Fibrous Networks with Incorporated Macrocycles: A Chiral Stimuli‐Responsive Supramolecular Supergelator and Its Application to Biocatalysis in Organic Media

Abstract

A new and versatile, crown ether appended, chiral supergelator has been designed and synthesized based on the bis-urea motif. The introduction of a stereogenic center improved its gelation ability significantly relative to its achiral analogue. This low-molecular-weight gelator forms supramolecular gels in a variety of organic solvents. It is sensitive to multiple chemical stimuli and the sol-gel phase transitions can be reversibly triggered by host-guest interactions. The gel can be used to trap enzymes and release them on demand by chemical stimuli. It stabilizes the microparticles in Pickering emulsions so that enzyme-catalyzed organic reactions can take place in the polar phase inside the microparticles, the organic reactants diffusing through the biphasic interface from the surrounding organic phase. Because of the higher interface area between the organic and polar phases, enzyme activity is enhanced in comparison with simple biphasic systems.

Pickering Interfacial Catalysis for Biphasic Systems: From Emulsion Design to Green Reactions

“…[52] A further evolution of such a concept allowed the generation of supramolecular gels in a variety of organic solvents using a crown-ether-appended, chiral supergelator based on a bis(urea) motif. [53] The gels could trap enzymes and release them on demand by chemical stimuli.…”

Self-recovering stimuli-responsive macrocycle-equipped supramolecular ionogels with unusual mechanical properties

“…This indicates that the LMWGs self-assemble into the typical gel networks that were already observed for gelator 1 in organic solvents. 18 A quite high thermostability of the ionogels is expressed in the gel-sol phase transition temperatures T gs , which reach values significantly higher than 373 K at increased gelator concentrations ( Fig. 2a).…”

Logic‐Gate Functions in Chemomechanical Materials

“…Many processes in nature rely on the transformation of chemical stimuli into mechanical movements and shape changes. Biomimetic smart materials open the way for many applications, including actuators, sensors, artificial muscles, drug delivery, self‐healing materials, and tissue engineering …”

“…Biomimetic smart materials open the way for many applications,i ncluding actuators, sensors, artificial muscles, drugd elivery, self-healing materials, and tissue engineering. [12][13][14][15][16] The focus of the present minireview is on chemomechanical polymers, which by molecular recognition exhibit selective swellingo rs hrinking under the influence of external effector compounds. [17] For example, ah ybrid chemomechanical system can consist of ap H-responsive hydrogel attachedt o flexible polymer structures that transform the external signal into micro-or macroscopic movements.…”