A simple AIE-active triphenylamine derivative for supersensitive detection of water in organic solvents with noticeable fluorescence color change

In this work, an extremely simple triphenylamine-based luminogen 1-(4-(diphenylamino)phenyl)-2-phenyl-ethanone (TPACO) with aggregation-induced emission (AIE) and twisted intramolecular charge transfer (TICT) characteristic was readily synthesized as a super-sensitive fluorescent water sensor. TPACO exhibits remarkable solvatochromic effect and ultrahigh sensitivity to trace water in organic solvents with good linear"intensity-to-content" relationships. The detection limit of TPACO for water in tetrahydrofuran and 1,4-dioxane can be as low as 76 ppm (0.0068 vol%) and 31 ppm (0.0032 vol%), respectively. Under UV irradiation, the probe can signify water content in organic solvents with distinguishable fluorescence color change observable by naked eye. In addition, the emission of TPACO can be quenched by alkali via keto-enol isomerization.