9-Aryl-1,2-dihydropyrrolo[3,4-b]indolizin-3-one (Seoul-Fluor) as a smart platform for colorful ratiometric fluorescent pH sensors

In this communication, we report that 9-aryl-1,2-dihydropyrrolo[3,4-b] indolizin-3-one (Seoul-Fluor) can serve as a potential platform for colorful ratiometric fluorescent pH sensors by simple incorporation of pH responsive elements on Seoul-Fluor. Seoul-Fluor-based fluorescent pH sensors allow the emission-and pH-tuning ability upon protonation by varying their pK(a) values and electronic characteristics of substituents by a rational design.