Acridinium salt-based fluoride and acetate chromofluorescent probes: molecular insights into anion selectivity switching.

A series of acridinium salt-based probes capable of detecting fluoride and acetate anions via a nucleophilic attack at the C9 position of the acridinium moiety is reported. The formation of corresponding acridane displays drastic changes, in both UV-vis absorption and fluorescence emission. The sensing mechanism is a reversible process upon treating either tetrafluoroborate salt or an acid.