A novel calix[4]arene bearing one 2,3-naphthocrown-6 andtwo coumarin amide units at the lower rim in partial-coneconformation (1) was synthesized as a colorimetric andFRET-based fluorometric sensor for F- and Cs+ ions.Intramolecular FRET from the naphthalene emission to thecoumarin absorption affords high fluorescence selectivitytoward F- and Cs+ ions.
