Highly FluorescentConjugated Polymer Network as Reversibleand Colorimetric Probe for Ultrafast Detection of BF₃ andAmine

Herein, we have designed and synthesized a fluorescent conjugated polymer network (CPN) for the detection of BF₃ and amine. The theoretical and photophysical study clearly indicates the presence of a twisted intramolecular charge transfer (TICT) process in the polymer resulting in strong fluorescence. Upon interacting with BF₃, the probe CPN exhibited a significant “turn-off” in fluorescence and also the appearance of a broad peak around 450 nm in UV–vis absorption spectra. The probe showed high and rapid sensitivity for BF₃ with a low detection limit (161 nM). Further, the CPN·BF₃ complex was utilized for rapid and sensitive detection of amine, which shows “turn-on” behavior in fluorescence. Using NMR, FTIR, and density functional theory (DFT) analysis, the sensing mechanism was thoroughly confirmed. Additionally, test paper-based portable detecting devices for BF₃ and volatile amines such as triethylamine in the gas phase were successfully prepared using this probe. Thus, CPN as a fluorescent probe has potential applications in chemical and industrial applications for the sensitive and selective detection of toxic species such as BF₃ and amine.