Remarkable role of positional isomers in the design of sensors for the ratiometric detection of copper and mercury ions in water

Kumari, Namita and Dey, Nilanjan and Bhattacharya, Santanu (2014) Remarkable role of positional isomers in the design of sensors for the ratiometric detection of copper and mercury ions in water. In: RSC ADVANCES, 4 (9). pp. 4230-4238.

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Abstract

Cation sensing properties of the three positional isomers of rhodamine based sensors (1-3) are studied in water. The sensors differ only in the position of pyridine's nitrogen. The chemosensor 1, with pyridine nitrogen at ortho-position, showed a selective colorimetric detection of Cu(II) ions in water, at physiological pH 7.4 and also in medium containing BSA (bovine serum albumin) and blood serum. Notably the compound 2 and 3, with pyridine end located at meta-and para-positions did not show any color change with Cu(II) ions, although both the compounds showed turn-on change both in color and fluorescence with Hg(II) ions specifically. All the probes showed ratiometric changes with the specific metal ions. The changing position of nitrogen also changed the complexation pattern of the sensors with the metal ions. Probe 1 showed 2 : 1 complexation with Cu(II), whereas 2 and 3 showed 1 : 1 complexation with Hg(II) ions. The mechanism investigation showed that the change in color upon addition of metal ions is due to the ring-opening of the spirolactam ring of the probes. Cu(II) interacted with ligand 1 through a three-point interaction mode comprising carbonyl oxygen, amido nitrogen and pyridine nitrogen end. But in case of 2 and 3, Hg2+ only interacted through pyridine nitrogen ends. Quantitative estimation of Cu2+ and Hg2+ in complex biological media such as bovine albumin protein (BSA) and human blood serum were performed using these sensors. Rapid on-site detection as well as discrimination of these toxic ions was demonstrated using easily prepared portable test-strips.

Item Type:	Journal Article
Publication:	RSC ADVANCES
Publisher:	ROYAL SOC CHEMISTRY
Additional Information:	Copyright for this article belongs to ROYAL SOC CHEMISTRY,ENGLAND
Department/Centre:	Division of Chemical Sciences > Organic Chemistry
Date Deposited:	28 Jan 2014 07:13
Last Modified:	28 Jan 2014 07:13
URI:	http://eprints.iisc.ac.in/id/eprint/48259

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