Catalytically-active porous assembly with dynamic pulsating motion for efficient exchange of products and reagents

Abstract

Despite recent advances in the use of porous materials as efficient heterogeneous catalysts which operate through effectively trapping reagents in a well-defined space, continuously uptaking reagents to substitute products in the cavity for efficient product turnover still remains challenging. Here, a porous catalyst is endowed with 'breathing' characteristics by thermal stimulus, which can enable the efficient exchange of reagents and products through reversible stacking from inflated aromatic hexamers to contracted trimeric macrocycles. The contracted super-hydrophobic tubular interior with pyridine environment exhibits catalytic activity towards a nucleophilic aromatic substitution reaction by promoting interactions between concentrated reagents and active sites. Subsequent expansion facilitates the exchange of products and reagents, which ensures the next reaction. The strategy of mesoporous modification with inflatable transition may provide a new insight for construction of dynamic catalysts.

Nanostructured Catalytic Reactors Produced by Supramolecular Materials Based on Aromatic Amphiphiles

“…(b) Thermoresponsive open-closed supramolecular nanotubule for S N Ar reaction. {Reproduced with permission from ref . Copyright 2020, Nature Publishing Group.]…”

“…Inspired by natural enzymatic systems entrapping reactants and releasing products, − Wu et al reported a supramolecular catalyst with thermally on/off-switchable activity (Figure b) . The author designed molecule 13 containing a pyridine unit positioned at the center of a bent aromatic amphiphile with a hydrophilic oligoether dendron at the top and decyl chains at both ends.…”

Switchable Aromatic Nanopore Structures: Functions and Applications

“…Self-assembly of aromatic building blocks provides a facile platform to construct switchable nanostructures with responsive features. , In contrast to the self-assembling systems based on H-bonds or coordination interactions that make it hard to conduct a dynamic structural switch without bond breaking, self-assembly based on nonspecific aromatic interactions allows neighboring aromatic segments to readily rearrange with each other in response to external stimuli, leading to a switchable nanostructure without structural collapse. ,, The aromatic tubular assembly with switchable internal pores can be rationally designed and synthesized by using the combination of bent-shaped aromatic building blocks and hydrophilic oligo­(ethylene oxide) dendrimers (Figure ). The bent-shaped molecular geometry with an internal angle of 120° is well fitted into a hexameric noncovalent macrocycle. − When they are grafted by hydrophilic chains at the apex such as molecule 1 , the noncovalent macrocycles are surrounded by hydrophilic chains outside the aromatic frameworks . Subsequently, the aromatic macrocycles are stacked on top of each other through hydrophobic interactions to form helical tubules with hydrophilic exterior and hydrophobic interior.…”

Transformation of Supramolecular Membranes to Vesicles Driven by Spontaneous Gradual Deprotonation on Membrane Surfaces

“…Although the transformation between membranes and vesicles is a significant phenomenon, the lack of a detailed understanding of the transformation at the molecular level can limit the development of synthetic systems to mimic the natural and reversible dynamic system. Therefore, investigations via synthetic model systems in the detailed mechanisms of such sophisticated membrane transformations can provide a tool for emerging synthetic materials, such as those required for drug delivery systems, , biosensors, − and catalysts. − …”