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 (NO 2 ) 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 NO 2 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 NO 2 is illustrated based on the energy analysis of the sensing products.