Ethidium benzoate methanol monosolvate.

In the title salt solvate (systematic name: 8-amino-5-ethyl-6-phenyl-phenanthridin-5-ium benzoate methanol monosolvate), C21H20N3 +·C6H5CO2 -·CH3OH, two ethidium cations, C21H20N3 +, dimerize about a twofold axis through π-π inter-actions [inter-centroid separation = 3.6137 (4) Å]. The benzoate anions are connected through hydrogen bonding with the -NH2 groups of the ethidium cations and the -OH group of the MeOH mol-ecule. The MeOH mol-ecule also accepts a hydrogen bond from the -NH2 group of the ethidium cation. The result is a one-dimensional hydrogen-bonded chain along the b-axis direction.

Ethidium hepta-fluoro-butyrate.

In the title compound (systematic name: 3,8-diamino-5-ethyl-6-phenylphenanthridin-5-ium 2,2,3,3,4,4,4-heptafluorobutyrate), C21H20N3 +·C4F7O2 -, two ethidium ions, C21H20N3 + form a dimerized structure due to π-π inter-actions, even though they are positively charged. The hepta-fluoro-butyrate anions are connected to neighbouring cation dimers via hydrogen-bonding inter-actions, the hydrogen-bonding donor sites of the -NH2 groups of the ethidium ions connecting to the hydrogen-bonding acceptor sites of the -COO- groups of the hepta-fluoro-butyrate anions.

Ethidium tetra-phenyl-borate aceto-nitrile disolvate.

In the title solvated salt, (C21H20N3){B(C6H5)4}·2CH3CN (systematic name 3,8-di-amino-5-ethyl-6-phenyl-phenanthridin-5-ium tetra-phenyl-borate aceto-nitrile disolvate), the dihedral angle between the tricyclic fused ring system (r.m.s. deviation = 0.021 Å) and the pendant phenyl group of the ethidium cation is 84.91 (7)°. The {B(C6H5)4}- anion has a typical tetra-hedral structure. The aceto-nitrile solvent mol-ecules do not accept hydrogen bonds from the -NH2 groups of the ethidium ions.