A Ratiometric pH Responsive Fluorescence Probe for Monitoring Wide pH Range

Abstract A novel ratiometric pH probe has been designed and synthesized on a Rhodamine B platform bearing one anthraquinone moiety and the photochemical properties of this system are evaluated. Changing the pH from acidic to basic condition, this probe exhibited 92 nm red‐shift of the emission maximum. This change is sufficiently large to permit its use as a ratiometric pH probe. With fast response time this chemosensor is fully reversible which is important and advantageous for practical applications. Furthermore, the p K a values of this probe can be predicted from the fluorescence titration. This design strategy is very simple and being modular, can be applicable to develop ratiometric pH probes for various applications.