A rhodamine-quinoline type molecular switch as a highly selective sequential sensor for Al super(3+) and F super(-) in aqueous solution

A novel optical rhodamine-quinoline type chemosensor (REQ) was successfully synthesized and characterized as a reversible molecular switch. It displayed high selectivity toward Al super(3+) among 19 metal ions and the resultant complex [REQ-Al super(3+)] acted as a sequential chemosensor toward F su...

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Bibliographic Details
Published in:RSC advances 2014-09, Vol.4 (80), p.42337-42345
Main Authors: Mi, Yong-Sheng, Liang, Dong-Ming, Chen, Ya-Ting, Luo, Xu-Biao, Xiang, Jian-Nan
Format: Article
Language:English
Subjects:
Anions
Binding
Chemoreceptors
Contaminants
Drinking water
Environment protection
Metal ions
Switches
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Summary:A novel optical rhodamine-quinoline type chemosensor (REQ) was successfully synthesized and characterized as a reversible molecular switch. It displayed high selectivity toward Al super(3+) among 19 metal ions and the resultant complex [REQ-Al super(3+)] acted as a sequential chemosensor toward F super(-) among 16 anions in neutral aqueous media (ethanol-water, v/v = 3/7, Tris-HNO sub(3), 20 mM, pH 7.0). Moreover, detecting fluoride at concentrations below the maximum contaminant level in drinking water defined by the U. S. Environmental Protection Agency (4.0 mg L super(-1), 211 mu M) could be achieved with a detection limit (LOD) estimated to be down to 8.0 mu M. The reversible ring-open mechanism of the rhodamine spirolactam induced by Al super(3+) binding and the 1 : 1 stoichiometric structure between REQ and Al super(3+) were adequately supported by Job plot evaluation, optical titration, and super(1)H NMR study. Finally, it could be conveniently used for the determination of Al super(3+) and F super(-) with the "naked eye" due to the obvious color change of the testing solution, showing its potential practical application.
ISSN:2046-2069
DOI:10.1039/c4ra06473a