ESIPT-active 8-hydroxyquinoline chemosensor for highly selective detection of diethyl chlorophosphate and molecular...

An ESIPT-active 8-hydroxyquinoline-based fluorescent chemosensor, HQHBI, has been synthesized for the sensitive detection of the nerve-agent simulant diethyl chlorophosphate (DCP). The probe exhibits a low detection limit of 1.5 × 10^-7 M and demonstrates excellent selectivity in the presence of a wide range of competing anions. Photophysical studies in different solvents reveal the involvement of ESIPT and ICT processes, while pH titrations confirm its operational stability under physiological and environmental conditions. The sensing mechanism is further validated through time-resolved fluorescence and NMR titration studies, indicating selective interaction via the phenolic -OH group. Additionally, DFT and TD-DFT calculations support the experimental findings by elucidating key electronic transitions responsible for the sensing response. Notably, HQHBI also enables molecular logic gate operations, highlighting its potential in chemical information processing.