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  • 1
    Electronic Resource
    Electronic Resource
    Application of Two-Dimensional NMR Spectroscopy to Wood Lignin Structure Determination and Identification of Some Minor Structural Units of Hard- and Softwood Lignins (1994)
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 42 (1994), S. 2790-2794 
    Details
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jf00048a026
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  • 2
    Electronic Resource
    Electronic Resource
    erythro-2-(2,6-Dimethoxyphenoxy)-1-(3,4,5-trimethoxyphenyl)-1,3-propanediol (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. o1219-o1221 
    Details
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In the crystals of the title lignin model compound, C20H26O8, the molecules adopt a conformation in which the bulky 2,6-dimethoxyphenoxy and 3,4,5-trimethoxyphenyl groups are distant from each other. The O(phenoxy)—C—C—C(phenyl) torsion angle between these groups is 178.58 (7)°. The hydrogen-bonding pattern is discussed in terms of graph-set theory.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S1600536801019390
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  • 3
    Electronic Resource
    Electronic Resource
    The racemate of pinoresinol (2001)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 57 (2001), S. o692-o694 
    Details
    ISSN: 1600-5368
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The molecules in the crystals of (±)-pinoresinol, C20H22O6, were found to be statistically disordered. A model of the disorder was deduced. The crystal structure of (±)-pinoresinol is compared with published crystal structures of (+)-pinoresinol and the related compound (−)-syringaresinol. Bond lengths and angles in the crystal structure of (+)-pinoresinol are reasonable, while the crystal structure of (−)-syringaresinol exhibits anomalies resembling those observed for (±)-pinoresinol before the disorder was resolved. The conformation of the dioxabicyclooctane ring system in (±)-pinoresinol differs from that of (+)-pinoresinol, but is similar to that of (−)-syringaresinol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S1600536801011084
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  • 4
    Electronic Resource
    Electronic Resource
    Crystal structure of the diacetate of (+)-epipinoresinol, C24H26O8 (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 733-744 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of the diacetate of (+)-epipinoresinol, C24H26O8, has been determined by single-crystal diffraction methods. The compound crystallizes in the monoclinic space groupP21 witha=7.506(3),b=8.526(4),c=17.746(8) Å,β=97.12(4)° andZ=2. A total of 3504 reflexion intensities were recorded on a Syntex P21 diffractometer (MoKα radiation) at room temperature. The structure was solved by direct methods and electron density calculations. Full-matrix least-squares refinement gaveR=0.056 for 2297 observed [I〉3σ(I] reflexions. The individual central tetrahydrofuran rings have envelope conformations with coplanar carbon atoms and the oxygen atoms as flaps; the carbon atom planes form an angle of 119.9(3)°. Bond distances are C-C (aromatic) 1.386(12) Å, C(sp 3)-O 1.421(12) Å, C(sp 2)-O 1.372(20) Å, and C(sp 2)=O 1.186(9) Å. The influence of molecular structure on the positions of signals in the1H nmr spectrum of the diacetate of (+)-epipinoresinol is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01179846
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  • 5
    Electronic Resource
    Electronic Resource
    Crystal structure of protogenkwanin, C16H14O6 (1991)
    Springer
    Journal of chemical crystallography 21 (1991), S. 183-188 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of protogenkwanin, C16H14O6, has been determined by single-crystal diffraction methods. The compound crystallizes in the monoclinic space groupP21/c witha=6.804(4),b=7.457(3),c=26.234(3)Å,β=95.66(2)° andZ=4. A total of 3275 unique reflection intensities were recorded on a Rigaku AFC6R diffractometer (MoKα radiation) at room temperature. The structure was solved by direct methods and electron density calculations. Full-matrix least-squares refinement gaveR=0.058 for 1257 observed [I〉3σ(I)] reflections. Thecrystal structure confirms results from earlier studies on protogenkwanin and elucidates the steric orientation of the hydroxyl substituents of the cyclohexadiene ring: the hydroxyl groups aretrans orientated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01161062
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  • 6
    Electronic Resource
    Electronic Resource
    Investigation of an inclusion compound of trans-1,3-bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone with chloroform by NMR spectroscopy and X-ray crystallography (1999)
    Springer
    Journal of chemical crystallography 29 (1999), S. 1023-1029 
    Details
    ISSN: 1572-8854
    Keywords: chalcone epoxide ; X-ray crystallography ; nuclear magnetic resonance ; inclusion compound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract trans-1,3-Bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone crystallizes in a monoclinic form (m.p. 155–156°C, from ethanol) and a trigonal form (m.p. 125–126°C, from chloroform/hexane or chloroform). NMR studies revealed that chloroform is present in the crystals of the trigonal form (epoxide/chloroform ratio ≈ 3:1). Solid-state NMR experiments showed that the trigonal form was gradually converted into the monoclinic form on storage in vacuo. On the basis of NMR and X-ray examinations it was concluded that the trigonal form is an inclusion compound of trans-1,3-bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone with chloroform. The crystal structure of the trigonal form with space group of R $${\bar 3}$$ , a = 36.0354(4), c = 8.2743(2) Å, and Z = 18, has been refined to R = 0.0506 by the employment of the SQUEEZE procedure implemented in PLATON-94.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009524801113
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  • 7
    Electronic Resource
    Electronic Resource
    On the stereochemistry of lignin model compounds of the arylglycerol-β-aryl ether type: Crystal structure oferythro-1-(4-hydroxy-3,5-dimethoxyphenyl)-2-(4-hydroxymethyl-2,6-dimethoxyphenoxy)-1,3-propanediol, C20H26O9 (1989)
    Springer
    Journal of chemical crystallography 19 (1989), S. 331-339 
    Details
    ISSN: 1572-8854
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The crystal structure of erythro-1-(4-hydroxy-3,5-dimethoxyphenyl)-2-(4-hydroxymethyl-2,6-dimethoxyphenoxy)-1,3-propanediol, C20H26O9, has been determined from single-crystal X-ray diffraction data. The compound crystallizes in the triclinic space groupP¯1 witha=8.705(6),b=8.893(5),c=13.211(8) Å,α=106.23(5),β=93.71(5), υ=82.97(5)° andZ=2. The structure was solved by direct methods. Full matrix least-squares refinement of 366 structural parameters gaveR=0.039 for 1402 observed [I〉3a(I)] reflexions. The molecules are held together by van der Waals forces and moderately strong hydrogen bonds. Average bond distances: C(sp 2)-O 1.370(6) Å and C(sp 3)-O 1.426(14) Å.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01194128
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  • 8
    Electronic Resource
    Electronic Resource
    Crystal structures of two modifications oftrans-1,3-bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone (1994)
    Springer
    Journal of chemical crystallography 24 (1994), S. 407-413 
    Details
    ISSN: 1572-8854
    Keywords: C19H20O6 ; chalcone ; dimorphism ; epoxide
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract trans-1,3-Bis(3,4-dimethoxyphenyl)-2,3-epoxy-1-propanone exhibits dimorphism and crystallizes in a monoclinic form from ethanol and in a trigonal form from chloroform/hexane. The crystal structures of the two modifications were determined by single-crystal X-ray diffraction methods. The monoclinic form crystallizes in space groupP2t/c with $$\dot a = 8.709(2)$$ ,b=7.986(1),c=25.223(4) Å, β=94.83(2)°,V=1747.9(6) Å andZ=4.R=0.052 for 1236 reflections [I〉3σ(I)]. The trigonal form crystallizes in space group $$R\bar 3$$ witha=36.048(6),c=8.313(5) Å,V=9355(6) Å andZ=18 (hexagonal axes).R=0.101 for 1216 reflections [I〉3σ(I)]. In the trigonal crystals there are channels in thec-direction with a diameter of approximately 10 Å. Possible explanations for the comparatively highR-value are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666086
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  • 9
    Electronic Resource
    Electronic Resource
    Investigation of lignin models of the biphenyl type by X-ray crystallography and NMR spectroscopy (1995)
    Springer
    Journal of chemical crystallography 25 (1995), S. 1-10 
    Details
    ISSN: 1572-8854
    Keywords: Lignin model ; biphenyl ; X-ray crystallography ; conformation ; nuclear magnetic resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Lignin models of the biphenyl type have been synthesized and crystal structures of two of them have been determined. The tetraacetate of 5,5′-bis(hydroxymethyl)-3,3′-dimethoxy-2,2′-biphenyldiol crystallizes in space group $$P\bar 1$$ witha=11.319(2),b=12.232(6),c=9.242(3) Å, α=101.66(3)°, β=108.14(2)°, γ=79.08(2)° andZ=2.R=0.036 (2720 observed [I〉3σ(I)] reflections). The acetate of 5,5′-di-tert-butyl-2′,3,3′-trimethoxy-2-biphenylol crystallizes in space group $$P\bar 1$$ witha=11.972(2),b=21.621(3),c=9.834(1) Å, α=91.18(1)°, β=113.13(1)°. γ=98.42(1)°, andZ=4.R=0.050 (8129 observed [I〉3σ(I)] reflections).1H NMR and13C NMR data for the above-mentioned compounds and a third model, the diacetate of 5,5′-bis(1-hydroxyethyl)-2,2′,3,3′-tetramethoxybiphenyl, are reported. Observed signal positions are compared with those calculated on the basis of crystal structure data. The possibilities to obtain structural information about biphenyl structures in lignins from NMR spectra are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01666186
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  • 10
    Electronic Resource
    Electronic Resource
    Investigation of 2-(3,4-dimethoxyphenyl)-5,6-dimethoxy-1H-indene by X-ray crystallography and NMR spectroscopy (1996)
    Springer
    Journal of chemical crystallography 26 (1996), S. 287-291 
    Details
    ISSN: 1572-8854
    Keywords: Lignin model ; indene ; X-ray crystallography ; nuclear magnetic resonance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract 2-(3,4-Dimethoxyphenyl)-5,6-dimethoxy-1H-indene (obtained by acid treatment of 1,2-bis(3,4-dimethoxyphenyl)-1,3-propanediol) crystallizes in space groupP21/c witha=6.836(6),b=28.631(9),c=16.344(6) Å, β=95.73(5)°, andZ=8. There are two molecules in the asymmetric unit; the conformations of these molecules exhibit minor differences. In the crystals the double bond in the five-membered ring of the compound is disordered over two positions. The nature of the bonds in the five-membered ring could be ensured by1H-NMR and13C-NMR spectral examinations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01677783
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