Fluoride sensing with a PCT-based calix[4]arene

Novel calix[4]arene-based anion sensor 1 with two coumarin units attached via amido functions acting also as binding sites is presented. Complexation of F− by PCT-based 1 causes selectively red-shift in UV-vis absorption and in fluorescence emission due to H-bonding followed by deprotonation of NH-amide groups.