Smart organic crystalline materials based on photo-induced topochemistry

Abstract Presponsive smart organic crystalline materials (SOCMs) have emerged as an attractive research topic because of their many advantages, such as well-defined structures, high structural order, and the resulting fast response speeds, as well as high energy conversion efficiency and remarkable dynamic optical/electronic changes or mechanical responses. In this review, we discuss the recent developments in SOCMs based on topochemistry beyond coordination compounds, which include [2 + 2] or [4 + 4] photocycloaddition of anthracene and olefin derivatives as well as 1, 4-addition-polymerization of diacetylenes. The detailed design principles and mechanisms associated with smart behavior, photoresponsive physical and chemical properties (i.e., photochromism, photo fluorochromism, and photodeformation), and structure–property relationships are discussed, along with their advanced applications in exciting fields such as intelligent microrobots, encryption, sensors, photoactuators, data storage, and displays. Finally, we summarize the current developments and discuss the major current challenges and future opportunities in this field. We expect that this review will inspire more innovative research into the development of advanced photoresponsive organic smart crystal materials with fast, accurate, and reversible responses, and promote the further development of smart materials and devices.