A Sol–Gel‐derived Optical Sensor Applicable for Determination of Extremely Low pH Values

摘要

This article describes the preparation and pHa??sensing characteristics of a sola??gela??based optical sensor. A fluorescent dye possessing a triethoxysilane pendant group (2) was synthesized and covalently immobilized onto a sola??gel matrix to afford an optically pHa??sensitive membrane that operates in acidic solutions. The sensor membrane displays two distinctive absorption bands around 374 and 439a??nm, and two emission bands around 520 with excitation at 340 and 460a??nm. The fluorescence intensity and absorbance ratio of the sensor membrane increases as the pH increases from a??1.0 to 2.0. The sensor membrane was reproducible, reversible, and stable for repeated measurements in acidic buffer solutions and has a long lifetime of at least a month without dye leaching.