Selective colorimetric sensing for F− by a cleft-shaped anion receptor containing amide and hydroxyl as recognition units

A simple cleft-shaped anion receptor 1 containing amide and hydroxyl as recognition units was synthesized and its anion recognition properties were investigated by naked-eye observation, UV–vis, fluorescence and 1H NMR spectra. Receptor 1 could effectively recognize F− via multiple H-bonding interactions, along with visible color change and remarkable fluorescence enhancement. Interestingly, reference compound 2 only containing amide groups did not display any interaction for all of the examined anions, including F−.