Supramolecular hydrogen‐bonding patterns in two cocrystals of the N(7)–H tautomeric form of N 6 ‐benzoyladenine: N 6 ‐benzoyladenine–3‐hydroxypyridinium‐2‐carboxylate (1/1) and N 6 ‐benzoyladenine–DL‐tartaric acid (1/1)

Two novel cocrystals of the N(7)—H tautomeric form of N 6 ‐benzoyladenine (BA), namely N 6 ‐benzoyladenine–3‐hydroxypyridinium‐2‐carboxylate (3HPA) (1/1), C 12 H 9 N 5 O·C 6 H 5 NO 3 , (I), and N 6 ‐benzoyladenine–DL‐tartaric acid (TA) (1/1), C 12 H 9 N 5 O·C 4 H 6 O 6 , (II), are reported. In both cocrystals, the N 6 ‐benzoyladenine molecule exists as the N(7)—H tautomer, and this tautomeric form is stabilized by intramolecular N—H...O hydrogen bonding between the benzoyl C=O group and the N(7)—H hydrogen on the Hoogsteen site of the purine ring, forming an S (7) motif. The dihedral angle between the adenine and phenyl planes is 0.94 (8)° in (I) and 9.77 (8)° in (II). In (I), the Watson–Crick face of BA (N6—H and N1; purine numbering) interacts with the carboxylate and phenol groups of 3HPA through N—H...O and O—H...N hydrogen bonds, generating a ring‐motif heterosynthon [graph set R 2 2 (6)]. However, in (II), the Hoogsteen face of BA (benzoyl O atom and N7; purine numbering) interacts with TA (hydroxy and carbonyl O atoms) through N—H...O and O—H...O hydrogen bonds, generating a different heterosynthon [graph set R 2 2 (4)]. Both crystal structures are further stabilized by π–π stacking interactions.