Two polymorphs of 2-(prop-2-yn-1-yloxy)naphthalene-1,4-dione: solvent-dependent crystallization

The title compound, C13H8O3, crystallizes in two polymorphs, namely the monoclinic (space group P21/c) and triclinic (space group Pī) forms, obtained from N,N-dimethylformamide and isopropyl alcohol solutions, respectively. The molecular structures and conformations in the two forms are essentially the same as each other. The naphthoquinone ring systems are essentially planar with r.m.s. deviations of 0.015 and 0.029 Å for the monoclinic and triclinic forms, respectively. The O-propargyl groups are coplanar with the naphthoquinone units with r.m.s deviations ranging from 0.04 to 0.09 Å. In the monoclinic crystal, molecules are linked via pairs of C—H...O hydrogen bonds, forming a tape structure running along [120]. The tapes are further linked by a C—H...π interaction into a layer parallel to the ab plane. Adjacent layers are linked by another C—H...π interaction. In the triclinic crystal, molecules are linked via C—H...O and π–π interactions, forming a layer parallel to the ab plane. Adjacent layers are linked by a C—H...π interaction