Concentration dependent colour switching of tryptophan-derived 3,5-dinitrobenzamide ligands in the presence of fluoride anions

•Ligands 1 and 2 show unique sensitivity to fluoride anions, and produce concentration-dependent colour switching in UV–vis spectra.•We demonstrate unusual role of tryptophan in the coordination of fluoride anion (as in ligand 2).•Based on this understanding, we have developed a thin-film sensor for...

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Bibliographic Details
Published in:Sensors and actuators. B, Chemical Chemical, 2014-07, Vol.197, p.321-325
Main Authors: Deka, Barnali, Sarma, Rupam J.
Format: Article
Language:English
Subjects:
Anion
Ecognition
Fluoride
Indole
Tryptophan
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Summary:•Ligands 1 and 2 show unique sensitivity to fluoride anions, and produce concentration-dependent colour switching in UV–vis spectra.•We demonstrate unusual role of tryptophan in the coordination of fluoride anion (as in ligand 2).•Based on this understanding, we have developed a thin-film sensor for fluoride anions, which can be utilised for real-time applications.•This work illustrates the chemical consequences of tryptophan-fluoride interactions from anion receptor perspective. Interactions of fluoride anions with 3,5-dinitrobenzamide ligands containing pendant leucine (1) and tryptophan (2) residues respectively, produced dramatic concentration-dependent switching of colour in solutions. 1H NMR spectroscopy revealed that the coordination of fluoride to 2 invoked participation of the tryptophan residue which was indicative of anion-π interactions. In addition, we have developed a chromogenic fluoride sensor from 2, immobilised in polystyrene film, which was applicable in aqueous solutions.
ISSN:0925-4005
1873-3077
DOI:10.1016/j.snb.2014.02.091