A visible colorimetric pH sensitive chemosensor based on azo dye of benzophenone

A visible colorimetric pH sensitive chemosensor (Dye A) based on a benzophenone azo dye was designed and synthesized. This chemosensor had a large wavelength shift (>170 nm) and showed excellent sensitivity in the range of pH from 7.9 to 9.3. In addition, the possible mechanism of the chemosensor with remarkable change of visible color was established by the 1H-NMR- and 13C-NMR-titration experiments. This pH chemosensor has a fast response time and is fully reversible, which is important for pH chemosensors in practical applications. In this study, Dye A was successfully applied to determine the pH of simulated small intestine fluid.

► A visible colorimetric sensitive sensor (Dye A) for pH based on azo dye of benzophenone exhibits a large wavelengths shift (>170 nm). ► The pH sensor has an excellent sensitivity in the range of pH 7.9–9.3. ► The response of the pH sensor was shown to be fast and fully reversible, which is an important feature for the practical application of the pH sensors.