Morphology-Regulated PET-Mediated Quenching in a Pyrene- o -carborane AIEgen Film for Rapid Aniline Vapor Sensing

Abstract

Solid-state photoinduced electron transfer (PET) sensing films require both strong fluorescence and efficient analyte-induced quenching, but molecular aggregation often creates a trade-off between emission efficiency and analyte accessibility. Herein, ano-carborane-containing pyrene derivative, 2CB-Py-2Ph, was designed as an aggregation-induced emission (AIE) luminogen for aniline vapor sensing. The conjugated pyrene framework provides an efficient emissive core, while the three-dimensionalo-carborane units modulate the aggregation behavior and excited-state electronic properties. The pristine solid powder of 2CB-Py-2Ph exhibits an exceptionally high fluorescence quantum yield of 98.7%, demonstrating its intrinsic solid-state emissive capability. By varying the film-forming concentration, the surface microstructure and sensing performance of the resulting films were regulated. The optimized film detects aniline vapor over a concentration range of 900 ppt to 900 ppm, with fluorescence quenching within 5 s and recovery to 90% of the initial intensity within 35 s. Spectroscopic measurements, density functional theory (DFT) calculations, and femtosecond transient absorption spectroscopy collectively support a dynamic-quenching contribution consistent with a PET-mediated pathway. This work highlights aggregation morphology regulation as an effective strategy for balancing solid-state emission and PET quenching in fluorescent vapor sensing films.