2-[(2-Hydroxybenzyl)amino]pyrazinium perchlorate-2-[(pyrazin-2-ylamino)methyl]phenol

In the crystal structure of the title co-crystal, C11H12N3O+center dot ClO4-center dot C11H11N3O, the perchlorate ion is disordered about a twofold rotation axis with the Cl atom located on the twofold rotation axis; the 2-[(2-hydroxybenzyl)amino] pyrazinium cation and the neutral 2-[(pyrazin-2-ylamino) methyl] phenol molecule are disordered about the rotation axis in a 1:1 ratio. These two are connected by a pyrazine-pyrazine N-1-H center dot center dot center dot N-4 hydrogen bond. The cation, whose two aromatic rings are twisted along the -CH2-NH- bond by 76.8 (1)degrees, is a hydrogen-bond donor to the perchlorate ion through the N atom of this link.