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Coordination of Distal Carboxylate Anion Alters Metal Ion Specific Binding in Imidazo[1,2-a]pyridine Congeners.
- Source :
- Journal of Fluorescence; Jul2023, Vol. 33 Issue 4, p1397-1412, 16p
- Publication Year :
- 2023
-
Abstract
- Imidazo[1,2-a]pyridine derivatives have excellent potential for chelation with transition metal ions. Two new imidazo[1,2-a]pyridine-8-carboxylates were synthesized and characterized by <superscript>1</superscript>H NMR, <superscript>13</superscript>C NMR, HRMS, and single crystal-XRD techniques. Methyl carboxylate (probe 1) turns on fluorescence upon coordination with Zn<superscript>2+</superscript>, while sodium carboxylate (probe 2) turns off its fluorescence upon coordination with Co<superscript>2+</superscript> or Cu<superscript>2+</superscript> ions present in aqueous acetonitrile medium. <superscript>13</superscript>C NMR study revealed that the change in metal ion specific binding was due to the involvement of carboxylate anion in complex formation with Co<superscript>2+</superscript> or Cu<superscript>2+</superscript> ions. The carboxylate anion at 8-position also enhanced the sensitivity of detection of probe 2 by an order of magnitude (detection limits: 3.804 × 10<superscript>–7</superscript> M, probe 1/Zn<superscript>2+</superscript>; 0.420 × 10<superscript>–7</superscript> M, probe 2/Co<superscript>2+</superscript> and 0.304 × 10<superscript>–7</superscript> M, probe 2/Cu<superscript>2+</superscript>). The detection limits of probes 1 and 2 comply well with the World Health Organization (WHO) and US Environmental Protection Agency (US-EPA) guidelines for detection of heavy metal ions present in drinking water and ground water. Both the probes form a 1:1 complex with Zn<superscript>2+</superscript>, Co<superscript>2+</superscript> or Cu<superscript>2+</superscript>, and the stoichiometry was verified by Job plot and ESI-mass analysis. The sensing mechanism is explained using <superscript>13</superscript>C NMR experiments, ESI-mass analytical data and theoretical DFT calculations. The suitability of probes 1 and 2 for on-site detection and quantitative determination of Zn<superscript>2+</superscript>, Co<superscript>2+</superscript> and Cu<superscript>2+</superscript> ions present in biological, environmental and industrial samples is demonstrated. In addition, both 1 and 2 are used for detection of intracellular contamination of Zn<superscript>2+</superscript>, Co<superscript>2+</superscript> or Cu<superscript>2+</superscript> ions in onion epidermal cells. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10530509
- Volume :
- 33
- Issue :
- 4
- Database :
- Complementary Index
- Journal :
- Journal of Fluorescence
- Publication Type :
- Academic Journal
- Accession number :
- 165465656
- Full Text :
- https://doi.org/10.1007/s10895-022-03122-x