Aggregation induced emission based fluorescent and colorimetric sensor for selective detection of Fe2+: experimental and computational insights with real-time applications.

Abstract

A highly responsive fluorescent and colorimetric sensor (N 2,N 6-bis(4-(phenylamino)phenyl)pyridine-2,6-dicarboxamide) DPD has been developed for the selective detection of Fe2+ ions. DPD was readily synthesized through a nucleophilic substitution reaction and characterized through spectroscopic techniques. Sensor DPD displayed aggregation-induced emission (AIE) accompanied by an increase in fluorescence intensity with a bathochromic shift. The aggregation behavior of DPD was further examined by dynamic light scattering analysis (DLS). Among the different metal ions investigated, DPD showed a distinct and highly selective response toward Fe2+, resulting in substantial fluorescence quenching due to photo-induced electron transfer (PET) and the paramagnetic behaviour of Fe2+. The interaction of DPD with Fe2+ was investigated by fluorescence and UV/visible spectroscopy, FTIR spectroscopy, mass spectrometry, and 1H NMR titration and cyclic voltammetry which collectively provide the evidence of DPD@Fe2+ interaction. Theoretical calculations, including frontier molecular orbital analysis and QTAIM analysis, were performed to support the experimental findings. Sensor DPD was successfully employed for the colorimetric detection of Fe2+ in the solid phase and in real potato samples. Furthermore, the sensor was evaluated for the detection of acidic vapors.

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