10-Methyl-9-(2-nitro-phenoxy-carbon-yl)acridinium trifluoro-methane-sulfonate.

The crystal structure of the title compound, C(21)H(15)N(2)O(4) (+)·CF(3)O(3)S(-), is stabilized by C-H⋯O and C-H⋯F hydrogen bonds, by C-F⋯π, N-O⋯π and S-O⋯π inter-actions, and by O⋯O [2.70 (4) Å] and O⋯F [2.85 (1) or 2.92 (1) Å] contacts; π-π interactions are also present. In the packing of the mol-ecules, acridine units are either parallel or inclined at an angle of 12.5 (1)°. The nitrophenoxycarbonyl unit is disordered over two position; the site occupancy factors are 0.89 and 0.11.