A New Spirobifluorene-Bridged Bipolar System for a Nitric Oxide Turn-On Fluorescent Probe

A new spirobifluorene-bridged bipolar molecule (EDADO) as a nitric oxide (NO) turn-on fluorescent probe was designed and synthesized. The fluorescence of EDADO is strongly quenched by photoinduced electron transfer (PET) from the electron-donating o-phenylenediamine-containing biphenyl branch to the orthogonally arranged electron-accepting 1,3,4-oxadiazole-containing conjugated oligoaryl system. Upon reacting with NO, EDADO is converted to EDADO-T, which exhibits strong fluorescence due to the suppression of PET.