Pilloin was synthesized by methylation of luteolin and its structure was characterized by element analysis, ^1H-NMR, IR, and single-crystal X-ray diffraction analysis. It crystallizes in the monoclinic crystal system, space group P2_1/n, with a = 7.336(3) Å, b = 14.257(5) Å, c = 13.298(5) Å, \beta = 93.516(5)°. The flavone molecules of pilloin are linked into puckering sheets via R_3^3(14) and R_2^2(9) graph-set ring motifs defined by the C-H...O and O-H...O hydrogen bonds. \pi -\pi stacking interactions lead to the flavone skeletons of columns that are held together through centrosymmetric R_2^2(8) motifs. Hydrogen bonding and aromatic \pi -\pi stacking interactions assemble the title compound into a 3-dimensional network structure.
YANG, HONG-BING; WANG, YAN-CHANG; ZHANG, ZUN-TING; and CHANG, YONG (2008) "Synthesis and Crystal Structure of Pilloin," Turkish Journal of Chemistry: Vol. 32: No. 1, Article 9. Available at: https://journals.tubitak.gov.tr/chem/vol32/iss1/9