Sequential Dynamic Fluorescence Switching Driven by Oxa-/Thiol-Michael Conjugate Addition–Elimination Reactions

A dynamic molecular system undergoing sequential reconfiguration and multi-state fluorescence switching via intramolecular oxa/thiol-Michael conjugate addition-elimination reactions is reported. Triggered sequentially by chemical, solvent, and most importantly pH stimuli, the controlled progression through distinct molecular states was monitored by ratiometric absorption/fluorescence and NMR spectroscopy. This stimulus-controlled fluorescence switching demonstrates utility for real-time monitoring of processes, like chemically induced polymer degradation.