Anilinomethylrhodamines: pH Sensitive Probes with Tunable Photophysical Properties by Substituent Effect
journal contributionposted on 18.10.2013, 00:00 by Quinn A. Best, Chuangjun Liu, Paul D. van Hoveln, Matthew E. McCarroll, Colleen N. Scott
A series of pH dependent rhodamine analogues possessing an anilino-methyl moiety was developed and shown to exhibit a unique photophysical response to pH. These anilinomethylrhodamines (AnMR) maintain a colorless, nonfluorescent spirocyclic structure at high pH. The spirocyclic structures open in mildly acidic conditions and are weakly fluorescent; however, at very low pH, the fluorescence is greatly enhanced. The equilibrium constants of these processes show a linear response to substituent effects, which was demonstrated by the Hammett equation.