Articles written in Bulletin of Materials Science
Volume 30 Issue 5 October 2007 pp 469-475 Polymers
X-ray diffraction studies were carried out on single crystals of two flavonoids, viz. 5-hydroxy-6,7,4′-trimethoxyflavone, C18H16O6, (I) and 5-hydroxy-3,7,4′-trimethoxyflavone, C18H16O6, (II). Crystal structures of both the flavonoids were solved by direct methods and refined by full-matrix least-squares procedures. In both the molecules, the benzopyran moiety is planar. The dihedral angle between the phenyl ring and the benzopyran portion is 5.50(4)° in (I) and 29.11(5)° in (II). In (I), the crystal packing is influenced by O–H…O hydrogen bonds, and weak C–H…O and $\pi \ldots \pi$ interactions whereas in (II) the crystal structure is stabilized by the presence of four intermolecular short contacts of the type C–H…O. There is also one C–H$\ldots \pi$ hydrogen bond with H… centroid distance of < 2.7 Å. The molecules are further stabilized by 𝜋–𝜋 interactions.
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