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Understanding the effect of an amino group on the selective and ultrafast detection of TNP in water by fluorescent organic probes

Abstract

We have designed and developed three single-molecule fluorescent probes differing in the number of amino groups. 5-((4,6-diamino-1,3,5-triazin-2-yl)amino)isophthalic acid (H2ATAIA, 1), 5-((4-amino-6-methoxy-1,3,5-triazin-2-yl)amino)isophthalic acid (H2AMTAIA, 2) and 5-((4,6-dimethoxy-1,3,5-triazin-2-yl)amino)isophthalic acid (H2DMTAIA, 3), from cheap and readily available starting materials via simple procedures in high yields for demonstrating their application in highly selective and ultrafast sensing of 2,4,6-trinitrophenol (TNP) in water (slurry mode). Probes 1-3 have been characterized by various analytical techniques, such as melting point, FTIR, UV-vis and NMR (1H and 13C) spectroscopy and high resolution mass spectrometry (HRMS). It is quite evident that the effect of an amino group is more prominent compared to a methoxy group towards the selective detection of TNP over other potentially interfering nitro compounds. The detection limit for the diamino derivative was found to be 120 ppb compared to those with one amino or no amino group (0.8 ppm and 1.2 ppm, respectively). We also report the ideal real time detection of TNP through contact mode or instant spot via paper strips. Spectral overlap, time-resolved fluorescence studies, quantum yield, Stern-Volmer plots, field emission scanning electron microscopy (FESEM) and DFT calculations have been used to establish their mechanism of action. Furthermore, competitive nitro-analyte tests demonstrate that the selectivity for TNP is more in 1 compared to 2 and 3. To the best on our knowledge, we have demonstrated for the first time molecular decoding of TNP based on the dual read-out identification scheme constructed from life-time and quantum yield. These probes have been found to be highly photostable in presence of acidic TNP as well as recyclable without much loss of sensitivity up to five cycles. These results vividly depict that these are excellent candidates for environmental monitoring.

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Publication details

The article was received on 20 Dec 2017, accepted on 29 Jan 2018 and first published on 29 Jan 2018


Article type: Paper
DOI: 10.1039/C7TC05852G
Citation: J. Mater. Chem. C, 2018, Accepted Manuscript
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    Understanding the effect of an amino group on the selective and ultrafast detection of TNP in water by fluorescent organic probes

    P. Das and S. Mandal, J. Mater. Chem. C, 2018, Accepted Manuscript , DOI: 10.1039/C7TC05852G

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