6-Amino-1,3-dimethyl-5-[(E)-2-(methyl­sulfan­yl)benzyl­idene­amino]­pyrimidine-2,4(1H,3H)-dione–1,3,7,9-tetra­methyl­pyrimido[5,4-g]pteridine-2,4,6,8-tetrone (1/1)

In the title co-crystal, C₁₂H₁₂N₆O₄·C₁₄H₁₆N₄O₂S, both mol­ecules are essentially planar [maximum deviations = 0.129 (1) and 0.097 (1) Å, respectively]. The tricyclic and Schiff base mol­ecules are alternately stacked along the a axis and are linked by π–π inter­actions with centroid–centroid distances of 3.5170 (16) and 3.6576 (17) Å. An intra­molecular C—H...O hydrogen bond and a C—H...S contact occur in the Schiff base molecule. In the crystal, N—H...O, N—H...N and C—H...O hydrogen bonds lead to the formation of a three-dimensional network.

N-[(E)-Thio­phen-2-yl­methyl­idene]-1,3-benzothia­zol-2-amine

In the title thio­phene-derived Schiff base compound, C₁₂H₈N₂S₂, the thio­phene ring is slighty rotated from the benzothia­zole group mean plane, giving a dihedral angle of 12.87 (6)°. The largest displacement of an atom in the mol­ecule from the nine-atom mean plane defined by the non-H atoms of the benzothia­zole ring system is 0.572 (1) Å, exhibited by the C atom at the 3-position of the thio­phene ring. In the crystal, weak C—H...S hydrogen bonds involving the thio­phene group S atom and the 4-position thio­phene C—H group of a symmetry-related mol­ecule lead to an infinite one-dimensional chain colinear with the c axis. The structure is further stabilized by π–π inter­actions; the distance between the thia­zole ring centroid and the centroid of an adjacent benzene ring is 3.686 (1) Å. The crystal studied was an inversion twin with the ratio of components 0.73 (3):0.27 (3).