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A benzimidazole-based non-symmetrical tripodal receptor for the ratiometric fluorescence sensing of fluoride ions and solid state recognition of sulfate ions

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Abstract

Herein, a novel non-symmetric tripodal receptor has been synthesized and reported as a fluorescent chemosensor for fluoride ions with a remarkable red shift of 100 nm. The receptor was designed with benzimidazole and amide NH functionalities to achieve fluorescence signals during anion sensing; the recognition behaviour of the probe towards fluoride ions was investigated using emission spectroscopy based on a ratiometric change with the limit of detection as low as 0.875 ppb as well as a visual change in colour from violet to cyan under UV light. 1H NMR studies confirmed the initial formation of the –NH⋯F hydrogen bond and the subsequent deprotonation of benzimidazole and amide upon the addition of fluoride ions. In addition, an INHIBIT-type logic gate at the molecular level could be fabricated using the reversibility and the reusability of the probe towards the F and H+ ions. Moreover, visual detection of fluoride ions in the solid state was feasible as the receptor-coated TLC plates and paper strips detected the former under UV light. In the protonated form, the asymmetric unit encompasses two molecules of the non-symmetrical receptor that bind two molecules of sulfate anions, and the benzimidazole NHs have been found to be potent hydrogen bond donors.

Graphical abstract: A benzimidazole-based non-symmetrical tripodal receptor for the ratiometric fluorescence sensing of fluoride ions and solid state recognition of sulfate ions

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Publication details

The article was received on 31 Jul 2019, accepted on 20 Sep 2019 and first published on 20 Sep 2019


Article type: Paper
DOI: 10.1039/C9NJ03961A
New J. Chem., 2019, Advance Article

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    A benzimidazole-based non-symmetrical tripodal receptor for the ratiometric fluorescence sensing of fluoride ions and solid state recognition of sulfate ions

    N. Borah, B. Nayak, A. Gogoi and G. Das, New J. Chem., 2019, Advance Article , DOI: 10.1039/C9NJ03961A

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