Premium
Triarylamine‐Cored Dendritic Molecular Gel for Efficient Colorometric, Fluorometric, and Impedometeric Detection of Picric Acid
Author(s) -
Mondal Sanjoy,
Bairi Partha,
Das Sujoy,
Nandi Arun K.
Publication year - 2018
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201705782
Subject(s) - picric acid , naked eye , fluorescence , chemistry , quenching (fluorescence) , microphonics , detection limit , photoinduced electron transfer , photochemistry , electron transfer , analytical chemistry (journal) , chromatography , organic chemistry , medicine , physics , quantum mechanics , audiology
Detection of nitroaromatics at ultralow concentration is a major security concern in defense, forensics, and environmental science. To this end, a new triarylamine‐cored dendritic gelator ( OGR ) was synthesized, which produced thermoreversible, thixotropic, and fluorescent gels in n ‐octanol. On gelation, both π–π* transitions and the emission peak of the gelator show redshifts with a 4.5‐fold increase of fluorescence intensity in the gel state indicating J‐aggregation. The nitrogen lone‐pair electrons of OGR make it a donor, and electron transfer occurs to acceptor nitroaromatics causing fluorescence quenching, which is further promoted due to its acidity. The Stern–Volmer rate constants measured for different nitroaromatics showed that it senses picric acid (PA) best. The contact‐mode technique with OGR ‐treated paper strips can allow naked‐eye detection of PA under UV light down to 10 −11 m concentration within 30 s. Reusability of the gel is achieved by treating OGR@PA x with NaOH solution. Impedance spectroscopic results indicated a decrease of both charge‐transport resistance and Warburg impedance on successive addition of PA. The limits of detection of PA determined from fluorescence and impedance measurements match well. Thus, the OGR gel is a reusable, low‐cost, specific sensor for PA by naked‐eye colorimetric, fluorescence, and impedance techniques.