Theoretical Perspective on the Sensing Mechanism of a Novel Fluorescent Probe for Nitramine Explosives: The Role of Radical Reactions

Rapid detection of hidden nitramine explosives in public areas is a pressing concern for public safety. Deep insight into the sensing mechanism is significant and inspiring to the design of new high-efficiency nitramine probes. This study has theoretically investigated the recognition and fluorescence mechanism of a newly reported high-efficiency nitramine probe, proposing a new reaction pattern and sensing product for the probe with the photodegraded radical nitro dioxide (NO2) of nitramines. The rationality of the new detection product is confirmed by the fluorescence properties, IR analysis, and energy profiles. The recognition mechanism is found to be an H-abstraction reaction via NO2 and the turn-off fluorescence mechanism is suggested as a photoinduced electron transfer (PET) process based on the results of the frontier molecular orbital (FMO) analysis. The high selectivity of the probe toward NO2 is illustrated based on the energy analysis of the sensing products.