Complexation of Zn2+ by the Fluorophore 2-((E)-2-Phenyl)ethenyl-8-(N-4-methylbenzenesulfonyl)aminoquinol-6-yloxyacetic Acid: A Preparative, Potentiometric, UV-visible, and Fluorescence Study

Hilary C. Coleman; Bruce L. May; Stephen F. Lincoln

doi:10.1071/CH10173

RESEARCH ARTICLE

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Complexation of Zn²⁺ by the Fluorophore 2-((E)-2-Phenyl)ethenyl-8-(N-4-methylbenzenesulfonyl)aminoquinol-6-yloxyacetic Acid: A Preparative, Potentiometric, UV-visible, and Fluorescence Study

Hilary C. Coleman ^A , Bruce L. May ^A and Stephen F. Lincoln ^A ^B

+ Author Affiliations

- Author Affiliations

^A School of Chemistry and Physics, University of Adelaide, Adelaide, SA 5005, Australia.

^B Corresponding author. Email: Stephen.Lincoln@adelaide.edu.au

Australian Journal of Chemistry 63(10) 1448-1452 https://doi.org/10.1071/CH10173
Submitted: 28 April 2010 Accepted: 1 July 2010 Published: 1 October 2010

Abstract

The preparation of the Zn²⁺ specific fluorophore 2-((E)-2-phenyl)ethenyl-8-(N-4-methylbenzene-sulfonyl)aminoquinol-6-yloxyacetic acid, H₂3, is described. The protonated form, H₃3⁺, is characterized by pK_a values of 2.71 ± 0.03, 4.92 ± 0.03, and 10.46 ± 0.03 in 25% (v/v) aqueous ethanol 0.10 mol L^–1 in NaClO₄ at 298.2 K determined by potentiometric titration. At pH 6.6, but otherwise under the same conditions, the dianion, 3^2–, forms the fluorescent complexes [Zn(3)] and [Zn(3)₂]^2–, characterized by log(K₁/L mol^–1) = 10.5 ± 0.20 and log(K₂/L mol^–1) = 11.1 ± 0.1, respectively, as determined by fluorimetry. These data are compared with analogous data for the structurally similar and widely used fluorophore 2-methyl-8-p-toluenesulfonamido-6-quinolyloxyacetic acid (Zinquin A).

Acknowledgements

The award of an Australian Postgraduate award to H. Coleman and funding of this research by the University of Adelaide is gratefully acknowledged. We thank Dr D.-T. Pham, Ms. C. Baker, and Dr J. Cawthray for their helpful input.

References

Complexation of Zn2+ by the Fluorophore 2-((E)-2-Phenyl)ethenyl-8-(N-4-methylbenzenesulfonyl)aminoquinol-6-yloxyacetic Acid: A Preparative, Potentiometric, UV-visible, and Fluorescence Study

Abstract

Acknowledgements

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Complexation of Zn²⁺ by the Fluorophore 2-((E)-2-Phenyl)ethenyl-8-(N-4-methylbenzenesulfonyl)aminoquinol-6-yloxyacetic Acid: A Preparative, Potentiometric, UV-visible, and Fluorescence Study