Encapsulation of biomacromolecules in metal− organic frameworks (MOFs) can preserve biological functionality in harsh environments. Despite the success of this approach, termed biomimietic mineralization, limited consideration has been given to the chemistry of the MOF coating. Here, we show that enzymes encapsulated within hydrophilic MAF-7 or ZIF-90 retain enzymatic activity upon encapsulation and when exposed to high temperatures, denaturing or proteolytic agents, and organic solvents, whereas hydrophobic ZIF-8 affords inactive catalase and negligible protection to urease.

The new agreement specifically addresses what authors can do with different versions of their manuscripte.g. use in theses and collections, teaching and training, conference presentations, sharing with colleagues, and posting on websites and repositories. The terms under which these uses can occur are clearly identified to prevent misunderstandings that could jeopardize final publication of a manuscript (Section II, Permitted Uses by Authors).

Inorganic functionalization of metal-organic frameworks (MOFs), such as incorporation of multiple inorganic building blocks with distinct metals into one structure and further modulation of the metal charges, endows the porous materials with significant properties toward their applications in catalysis. In this work, by an exploration of the role of 4-pyrazolecarboxylic acid (HPyC) in the formation of trinuclear copper pyrazolate as a metalloligand in situ, four new MOFs with multiple components in order were constructed through one-pot synthesis. This metalloligand strategy provides multicomponent MOFs with new topologies (tub for FDM-4 and tap for FDM-5) and is also compatible with a second organic linker for cooperative construction of complex MOFs (1,4-benzenedicarboxylic acid for FDM-6 and 2,6-naphthalenedicarboxylic acid for FDM-7). The component multiplicity of these MOFs originates from PyC's ability to separate Cu and Zn on the basis of their differentiated binding affinities toward pyrazolate and carboxylate. These MOFs feature reversible and facile redox transformations between Cu(PyC) and Cu(μ-OH)(PyC)(OH) without altering the connecting geometries of the units, thus further contributing to the significant catalytic activities in the oxidation of CO and aromatic alcohols and the decomposition of HO. This study on programming multiple inorganic components into one framework and modulating their electronic structures is an example of functionalizing the inorganic units of MOFs with a high degree of control.

In principle, polymerization tends to produce amorphous or poorly crystalline materials. Efficiently producing high-quality single crystals by polymerization in solvent remains as an unsolved issue in chemistry, especially for covalent organic frameworks (COFs) with highly complex structures. To produce μm-sized single crystals, the growth time is prolonged to >15 days, far away from the requirements in practical applications. Here, we find supercritical CO2 (sc-CO2) accelerates single-crystal polymerization by 10,000,000 folds, and produces two-dimensional (2D) COF single crystals with size up to 0.2 mm within 2~5 min. Although it is the fastest single-crystal polymerization, the growth in sc-CO2 leads to not only the largest crystal size of 2D COFs, but also higher quality with improved photoconductivity performance. This work overcomes traditional concept on low efficiency of single-crystal polymerization, and holds great promise for future applications owing to its efficiency, industrial compatibility, environmental friendliness and universality for different crystalline structures and linkage bonds.

By downsizing Co-MOF-74 crystals with distinct morphologies, high capacities were achieved when they were employed in Li–O2 batteries.

Trimethylamine (TMA) sensors based on metal oxide semiconductors (MOS) have drawn great attention for realtime seafood quality evaluation. However, poor selectivity and baseline drift limit the practical applications of MOS TMA sensors. Engineering core@shell heterojunction structures with accumulation and depletion layers formed at the interface is regarded as an appealing way for enhanced gas sensing performances. Herein, we design porous hollow Co 3 O 4 @ZnO cages via a facile ZIF-67@ZIF-8-derived approach for TMA sensors. These sensors demonstrate great TMA resistive sensing performance (linear response at moderate TMA concentrations (<33 ppm)), and a high sensitivity of ∼41 is observed when exposed to 33 ppm TMA, with a response/recovery time of only 3/2 s. This superior performance benefits from the Co 3 O 4 @ZnO porous hollow structure with maximum heterojunctions and high surface area. Furthermore, great capacitive TMA sensing with linear sensitivity over the full testing concentration range (0.33−66 ppm) and better baseline stability were investigated. A possible capacitive sensing mechanism of TMA polarization was proposed. For practical usage, a portable sensing prototype based on the Co 3 O 4 @ZnO sensor was fabricated, and its satisfactory sensing behavior further confirms the potential for real-time TMA detection.

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Pillared-layer metal–organic frameworks (MOFs) are often encountered to “collapse” upon external stimuli due to weak interactions between the layers and the pillars. However, the detailed local structural change, especially the accumulation of defects due to intricately disordered bond dissociations, is not clear due to the complicated and dynamic nature of the collapse. We report a luminescent pillared-layer MOF structure, FDM-22, using zinc dicarboxylates as layers and dipyridyl ligands as pillars, in which three different transformed structures were captured along the increasing number of coordination bond dissociations between zinc metals and pyridine linkers. The transformation is triggered by these local point defect formations in the MOF, which further contribute to the modulation of its luminescence property, as well as prominent change in the morphology and pore distribution of the MOF. Evidenced by Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS), each of the pillar ligands has only one pyridyl group coordinated to a Zn­(II) ion eventually, with the other uncoordinated pyridyl group pointing to the pore. With ∼10% of the coordination bonds breaking within the framework, FDM-22 provides a high concentration of active metal sites in the framework.