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

The title compound, CHO, crystallizes in two polymorphs, namely the monoclinic (space group 2/) and triclinic (space group ī) forms, obtained from ,-di-methyl-formamide and isopropyl alcohol solutions, respectively. The mol-ecular structures and conformations in the two forms are essentially the same as each other. The naphtho-quinone 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 -propargyl groups are coplanar with the naphtho-quinone units with r.m.s deviations ranging from 0.04 to 0.09 Å. In the monoclinic crystal, mol-ecules are linked pairs of C-H⋯O hydrogen bonds, forming a tape structure running along [120]. The tapes are further linked by a C-H⋯π inter-action into a layer parallel to the plane. Adjacent layers are linked by another C-H⋯π inter-action. In the triclinic crystal, mol-ecules are linked C-H⋯O and π-π inter-actions, forming a layer parallel to the plane. Adjacent layers are linked by a C-H⋯π inter-action.