Switching Sides: Regiochemistry and Functionalization Dictate the Photoswitching Properties of Imines

Abstract

Photoswitchable imines demonstrate light‐dependent dynamic covalent chemistry and can function as molecular ratchets. However, the design of aryliminopyrazoles (AIPs) has been limited to N‐pyrazole derivatives with ortho‐pyrrolidine motifs. The impact of other functionalization patterns on the photoswitching properties remains unknown. Here, we present a systematic structure‐property analysis and study how the photoswitching properties can be tuned through ortho‐ and para‐functionalization of the phenyl ring in N‐pyrazole and N‐phenyl AIPs. This study establishes the first set of design rules for these AIP photoswitches and reports the most stable Z‐isomer of an AIP to date, enabling its crystallization and resulting in the first reported crystal structure of a metastable Z‐aldimine. Finally, we demonstrate that the AIPs are promising candidates for photoswitching in the condensed phase.