Fluorescence based detection of industrially important and hazardous 4-Nitrophenol in real Samples: A combination of Extensive optical and theoretical studies

A triphenylamine (TPA) based fluorescent sensor T-TPA was elaborately designed which exhibited high quantum yield (QY). The sensor T-TPA displayed aggregation induced emission enhancement (AIEE) character that was confirmed by dynamic light scattering (DLS) analysis. The AIEE active & pi;-electron rich sensor bearing thiourea moiety was employed for the detection of 4-nitrophenol (4-NP) in solution as well as vapor phase. In solution, sensor displayed fluorescence turn-off response towards 4-NP that was attributed to photoinduced electron transfer (PET). The quenching response of sensor T-TPA against 4-NP was highly selective even in the presence of higher concentration of interferences. The mechanistic approach for 4-NP sensing was confirmed through 1H NMR titration experiment, UV-Vis absorption spectroscopy, dynamic light scattering (DLS), and density functional theory (DFT) methodologies. Moreover, non-covalent interaction (NCI) and Bader's quantum theory of atoms in molecules (QTAIM) analysis was performed to support the presence of non-covalent interactions. Furthermore, the sensor was employed for the detection of 4-NP in industrial waste and lake water samples. Additionally, sensor coated paper strips were prepared to do the contact mode detection of 4-NP. Finally, the fluorescence quenching response of sensor was used for the fabrication of logic gate.

Automated summary

A triphenylamine-based fluorescent sensor T-TPA was designed with high quantum yield and exhibited aggregation induced emission enhancement (AIEE) character. It was employed for the detection of 4-nitrophenol (4-NP) in solution and vapor phase, showing fluorescence turn-off response and high selectivity even in the presence of interferences. Mechanistic approaches were employed to confirm the sensing of 4-NP and non-covalent interactions were supported by NCI and QTAIM analysis.