The boron-containing π-conjugated systems, including tri (9-anthryl) borane (1) and tris [(10- dimesitylboryl)-9-anthryl] borane (2), have been investigated as a new type of fluoride chemosensor. Upon complexation of 1 with a fluoride ion, a significant color change from orange to colorless was observed and, in the UV-visible absorption spectra, the characteristic band of 1 at 470 nm disappeared and new bands around 360-400 nm ...