Conformers of 2-(2,6-Dimethoxyphenyl)-4H-1-Benzopyran-4-One (2′,6′-Dimethoxyflavone) and its Solvates with Formic and Propionic Acids

Abstract

(1): C17 H14O4 Mr=282.30, triclinic, P-1, a=10.509(2), b=13.448(1), c=17.061(2)Å, α=67.24(1), ß=107.72(2), γ=103.59(1)°, V=2099.0(5)Å3, Z=6, (3 independent molecules), Dx=1.34 g·cm−3, CuKα, λ=1.54178Å, μ=7.98cm−1, F(000)=888, T=291K, R =0.052 for 5178 observed reflections. (2): C17 H14O4.CH2O2, Mr=328.32, orthorhombic, P212121, a=23.614(8), b=4.691(1), c=14.327(4)Å, V=1587.1(8)Å3, Z=4, Dx=1.37 g6middot;cm−3, CuKα, λ=1.54178Å, μ=8.79cm−1, F(000)=688, T=291K, R=0.074 for 2038 observed reflections. (3): C1 · H14O4.C3H6O, Mr=356.37, triclinic, P-1, a=7.596(3), b=9.624(5), C=13.122(2)Å, α=91.54(3), ß=100.26(3), γ=76.30(4)°, V=916.9(6)Å3, Z=2, Dx=1.29 g6middot;cm−3, MoKα, λ=0.71069Å, μ=1.03cm−1, F(000)=376, T=291K, R=0.053 for 1959 observed reflections. In the non-solvated molecule (1), the three independent molecules in the unit cell differ only by the dihedral angle between the benzopyrone and the phenyl ring, 68(1), 86(1) and 84(1)° respectively. For the formic (2) and propionic acid (3) solvates, the dihedral angle between the heterocycle and the phenyl ring are 80(1) and 64(1)° respectively. In the two solvates the hydrogen bonding involving the carbonyl oxygen is alike. It may be thus concluded that this hydrogen bond has no effect on the conformation of 2′,6′-dimethoxyflavone.