Host–guest complexation of a fluorescent and electrochemical chemsensor for fluoride anion

Abstract

Host–guest complexation of a ferrocenenylphalene dyad 1, 1,1′-diaceylferrocenyl-3-hydroxyl-2-naphthoylhydrazone, as a fluorescent and electrochemical chemosensor for fluoride anion, was investigated. Crystal structure analysis revealed that the two naphthyl arms of compound 1 positioned in the same side about the ferrocene moiety and interacted through π–π stacking interactions. The intermolecular π–π stacking interactions and the C–H⋯π interactions between the ferrocene moieties and the naphthalene rings linked the molecules together featuring a two-dimensional layered structure. Fluorescence titrations of compound 1 indicated that in the presence of F⁻ and H₂PO₄⁻, the emission intensities enhanced significantly. Electrochemical titrations revealed that compound 1 sensed the F⁻ anion in high selectivity with a cathodic shift of 120 mV, and had no sense in recognizing H₂PO₄⁻ anion. ¹H NMR titrations demonstrated that while compound 1 hydrogen-bonded to H₂PO₄⁻ forming simple 1 : 1 host–guest complex, further addition of F⁻ induced the deprotonation of compound 1.