Molecular Photoswitching of Main-Chain α-Bisimines in Solid-State Polymers

Photoisomerization of chromophores usually shows significantlyless efficiency in solid polymers than in solution as strong intermolecularinteractions lock their conformation. Herein, we establish the impactof macromolecular architecture on the isomerization efficiency ofmain-chain-incorporated chromophores (i.e., & alpha;-bisimine) in bothsolution and the solid state. We demonstrate that branched architecturesdeliver the highest isomerization efficiency for the main-chain chromophorein the solid state remarkably as high as 70% compared to solution.The macromolecular design principles established herein for efficientsolid-state photoisomerization can serve as a blueprint for enhancingthe solid-state isomerization efficiency for other polymer systems,such as those based on azobenzenes.