Broad range ON/OFF pH sensors based on pKa tunable fluorescent BODIPYs

A set of pH responsive boron dipyrromethene (BODIPY)-based optical pH sensors with tunable pKa values for application in aqueous-organic mixed media and a polymer matrix is presented. pKa values from 6 to 11 were achieved by modifying the substitution pattern of the meso-aryl substituent, without significant shifts in absorption and emission as prerequisite for broad band pH-sensing via fluorescence intensity measurements.