Lattice inclusion compounds of gossypol. Structure of the 2:3 gossypol–benzaldehyde coordinatoclathrate

Gdaniec, Мaria; Ibragimov, B. T.; Talipov, S. A.

doi:10.1107/s0108270190005133

Cited by 3 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The torsion angles are reported in Table . The unsubstituted Ph−CHO ( 1 ) is planar, in accord with gas-phase electron diffraction and early microwave results and even with X-ray data in cocrystals, where 1 is found to be mostly planar with packing-induced twists of less than 5° . In contrast to this consensus, 2,6-dimethyl Ph−CHO ( 1-Me ) is also calculated to possess a planar global minimum, whereas experimental torsion angles differ.…”

Section: Resultssupporting

confidence: 76%

Changes in the Isotropic Shielding of the¹⁷O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin

Muchall

2008

J. Phys. Chem. A

View full text Add to dashboard Cite

We are presenting a computational study on the isotropic shielding, charge, and orbital contributions to the shielding of oxygen in benzaldehydes (Ar-CHO), nitrobenzenes (Ar-NO2), phenyl isocyanates (Ar-NCO), anilides (Ar-NHCOCH3), and N-sulfinylamines (Ar-NSO). In particular, changes upon ortho substitution of the aromatic ring and upon torsion of the unsubstituted parent molecules are examined. The experimentally observed changes in (17)O chemical shift, be they upfield or downfield, upon substitution by ortho-alkyl groups are reproduced well by the calculations. Relaxed torsional scans of the parent systems reveal that (a) charges change as expected from resonance arguments and (b) changes in isotropic shielding are monotonic and in line with changes upon substitution, with N-sulfinylaniline as an exception. In general, the changes in isotropic shieldings are explained in terms of changes in molecular orbitals, their energies, and relative alignments, whose mixing is magnetically active. Thus, for example, the observed deshielding of (17)O upon methyl substitution and upon torsion of benzaldehyde is mainly caused by a contribution from the pi-type oxygen lone pair, yet how these contributions change is fundamentally different. As a consequence, the experimentally observed downfield shift upon methyl substitution cannot be interpreted to imply a change in torsion angle between the phenyl ring and the aldehyde group. For N-sulfinylaniline, the consecutive downfield shifts upon methyl and tert-butyl substitution and the associated changes in torsion angle are in contrast to the 45 degrees maximum in isotropic shielding that is determined from a relaxed torsional scan.

show abstract

Section: Resultssupporting

confidence: 76%

Changes in the Isotropic Shielding of the¹⁷O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin

Muchall

2008

J. Phys. Chem. A

View full text Add to dashboard Cite

show abstract

“…This compound has a very large TBDIE of 0.85 ppm ( Figure 11). It has also been reasoned that the compound does not show tautomeric behavior despite the very short O•••O distance calculated as 2.47 Å (B3LYP) compared to the X-ray distance of 2.46 Å [25]. From the plot of…”

Section: Discussionmentioning

confidence: 99%

“…Structures were optimized and energies calculated in two different ways: MP2 with the basis set 6-311++G(d,p), or using the B3LYP functional with the same basis set. The structure of gossypol (11) is extraordinary with a very short O•••O distance (2.46 Å) [25]. In 5-nitrosalicylaldehyde (17), the nitro group is twisted slightly out of the benzene ring plane in the MP2 calculations, whereas it is in the ring plane in the B3LYP calculations.…”

Section: Structures and Energiesmentioning

confidence: 99%

Intramolecular Hydrogen Bonds in Normal and Sterically Compressed o-Hydroxy Aromatic Aldehydes. Isotope Effects on Chemical Shifts and Hydrogen Bond Strength

et al. 2019

View full text Add to dashboard Cite

A number of o-hydroxy aromatic aldehydes have been synthesized to illustrate the effect of steric compression and O···O distances on the intramolecular hydrogen bond and the hydrogen bond energies. Hydrogen bond energies have been calculated using the ‘hb and out’ method using either the MP2 method or the B3LYP functional with the basis set 6-311++G(d,p). However, several compounds cannot be treated this way. Hydrogen bond energies are also determined using electron densities at bond critical points and these results are in good agreement with the results of the ‘hb and out’ model. Two-bond deuterium isotope effects on 13C chemical shifts are suggested as an experimental way to obtain information on hydrogen bond energies as they easily can be measured. Isotope effects on aldehyde proton chemical shifts have also been measured. The former show very good correlation with the hydrogen bond energies and the latter are related to short O···O distances. Short O···O distances can be obtained as the result of short C=C bond lengths, conjugative effects, and steric compression of the aldehyde group. Short O···O distances are in general related to high hydrogen bond energies in these intramolecularly hydrogen-bonded systems of resonance assisted hydrogen bond (RAHB) type.

show abstract

“…In addition, the O-2 and O-2′ hydrogen atoms donate to the carbonyl oxygen atoms of two separate acetic acid molecules. The O-1′ hydroxyl hydrogen, which is often found to donate to an acceptor moiety of a hydrophilic guest molecule (36), bonds to the carbonyl oxygen of the third acetic acid molecule. One gossypol-to-gossypol intermolecular hydrogen bond is present: the O-1 hydrogen donates to the O-4 oxygen of an adjacent molecule.…”

Section: Resultsmentioning

confidence: 99%

Crystal and molecular structure of an enantiomeric gossypol‐acetic acid clathrate

Dowd

Thomas

Calhoun

1999

J Americ Oil Chem Soc

View full text Add to dashboard Cite

Single crystals of gossypol with three molecules of acetic acid (gossypol triacetic acid) were grown from solutions of gossypol acetic acid and acetone. The crystals were unstable in air but could be stabilized for X-ray diffraction analysis by coating the crystal surfaces with a thin layer of mineral oil. The gossypol triacetic acid complex (C 30 H 30 O 8 ·3C 2 H 4 O 2 ) forms an orthorhombic crystal system with P2 1 2 1 2 1 (Z = 4) symmetry. Unit cell dimensions were a = 9.0208(7) Å, b = 17.4884(10) Å, and c = 24.358(2), Å yielding a volume of 3842.7(5) Å 3 and a density of 1.2077(2) g/cm 3 . As with all previously reported crystals of gossypol, the gossypol molecules were of the aldehyde tautomer, and the two planar naphthalene rings were approximately perpendicular. Acetic acid molecules were found to lie in channels within the gossypol matrix. Individual crystals contained only one gossypol enantiomer, but both enantiomers crystallized from solution. Although the crystal habit could not be used to distinguish between the gossypol enantiomers, a fragment of the crystal could be derivatized and analyzed by high-performance liquid chromatography for this purpose. The ability to grow large, nonracemic crystals leads to a simple procedure for separating small quantities of the individual gossypol enantiomers.

show abstract

Lattice inclusion compounds of gossypol. Structure of the 2:3 gossypol–benzaldehyde coordinatoclathrate

Cited by 3 publications

References 0 publications

Changes in the Isotropic Shielding of the¹⁷O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin

Changes in the Isotropic Shielding of the¹⁷O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin

Intramolecular Hydrogen Bonds in Normal and Sterically Compressed o-Hydroxy Aromatic Aldehydes. Isotope Effects on Chemical Shifts and Hydrogen Bond Strength

Crystal and molecular structure of an enantiomeric gossypol‐acetic acid clathrate

Contact Info

Product

Resources

About

Lattice inclusion compounds of gossypol. Structure of the 2:3 gossypol–benzaldehyde coordinatoclathrate

Cited by 3 publications

References 0 publications

Changes in the Isotropic Shielding of the17O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin

Changes in the Isotropic Shielding of the17O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin

Intramolecular Hydrogen Bonds in Normal and Sterically Compressed o-Hydroxy Aromatic Aldehydes. Isotope Effects on Chemical Shifts and Hydrogen Bond Strength

Crystal and molecular structure of an enantiomeric gossypol‐acetic acid clathrate

Contact Info

Product

Resources

About

Changes in the Isotropic Shielding of the¹⁷O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin

Changes in the Isotropic Shielding of the¹⁷O Nucleus upon Torsion in Terminal Oxygen Systems: A Computational Study on Their Origin