2-Ethylphenyl acridine-9-carboxylate and 2,5-dimethylphenyl acridine-9-carboxylate.

The title compounds, 2-ethylphenyl acridine-9-carboxylate, C22H17NO2, (I), and 2,5-dimethylphenyl acridine-9-carboxylate, C22H17NO2, (II), form triclinic and monoclinic crystals, respectively. Related by a centre of symmetry, adjacent molecules of (I) are linked in the lattice via a network of C-H...pi and non-specific dispersive interactions. As a result, acridine moieties and independent phenyl moieties of (I) are parallel in the lattice. The molecules of (II), arranged in a 'head-to-tail' manner and related by a centre of symmetry, form pairs stabilized via C-H...pi interactions. These are linked in the crystal via dispersive interactions. Acridine and independent phenyl moieties lie parallel within the pairs, while adjacent pairs are perpendicular, forming a herring-bone pattern.