Catechol Derivatives as Fluorescent Chemosensors for Wide-Range pH Detection

The synthesis and characterization of a new family of catechol derivatives designed to behave as fluorescent chemosensors for wide-range pH detection has been described. These compounds were prepared by covalently coupling a catechol unit with other aromatic rings, thus obtaining pi-delocalized systems with both pH-responsive groups and fluorescent behavior. In the case of a pyridine-catechol derivative, this leads to Up to three different protonation states with distinct optical properties in organic media, as corroborated by density functional theory calculations. By applying dual-wavelength detection techniques, this compound shows complementary off- on-off and on-off-on emission profiles upon pH variation, a behavior that call be exploited to perform acidity detection over a broad pH range.