(Tetracycline)europium(III) Complex as Luminescent Probe for Hydrogen Peroxide Detection

✍ Scribed by Geert Dehaen; Gregory Absillis; Kris Driesen; Koen Binnemans; Tatjana N. Parac-Vogt

• Publisher: John Wiley and Sons
• Year: 2009
• Tongue: German
• Weight: 194 KB
• Volume: 92
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.200900184

✦ Synopsis

Abstract

Luminescence spectra of aqueous solutions containing a fixed concentration of tetracycline (TC) and increasing concentrations of Eu^3+^ were recorded both in the absence and presence of hydrogen peroxide (H~2~O~2~). In H~2~O~2~‐free solutions in which the Eu/TC molar ratio was varied from 1 : 1 to 8 : 1, the ^5^D~0~→^7^F~0~ transition consisted of only one peak at 580 nm. In the presence of H~2~O~2~, an extra peak appeared in the spectrum at 578 nm when the Eu/TC molar ratios were above 2.5. A detailed analysis of this spectral region revealed that at lower Eu/TC molar ratios (up to 2 : 1), the ^5^D~0~→^7^F~0~ transition experienced a slight blue shift. This indicates that at low Eu/TC molar ratios, the presence of H~2~O~2~ leads to two different environments of the trivalent europium ions, which most likely form bridged peroxide complexes with hydrogen peroxide (μ‐H~2~O~2~ ligand). Luminescence spectra measured in the presence of molybdate ions, which catalytically decompose H~2~O~2~, led to the disappearance of the extra europium(III) site that was formed in the presence of H~2~O~2~. The intensity of the hypersensitive ^5^D~0~→^7^F~2~ transition did not linearly depend on the H~2~O~2~/TC molar ratio. For H~2~O~2~/TC ratios up to 10, a sharp linear increase of the peak intensity was observed, but with further increase of the H~2~O~2~ concentration, the intensity remained nearly constant. For H~2~O~2~/TC ratios above 100, the intensity of this transition even started to decrease, which limits the use of the (tetracycline)europium(III) system to quantify hydrogen peroxide in solution.