Pyrene-armed calix[4]azacrowns as new fluorescent ionophores: "molecular taekowndo" process via fluorescence change.

A series of new calixarene-based fluoroionophores were synthesized. With our new calixarene derivative bearing a crown ether and an azacrown ether as two binding sites, the metal ion was found to selectively choose its better binding pocket between these two ligands. Interesting "molecular taekowndo" processes between Ag(+)-K(+), Cu(2+)-K(+), and Ag(+)-Cs(+) pairs were easily monitored via fluorescence change.