Photoswitches: From Molecules to Materials

Graphical Abstract

Switching materials ON and OFF: Light triggers photochromic molecules to switch between two different isomers with largely altered structures and properties, which can be utilized for designing next-generation photoresponsive “smart” materials. This progress report provides a focused overview of photoswitchable materials ranging from molecular design and supramolecular systems in solution over surfaces to bulk materials.

Abstract

Small organic molecules, capable of undergoing efficient and reversible photochemical reactions to switch them between (at least) two (meta)stable isomers associated with markedly different properties, continue to impact the materials world. Such photoswitches are being implemented in a variety of materials for applications ranging from optical devices to “smart” polymers. All approaches exploit the photoswitching molecular entities as gates, which translate an incoming light stimulus to trigger macroscopic property changes of the materials. In this progress report, the most promising recent examples in this field are highlighted and put in perspective. Moving from supramolecular systems in solution to surfaces and finally to bulk materials, important design concepts are discussed, emphasizing both the challenges as well as the great promise of such truly advanced materials.