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Encapsulation of enzymes within porous materials has shown great promise for protecting enzymes from denaturation, increasing their tolerance to harsh environments and promoting their industrialization. However, controlling the conformational freedom of the encapsulated enzymes to enhance their catalytic performance remains a great challenge. To address this issue, herein, following immobilization of GOx and HRP on a thermo-responsive porous poly(styrene-maleic-anhydride- N -isopropylacrylamide) (PSMN) membrane, a GOx-HRP@PSMN@HZIF-8 composite was fabricated by encapsulating GOx-HRP@PSMN in hollow ZIF-8 (HZIF-8) with liposome (L) as the sacrificial template. The improved conformational freedom for enzymes arising from the hollow cavity formed in ZIF-8 through the removal of L enhanced the mass transfer and dramatically promoted the catalytic activity of the composite. Interestingly, at high temperature, the coiled PN moiety in PSMN provided the confinement effect for GOx-HRP, which also significantly boosted the catalytic performance of the composites. Compared to the maximum catalytic reaction rates ( V max ) of GOx-HRP@PSMN@LZIF-8, the free enzyme and GOx-HRP@ZIF-8, the V max of the GOx-HRP@PSMN@HZIF-8 composite exhibited an impressive 17.8-fold, 10.8-fold and 6.0-fold enhancement at 37 °C, respectively. The proposed composites successfully demonstrated their potential as catalytic platforms for the colorimetric detection of glucose in a cascade reaction. This study paves a new way for overcoming the current limitations of immobilizing enzymes in porous materials and the use of smart polymers for the potential fabrication of enzyme@polymer@MOF composites with tunable conformational freedom and confinement effect.

Bioinspired metal-organic frameworks (MOFs) serve as suitable crystalline models for recognition and sensing of biomolecules mimicking natural processes, providing new ideas and concepts for cutting-edge biomedical applications. Here, we have successfully prepared a robust biological metal-organic framework with periodic docking grooves resembling the major and minor grooves in the DNA double helix structure, which can be used as unique recognition sites for selectively identifying l-/d-tryptophan (l-/d-Trp). Notably, successful encapsulation of Trp could be observed by single-crystal X-ray diffraction for the first time. Trp has matched size and shape to fit snugly into the major groove. Combined with isothermal titration calorimetry, it was found that ZnBTCHx could spontaneously capture l-/d-Trp through two different thermodynamic pathways: enthalpy-driven for encapsulating l-Trp and entropy-driven for uptaking d-Trp. Furthermore, molecular dynamics and density functional theory verified the role of hydrogen bonding and π-π/C-H···π interactions in the host-guest interface. This work provides unique insight for the construction of bionic models to mimic the natural binding properties, which is of great significance for the fields of pharmaceutical chemistry and biomedical science.

Two isostructural pillar-layer MOFs (JNU-105 and JNU-105-(NH2)2) have been successfully synthesized. JNU-105-(NH2)2 exhibits a red-shifted luminescence "turn on" for formaldehyde without the interference from other VOCs and a detection limit of 1.87 ppb. In situ single-crystal transformation studies confirm the aminal formation on the pillar linker, which was attributed to the exclusive luminescence response toward formaldehyde.

Metal-organic cages are potential artificial models for mimicking biological functions due to their capability of selective encapsulation for certain guest molecules. In this work, we designed and synthesized a series of rhombic dodecahedral Ni-imidazolate cages (Ni 14 L 24 ) with precisely controlled aperture for CO 2 encapsulation. The aperture of the cages can be tuned by the strategies of ligand decoration and metal-ion hybridization. Similar to the breathing function of alveoli, CO 2 passes through the dynamic aperture into the cages under a pressure of 2.0-3.0 bar in methanol solution, and slowly move out of the cages when the pressure goes down. In the solid state, CO 2 is encapsulated and prisoned in the cages under a high pressure of 15.0-30.0 bar or supercritical conditions. By replacing the square-coordinated Ni 2+ with Cu 2+ , the resulting Ni-Cu heteronuclear cage lost the capability of physically encapsulating CO 2 even though the aperture's size is only slightly changed.

Metal‐organic frameworks (MOFs) that exhibit dynamic phase‐transition behavior under external stimuli could have great potential in adsorptive separations. Here we report on a zinc‐based microporous MOF (JNU‐80) and its reversible transformation between two crystalline phases: large pore (JNU‐80‐LP) and narrow pore (JNU‐80‐NP). Specifically, JNU‐80‐LP can undergo a dehydration‐induced cluster consolidation under heat treatment, resulting in JNU‐80‐NP with a reduced channel that allows exclusion of di‐branched hexane isomers while high adsorption of linear and mono‐branched hexane isomers. We further demonstrate the fabrication of MOF‐polymer composite (JNU‐80‐NP‐block) and its application in the purification of di‐branched isomers from liquid‐phase hexane mixtures (98 % di‐branched) at room temperature, affording the di‐branched hexane isomers with 99.5 % purity and close to 90 % recovery rate over ten cycles. This work illustrates an interesting dehydration‐induced cluster consolidation in MOF structure and the ensuing channel shrinkage for sieving di‐branched hexane isomers, which may have important implications for the development of MOFs with dynamic behavior and their potential applications in non‐thermal driven separation technologies. [ABSTRACT FROM AUTHOR]

Hollow nanoporous carbon architectures (HNCs) present significant utilitarian value for a wide variety of applications. Facile and efficient preparation of HNCs has long been pursued but still remains challenging. Herein, we for the first time demonstrate that single‐component metal–organic frameworks (MOFs) crystals, rather than the widely reported hybrid ones which necessitate tedious operations for preparation, could enable the facile and versatile syntheses of functional HNCs. By controlling the growth kinetics, the MOFs crystals (STU‐1) are readily engineered into different shapes with designated styles of crystalline inhomogeneity. A subsequent one‐step pyrolysis of these MOFs with intraparticle difference can induce a simultaneous self‐hollowing and carbonization process, thereby producing various functional HNCs including yolk‐shell polyhedrons, hollow microspheres, mesoporous architectures, and superstructures. Superior to the existing methods, this synthetic strategy relies only on the complex nature of single‐component MOFs crystals without involving tedious operations like coating, etching, or ligand exchange, making it convenient, efficient, and easy to scale up. An ultra‐stable Na‐ion battery anode is demonstrated by the HNCs with extraordinary cyclability (93 % capacity retention over 8000 cycles), highlighting a high level of functionality of the HNCs. [ABSTRACT FROM AUTHOR]

Separation of acetylene (C2H2) from carbon dioxide (CO2) or ethylene (C2H4) is industrially important but still challenging so far. Herein, we developed two novel robust metal organic frameworks AlFSIX‐Cu‐TPBDA (ZNU‐8) with znv topology and SIFSIX‐Cu‐TPBDA (ZNU‐9) with wly topology for efficient capture of C2H2 from CO2 and C2H4. Both ZNU‐8 and ZNU‐9 feature multiple anion functionalities and hierarchical porosity. Notably, ZNU‐9 with more anionic binding sites and three distinct cages displays both an extremely large C2H2 capacity (7.94 mmol/g) and a high C2H2/CO2 (10.3) or C2H2/C2H4 (11.6) selectivity. The calculated capacity of C2H2 per anion (4.94 mol/mol at 1 bar) is the highest among all the anion pillared metal organic frameworks. Theoretical calculation indicated that the strong cooperative hydrogen bonds exist between acetylene and the pillared SiF62− anions in the confined cavity, which is further confirmed by in situ IR spectra. The practical separation performance was explicitly demonstrated by dynamic breakthrough experiments with equimolar C2H2/CO2 mixtures and 1/99 C2H2/C2H4 mixtures under various conditions with excellent recyclability and benchmark productivity of pure C2H2 (5.13 mmol/g) or C2H4 (48.57 mmol/g). [ABSTRACT FROM AUTHOR]

To develop a simple and general method for improving the circularly polarized luminescence (CPL) performances of materials is of great significance. In this work, two pairs of CPL‐active homochiral metal–organic frameworks (MOFs) P/M‐Et and P/M‐Et(Cd) with eta topology are reported. In comparison to the reported isomorphic Zn‐imidazolate MOFs P‐Me and M‐Me, both luminescence dissymmetry factor (glum) and photoluminescence quantum yields (ΦPL) of P‐Et and M‐Et are largely improved by simply changing the methyl group to an ethyl group of ligands in P‐Et and M‐Et. Furthermore, the |glum| values are significantly amplified up to 0.015 from 0.0057 by introducing the non‐luminescent halogenated aromatics, while an enhanced fluorescence efficiency is observed simultaneously (from 27.2% to 47.3%). The figure of merit value is about 40 times larger than that of P‐Me and M‐Me. Similarly, the CPL performances of P/M‐Et(Cd) are improved by about five times after encapsulating fluorobenzene molecules. This work represents a new and simple method for developing CPL‐active MOF materials. [ABSTRACT FROM AUTHOR]

Because of their misuse and poor management, antibiotics pose a significant threat to the ecological environment and human health. The development of highly sensitive and effective sensors to detect such environmental contaminants is a crucial and challenging task. As a new class of desirable biocompatible materials, biological metal‐organic frameworks are considered as a viable platform for sensing applications. Herein, we report the synthesis of biological luminescent metal‐organic framework [Zn6Ad4(BPDC‐(OH)2)4]n (JNU‐104) using adenine (Ad) and 2,2′‐dihydroxy‐1,1′‐biphenyl‐4,4′‐dicarboxylic acid [BPDC‐(OH)2] as organic linkers. JNU‐104 serves as a robust and sensitive luminescent sensor for detecting tetracycline antibiotics in aqueous media with low limits of detection (LODs) of 0.023, 0.029 and 0.024 μM for tetracycline (TC), oxytetracycline (OTC), and chlortetracycline (CTC), respectively. Furthermore, the MOF‐based test strips show a rapid and visualizable luminescence response to tetracycline antibiotics, making JNU‐104 a promising candidate for practical applications in sensing. [ABSTRACT FROM AUTHOR]

A two-dimensional (2D) chiral heterometallic Zn(II)-Cd(II) metal-organic framework (MOF), {[(CdI2(ZnL)2·DMF}n (1, H2L = (R,R)-N,N'-bis(3-(4-pyridyl)salicylidene)-1,2-cyclohexanediamine, DMF = N,N-dimethylformamide), was synthesized with predesigned chiral metallosalen ZnL and CdI2 via solvothermal reaction. MOF 1 crystallizes in the orthorhombic chiral space group P21212 and exhibits a 2D chiral framework consisting of right (P) handed 21 helices. Topological analysis indicates that the 2D structure of 1 could be simplified as a uninodal sql topology. The luminescence experiment revealed that MOF 1 showed intense circularly polarized luminescence (CPL), suggesting that it can be a potential CPL material. [ABSTRACT FROM AUTHOR]

Gyroid materials have received considerable attention from scientists due to their beautiful structures and advanced functions. On the other side, metal–organic frameworks are inorganic–organic hybrid crystalline porous materials with atomic precision, and can provide good structural models and rich topologies for gyroid materials. In this review, we will briefly introduce the structures of gyroid metal–organic frameworks and their topologies. In addition, their applications in gas adsorption, catalysis, sensors, and luminescent materials are also discussed in detail. [ABSTRACT FROM AUTHOR]

A variety of planar organic fluorophores (R=phenyl, naphthalenyl, pyrenyl) and luminescence promotors (X=Cl, Br, I) were equipped, respectively, on the alternatively arranged vertices of cubic ZnII‐imidazolate cages through orthogonal subcomponent self‐assembly. It was found that supramolecular interactions, especially weak C−H⋅⋅⋅X interactions, play a key role in activating an efficient radiative pathway, coupled with reduced nonradiative decay rate through metal coordination, therefore significantly boosting the emission quantum yields of the system. This finding provides a strategy that utilizes molecular geometry and supramolecular interactions to modulate the emission efficiency of luminescent cage‐based materials. [ABSTRACT FROM AUTHOR]

Chiral coordination cages feature both chirality and defined inner space, providing advanced molecular materials. A series of chiral 20-nucleus cobalt- imidazolate cages were synthesized by self-assembly of 72 subcomponents, featuring a novel tetartoid (tetragonal pentagonal dodecahedron) structure. Spontaneous resolution of racemic tetartoidal cages (Δ and Λ) into a conglomerate of homochiral crystals are observed, while both homochiral Δ and Λ tetartoidal cages can be obtained through chiral induction of (D)- and (L)- enantiomers of menthol, respectively. The 2-methyl substituent on imidazolyl is critical to the formation of a tetartoidal cage, and the absence of such steric effect will switch the final structure to a cubic cage. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel TIFSIX pillared MOF is prepared with unprecedented zsd topology. • Cooperative Ti-F···HC≡CH···N(DIB) hydrogen bonding for strong C 2 H 2 capture. • High C 2 H 2 capacity and high selectivity over CO 2 , C 2 H 4 , and CH 4. • Excellent practical C 2 H 2 separation performance from quaternary mixtures. The separation of acetylene (C 2 H 2) from carbon dioxide (CO 2) and other C 1 -C 2 light hydrocarbons is important to produce C 2 H 2 in high purity as well as recover other gases. However, it is challenged by the trade-off between the adsorption capacity and selectivity due to the similar physical properties. In this work, we reported a new TiF 6 2− anion (TIFSIX) pillared porous metal organic framework ZNU-4 (ZNU = Zhejiang Normal University) with unprecedented zsd topology for selective C 2 H 2 capture. The utilization of 1,4-di(1H-imidazol-1-yl)benzene (DIB) as the organic linker in ZNU-4 generates a highly twisted framework, resulting in a distinctive topological net with unique narrow 1D channels suitable for C 2 H 2 trap. ZNU-4 features robust-flexible isotherms for C 2 H 2 adsorption and the capacity under 1 bar and 298 K is as high as 85 cm3/g, 1.9, 2.1 and 7.1 folds of CO 2 , C 2 H 4 and CH 4 uptake. The IAST selectivity of C 2 H 2 over CO 2 , C 2 H 4 , CH 4 is 9, 12, and 300, respectively, higher than those of most popular porous materials. Modelling study indicated that C 2 H 2 is trapped by cooperative Ti-F···HC≡CH···N(DIB) hydrogen bonding along with other weak Van der Waals interactions. Such cooperative bonding interactions have never been disclosed in other fluorinated anions pillared MOFs due to the absence of second binding site from organic linkers. The breakthrough experiments further confirmed the highly selective C 2 H 2 separation performance from binary C 2 H 2 /CO 2 mixtures, ternary C 2 H 2 /CO 2 /CH 4 mixtures and quaternary C 2 H 2 /CO 2 /CH 4 /C 2 H 4 mixtures. The separation factor of ZNU-4 for equimolar C 2 H 2 /CO 2 mixture is 5.4, superior to those of many other benchmark materials. [ABSTRACT FROM AUTHOR]