Highly selective fluorescent sensing of Cu2+ ion by an arylisoxazole modified calix[4]arene

A novel fluorescent chemosensor 1 with two anthraceneisoxazolymethyl groups at the lower rim of calix[4]arene has been synthesized, which revealed a dual emission (monomer and excimer) when excited at 375 nm. This chemosensor displayed a selective fluorescence quenching only with Cu2+ ion over all other metal ions examined. When Cu2+ ion was bound to 1, the fluorescence intensities of both monomer and excimer were quenched. Furthermore, the association constant for the 1:1 complex of 1·Cu2+ was determined to be (1.58 ± 0.03) × 104 M−1.