A Modulator‐Induced Defect‐Formation Strategy to Hierarchically Porous Metal–Organic Frameworks with High Stability

Abstract

The pore size enlargement and structural stability have been recognized as two crucial targets, which are rarely achieved together, in the development of metal-organic frameworks (MOFs). Herein, we have developed a versatile modulator-induced defect-formation strategy, in the presence of monocarboxylic acid as a modulator and an insufficient amount of organic ligand, successfully realizing the controllable synthesis of hierarchically porous MOFs (HP-MOFs) with high stability and tailorable pore characters. Remarkably, the integration of high stability and large mesoporous property enables these HP-MOFs to be important porous platforms for applications involving large molecules, especially in catalysis.Scheme 1. Schematic illustration of the synthesis of HP-MOFs with adjustable porosity using UiO-66 as an example, see text for details.

Coordination-responsive drug release inside gold nanorod@metal-organic framework core–shell nanostructures for near-infrared-induced synergistic chemo-photothermal therapy

“…Metal-organic frameworks (MOFs), which are typical inorganic-organic hybrid materials composed of metal ions or clusters bridged by organic linkers, have emerged as a promising platform in biomedical applications owing to their high tenability of composition and structure, easy functionalization, good biocompatibility, and intrinsic biodegradability [23][24][25][26]. It is noteworthy that both bulk MOFs and nanoscale MOFs (NMOFs) have exhibited many intriguing characteristics as drug carriers, such as exceptionally high surface areas and large pore sizes for drug loading as well as versatile interactions (van der Waals forces, π−π stacking, hydrogen bonds, electrostatic forces, or coordination bonds) for drug adsorption [27][28][29]. More importantly, their versatile structures endow MOFs with multifunctionalities and offer the opportunity for stimuli-responsive drug release.…”

Novel Hierarchical Copper-Based Metal-Organic Frameworks for Improved Catalytic Performance

“…The resultant hierarchical porous sample was loaded with phosphomolybdic acid hydrate (HPMo) as a catalytic guest species and tested for the methanolysis of styrene oxide, showing an enhanced catalytic performance (99.6 % in reaction conversion using hierarchical HKUST-1 at 40 o C in 20 min compared to ~50 % using normal HKUST-1). Advantages of the facile mass transport originating from its hierarchical porous nature in this reaction were also confirmed in hierarchical porous UiO-66 20 and FeBTC 32 . These results are evidence that MOFs with hierarchically porous structures are very promising when employed in catalysis.…”

“…Inspired by previous findings on the methanolysis of styrene oxide reaction, 20,31 phosphomolybdic acid hydrate (HPMo) was chosen as the catalytic guest species to be immobilised within the pores of the hierarchical porous platform. To achieve this, 30 mg of each MOF sample was soaked in 18 ml ethanol solution containing 135 mg HPMo and sonicated at room temperature for 18 h. After encapsulation of the HPMo, the solid MOF was isolated by centrifugation (8,000 rpm for 5 minutes), washed with pure ethanol, re-centrifuged and re-washed three times and dried at 60 o C overnight.…”

“…32 However, reactions on these MOFs did not prove to be particularly efficient, requiring e.g. a large amount of catalyst or a long reaction time 20,[54][55][56] . Indeed, as presented in Figure 5 increase the reaction rate, all samples were impregnated with HPMo, which was shown to be an efficient Brønsted site for these kind of reactions.…”

Self-Recognizing π-π Stacking Interactions Designed for the Generation of Ultrastable Mesoporous Hydrogen-Bonded Organic Frameworks

“…Besides, large pore size and high stability are usually contradictory to each other and rarely combined into one single porous material. 25,26 Thus, development of an alternative pore size expansion strategy for the construction of stable mesoporous HOF materials is highly desirable. Among various approaches to stabilize HOFs, design of two-dimensional (2D) HOFs with intermolecular π-π interactions was found to be the most effective.…”