A New Polymorph of 7-Hydroxy-2',3',4'-trimethoxyflavone

Abstract

The crystal structure of the monoclinic form of 7-hydroxy -2 -(2,3,4 -trimethoxyphenyl )-4H-1 -benzopyran-4-0ne, C18H1606, contains two molecules in the asymmetric unit which differ from each other in both the torsion angle between the 7-benzopyrone portion and the trimethoxylated phenyl ring, and the orientation of the out-of-plane methoxy groups. The torsion angle values are different from those of the previous form [Llorca, Molins, Miravitlles, Cody, Wallet & Gaydou (1993). J. Crystallogr. Spectrosc. Res. 23,[481][482][483][484] and are indicative of a large degree of 'floppiness' in the trirnethoxylated phenyl ring.

5,7-Bis(benzyloxy)-4H-benzopyran-4-one

“…1) contains two independent molecules, A and B, in the asymmetric unit. The geometrical parameters of the chromone group in (I) are comparable to those of related structures reported earlier (Wallet & Cody, 1995). The chromone group is essentially planar in both molecules, with maximum deviations of 0.112 (3) Å for atom O2 and 0.108 (3) Å for O2 0 .…”

5-Hydroxy-7-methoxy-4H-chromen-4-one

“…The chromene ring system is essentially planar with maximum deviation of -0.007 (2) Å for C2. The geometrical parameters of the chromene group are comparable to those of related structures reported earlier (Wallet & Cody, 1995). The mean bond distances are: O-Csp 2 1.3552 (17) Å, and aromatic C-C 1.391 (2) Å, while C4=O2 is 1.2531 (18)Å and C2=C3 is essentially a double bond with a distance of 1.330 (2) Å Å.…”

“…For related literature, see: Gabor (1988); Valenti et al (1993Valenti et al ( , 1998; Vasconcelos et al (1998); Bernstein et al (1995); Wickens (1995); Wallet & Cody (1995).…”

Crystal and molecular structure of an inclusion compound formed between 2′,6′-dimethoxyflavone and perchloric acid. Comparative study with other acid solvates

“…This can be attributed to the fact that the inclusion compound with formic acid crystallizes in a noncentrosymmetric space group (P212120, whereas the other inclusion compounds crystallize in centrosymmetric space groups. When a flavone packs in more than one crystallographic space group, large differences exist in torsion angles [22,23,24]. Had the inclusion compound with formic acid crystallized in a centrosymmetric space group, a better correlation would be expected.…”