A Fluorescent Covalent Organic Multicycle Film for Rapid Arylamine Vapor Detection

Abstract Covalent organic multicycles (COMs) are promising platforms for vapor sensing due to their tunable structures and facile processability. Herein, we report the construction of COM-35 films for the rapid detection of arylamine vapors. The π-conjugated COM-35 was rationally synthesized via a one-pot Knoevenagel condensation, exhibiting exceptional photophysical properties and excellent film-forming ability. Spin-coated thin film of COM-35 demonstrated high-performance sensing toward arylamine vapors, featuring a rapid response to o-toluidine vapor (<10 s), a low detection limit of 2.5 ppm, and robust reversibility over five cycles. Mechanistic studies reveal that fluorescence quenching is governed by photoinduced electron transfer from arylamine donors to the COM-35 structure. This work highlights the potential of fluorescent COMs as high-performance sensing materials for vapor monitoring.