Halogen‐Free Selenophene‐Modified Diarylethene–Perylenebisimide Dyad for Efficient and Robust Visible/Near‐Infrared‐Light Photoswitching

A diarylethene–perylenebisimide (DAE–PBI) dyad capable of efficient photoswitching under visible and near‐infrared (NIR) light was designed and synthesized. To enhance visible‐light‐induced cyclization and improve photoswitching repeatability, a selenophene unit was introduced as a halogen‐free heavy‐atom substitute, replacing the bromine‐substituted thiophene unit. The resulting dyad exhibited a high conversion yield (>80%) from the open to the closed form under green‐light irradiation (500–550 nm). This high conversion was observed not only in heavy‐atom‐containing solvents but also in common halogen‐free solvents. The quantum yield of photocyclization under green light was significantly higher than that of the bromine‐free analog, and the photoswitching durability was markedly improved compared to the bromine‐containing analog. These findings demonstrate that incorporating a selenophene unit as a halogen‐free heavy atom effectively enhances the photochromic performance of DAE–PBI systems. This strategy offers a promising approach for developing UV‐free, visible/NIR‐light‐responsive photoswitchable molecular systems.