Colorimetric Sensing of Fluoride Ion by New Expanded Calix[4]pyrrole through Anion−π Interaction

Abstract

Three new expanded calix[4]pyrroles were synthesized, where the two dialkylldipyrromethane units are linked via C-C double bonds. One of them, calix[2]bispyrrolylethene, colorimetrically senses fluoride ion only, owing to anion-π interaction in polar aprotic solvents.