9-(4-Fluoro-phen-oxy-carbon-yl)-10-methyl-acridinium trifluoro-methane-sulfonate.

In the crystal structure of the title compound, C(21)H(15)FNO(2) (+)·CF(3)SO(3) (-), the cations form inversion dimers through C-H⋯O, C-F⋯π and π-π inter-actions. These dimers are further linked by π-π inter-actions. The cations and anions are connected through C-H⋯O, C-F⋯π and S-O⋯π inter-actions. The acridine and benzene ring systems are oriented at a dihedral angle of 74.1 (1)°. The carboxyl-ate group is twisted at an angle of 4.4 (1)° relative to the acridine skeleton. The mean planes of the adjacent acridine moieties are parallel or inclined at an angle of 55.4 (1)° in the crystal structure.