Acridinium 3-carb-oxy-pyrazine-2-carboxyl-ate.

The title ion pair, C(13)H(10)N(+)·C(6)H(3)N(2)O(4) (-), contains a protonated acridine cation and a 3-carb-oxy-pyrazine-2-carboxyl-ate monoanion, which are linked together through O-H⋯O, N-H⋯O and weak C-H⋯O hydrogen bonds. These hydrogen bonds generate a C(10) chain graph-set motif. The crystal structure is further stabilized by extensive π-π stacking inter-actions between nearly parallel [dihedral angle = 1.21(2)°] acridine systems. The shortest distance between the centroids of the six-membered rings within the cations is 3.6315†(8)†à . In addition, C-H⋯π edge-to-face inter-actions are present.