Two chromone derivatives C11H10O3 (1) and C11H10O2 (2) have been synthesized and characterized by X-ray structural studies with a detailed analysis of the Hirshfeld surfaces and fingerprint plots facilitating a comparison of intermolecular interactions in building different supramolecular architectures. The title compounds are associated through π–stacking interactions and the linear stacking of π–π forces can be thought as the influencing agent for the organization of the title compounds into hydrogen bonded supramolecular layers and are responsible as well for the strengthening of the molecular assembly. Investigation of the intermolecular interactions and crystal packing via Hirshfeld surface analysis reveals that more than two-thirds of the close contacts are associated with weak interactions. The fingerprint plots demonstrate that these weak interactions are important for both local and crystal packing. A comparison of the Hirshfeld surface in the compounds with similar substituted chromone derivatives in the Cambridge Structural Database (CSD) has been presented.

Use of π–π forces to steer the assembly of chromone derivatives into hydrogen bonded supramolecular layers: crystal structures and Hirshfeld surface analyses

Correlations between hydrogen bonds and solvent effects on phenol –OH proton shieldings, temperature coefficients (Δδ/ΔT) and effects on OH diffusion coefficients for numerous phenolic acids, flavonols, flavones, and oleuropein derivatives of biological interest were investigated in several organic solvents and were shown to serve as reliable indicators of hydrogen bonding and solvation state of –OH groups. The temperature coefficients span a range of −0.5 to −12.3 ppb K−1. Shielding differences of 2.0 to 2.9 ppm at 298 K were observed for solvent exposed OH groups between DMSO-d6 and CD3CN which should be compared with a shielding range of ∼7 ppm. This demonstrates that the solvation state of hydroxyl protons is a key factor in determining the value of the chemical shift. For –OH protons showing temperature gradients more positive than −2.5 ppb K−1, shielding changes between DMSO-d6 and CD3CN below 0.6 ppm, and diffusion coefficients significantly different from those of traces of H2O, there is an intramolecular hydrogen bond predictivity value of 100%. The C-3 OH protons of flavonols show very significant negative temperature coefficients and shielding changes between DMSO-d6 and CD3CN of ∼2.3 ppm, which indicate the absence of persistent intramolecular hydrogen bonds, contrary to numerous X-ray structures.

Hydrogen bonding probes of phenol –OH groups

Structural bases for the inhibition of aldose reductase by phenolic compounds.

Flavone norartocarpetin and isoflavone 2′-hydroxygenistein: A spectroscopic study for structure, electronic property and antioxidant potential using DFT (Density functional theory)

A quantum chemical and statistical study of flavonoid compounds (flavones) with anti-HIV activity.

Structure of 2-(2,6-dimethoxyphenyl)-4H-1-benzopyran-4-one (2',6'-dimethoxyflavone)

(1) C 16 H 12 O 3 cristallise dans P1 avec a=7,245, b=8,305, c=10,800 A, α=97,7, β=93,1, γ=111,2°, Z=2; affinement jusqu'a R=0,053. Deux liaisons hydrogene intramoleculaires peuvent contribuer a la planeite marquee de la molecule. (2) C 19 H 18 O 6 cristallise dans P21/n avec a=7,205, b=12,769, c=17,567 A, β=93,27°, Z=4; affinement jusqu'a R=0,041. L'angle diedre entre le cycle phenyl plan et la portion γ-benzopyrone legerement plissee est de 24°. Pas de liaisons hydrogene intramoleculaires

http://journals.iucr.org/c/issues/1990/08/00/pa0128/pa0128.pdf

Structures of 2‐(2‐methoxyphenyl)‐4H‐1‐benzopyran‐4‐one (1) and 5,7‐dimethoxy‐2‐(2,4‐dimethoxyphenyl)‐4H‐1‐benzopyran‐4‐one (2) (2'‐methoxyflavone and 2',4',5,7‐tetramethoxyflavone)

(1): C-17H14O4, Mr = 282.30, triclinic, P-1, a = 10.509(2), b = 13.448(1), c = 17.061(2)angstrom, alpha = 67.24(1), beta = 107.72(2), gamma = 103.59(1)-degrees, V = 2099.0(5)angstrom(3), Z = 6, (3 independent molecules), Dx = 1.34 g.cm-3, CuK-alpha, lambda = 1.54178 angstrom, mu = 7.98 cm-1, F(000) = 888, T = 291K, R = 0.052 for 5178 observed reflections. (2): C-17H14O.CH2O2, Mr = 328.32, orthorhombic, P2(1)2(1)2(1), a = 23.614(8), b = 4.691(1), c = 14.327(4) angstrom, V = 1587.1(8) angstrom-3, Z = 4, Dx = 1.37 g.cm-3, CuK-alpha, lambda = 1.54178 angstrom, mu = 8.79cm-1, F(000) = 688, T = 291K, R = 0.074 for 2038 observed reflections. (3): C-17H14O4.C3H6O, Mr = 356.37, triclinic, P-1, a = 7.596(3), b = 9.624(5), c = 13.122(2) angstrom, alpha = 91.54(3), beta = 100.26(3), gamma = 76.30(4)-degrees, V = 916.9(6) angstrom-3, Z = 2, Dx = 1.29 g.cm-3, MoK-alpha, lambda = 0.71069 angstrom, mu = 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)-degrees 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)-degrees 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.

Conformers of 2-(2,6-dimethoxyphenyl)-4h-1-benzopyran-4-one (2',6'-dimethoxyflavone) and its Solvates With Formic and Propionic Acids

http://journals.iucr.org/c/issues/1988/02/00/hp0467/hp0467.pdf

Structure of 3‐methoxy‐2‐phenyl‐4H‐1‐benzopyran‐4‐one (3‐methoxyflavone)

C17H14O4, M(r) = 282.30, monoclinic, P2(1)/c, a = 12.498 (4), b = 9.490 (2), c = 12.184 (2) angstrom, beta = 107.87 (2)degrees, V = 1375.4 (6) angstrom 3, Z = 4, D(x) = 1.36 g cm-3, Cu K-alpha, lambda = 1.54178 angstrom, mu = 7.98 cm-1, F(000) = 592, T = 291 K, R = 0.042 for 1848 observed reflections. The benzopyran heterocycle is planar within experimental errors (max. deviation from the best mean plane through the ten atoms 0.031 angstrom). The dihedral angle between the heterocycle and the phenyl ring is 23.5 (5)degrees. The methoxy groups are nearly coplanar with their aromatic rings (torsion angles about C(arom)-O are 4-6-degrees).

E. M. Gaydou

Papers

Structure of 2-(2,6-dimethoxyphenyl)-4H-1-benzopyran-4-one (2',6'-dimethoxyflavone)

Structures of 2‐(2‐methoxyphenyl)‐4H‐1‐benzopyran‐4‐one (1) and 5,7‐dimethoxy‐2‐(2,4‐dimethoxyphenyl)‐4H‐1‐benzopyran‐4‐one (2) (2'‐methoxyflavone and 2',4',5,7‐tetramethoxyflavone)

Conformers of 2-(2,6-dimethoxyphenyl)-4h-1-benzopyran-4-one (2',6'-dimethoxyflavone) and its Solvates With Formic and Propionic Acids

Structure of 3‐methoxy‐2‐phenyl‐4H‐1‐benzopyran‐4‐one (3‐methoxyflavone)

Structure of 7-methoxy-2-(2-methoxyphenyl)-4h-1-benzopyran-4-one (2',7-dimethoxyflavone)