensitivity and selectivity. In this work, we report new hydrazine-functionalized LnMOFs (Ln = Eu3+, Gd3+, Tb3+, H2BDC–NH–NH2 = 2-hydrazine-terephthalic acid), having an fcu topology for the sensitive and selective detection of formaldehyde gas. The ligands with hydrazine groups not only act as an "antenna effect" between the ligands and Eu3+ ions, but also act as formaldehyde recognition sites, enabling Eu-BDC–NH–NH2 to be used for fluorescence enhanced sensing of formaldehyde gas in gaseous environments. Eu-BDC–NH–NH2 thus exhibits low detection limit (41.7 ppb), high selectivity, and fast (3 minutes) formaldehyde gas response, showing great potential to be practically applied in the field of early diagnosis of lung cancer. [ABSTRACT FROM AUTHOR]

We report the synthesis, structures and gas sorption studies of two three-dimensional (3D) metal–organic frameworks (MOFs) namely {[Zn2(OBZ)2L1]·4DMF}n (1) and {[Co3(TER)3(L2)(DMF)]·5DMF}n (2), where OBZ2− is deprotonated 4,4′-oxybis(benzoic acid), TER2− is deprotonated terephthalic acid, DMF is N,N-dimethylformamide, L1 is 2,2′-bis(pyridin-3-ylmethyl)-[5,5′-biisoindoline]-1,1′,3,3′-tetraone and L2 is 5,5′-carbonylbis(2-(pyridin-3-ylmethyl)isoindoline-1,3-dione). 1 and 2 are 3D MOFs containing 2D channels. The desolvated phases of 1 and 2 (1-d and 2-d) adsorb modest amounts of carbon dioxide (CO2) at 195 K and 273 K; however, 1-d displays stepwise adsorption of CO2 at 195 K and hysteretic desorption. Notably, a gate-opening effect is triggered after 1-d adsorbs 63 cm3 (STP) g−1, allowing the structure to open and adsorb an additional 54 cm3 (STP) g−1. In contrast, 1-d adsorbs relatively small amounts of hydrogen (H2) and nitrogen (N2) gases, 3 cm3 (STP) g−1 and 12 cm3 (STP) g−1, respectively, suggesting selectivity of CO2 over H2 and N2. [ABSTRACT FROM AUTHOR]

A novel metal–organic framework based on octa-nuclear zinc clusters, namely [Zn4(L)(OH)2(H2O)4] (Zn-MOF) (H6L = hexakis(4-carboxylatophenoxy)cyclotriphosphazene), has been synthesized and structurally characterized by a solvothermal method. Single-crystal X-ray diffraction shows that eight zinc ions form a linear octa-nuclear cluster via a μ3-OH group, and each hexakis(4-carboxylatophenoxy)-cyclotriphosphazene connects four octa-nuclear clusters to construct 3D frameworks with one-dimensional pore structures. Zn-MOF exhibits suitable fluorescence properties, water stability as well as thermal stability, and can be applied as a convenient fluorescent probe for the detection of radioactive uranyl cations (UO22+) and ferric ions (Fe3+) through fluorescence quenching behavior. The corresponding Ksv values can reach 7.44 × 103 M−1 and 1.49 × 104 M−1. Meanwhile, the theoretical calculations fully indicated that the introduction of UO22+ effectively inhibited the metal-to-ligand charge transfer (MLCT) of Zn-MOF, which in turn led to the fluorescence quenching phenomenon. Therefore, Zn-MOF prepared using crystal engineering can be used to construct an efficient and reliable fluorescent probe used in the fields of environmental monitoring and nuclear waste treatment. [ABSTRACT FROM AUTHOR]

The construction of Z-scheme heterojunctions is still a challenge. Structure tailoring and energy band engineering of metal–organic frameworks (MOFs) permit the rational design and fabrication of Z-scheme MOF/graphene oxide (GO) heterojunctions to enhance photocatalytic performance. Herein, a novel Z-scheme Zn-MOF/GO heterojunction as an environmentally friendly, reusable, and highly efficient visible-light-induced photocatalyst for methylene blue (Mb) decoloration and/or Cr(VI) reduction was synthesized. The Zn-MOF/GO composite displayed much higher photodegradation performance than pure Zn-MOF. Besides, the photocatalytic performance of composites is related to the amounts of GO, and Zn-MOF/GO(15%) showed the best activity. Specifically, Zn-MOF/GO(15%) presented 92.6% Mb decoloration, 98.8% Cr(VI) reduction, and the simultaneous removal of Mb (87.9%) and Cr(VI) (99.8%) with good stability. The improved performance for Zn-MOF/GO(15%) can be due to the formation of the Z-scheme heterojunction and built-in electric field, which can not only promote the photogenerated electron–hole separation and transfer, but also broaden the spectrum of light absorption. Furthermore, the improved plausible photodegradation mechanism of Zn-MOF/GO(15%) was provided, and e−, h+ and ·OH were the primary reactive species during the photodegradation reactions. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) zirconium-based metal–organic framework (Zr-MOF) with abundant terminal –OH/–OH2 groups on its nodes, ZrBTB (BTB = 1,3,5-tris(4-carboxyphenyl)benzene), is utilized as a platform for dual post-synthetic modifications (PSM) to immobilize both the benzophenone-based photosensitizer (benzophenone-4,4′-dicarboxylate, bzpdc) and terbium ions onto the 2D Zr-MOF molecular sheets. Terbium ions are installed on the 2D Zr-MOF at various temperatures to adjust the loading of terbium ions on the 2D Zr-MOF while preserving the loading of the photosensitizer. The crystallinity, morphology, porosity, and loadings of both bzpdc ligands and terbium ions are characterized for each material, and the coordinating locations of terbium ions in the Zr-MOF structure are investigated. The photoluminescence (PL) properties of these materials are then examined. Since the installed bzpdc ligand can induce a highly efficient energy transfer to the neighbouring terbium ion upon excitation, the obtained material after dual PSM (ZrBTB-bzpdc-Tb-120) can show strong PL emissions of terbium ions upon the excitation of the bzpdc ligand at 355 nm, with a PL quantum yield of 5.04%. It is more advantageous than the 2D Zr-MOF solely functionalized with terbium ions, which can only exhibit similar emissions upon the excitation of the BTB linker at a less friendly wavelength of 310 nm, with a lower PL quantum yield of 2.94%. Owing to the high chemical stability as well as good dispersity of the luminescent ZrBTB-bzpdc-Tb-120 in water, its performances in selective PL sensing of Fe(III) ions present in aqueous solutions are investigated. [ABSTRACT FROM AUTHOR]

Defects and functional groups on ligands in metal organic frameworks affect porosity and surface area, which successively impacts proton mobility. Defective UiO-66-Hf frameworks with different defect numbers and functional groups were synthesized by adding aromatic monocarboxylic modulators. Thus, an optimal proton conductivity at 4.56 × 10-2 S cm-1 was achieved, which was four orders of magnitude greater than the original UiO-66-Hf. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm, which focuses on the design and understanding of solid-state and crystalline materials. The contents list includes various articles on topics such as ionic liquid-functionalized metal organic frameworks, stable metal azolate frameworks, and the synthesis and properties of a novel insensitive energetic material. The journal is published by The Royal Society of Chemistry, a leading chemistry community. [Extracted from the article]

Herein, we present the synthesis and crystal structure of a series of heteronuclear metal–organic frameworks consisting of cobalt(II) and lanthanide(III) ions or yttrium(III) ions that are connected by oxydiacetato (oda2−) as a ligand. Our investigation led to the discovery of 16 new compounds that were categorized into two distinct structural types. Bigger lanthanide ions (La to Ho) and Y favor the formation of a neutral, highly porous hexagonal structure (space group P6/mcc). This assembly gives rise to nano-sized channels accommodating a significant number of crystallization water molecules (12–14 per formula unit). Conversely, smaller lanthanide ions (Sm to Lu) and Y favor the formation of an extended anionic cubic network neutralized by Co(II) hexaaqua ions (space group Fd3¯c). Both structures are assembled from the same building blocks, [Ln(oda)3]3− and Co(II), connected by either a syn–anti or an anti–anti carboxylate bridge. Both the hexagonal and cubic compounds show the same general formula [Ln2Co3(oda)6(H2O)6]·nH2O with different numbers of crystallization water molecules. Although the formation of different frameworks from the same combination of ligands and metal ions has already been reported, an exceptionally extended phenomenon is observed in this case, encompassing a total of seven isomers from Sm to Ho and Y. The synthesis of these compounds can be achieved either through a direct reaction at room temperature or by a hydrothermal reaction, and this has a marked influence on the obtained crystal structure. Our findings offer valuable data to discuss the rationale concerning the main chemical aspects of the synthetic strategies that can lead to the isolation of a unique pure phase, especially in systems where two structures are feasible. [ABSTRACT FROM AUTHOR]

Post-synthetic modification is gaining prominence as a highly effective strategy for enhancing the functionality of porous materials without significant structural changes. Recently, there is growing interest in research focusing on elevating proton conductivity through the post-synthetically incorporation of ionic liquids (ILs) into metal–organic frameworks (MOFs). This approach is pivotal as it not only addresses the viscosity challenges associated with ILs but also simultaneously resolves the issue of low proton conductivity observed in MOFs under anhydrous conditions. This review aims to provide initial insights into the field of IL-functionalized MOFs designed for enhanced proton conductivity and their composite of mixed matrix membranes (MMMs) for practical usability. [ABSTRACT FROM AUTHOR]

Enantioselective enrichment of R- or S-1-phenylethanol from racemic mixtures, reaching up to 42% enantiomeric excess and >60 wt% loading in the chiral CFA-22 (Coordination Framework Augsburg-22) metal–organic framework prepared from novel, scalable, and readily available camphor-based ligands, is demonstrated through single-crystal X-ray studies in conjunction with chiral high-performance liquid chromatography. [ABSTRACT FROM AUTHOR]

The construction of multifunctional metal-organic frameworks (MOFs) has attracted considerable attention. Two novel Dy-MOFs namely [Dy2(TPTC-2OMe)1.5(H2O)4·H2O]n (1) and {[Dy2(TPTC-2OMe)(H2TPTC-2OMe) (H2O)2]·2H2O}n (2) were obtained by a solvothermal method using 2′,5′-dimethoxy-[1,1′:4′,1″-terphenyl]- 4,4″-dicarboxylic acid (H4TPTC-2OMe) as the ligand. Structure analysis demonstrates that both MOFs 1 and 2 displayed three-dimensional framework structures, in which MOF 1 was with Dy(III) metal chains as nodes, while MOF 2 was with Dy2 binuclear metal clusters as nodes. Interestingly, MOFs 1 and 2 exhibited high thermal and chemistry stabilities and presented relatively high proton conductivity (σ) values of 1.69 × 10-4 S cm-1 and 3.52 × 10-6 S cm-1 at 50 °C and 98% RH. Although there exist a large number of coordinated or free H2O molecules in both structures, it is easier to form an ordered hydrogen-bonding network between the coordinated H2O molecules in the structure of MOFs, resulting in a more excellent proton conductivity of MOF 1. Moreover, MOF 1 exhibited field-induced single-molecule magnet (SMM) behavior with energy barriers (Ueff) of 37.22 K (τ0 = 9.27 × 10-8 s). Furthermore, MOF 1 exhibits obvious second-order nonlinear optical properties. This research provides guidance for the design of novelty multifunctional MOF materials. [ABSTRACT FROM AUTHOR]

The assembly of a metal–organic framework (MOF) containing bent phenanthroline linkers and iron trinuclear clusters remains rare. Herein, we report the synthesis and single crystal structure of a two-dimensional (2D) MOF, Fe-cage-MOF, assembled from 2,9-substituted phenanthroline based carboxylate linkers and pre-synthesized iron trinuclear clusters. The distinctive octahedral cages and ordered 1D channels endow the MOF with permanent porosity and potential for selective capture of the greenhouse gas sulfur hexafluoride. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) have garnered significant interest owing to their tunable structures and versatile properties. In this study, the construction of MOF-74 analogues based on pre-installation of functional ligands has been investigated. Five distinct ligands and their corresponding complexes are synthesized and characterized. The ligands are strategically designed to impart specific functional groups, enabling enhanced reactivity and tailored properties. Building upon the previously synthesized compounds, an efficient method for the directional functionalization of MOF-74 analogues under moderate conditions has been outlined. This method involves pre-installation through directive substitution of the ligands with suitable functional groups viz. –F, –Br, –I, –CH3 and –CN, allowing precise control over the resulting MOF's properties and functionalities. The study presents the characteristics and properties of [Cu(L1)]n (1), [Cu(L3)]n (2), [Cu(L4)]n (3), [Cu(L5)]n (4) and [Cu(L6)]n (5) complexes, highlighting their distinct features and potential applications. The findings from this research contribute to the fundamental understanding of MOF-74 analogues' synthesis and the efficient functionalization of these materials. The outlined methodology opens new avenues for the tailored design of MOFs with desired properties, enabling their potential utilization in diverse applications, such as catalysis, gas storage and luminescence sensing properties. [ABSTRACT FROM AUTHOR]

Angular ligands are a class of important linkers to design and construct new metal–organic frameworks (MOFs). Herein, solvothermal reaction of 4,4′-(4H-1,2,4-triazole-3,5-diyl)dibenzoic acid (TZDB), a triazole-inserted dicarboxylate, acetate, and Cu(NO3)2·3H2O afforded a copper(II)-organic framework of Cu-TZDB. Structural analysis shows that Cu-TZDB displays an unusual (4,6)-c topological network concomitant with the generation of metalloligand [Cu(TZDB)(H2O)2] in situ. Due to its bi-channel cavities replete with triazolate, coordinated water and methyl groups, Cu-TZDB exhibits CO2 selective adsorption over N2 and CH4, which was not only predicted by ideal adsorption solution theory (IAST), but also verified by dynamic column breakthrough tests. [ABSTRACT FROM AUTHOR]

The information-entropy measures of the complexity of nets are proposed that take into consideration both the vertices and edges of nets. The parameters quantify the amount of Shannon information per element (vertex or edge) and per the translationally independent parts of the nets. The nets can be classified according to their complexity into very simple (0–20 bit per cell), simple (20–100 bit per cell), intermediate (100–500 bit per cell), complex (500–1000 bit per cell), and very complex (>1000 bit per cell). The information entropies for 1936 3D nets were calculated and analysed, showing that the simplest (information-poor) nets possess the lowest transitivities. The majority of the most common nets in metal–organic frameworks (MOFs) are the simplest nets within their respective categories (i.e. among the nets with the same coordination of vertices). Since the information is directly related to entropy, which is understood as a statistical parameter, the preference of the simplest nets in MOFs is at least in part governed by their low information contents and high configurational entropies. [ABSTRACT FROM AUTHOR]

Metal–organic framework (MOF)-derived hollow Co3O4 has attracted considerable attention owing to its porosity, high dispersion and large specific surface area. To further improve its activity, well-dispersed Co3O4-decorated MnO2 was successfully fabricated using MnO2@ZIF-67 as the precursor. Initially, MnO2 nanowires were prepared, which acted as a structure-directing support for the growth of ZIF-67. Polyvinylpyrrolidone (PVP) was exploited as a surface stabilizer, growth modifier and dispersant. After calcination, the one-dimensional shish-kebab MnO2@Co3O4 composite was obtained. Subsequently, its oxidase-mimicking performance was validated using 3,3′,5,5′-tetramethylbenzidine (TMB) as the substrate. This composite possessed abundant active sites, continuously ordered hetero-interface, and increased diffusion pathway, and thereby high oxidase-mimicking activity, which was 2 times higher than that of MnO2 and 14.6 times higher than that of Co3O4. The mechanism studies revealed that MnO2@Co3O4 enhanced the O2 adsorption ability and facilitated the production of O2˙− radicals, resulting in improved activity. Considering the selective inhibition of L -cysteine, a sensitive and selective assay for the detection of L -cysteine was established. This work presents an effective strategy for designing new types of hybrid materials with potential prospect in the fields of bioanalysis, catalysis, and environmental monitoring. [ABSTRACT FROM AUTHOR]

Precise control over the crystalline phase and crystallographic orientation within thin films of metal–organic frameworks (MOFs) is highly desirable. Here, we report a comparison of the liquid- and vapour-phase film deposition of two copper-dicarboxylate MOFs starting from an oriented metal hydroxide precursor. X-ray diffraction revealed that the vapour- or liquid-phase reaction of the linker with this precursor results in different crystalline phases, morphologies, and orientations. Pole figure analysis showed that solution-based growth of the MOFs follows the axial texture of the metal hydroxide precursor, resulting in heteroepitaxy. In contrast, the vapour-phase method results in non-epitaxial growth with uniplanar texture only. [ABSTRACT FROM AUTHOR]

Two organic ligands, one rigid and one flexible, were designed and used to construct two cobalt-based metal–organic frameworks (MOFs) with coligands to obtain 3D and 2D structures, respectively. Both the Co-based MOFs were pyrolyzed at different temperatures to obtain the derived materials, and their electrocatalytic hydrogen evolution properties were studied. The results show that the electrocatalytic hydrogen evolution performance of MOF derivatives based on the rigid ligand was better than that of MOF derivatives based on the flexible organic ligand. [ABSTRACT FROM AUTHOR]

This study presents the utilization of 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) radical-immobilized metal–organic frameworks (MOFs) for the oxidative cyclization of aldehydes and aminophenols, leading to the heterogeneous synthesis of 2-substituted benzoxazole molecules. The TEMPO-immobilized MOFs are successfully employed in one-pot sequential aerobic oxidation and oxidative cyclization reactions that enable the synthesis of 2-phenyl benzoxazoles from readily available benzyl alcohols and ortho-aminophenol precursors. The modified MOFs exhibit exceptional reactivity towards benzoxazole synthesis, demonstrating a wide range of substrate compatibilities and efficient performance under simple reaction conditions. Through the implementation of a mixed-ligand approach, precise control over the molar fraction and density of TEMPO radicals is achieved. Among the synthesized catalysts with radical density control, UiO-68-(TEMPO)1.0, which features the complete immobilization of TEMPO, displays the highest catalytic efficiency in the oxidative cyclization process. This enhanced performance can be attributed to the dual involvement of TEMPO species in the proposed reaction mechanism for oxidative cyclization. Notably, the MOF-TEMPO catalyst can be recycled up to five times without any loss of catalytic activity or crystallinity. This research is significant because the sequential approach proposed in this study bridges the TEMPO-catalyzed aerobic oxidation of alcohols and TEMPO-catalyzed oxidative cyclization of aldehydes with aminophenols under the same TEMPO catalyst and O2 atmosphere. [ABSTRACT FROM AUTHOR]

Hierarchically porous metal–organic frameworks (HP-MOFs) possess the advantages of the high porosity of MOFs and unique properties, such as a wide pore size range. Hierarchically porous ZIF-8 (HP-ZIF-8) was facilely fabricated via a one-step method in supercritical CO2 (scCO2) using a competitive ligand. The mesoporous structure and morphology of HP-ZIF-8 can be easily adjusted by changing the dosage of competing ligands and the reaction temperature. When the molar ratio of zinc acetylacetonate, 2-methylimidazole, and 2-butyl-1H-imidazole was 1 : 1 : 6, the HP-ZIF-8 with micropores (1.7 nm) and mesopores (3.9–30 nm) was synthesized at 50 °C and 30 MPa for 3 hours with excellent reproducibility. The as-synthesized ZIF-8 shows a high activity for CO2 adsorption, and the CO2 equilibrium adsorption capacity reached up to 1.49 mmol g−1 sorbent at 25 °C and 0.1 MPa. Moreover, the CO2 equilibrium adsorption capacity of HP-ZIF-8 was maintained at 1.36 mmol g−1 sorbent after 7 cycles. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) with uniform pore size and rich functionality are promising candidates for membrane materials. However, the relatively weak stability of MOFs inhibits their applications in liquid separation. Herein, we proposed a simple and efficient strategy for the preparation of a well-intergrown and stable Ni-MOF-74 tubular membrane by the self-conversion of a nickel-based nanosheet layer (Ni-NSL). In this method, the Ni-NSL not only serves as a metal source for promoting heterogeneous nucleation to achieve high-quality Ni-MOF-74 membranes, but also acts as an inorganic linker between the support and membrane for enhancing membrane stability. Owing to the existence of the Ni-NSL, a thin Ni-MOF-74 membrane with a thickness of ca. 2.5 μm was obtained. The membrane exhibited excellent pervaporation performance with a separation factor of 1094 and a flux of 1.75 kg m−2 h−1 for n-butanol dehydration. Furthermore, the as-prepared Ni-MOF-74 membrane has good stability for 120 h of the separation of n-butanol/water. Therefore, the Ni-MOF-74 membrane by the self-conversion strategy is very promising for pervaporation separation of n-butanol. [ABSTRACT FROM AUTHOR]

High-pressure single crystal X-ray diffraction has been used to probe framework–guest interactions in the Co-based metal–organic framework ZIF-67 during compression in 4 : 1 MeOH : EtOH and liquid nitrogen (LN2) pressure-transmitting media. On increasing pressure, the structure undergoes a gate-opening phase transition, characterised by rotation of the 2-methylimidazolate ligand, at 1.57 GPa in MeOH : EtOH and at 0.43 GPa LN2. Adsorption of N2 occurred progressively with increasing pressure into 6 adsorption sites and resulted in the first documented instance of pressure-induced solvatochromism in ZIF-67. [ABSTRACT FROM AUTHOR]

A dual-emission ratiometric fluorescent sensor consisting of a Tb-based metal organic framework (MOF, Tb-DOBDC) has been developed based on an excited-state proton transfer (ESPT) response linker. Due to the ESPT process, Tb-DOBDC exhibits dual emission, which affords a crucial condition for the detection of ammonia as a ratiometric fluorescent sensor. [ABSTRACT FROM AUTHOR]

Metal–organic frameworks (MOFs) capable of post-synthetic metalation (PSMet) have garnered significant interest as supports for catalytic metals. The Mn-based MOF, MnMOF-1 ([Mn3(L2Me)3] where L2Me = bis-(4-carboxyphenyl-3,5-dimethylpyrazolyl)methane), has been an exemplar for studying PSMet. Herein we investigate the synthesis of Mn-based MOFs from related flexible ditopic pyrazole carboxylate links, along with the formation of MOFs with similar tetratopic hinged linkers. We show for the first time that MnMOF-1 is likely a kinetic or metastable phase and a newly identified 2D layered material (MnMOF-2D) is the thermodynamically favoured product for this metal–linker combination. Formation of a MnMOF-1 structure with shorter linkers is thwarted by steric clashes that preclude the formation of the Mn3 cluster. This observation prompted the use of density functional theory (DFT) simulations that showed the target material to be very dense, highly strained and thereby energetically unfavourable, but potentially, a hypothetical MnMOF-1 structure with a longer phenylethynyl spacer would be energetically feasible. Finally, the predominance of 2D MOFs formed with shorter flexible links encouraged us to use tetratopic hinged linkers to form 3D frameworks, which was vindicated by the successful synthesis of two new porous 3D Mn-based MOFs, MnMOF-L4 and MnMOF-L5. These results highlight that reticular synthesis of MOFs formed with flexible, non-linear linkers is challenging. [ABSTRACT FROM AUTHOR]

By utilizing a winding carboxylic acid ligand as the linker and 12-connected Hf6 clusters as the metal node, we successfully construct a novel hafnium-based metal–organic framework [Hf6O4(OH)4(DCPB)6]·(Hf-MOF, 1,3-di(4-carboxyphenyl)benzene (H2DCPB)) with ultra-microporous structure. Benefitting from the strong coordination bond between Hf6 clusters and the carboxylic acid ligand, the synthesized Hf-MOF displays extraordinarily high thermal and chemical stability, in which the Hf-MOF can maintain high crystallinity under both acidic and basic aqueous solutions, and its decomposition temperature is as high as about 400 °C. Moreover, the interpenetrated framework can endow the Hf-MOF with ultra-microporous pores, which can provide multiple adsorption sites and play a role in the size sieving effect of CO2 molecules. Thus, the Hf-MOF displays excellent CO2 adsorption and separation performance, in which the maximum CO2 adsorption amount can reach up to 65.5 cm3 g−1 at 273 K and 1 bar, and the selectivities for CO2/CH4 = 0.5/0.5 and CO2/CH4 = 0.05/0.95 are as high as 6.9 and 6.0 under 1 bar at 298 K, respectively, and surpass many reported water stable MOF materials. The commendable stability and the CO2 adsorption/separation ability are of extreme importance for its practical industrial applications. [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]

A new Zn(II) metal–organic framework (MOF) with the formula [Zn(BBIP)(2,6-NDC)]n (JXUST-44, BBIP = 3,5-bis(1H-benzo[d]imidazol-1-yl)pyridine and 2,6-H2NDC = 2,6-naphthalic acid) was synthesized under solvothermal conditions. The adjacent Zn(II) ions are connected by BBIP ligands to form one-dimensional (1D) chains, which are further linked by carboxylate groups of 2,6-NDC2− ligands to obtain a two-dimensional layer structure, resulting in a 2D → 3D polycatenated MOF. JXUST-44 can be simplified as a 4-connected sql topology and shows good chemical stability in a wide pH range from 2 to 12 at room temperature. The fluorescence experiments indicate that JXUST-44 presents sensitive and selective detection of salicylaldehyde (SA), acetylacetone (acac) and H2PO4− with the detection limits of 0.074, 10.311 and 0.011 ppm, respectively. It is worth noting that JXUST-44 shows turn-on fluorescence toward acac and H2PO4−, as well as good recyclability and stability for acac, SA and H2PO4−. Therefore, JXUST-44 can be considered as a good fluorescent sensor for acac, SA and H2PO4−. The sensing mechanism has also been studied in detail. [ABSTRACT FROM AUTHOR]

Five Metal–Organic Frameworks ({[M2(tdc)2(L)2]·2DMF}, tdc = 2,5-thiophenedicarboxylate, M = ZnII (1–Zn), CuII (1–Cu), MnII (1–Mn), {[Zn(oba)(L)]·DMF·H2O} (2–Zn), oba = 4,4′-oxybisbenzoate, and {[Zn2(bpdc)2(L)2]·L}, (3–Zn) bpdc = 4,4′-biphenyldicarboxylate) that incorporate the redox-active 2,5-dipyridylthiazolo[5,4-d]thiazole (DPTzTz) ligand (L) have been synthesised and their electronic properties elucidated. The ligand-based organic radicals were generated using in situ techniques and monitored using a suite of solid-state spectroelectrochemistry techniques. The absence of a near infra-red band (NIR), indicating through-space intervalence charge transfer (IVCT), in all analysed materials suggests that both the inter-ligand distance between cofacial TzTz moieties and the flexibility of the TzTz moiety affect the through-space IVCT. [ABSTRACT FROM AUTHOR]

A new Zn(II) metal–organic framework (MOF) with the formula [Zn(BBIP)(2,6-NDC)]n (JXUST-44, BBIP = 3,5-bis(1H-benzo[d]imidazol-1-yl)pyridine and 2,6-H2NDC = 2,6-naphthalic acid) was synthesized under solvothermal conditions. The adjacent Zn(II) ions are connected by BBIP ligands to form one-dimensional (1D) chains, which are further linked by carboxylate groups of 2,6-NDC2− ligands to obtain a two-dimensional layer structure, resulting in a 2D → 3D polycatenated MOF. JXUST-44 can be simplified as a 4-connected sql topology and shows good chemical stability in a wide pH range from 2 to 12 at room temperature. The fluorescence experiments indicate that JXUST-44 presents sensitive and selective detection of salicylaldehyde (SA), acetylacetone (acac) and H2PO4− with the detection limits of 0.074, 10.311 and 0.011 ppm, respectively. It is worth noting that JXUST-44 shows turn-on fluorescence toward acac and H2PO4−, as well as good recyclability and stability for acac, SA and H2PO4−. Therefore, JXUST-44 can be considered as a good fluorescent sensor for acac, SA and H2PO4−. The sensing mechanism has also been studied in detail. [ABSTRACT FROM AUTHOR]

The design and fabrication of a homojunction with similar lattice constant, modulated configuration, and morphology is essential for the efficient separation and transport of photo-generated charge carriers. Herein, the transition metal oxide (NiO) was selected as an example for the fabrication of NiO-porous NiO homojunction. Flower-like Ni(OH)2 was adopted as a template for the fabrication of Ni(OH)2–Ni-MOF, which was then converted to NiO and porous NiO homojunction. Notably, the NiO and the porous NiO derived from Ni(OH)2 and Ni-MOF, respectively, exhibited a different band structure, and hence the homojunction was formed. Due to the enhanced separation efficiency of the photo-generated charge carriers and the more exposed active sites, the optimal NiO@PNiO homojunction exhibited an excellent photocatalytic hydrogen production of 48.67 μmol h−1 g−1, corresponding to 6.7 and 3.4 times that of NiO and porous NiO, respectively. This study provides insight into the design and flexible synthesis of the MOF-derived metal oxide, sulfide, and phosphide homojunction. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal CrystEngComm. It provides information about the journal's focus on the design and understanding of solid-state and crystalline materials. The contents list includes various papers on topics such as emerging porous solids, cationic substructures, spintronic materials, and CO2 utilization. The document also includes information about the journal's editorial board, submission guidelines, and contact information. [Extracted from the article]

Sonochemistry is a specialized field dedicated to investigating ultrasound-promoted (US-promoted) chemical reactions and exploring new applications of US radiation. In recent years, US has been used as a valuable and practical tool combined with emerging porous solids, including metal–organic frameworks, crystalline covalent organic frameworks, and amorphous porous organic polymers, which belong to a family of new functional materials. This review highlights the sonosynthesis of porous solids and explores their use in sonochemical applications, including sonocatalysis and sonodynamic therapy. Moreover, this review presents the first comprehensive introduction to the use of sonochemistry in porous organic material applications. [ABSTRACT FROM AUTHOR]

Highly selective adsorptive separation of propylene/propane (C3H6/C3H8) using metal–organic frameworks (MOFs) is a promising approach to reducing energy consumption in the chemical industry. Here, we report a 3D anionic MOF obtained by the exchange of dimethylamine cations with small K+ ions. 77 K N2 isotherms proved that the pore volume increased from 0.30 cm3 g−1 to 0.42 cm3 g−1 after ion exchange. Moreover, at near room temperatures (273 K and 298 K), both single-component gas adsorption capacity and selectivity of C3H6/C3H8 were enhanced. The C3H6/C3H8 separation potential was further confirmed by breakthrough experiments with equimolar C3H6/C3H8 mixtures. Similar separation properties were also observed in ethylene/ethane separation. [ABSTRACT FROM AUTHOR]

This highlight article features selected examples of heterogeneous catalytic reactions (i.e., industrial and chemical-relevant reactions) using traditional inorganic materials such as silica-based materials (MCM-41 and SBA-15), aluminium-based materials (aluminophosphates and oxides), and zeolites to the evolution of these reactions using novel metal–organic frameworks (MOFs). The textural properties such as the large surface area, high porosity, and high density of active sites, make meso- and micro-porous materials up-and-coming for catalytic applications. Herein, we systematically summarise selected contributions showing the evolution of catalytic active materials (from classic to new generation candidates), and we provide an overview of the reactions where the crystalline structure and the surface area of these materials play a crucial role in the solid–liquid and solid–gas catalytic reactions. [ABSTRACT FROM AUTHOR]

The optimisation of the crystallisation of the hydrothermally-stable metal–organic framework Yb6-MOF (Yb6(BDC)7(OH)4(H2O)4) to provide a reproducible one-step synthesis is achieved by use of the sodium salt of benzene-1,4-dicarboxylate (Na2BDC) as ligand precursor and control of pH with aqueous NaOH at 190 °C over 3 days. Phase purity is confirmed using powder X-ray diffraction (PXRD) and thermogravimetric analysis (TGA). During exploration of synthesis conditions from the same set of chemical reagents, three further ytterbium benzene-1,4-dicarboxylates have been isolated and structurally characterised using single-crystal X-ray diffraction, with phase purity assessed by PXRD and TGA. UOW-3 (Yb2(H2O)6(BDC)3) crystallises by lowering pH, and has a relatively dense three-dimensionally connected structure with no Yb–O–Yb linkages but dimers of Yb bridged by BDC linkers lying in the ab plane with a pseudo, pillared-layered structure, where BDC connects along c. UOW-4 (Yb4(BDC)6(H2O)6) forms under the same chemical conditions but upon lowering the temperature to 100 °C, and this material again contains no Yb–O–Yb linkages, but chains of BDC-bridged Yb centres cross-linked to give a dense three-dimensional structure. Upon increasing pH of the synthesis mixture, the material UOW-5 forms, Yb5O(OH)8(BDC)2(HBDC), consisting of dense inorganic layers of ytterbium oxyhydroxide, cross linked by BDC and HBDC pillars. The formulation is supported by infrared spectroscopy, which provides evidence for the HBDC monoanion, and also the presence of a short O–O distance indicative of hydrogen bonding between a carboxylate OH and an oxide anion of the inorganic layer. UOW-3 and UOW-4 both convert to Yb6-MOF upon heating in water above their synthesis temperature, whereas UOW-5 is hydrothermally stable at 240 °C. The structures of the new materials are discussed in terms of ligand binding modes, and connectivity of metal centres, with comparison to other reported Yb-BDC phases in order to relate structural chemistry to their synthesis conditions and the hydrothermal stability of the materials. [ABSTRACT FROM AUTHOR]

Design of metal–organic frameworks (MOFs) with elaborate structural features is of great significance for their applications with improved performances. In this work, we report the construction of unique zinc-based zeolite imidazole framework (ZIF-8) microrings via an anisotropic growth-etching route. The synthesis relies on the anisotropic deposition of ZIF-8 crystals on the edges with coordinatively unsaturated Zn2+ of leaf-like ZIF (ZIF-L) nanosheets and subsequent selective etching of alkaline unstable ZIF-L. Furthermore, functional carbon materials with a ring-like structure can be prepared by pyrolysis of ZIF-8 microrings as precursors, exhibiting enhanced oxygen reduction reaction performance compared to the traditional ZIF-8 derived counterparts. Our work may pave the way for the design of MOFs with sophisticated micro/nanostructures. [ABSTRACT FROM AUTHOR]

We highlight two key examples of where the achirality of reagents used in MOF syntheses transposes to chiral structures, thereby expanding the potential ligand pool used in the future design of chiral MOFs. Herein, we report the characterisation of two new chiral CdIIMOFs: (1) a pair of enantiomorphous structures produced from the achiral bicyclo[1.1.1]pentane-1,3-dicarboxyate linker, [Cd(pdc)(DMF)] (pdc = bicyclo[1.1.1]pentane-1,3-dicarboxylate; DMF = N,N-dimethylformamide) (3DL-MOF-3), and (2) a similar chiral network featuring cubane-1,4-dicarboxylate, [Cd3(cdc)3(DMF)3] (cdc = cubane-1,4-dicarboxylate) (3DL-MOF-4). Conventional solvothermal synthesis of 3DL-MOF-3 yields a conglomerate of two enantiomorphs that spontaneously resolve into their respective right- or left-handed chiral hexagonal space groups (space groups P61/P65). Similarly, 3DL-MOF-4 resolves into a non-centrosymmetric orthorhombic phase (P21212). Both 3DL-MOF-3 and 3DL-MOF-4 possess infinitely-linked, chiral, and 1D Cd-O helical chains which are observed to be the apparent cause of chirality in each system. In both cases, homochirality is preserved within each individual crystal where only one type of helical handedness is observed. We consider a general mechanism for this preservation of homochirality to include an avoidance of a physical analogue of geometric frustration which manifests due to the tripartite nature of the underlying triangular lattice upon which each chiral chain is located. [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]

Electrocatalysis plays a significant role in many value-added chemical transformations in advanced clean energy production technologies such as fuel cells and metal–air batteries. Among various catalysts, traditional materials made of noble metals are widely used as electrocatalysts; however, they often suffer from disadvantages such as low abundance, low surface area, and high cost. The intrinsic advantages of metal–organic frameworks (MOFs) have been explored in various application fields. However, their insulating property and poor electrolyte stability limited their utility in desirable technologies such as fuel cells, batteries, and supercapacitors. New designs and synthetic strategies have ushered in a new era of fabricating electrocatalytically active MOFs for energy and environmental concerns. This review details the synthetic approaches to fabricate electrocatalytically active pristine MOFs and their recent progress in electrocatalytic applications such as oxygen reduction, oxygen/hydrogen evolution, and carbon dioxide reduction. The present review assists in advancing MOF research in emergent technologies such as fuel cells and metal–air batteries. [ABSTRACT FROM AUTHOR]