Naphthalimide‐Hydroxyquinoline Conjugates for Discriminative Detection of Nitro Aromatic Compounds in Aqueous Medium and Soil Sample

Abstract

AbstractNaphthalimide‐hydroxyquinoline based conjugates (NQ1 and NQ2) were synthesized for the detection of nitroaromatics in HEPES buffer/DMSO (9/1, v/v, pH=7.4) and Fe3+/Pd2+ in CH3CN solvent. The NQ1 and NQ2 were characterized using NMR (1H, 13C, COSY) and IR spectroscopies. Theoretical studies revealed that 8‐HQ moiety in NQ1 and NQ2 placed at orthogonal position with respect to naphthalimide core to minimize steric crowding. The energy gap between HOMO and LUMO for NQ1 and NQ2 were found to be −3.1 eV. The emission spectrum of NQ1 and NQ2 showed decrease in the emission intensity at 450 nm upon addition of picric acid (PA) and trinitrotoluene (TNT) whereas addition of 2‐nitroaniline caused quenching with concomitant red‐shift of the emission band in 90 % HEPES buffer‐DMSO. The detection limit of NQ1 for PA, TNT and 2‐NA detection was calculated as 8.7×10−6 M, 2.2×10−5 M and 1.8×10−5 M. The complexation of NQ1 with PA, TNT and 2‐NA was further supported by Job's plot, dynamic light scattering studies and NMR titrations. We successfully utilized NQ1 and NQ2 for the detection of PA, TNT and 2‐NA in real soil samples with excellent recovery. NQ1 also showed quenching of the emission intensity at 450 nm upon addition of Fe3+ and Pd2+ ions in CH3CN. Thus, NQ1 showed solvent‐dependent dual chemosensor type behavior. The functioning of NOR gate has been achieved using Fe3+/NACs with NQ1.