(Het)aryl-substituted monoazatriphenylenes as luminescent “turn-off” chemosensors for nitroaromatic compounds with internal filter effect correction

(Het)aryl-substituted monoazatriphenylenes with an extended conjugated system were synthesized from 1,2,4-triazines via Boger reaction, and their photophysical properties were studied, including aggregation induced emission (AIE), as well as fluorescence “turn-off” response to nitroexplosives. Although obtained compounds showed fluorescence “turn-off” sensory response to the presence of all common nitroaromatic explosives, such as 2,4-dinitrotoluene (2,4-DNT), 2,4,6-trinitrotoluene (TNT) and 2,4,6-trinitrophenol (picric acid, PA), a well pronounced selectivity to PA was observed, and the fluorescence quenching efficiency was not based on inner filter effect (IFE). For the most representative chemosensor, the highest Stern-Volmer fluorescence quenching constant of 5.93 × 106 M−1 with quenching efficiency of 99.68 % was observed in the presence of PA with a limit of detection as low as 33.4 ppm.