Multi‐shelled Hollow Metal–Organic Frameworks

Abstract

Hollow metal-organic frameworks (MOFs) are promising materials with sophisticated structures, such as multiple shells, that cannot only enhance the properties of MOFs but also endow them with new functions. Herein, we show a rational strategy to fabricate multi-shelled hollow chromium (III) terephthalate MOFs (MIL-101) with single-crystalline shells through step-by-step crystal growth and subsequent etching processes. This strategy relies on the creation of inhomogeneous MOF crystals in which the outer layer is chemically more robust than the inner layer and can be selectively etched by acetic acid. The regulation of MOF nucleation and crystallization allows the tailoring of the cavity size and shell thickness of each layer. The resultant multi-shelled hollow MIL-101 crystals show significantly enhanced catalytic activity during styrene oxidation. The insight gained from this systematic study will aid in the rational design and synthesis of other multi-shelled hollow structures and the further expansion of their applications.

Hollow Micro/Nanostructured Ceria‐Based Materials: Synthetic Strategies and Versatile Applications

“…[86] Copyright 2006, American Chemical Society. [94] To illustrate the gradient in condensation degree and chemical stability of materials by location, we denote the easily etchable inner section as the "less stable" part and the remaining section as the "more stable" part, and abbreviated as "LS" and "MS" respectively. And the size of the polymeric ligands should be large enough, which means they can hardly penetrate inside via grain boundaries, ensuring the protection works only near surfaces.…”

“…www.advmat.de www.advancedsciencenews.com of the materials. [92][93][94] So even without surface protection, because of the stability difference between the central part and outer parts, chemical reactions can selectively etch the inner part to create CeO 2 hollow structures. Equally importantly, appropriate etching agents are also prerequisite which dissolve the inner material, while not destroy the protective ligands.…”

Hollow Polypyrrole Nanospindles for Highly Effective Cancer Therapy

“…[28][29][30] MOFs have so outstanding performances that great efforts have been made to fabricate hollow structures use MOFs as hard templates. [32] These hollow structures maintain morphologies from MOFs and have more attractive performances due to large enclosed cavities. [31] Liu et al used the "less stable" part of MIL-101 to fabricate well-defined multi-shelled hollow MOFs.…”

Recent Advances of MOFs and MOF‐Derived Materials in Thermally Driven Organic Transformations

“…To follow this work, in 2017, Huo et al. discovered that a multi‐shelled hollow chromium(III) terephthalate MOF, known as MIL‐101‐Cr ([Cr 3 OX(BDC) 3 (H 2 O) 2 ] (X=OH or F)), could be obtained through a step‐by‐step crystal growth followed by subsequent etching strategies using acetic acid (Figure ) . They reason that the successful etching of the MOF core was due to inhomogeneous MOF crystals in which the outer layer is chemically more robust than the inner layer.…”