Anion Recognition by a Pyrene Derivative with a Thiourea Function

Abstract

A novel fluorescent indicator for anions, which contains both a fluorescent pyrenyl moiety and a thiourea group as a recognition site, is described. Hydrogen bond-mediated complexation with oxo anions such as CH₃COO^- and H₂PO₄^- induces a dual fluorescence consisting of two bands, namely, a normal emission due to the pyrene unit and an anomalous long-wavelength emission. The intensity of the new emission increases as anion concentration increases, while the normal emission is relatively unaffected. The degree of the changes is in the order of CH₃COO^->H₂PO₄^-_??_ClO₄^-, reflecting the binding selectivity of the probe molecule.