9-(2-Ethyl-phenoxy-carbon-yl)-10-methyl-acridinium trifluoro-methane-sulfonate.

In the crystal structure of the title compound, C(23)H(20)NO(2) (+)·CF(3)SO(3) (-), the cations form inversion dimers through π-π inter-actions between the acridine ring systems. These dimers are further linked by C-H⋯π inter-actions. The cations and anions are connected by C-H⋯O and C-F⋯π inter-actions. The acridine and benzene ring systems are oriented at a dihedral angle of 20.8 (1)°. The carboxyl group is twisted at an angle of 66.2 (1)° relative to the acridine skeleton. The mean planes of adjacent acridine units are parallel in the lattice.