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An Azo Dye Based D‐π‐A Chromogenic Probe for Selective Naked‐Eye Detection of Hg 2+ Ion: Application in Logic Gate Operation
Author(s) -
Tripathy Madhusmita,
Subuddhi Usharani,
Patel Sabita
Publication year - 2020
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.202000659
Subject(s) - hypsochromic shift , chemistry , naked eye , salicylaldehyde , chromogenic , nitrobenzene , metal ions in aqueous solution , photochemistry , acceptor , binding constant , detection limit , bathochromic shift , ion , inorganic chemistry , crystallography , organic chemistry , schiff base , fluorescence , chromatography , binding site , biochemistry , physics , quantum mechanics , condensed matter physics , catalysis
The current work describes the selective colorimetric detection of metal ions using a simple azo dye (L1) containing donor‐π‐acceptor framework. In this chromogenic probe, salicylaldehyde is used as donor and nitrobenzene group as acceptor unit. L1 is found to show selective recognition of mercuric ion both visually and spectrophotometrically with no interference from environmentally relevant metal ions in DMSO‐water mixture. It exhibits reddish‐pink colour in DMSO‐water medium as a result of intramolecular charge transfer (ICT) from the electron donating phenolic group to electron withdrawing nitrobenzene group. It selectively binds with Hg 2+ even in presence of other interfering metal ions and form a 1 : 1 L1‐Hg 2+ adduct. It is evident from a change in colour along with a decrease of ICT absorption band and hypsochromic shift of π‐π* band. The binding of the chemosensor and mercuric ion through the salicylaldehyde unit is proved from 1 H‐NMR data and DFT calculations. Using UV‐Vis spectroscopic technique the detection limit and binding constant values are calculated to be 6 μM and 3.3 x 10 3 M −1 respectively. Hg 2+ probing process displays reversibility upon addition of fluoride ion. The on‐off‐on colorimetric change on sequential addition of Hg 2+ and F − mimics an IMPLICATION type logic gate.