π-Bridge Substitution in DASAs: The Subtle Equilibrium between Photochemical Improvements and Thermal Control**

摘要: Donor-acceptor Stenhouse adducts (DASAs) are playing an outstanding role as innovative and versatile photoswitches. Until now, all the efforts have been spent on modifying donor acceptor moieties to modulate absorption energy improve cyclization reversion kinetics. However, there is a strong dependence specific structural modifications lack of predictive behavior, mostly owing complex photoswitching mechanism. Here, by means combined experimental theoretical study, effect chemical modification π-bridge linking systematically explored, revealing significant impact absorption, photocyclization, relative stability open form. In particular, position along found be most suited redshift while preserving cyclization. thermal back-reaction initial isomer blocked. These effects explained in terms increased capability offered substituent that can modulated. This strategy opens path toward derivatives with infra-red potential anchoring point for further functionalization.