Dicyanovinyl terthiophene as a reaction based colorimetric and ratiometric fluorescence probe for cyanide anions

Abstract

3′-Dicyanovinyl terthiophene 3 was synthesized and the changes in absorption and emission properties of 3 in the presence of various anions were evaluated. Compound 3 acts as a selective colorimetric as well as a ratiometric fluorescence probe for cyanide anions in aqueous THF solution even in the presence of other anions such as AcO⁻, F⁻, Cl⁻, Br⁻, NO₂⁻, N₃⁻, HS⁻ and ClO₄⁻. Obstruction in an intramolecular charge transfer (ICT) by the nucleophilic addition of a cyanide anion to the dicyanovinyl group induces remarkable changes in the absorption and emission spectra of 3. The signal transduction mechanism was investigated by absorption and emission spectroscopy, ¹H NMR titration and DFT calculations.