X-ray study of weak interactions in two flavonoids |
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Authors: | Deepak Sharma Vivek K Gupta Goutam Brahmachari Sadhan Mondal Arindam Gangopadhyay |
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Affiliation: | (1) Post Graduate Department of Physics, University of Jammu, Jammu Tawi, 180 006, India;(2) Department of Chemistry, Visva Bharati University, Santiniketan, 731 235, India |
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Abstract: | 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 π…π 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…π hydrogen bond with H… centroid distance of <2.7 Å. The molecules are further stabilized by π-π interactions. |
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Keywords: | Flavonoid direct methods C-H… π hydrogen bond π -π interaction gauche benzopyran |
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