Analytical Sciences

Fluorescent Character of Cu(I/II) Complexes with Bisquinoline-based Ligands and Fluorometric Detection of Reductants

Makoto SAGA,* Tatsuya ANAMUSHI,** Wakayo MIYAHARA,*** Shigeo YAMAZAKI,*** and Keiitsu SAITO*

*Department of Human Environmental Science, Graduate School of Human Development and Environment, Kobe University, 3-11 Tsurukabuto, Nada, Kobe 657-8501, Japan
**Department of Human Environmental Science, Faculty of Human Development, Kobe University, 3-11 Tsurukabuto, Nada, Kobe 657-8501, Japan
***Department of Applied Science, Faculty of Science, Okayama University of Science, 1-1 Ridaicho, Kita, Okayama 700-0005, Japan

The fluorescence ligands N,N′-bis(2-methylquinolyl)dimethylethylenediamine (BQDMEN) and N,N′-bis(2-methylquinolyl)dimethyl-1,3-propanediamine (BQDMPN) were synthesized. [Cu(II)(bqdmen)]²⁺ and [Cu(II)(bqdmpn)]²⁺ were prepared, and their reduction to [Cu(I)(bqdmen)]⁺ and [Cu(I)(bqdmpn)]⁺ was confirmed by the observed UV-Vis spectral change. Then, the fluorescence of [Cu(I/II)(bqdmen)]^+/2+ and [Cu(I/II)(bqdmpn)]^+/2+ in aqueous solution was characterized; [Cu(I)(bqdmen)]⁺ and [Cu(I)(bqdmpn)]⁺ were found to fluoresce in aqueous solution, whereas the fluorescence of [Cu(II)(bqdmen)]²⁺ and [Cu(II)(bqdmpn)]²⁺ was completely quenched. On the basis of these findings, fluorometric detection of reductants with a flow-injection system using a [Cu(II)(bqdmen)]²⁺ or [Cu(II)(bqdmpn)]²⁺ solution as a carrier was explored.

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