Redox/pH Dual Stimuli‐Responsive Acridine Spiropyran

Abstract A spiropyran derivative containing an acridinium and a phenoxide moieties was found to exhibit both halochromism and electrochromism in response to acid stimulation and oxidative stimulation, respectively. Variable scan‐rate voltammetric studies revealed that the acridine spiropyran undergoes a reversible conversion between a closed‐ring and an open‐ring form during the redox cycle. The presence of a ring‐opened radical cation species was demonstrated by simultaneous electrochemical ESR measurements.