7-Ethoxy-4′-methoxyisoflavone (monoethylformononetin)

Abstract

The title compound, C18H16O4, is composed of a benzopyran­one core with a 4-methoxy­phenyl subsituent in the 3-position and an additional eth­oxy group in the 7-position. The benzopyran­one ring is not coplanar with the benzene ring, the dihedral angle between them being 41.76 (7)°. The meth­oxy and eth­oxy substituents are nearly coplanar with the ring systems to which they are attached. Individual mol­ecules are linked by two kinds of inter­molecular hydrogen bonds into chains containing classical R 2 2(8) rings. The chains are further assembled by aromatic F-tape and T-tape stacking inter­actions and additional inter­molecular hydrogen bonding to give a two-dimensional network.

A conformational study of hydroxylated isoflavones by vibrational spectroscopy coupled with DFT calculations

“…The presently obtained conformations for GEN, DAID and FOR were found to be in good accordance with previously reported X-ray data for similar compounds. Furthermore, the crystallographic structures previously gathered for GMC and EFOR [45,46] corroborate the differences between GEN and the other two studied isoflavones, which seem to be well reproduced by the DFT calculated data.…”

“…Regarding the aforementioned (C 8a O 1 C 2 ) bond angle, a remarkable feature can be observed in these systems: the value of 118.5 • , obtained for 7-ethoxy-formononetin (EFOR) by crystallography [46], is very close to 118.8 • calculated for both DAID and FOR, while presenting a slight difference from the 119.4 • value reported for GMC (Table 2). Concomitantly, the values of 126.3 and 123.1 pm measured for the C 4 O 12 bond for GMC and EFOR, respectively, can be compared to the larger calculated value of 125.2 pm for GEN, evidencing the distinct chemical nature of this molecule, due to the six-membered intramolecular ring ( Fig.…”

“…The theoretical DFT geometries obtained for the isolated molecules under study were compared to the X-ray crystallographic data found in the literature for similar systems [45,46], a very good agreement having been found both for bond distances and angles. The calculated distance for the H-bond involving the (C 5 OH) moiety in GEN is 166 pm (Fig.…”