Aldehyde-based triphenylethylene organic crystals for aniline vapour detection†

Air pollution, particularly from volatile organic compounds (VOCs), has been a major concern in the past century, especially with the increase in industrial activities. Aniline, one example of VOCs, is mainly involved in the manufacturing industry. Sensing the presence of aniline in prone locations is of great importance due to its hazardous environmental and health implications. This work presents the synthesis of fluorescent organic crystals of a novel compound, an aldehyde derivative of triphenylethylene, namely TrPE-(CHO)₃, which can visually portray the presence of aniline vapour by fluorescence quenching. Herein, we investigate the solid-state packing of TrPE-(CHO)₃ in crystals and its properties, as well as the interactions occurring between the crystals and aniline, and thus elucidate the underlying reason for the selective sensing of aniline as compared to other VOCs. We also demonstrate a proof-of-concept display by coating a light-emitting diode with the synthesized material, which upon exposure to aniline, loses its cyan emission colour.