Fluorometric detection of fluoride ion by ligand exchange reaction with 3-hydroxyflavone coordinated to a zirconium(iv)–EDTA complex

An aqueous solution composed of [Zr(H₂O)₂edta]·2H₂O and 3-hydroxyflavone (flavonol) exhibits an intense blue fluorescence (Λ_max = 460 nm) upon excitation at 400 nm and the signal intensity decreases with the addition of fluoride ion. This observation has been interpreted by the ligand exchange of flavonol coordinated to Zr(iv) with fluoride ion. Based on this phenomenon, we have fabricated a simple fluorescent detection system of fluoride ion available in aqueous media. The present signaling system provides a simple, rapid and selective detection method of fluoride ion, which covers the concentration range from 1 × 10⁻³ to 3 × 10⁻⁶ M without any significant interference from common anions.