Motorized Photomodulator: Making A Non‐photoresponsive Supramolecular Gel Switchable by Light

Abstract

AbstractIntroducing photo‐responsive molecules offers an attractive approach for remote and selective control and dynamic manipulation of material properties. However, it remains highly challenging how to use a minimal amount of photo‐responsive units to optically modulate materials that are inherently inert to light irradiation. Here we show the application of a light‐driven rotary molecular motor as a “motorized photo‐modulator” to endow a typical H‐bond‐based gel system with the ability to respond to light irradiation and create a reversible sol‐gel transition. The key molecular design feature is the introduction of a minimal amount (2 mol %) of molecular motors into the supramolecular network as photo‐switchable non‐covalent crosslinkers. Advantage is taken of the subtle interplay of the large geometry change during photo‐isomerization of the molecular motor guest and the dynamic nature of a supramolecular gel host system. As a result, a tiny amount of molecular motors is enough to switch the mechanical modulus of the entire supramolecular systems. This study proves the concept of designing photo‐responsive materials with minimum use of non‐covalent light‐absorbing units.