Bo Gui

Mechanized azobenzene-functionalized zirconium metal-organic framework for on-command cargo release.

A simple strategy to construct a stimuli-responsive mechanized zirconium metal-organic framework for on-command cargo release. Stimuli-responsive metal-organic frameworks (MOFs) have gained increasing attention recently for their potential applications in many areas. We report the design and synthesis of a water-stable zirconium MOF (Zr-MOF) that bears photoresponsive azobenzene groups. This particular MOF can be used as a reservoir for storage of cargo in water, and the cargo-loaded MOF can be further capped to construct a mechanized MOF through the binding of β-cyclodextrin with the azobenzene stalks on the MOF surface. The resulting mechanized MOF has shown on-command cargo release triggered by ultraviolet irradiation or addition of competitive agents without premature release. This study represents a simple approach to the construction of stimuli-responsive mechanized MOFs, and considering mechanized UiO-68-azo made from biocompatible components, this smart system may provide a unique MOF platform for on-command drug delivery in the future.

Tackling poison and leach: catalysis by dangling thiol–palladium functions within a porous metal–organic solid

Self-standing thiol (-SH) groups within a Zr(IV)-based metal-organic framework (MOF) anchor Pd(II) atoms for catalytic applications: the spatial constraint prevents the thiol groups from sealing off/poisoning the Pd(II) center, while the strong Pd-S bond precludes Pd leaching, enabling multiple cycles of heterogeneous catalysis to be executed.

Immobilizing Organic‐Based Molecular Switches into Metal–Organic Frameworks: A Promising Strategy for Switching in Solid State

Organic-based molecular switches (OMS) are essential components for the ultimate miniaturization of nanoscale electronics and devices. For practical applications, it is often necessary for OMS to be incorporated into functional solid-state materials. However, the switching characteristics of OMS in solution are usually not transferrable to the solid state, presumably because of spatial confinement or inefficient conversion in densely packed solid phase. A promising way to circumvent this issue is harboring the functional OMS within the robust and porous environment of metal-organic frameworks (MOFs) as their organic components. In this feature article, recent research progress of OMS-based MOFs is briefly summarized. The switching behaviors of OMS under different stimuli (e.g., light, redox, pH, etc.) in the MOF state are first introduced. After that, the technological applications of these OMS-based MOFs in different areas, including CO2 adsorption, gas separation, drug delivery, photodynamic therapy, and sensing, are outlined. Finally, perspectives and future challenges are discussed in the conclusion.

Engineering a Zirconium MOF through Tandem “Click” Reactions: A General Strategy for Quantitative Loading of Bifunctional Groups on the Pore Surface

Metal-organic frameworks (MOFs) assembled from linkers of identical length but with different functional groups have gained increasing interests recently. However, it is very challenging for precise control of the ratios of different functionalities. Herein, we reported a stable azide- and alkyne-appended Zr-MOF that can undergo quantitative tandem click reactions on the different functional sites, thus providing a unique platform for quantitative loading of bifunctional moieties. As an added advantage, the same MOF product can be obtained via two independent routes. The method is versatile and can tolerate a wide variety of functional groups, and furthermore, a heterogeneous acid-base MOF organocatalyst was synthesized by tandemly introducing both acidic and basic groups onto the predesigned pore surface. The presented strategy provides a general way toward the construction of bifunctional MOFs with a precise control of ratio of different functionalities for desirable applications in future.

Erratum: Tackling poison and leach: Catalysis by dangling thiol-palladium functions within a porous metal-organic solid Chemical Communications (2015) DOI: 10.1039/c5cc00140d)

a Key Laboratory of Biomedical Polymers (Ministry of Education), College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, China. E-mail: chengwang@whu.edu.cn b Department of Biology and Chemistry, City University of Hong Kong, 83 Tat Chee Avenue, Kowloon, Hong Kong, China. E-mail: zhengtao@cityu.edu.hk c Department of Chemistry, Youngstown State University, One University Plaza, Youngstown, OH 44555, USA DOI: 10.1039/c5cc90141c