tert-Butyl 1,4-dioxo-3,6-di­phenyl-1,2,4,5-tetrahydro­pyrrolo­[3,4-c]­pyrrole-2-carboxyl­ate

The title compound, C₂₃H₂₀N₂O₄, is a soluble precursor (`latent pigment') of diketopyrrolo­pyrrole pigments. The tert-butoxy­carbonyl group is twisted by 78.5 (1)° with respect to the heterocyclic ring system. In the crystal structure, pairs of mol­ecules form centrosymmetric dimers through N—H...O intermolecular hydrogen bonds and are stacked in a herring-bone fashion along the a axis.

N,N'-Bis(4-pyrid­yl)naphthalene-3,4:7,8-dicarboximide dimethyl­formamide disolvate

In the title compound, C₂₄H₁₂N₄O₄·2C₃H₇NO, the naphthalene imide, which is an organic pigment utilized for H₂ gas sensors, has inversion symmetry. The pyridyl rings are twisted, in the same direction, out of the plane of the naphthalene imide skeleton by 69.5 (2)°.