Fabrication of Microporous Metal-Organic Frameworks in Uninterrupted Mesoporous Tunnels: Hierarchical Structure for Efficient Trypsin Immobilization and Stabilization.

Hierarchically porous metal-organic frameworks (HP-MOFs) are promising in various applications. Most reported HP-MOFs are prepared based on the generation of mesopores in microporous frameworks, and the formed mesopores are connected by microporous channels, limiting the accessibility of mesopores for bulky molecules. A hierarchical structure is formed by constructing microporous MOFs in uninterrupted mesoporous tunnels. Using the confined space in as-prepared mesoporous silica, highly dispersed metal precursors for MOFs are coated on the internal surface of mesoporous tunnels. Ligand vapor-induced crystallization is employed to enable quantitative formation of MOFs in situ, in which sublimated ligands diffuse into mesoporous tunnels and react with metal precursors. The obtained hierarchically porous composites exhibit record-high adsorption capacity for the bulky molecule trypsin. The thermal and storage stability of trypsin is improved upon immobilization on the composites.

Fabrication of Photothermal Silver Nanocube/ZIF-8 Composites for Visible-Light-Regulated Release of Propylene.

Releasing propylene from metal-organic frameworks (MOFs) after adsorption is attractive, but remains challenging because of the energy penalty in desorption by traditional techniques. Now, a metal-organic framework composite is constructed by encapsulating Ag nanocubes into ZIF-8 for controllable propylene desorption. ZIF-8 acts as an effective porous shell for accommodating propylene molecules, and Ag nanocubes perform as local "nanoheaters" to elevate the temperature by utilizing optical energy. Based on the surface plasmon resonance of Ag nanocubes, light energy can be converted into thermal energy and further transferred to the surroundings. The desorption capacity can be controlled by varying the content of Ag nanocubes introduced, and almost 100% of the propylene is released for the optical sample. Distinct from the electrical heating in industry, light-triggered heating remotely elevated the temperature of adsorbents from the inside out, which is particularly beneficial to heat-insulating MOFs. In addition, this approach heats only adsorbents rather than the entire fixed beds, improving the energy and time efficiency. The present light-triggered desorption may open up a new avenue to develop advanced adsorption/desorption cycles.