3-{[4-Amino-6-methoxy-2-(methylsulfanyl)pyrimidin-5-yl]amino}-1,2'-biindenylidene-1',3'-dione dimethyl sulfoxide solvate: pi-stacked sheets of hydrogen-bonded chains of edge-fused rings.

In the title compound, C(24)H(18)N(4)O(3)S.C(2)H(6)OS, the biindenylidene component shows evidence of polarization of the electronic structure. The dimethyl sulfoxide solvent molecules are disordered over two sites, and they are linked to the biindenylidenedione components via N-H...O and C-H...O hydrogen bonds. A combination of N-H...N and N-H...O hydrogen bonds links the nonsolvent components into a chain of edge-fused centrosymmetric R(2)(2)(8) and R(2)(2)(22) rings, and these chains are linked into sheets by a single aromatic pi-pi stacking interaction.