Molecular-Rotor-Engineered Metal-Organic Frameworks with Various Interpenetrated Degrees/Modes Featuring Tunable Porosity/Stability for Binary/Ternary C2H2/CO2/C2H4 Separation.

Efficient separation of challenging acetylene/ethylene (C 2 H 2 /C 2 H 4 ) and acetylene/carbon dioxide (C 2 H 2 /CO 2 ) mixtures is crucial for the chemical industry. Interpenetrated metal–organic frameworks (MOFs) hold significant promise for separating complex gas mixtures but often face a trade‐off between porosity and stability. Herein, three different entangled degrees and modes of MOFs, namely Ni‐dcpp‐bpb , Ni‐dcpp‐bpn , and Ni‐dcpp‐bpan , were yielded by the crystal engineering strategy using molecular‐rotor‐based co‐ligands (benzene, naphthalene, and anthracene groups) to systematically modulate their porosity and stability. As expected, the stable Ni‐dcpp‐bpb / Ni‐dcpp‐bpn achieve enhanced porosity (27.2%/32.1%) and improved C 2 H 2 uptake (73.9/75.8 cm 3 g −1 , 298 K, 100 kPa). Interestingly, Ni‐dcpp‐bpan exhibits the unique rotor‐driven gating effect with free bpan ligands, facilitating the pressure‐dependent switching between nonporous (10.8%) and open states at 195 K. Breakthrough experiments confirm excellent C 2 H 2 separation performance from binary/ternary mixtures and achieve one‐step purification of C 2 H 4 (>99.9%) from C 2 H 2 /CO 2 /C 2 H 4 (1/9/90, v/v/v) mixture with a new benchmark productivity of 396.9 L kg −1 ( Ni‐dcpp‐bpb ). Theoretical calculations and in situ IR spectra reveal that C 2 H 2 /C 2 H 4 and C 2 H 2 /CO 2 separation are primarily governed by the abundant C─H⋯O/N and C─H⋯π interactions. This study establishes a molecular‐rotor‐engineered approach to precisely modulate interpenetration in MOFs and offers a robust platform for high‐performance gas purification.

Steady state fluorescence has been used to study the efficiency of nonradiative single energy transfer for naphthalene → naphthalene and naphthalene → anthracene for polyesters and their bichromophoric model compounds. Polyesters containing only naphthalene groups were derived from 2,6‐naphthalene dicarboxylic acid as the rigid unit, and two series of glycols, HO(CH2)mOH and HO(CH2CH2O)n;OH, where m=2–6 and n=1–4, as flexible spacers. Bichromophoric model compounds were derived from 2‐naphthoic acid and the same glycols. In order to study the transfer for naphthalene → anthracene, a first attempt was made by studying bichromophoric model compounds D(CH2)mA, where D and A denote 2‐naphthoate (donor) and 9‐anthranoate (acceptor) groups, respectively. The fluorescence anisotropy measurements in a solid matrix of glassy poly(methyl methacrylate), for the compounds containing only naphthalene groups, and the simple excitation and emission spectra, for the compounds containing naphthalene and antharacene groups, clearly demonstrate the presence of non‐radiative singlet–singlet energy transfer, the efficiency of which depends mainly on n (or n). A theoretical treatment using the rotational isomeric state model of the conformatin of these molecules has also been performed. The combination of the experiments and the theoretical analysis establishes that the Förster radii are 1.2 and 1.4 nm for the naphthalene → naphthalene transfer in the bichromophoric model compounds and polyesters, respectively, and 1.6 ± 0.2 nm for the naphthalene → anthracene transfer in the model compounds studied.

Herein, we report coupling in situ high temperature postsynthetic modifications (PSMs) in metal-organic frameworks (MOFs). Thermo-reactive propargyloxy-functionalized zinc IRMOFs (isoreticular metal-organic frameworks) prepared from 2-(prop-2-yn-1-yloxy)-[1,1'-biphenyl]-4,4'-dicarboxylic acid (H2bpdcOCH2CCH) were investigated for their high-temperature postsynthetic rearrangement (PSR) chemistry to heterocyclic chromenes and benzofurans and then coupled to solid-gas reactions with molecular oxygen. The selectivity for the initial molecular rearrangements was found to be inverted in the porous MOF environment compared to conventional melt reactions of the ester compound Me2bpdcOCH2CCH and proceeded far more easily than the solid-state transformation from H2bpdcOCH2CCH, showing the potential of MOFs to give rise to different chemistry. The major oxidative process was thermolysis of the chromene ring with a minor pathway of allylic-type oxidation to give heterocyclic chromenone functionality. The sequence was also successful on a series of two-component multivariate IRMOF frameworks prepared from thermo-reactive H2bpdcOCH2CCH and thermo-resistant H2bpdcOMe linkers, demonstrating that these reactions can be used with known crystal engineering strategies. All transformations were fully compatible with the requirements to maintain MOF crystallinity and porosity as evidenced by surface area analysis and X-ray powder diffraction measurements. This work contributes to establishing the feasibility of high-temperature solid-gas manifolds for MOF PSM.

Fluorous Metal–Organic Frameworks with Unique Cage-in-Cage Structures Featuring Fluorophilic Pore Surfaces for Efficient C ₂ H ₂ /CO ₂ Separation

Anode-Driven Controlled Release of Cathodic Fuel via pH Response for Smart Enzymatic Biofuel Cell.

Imparting Superhydrophobicity to Porphyrinic Coordination Frameworks Using Organotin

Metal organic frameworks (MOFs) are attracting increasing attention in the field of pollution control due to their inherent characteristics, such as high porosity, large specific surface areas, and tunable structure and composition. Though more than 20000 kinds of MOFs structures have been reported so far, the majority of them are regular and composed of different kinds of building units. Defect engineering in MOFs is an exciting concept for tailoring material properties, which opens up novel opportunities in practical application. Defects are usually present in MOFs, which would alter the performance of MOFs by changing surface properties, pore structure, and the number of active sites. Since defects can enhance the performance of MOFs in adsorption and catalytic degradation of pollutants, various methods for designing and generating defects have been employed. Based on selected reports spanning the last decades, this review focuses on the most recent and significant developments in the classification of defects in MOFs and methods of introducing defects into MOFs. According to the composition of MOFs, defects can be divided into missing-linkers defect and missing-clusters defect. The main methods of introducing defects into MOFs include de novo synthesis and post-synthetic treatment. De novo synthesis method includes mixed linker approach, modulation approach and fast crystal growth approach. Post-synthetic treatment method involves acid/base treatment approach, harsh activation approach, solvent-assisted linker exchange and mechanical treatment approach. The use of defective MOFs as adsorbent and catalyst in pollutant removal is also highlighted. Because single physical-chemical characterization has its limitations, researchers adopt various techniques to characterize the existence and concentration of defects, such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), etc. Reasonable defects could be controlled by adjusting the synthesis conditions in an attempt to obtain MOFs with excellent performance in adsorption and catalysis. At the hand of adsorption, the adsorption of pollutants in water and gases onto defective MOFs is mainly affected by pore distribution, specific surface area and surface charge. The introduction of missing-linkers defect or missing-clusters defect would make the regular pore structure into locally disordered structure, and create new micropores, mesopores even macropores. Thereby, the pore volume and specific surface area of MOFs are increased, and then enhancing the adsorption performance. In view of photocatalysis, introducing defects into photo-responsive MOFs can not only promote the transfer of photo-generated electrons, but also inhibit electron-hole recombination, and even optimize the energy band structure, which synergistically results in the improvement of photocatalytic performance. From the perspective of chemical catalysis, the pores formed by missing-linkers defect or missing-clusters defect in MOFs would expose the interior surface, which creates additional catalytic sites for pollutants reaching, and then enhances the catalysis performance of MOFs. In short, defective MOFs have a wide range of applications in the fields of adsorption and catalysis. After summarizing the recent progress of the field, the advantages and shortcomings of present defective MOFs in pollution control are presented. On the basis of this, it is apparent that further deepening the basic theoretical study of defective MOFs will be helpful for its wide applications. The defect engineering of MOFs is beneficial for further industrialization. Finally, some potential research topics in construction of defects in MOFs for environmental application have also been proposed in the review.

As a modulatable class of porous crystalline materials, metal-organic frameworks (MOFs) have gained intensive research attention in the domain of gas storage and separation. In this study, we report on the synthesis and gas adsorption properties of two robust MOFs with the general formula [Co3(μ3-OH)(cpt)3Co3(μ3-OH)(L)3(H2O)9](NO3)4(guests) n [L = 3-amino-1,2,4-triazole (1) and 3,5-diamino-1,2,4-triazole (2); Hcpt = 4-(4-carboxyphenyl)-1,2,4-triazole], which show the same pacs topology. Both MOFs are isostructural to each other and show MIL-88-type frameworks whose pore spaces are partitioned by different functionlized trinuclear 1,2,4-triazolate-based clusters. The similar framework components with different amounts of functional groups make them an ideal platform to permit a systematic gas sorption/separation study to evaluate the effects of distinctive parameters on the C2H2 uptake and separation performance. Because of the presence of additional amido groups, the MOF 2 equipped with a datz-based cluster (Hdatz = 3,5-diamino-1,2,4-triazole) shows a much improved C2H2 uptake capacity and separation performance over that of the MOF 1 equipped with atz-based clusters (Hatz = 3-amino-1,2,4-triazole), although the surface area of the MOF 1 is almost twice than that of the MOF 2. Moreover, the high density of open metal sites, abundant free amido groups, and charged framework give the MOF 2 an excellent C2H2 separation performance, with ideal adsorbed solution theory selectivity values reaching up to 11.5 and 13 for C2H2/C2H4 (1:99) and C2H2/CO2 (50:50) at 298 K and 1 bar, showing potential for use in natural gas purification.

Simultaneous quantitative recognition of all purines including N6-methyladenine via the host-guest interactions on a Mn-MOF

The effect of linkers with extended π-system on the topological preference of (4,4)-connected copper paddle-wheel-based metal–organic frameworks (MOFs) was investigated using the reverse topological approach (RTA) in which a genetic algorithm (GA) and the DFT-derived force field MOF-FF were used for ranking and predicting the most stable phase. Three tetracarboxylate linkers bearing different functionality, namely, phenylene (L1), naphthalene (L2), and anthracene (L3) groups, were studied. All potential topologies including nbo-b, ssa, ssb, pts, and lvt-b were considered. The computational results reveal that nbo-b is the most stable topology for all three investigated linkers. However, L2 is also formed in ssb according to experimental findings. Our simulation results show that the CH−π interactions with a Y-shaped configuration between naphthalene moieties of L2 stabilize the ssb framework. Unlike L2, CH−π interactions are not favorable for L1 and L3 because of unsuitable size of the π-system. The resul...

Ultrafine PdRu Nanoparticles Immobilized in Metal–Organic Frameworks for Efficient Fluorophenol Hydrodefluorination under Mild Aqueous Conditions

Porous carbon materials based on MOFs in microwave absorbing

Self-Assembly Ultrathin Fe-Terephthalic Acid as Synergistic Catalytic Platforms for Selective Hydrogenation

Topological Strain-Induced Regioselective Linker Elimination in a Chiral Zr(IV)-Based Metal-Organic Framework

Mixed-matrix membranes (MMMs) with excellent mechanical and separation performance are usually challenging to be fabricated due to the significant incompatibility between nanofillers and the polymer matrix. This work provides a facile technique to construct MMMs through covalently attaching metal-organic frameworks (MOFs) within the polymer matrix via ring-opening metathesis polymerization. Norbornene-modified UiO-66-NH2 was successfully copolymerized into polynorbornene matrix in less than 10 min. Owing to strong covalent interaction among MOFs and polymers, exceptional toughening effects for MMMs through cavitation were observed. For MMMs with 20 wt % MOF loading, 520 times improvement in mechanical toughness was realized in comparison with neat polymers (52 vs 0.1 MJ/m3), far exceeding most of the previous MMMs. Such MMMs exhibited excellent gas separation performance for H2/CO2 and H2/N2 with high H2 permeability at 91-230 barrers and H2/N2 and H2/CO2 selectivity at >1000 and 6-7, respectively, surpassing the 2008 Robeson Upper Bound. As a proof for the scalable preparation of MMMs, a large and thin MMM (dimension: 98 × 165 cm; thickness: 3-5 μm) was also prepared in the factory for gas separation.