Acridone heterocycles as fluorescent sensors for anions

An acridone heterocycle with a suitable functionalization can be used as a fluorescent sensor for anions. Large differences in fluorescence efficiency are observed when chlorides are associated in the receptor cavity. Chlorides form two different complexes in chloroform, with 2:1 and 1:1 stoichiometries. The combined presence of receptor (1) and 18-crown-6 ether allows the extraction of aqueous α-amino acids to the chloroform phase. This extraction is very sensitive to temperature.