Novel Molecular Conformation of (R, S)-Hesperetin in Anhydrous Crystal

概要

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Novel molecular conformation of racemic hesperetin, (±)-2,3-dihydro-5,7,-dihydroxy-2-(3-hydroxy-4-methoxy-phenyl)-4H-1-benzopyran-4-one, was determined by X-ray analysis. A new form was crystallized from ethanol solution and its molecular conformation is quite different from that of monohydrate crystal (Acta Crystallogr., C43,1946 (1987)). The aromatic ring part of benzopyrone and the phenyl ring form the twist orientation (dihedral angle of two rings, Φ is 53.1(3)°), in contrast to the parallel arrangement in the monohydrate form (Φ=0.6°). The pyrone ring forms a slightly flattened sofa conformation, where C(2) is displaced by 0.40(2) Å from the pyrone plane, in contrast to the large displacement in the monohydrate form (0.54Å). There is a strong intramolecular hydrogen bond between keto O(4) atom and hydroxy H(O5)-O(5) group which forms a six-membered ring conjugated with benzopyrone rings. The degree of conjugation is also slightly different of the two forms and may relate to the difference of hydrogen bonding network and stacking mode of aromatic rings.
社団法人日本薬学会の論文
1994-05-15