The effect of absorbance of Fe3+ on the detection of Fe3+ by fluorescent chemical sensors

We investigated the effect of ferric ion absorbance on the detection of Fe3+ by fluorescent sensors. The presence of Fe3+ ion resulted in a decrease of emission intensity of fluorophores (naphthalene, dansyl chloride, and anthracene) excited with UV light. Absorbance spectrum and reversibility studies revealed that the decrease in emission intensity of the fluorophores without a receptor moiety was mainly due to the absorbance of ferric ion. We synthesized fluorescent chemical sensors consisting of the receptor for Fe3+ and naphthyl fluorophore or dansyl fluorophore, respectively. The sensors detected Fe3+ by a fluorescent quenching effect of Fe3+, as well as by the absorbance effect of Fe3+. The absorbance of Fe3+ has a considerable interference effect on the excitation of the fluorophore with a short excitation wavelength range in UV light. Hence, fluorophores with longer excitation wavelength are highly recommended in the synthesis of fluorescent sensors for Fe3+.