A Pyrene-Benzothiazole Probe that is Ultrasensitive to the Environment Polarity and Its Own Characteristics

Environment-sensitive fluorescent probes are of great importance in chemical and biological research. We have developed a cationic benzothizole derivative that has a pyrene moiety at the tip of the hydrophobic tail. The probe is of comparable length as the cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) surfactants. The compound shows characteristic fluorescence from its own locally excited (LE) state in non-polar medium. However, it is weakly fluorescent in the aqueous environment that comes from the pyrene excimer. It is found that the polarity of this compound reverses in the excited state that substantially affects the LE fluorescence.