| Summary: | A new polymorphic form of the title compound, C12H10O4, is described in the orthorhombic space group Pbca and Z = 8, as compared to polymorph I, which crystallizes in the monoclinic space group C2/c and Z = 8 [Li et al. (2012). Chin. J. Struct. Chem. 31, 1003–1007.]. In polymorph II, the coumarin ring system is almost planar (r.m.s. deviation = 0.00129 Å). In the crystal, molecules are connected by Csp3—H...O and Car—H...O hydrogen bonds, forming molecular sheets linked into zigzag shaped layers along the b-axis direction. The three-dimensional lattice is assembled through stacking of the zigzag layers by π–π interactions with a centroid-to-centroid distance of 3.600 (9) Å and antiparallel C=O...C=O interactions with a distance of 3.1986 (17) Å, which give rise to a helical supramolecular architecture.
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