An aggregation-induced emissive NIR luminescent based on ESIPT and TICT mechanisms and its application to the detection of Cys

A series of red to near-infrared (NIR) emissive organic compound 1-3 based on the 2′-hydroxyacetophenone derivatives were synthesized through a mild condensation reaction, which exhibit typical AIE properties and long fluorescence lifetime in an aggregated state. Compound 2 displays the highest quantum yield (Φf) of 0.49 among the reported organic compound with an emission maximum (λem) 700 nm. Comparison between the bright emissive compound 2 and the weak fluorescence compounds 1 and 3 clearly gives evidence that a subtle structure modification can arouse great property changes, which is instructive in designing new high-efficiency organic luminescent materials. In demonstration of the potential application of these new fluorescence dyes, Probe 4 that is capable of unique detecting Cys in water media is also reported.