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  • hydrogen bonding  (6)
  • Drought  (1)
  • Glomus intraradices  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 931-933 
    ISSN: 1572-8854
    Keywords: Flavone ; hydrate ; hydrogen bonding ; X-ray crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray crystal structure of 7-hydroxyflavone monohydrate, C14H10O3 · H2O, is determined. The compound crystallizes in the monoclinic space group, P21/n with a = 3.801(3), b = 19.665(4), c = 16. 039(6), β = 93.69(3)°, and μ = 0.68 mm−1 for Z = 4. The phenyl ring of the flavone moiety is rotated 18.6(1)° out of the penzopyran plane, which is a typical value for flavones. In the crystal lattice, there are wide channels which are lined mainly by C–H groups. The water molecules enclosed in these channels are severely disordered.
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  • 2
    ISSN: 1572-8854
    Keywords: Cyclohexane ; alkyne ; hydrogen bonding ; X-ray crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray crystal structure of the title compound, C18H28O3, is determined. The hydrogen bond scheme does not follow considerations based on hierarchies of donor and acceptor strengths. The hydroxyl group of the molecule accepts only very weak C–H···O interactions.
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  • 3
    ISSN: 1572-8854
    Keywords: alkyne ; hydrogen bonding ; x-ray crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In the x-ray crystal structure of the alkynol 5β-hydroxy-5α-ethynyl-10β-methyl-Δ1(9)-octalin-2-one [C13H16O2, Pbca, a = 10.244(7), b = 12.734(2), c = 17.125(2) Å, Z = 8], the hydroxyl and ethynyl groups are involved in a hydrogen bond arrangement C—C—H···O···H—O, which is supposed to be anticooperative, i.e., weaker than the sum of two isolated hydrogen bonds.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 29 (1999), S. 99-102 
    ISSN: 1572-8854
    Keywords: Isoflavone ; natural compound ; Dalbergia spinosa ; X-ray crystal structure ; hydrogen bonding
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray crystal structure of the plant isoflavone dalspinin from Dalbergia spinosa is determined. The compound, C17H12O7, is monoclinic in P21/n with a = 3.970(1), b = 23.607(5), c = 14.633(3) Å, β = 94.46(3)°, V = 1367.2(5) Å3, D calc = 1.595 g cm−1 and Z = 4. The molecular structure is characterized by a short intramolecular O–H···O=C hydrogen bond, and a large tilt angle of the two rigid ring systems with respect to each other. The intermolecular interactions in the crystal are discussed.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 28 (1998), S. 581-584 
    ISSN: 1572-8854
    Keywords: Cyclohexane ; alkyne ; hydrogen bonding ; X-ray crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract In the X-ray crystal structure of the alkynol 5β-hydroxy-5α-(prop-2-ynyl)-10β-methyl-Δ1(9)-octalin-2-one [C14H18O2, Pca2 1, a = 13.559(1), b = 7.960(2), c = 21.748(3) Å], the hydroxyl and propynyl groups form a hydrogen bond chain C---C-H⋯O-H⋯O which is supposed to be a cooperative arrangement. Quantum chemical calculations estimate cooperativity enhancement within the array to be 0.4 kcal/mol, which is only a small (but recognizable) effect.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical crystallography 30 (2000), S. 143-145 
    ISSN: 1572-8854
    Keywords: thian ; oxime ; hydrogen bonding ; x-ray crystal structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract The X-ray crystal structure of γ-2-trans-2,6-diphenylthian-1,1-dioxide-4-one oxime is determined [C17H17NO3S, space group P21 n, a = 8.177(1) b = 9.574(1)c = 19.730(5) Å, β = 97.35(5)°]. The oxime group does not form an oxime dimer, but is involved in an O-H···O=S hydrogen bond.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Mycorrhiza 5 (1995), S. 273-278 
    ISSN: 1432-1890
    Keywords: Key words Drought stress ; Tropical maize cultivars ; Glomus intraradices ; Metabolic changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  A greenhouse experiment was carried out to investigate the influence of the arbuscular mycorrhizal (AM) fungus (Glomus intraradices Schenck & Smith) on metabolic changes in tropical maize (Zea mays L.) under drought. Two cultivars, Tuxpeno sequia C0 (drought sensitive) and C8 (drought resistant), were subjected for 3 weeks to water stress following tasselling (75–95 days after sowing). Fully expanded 7th or 8th leaves were sampled and assessed for levels of chlorophyll, sugars, proteins, and amino acids. Chlorophyll content was not altered either by water stress or the presence of mycorrhizae. Mycorrhizal plants (M+) had higher total and reducing sugars than nonmycorrhizal plants (M–) at the end of 3 weeks of the drought cycle. An increase in protein content was observed with drought stress in M+ plants of the cultivar C0. Most of the amino acids showed a linear increase during the period of water stress in M+ and M– plants for both cultivars. Total amino acids increased by 40.6% and 43.7% in M– plants of C0 and C8, respectively. With the presence of AM fungus, amino acid levels increased by only 10.7% and 19.2% of leaf dry mass in C0 and C8, respectively. Alanine, asparagine, glutamine, and glycine accounted for 70% of the amino acid pool. Under drought, AM inoculation enabled the plants to retain considerable amounts of sugars and proteins, especially in the drought-sensitive cultivar C0. This may be of physiological importance in helping the plant to withstand moderate drought.
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  • 8
    ISSN: 1432-1890
    Keywords: Key words Arbuscular mycorrhizae ; Drought ; Grain yield ; Maize ; Nutrition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  The effects of root colonization by the arbuscular mycorrhizal (AM) fungus Glomus intraradices Schenck & Smith on nutritional, growth, and reproductive attributes of two tropical maize cultivars with different sensitivities to drought were studied. Freshly regenerated seeds of selection cycles 0 (cv. C0, drought-sensitive) and 8 (cv. C8, drought-resistant) of the lowland tropical maize population "Tuxpeño sequía" were used in this greenhouse experiment. Maize plants were subjected to drought stress for 3 weeks following tasselling (75–95 days after sowing) and rewatered for the subsequent 5 weeks until harvest. Mycorrhizal (M+) plants had significantly higher uptake of N, P, K, Mg, Mn, and Zn into grain than non-mycorrhizal (M–) plants under drought conditions. AM inoculation also produced significantly greater shoot masses in C0 and C8 regardless of the drought-stress treatment. In the sensitive cultivar C0, drought stress reduced the shoot mass and grain yield by 23% and 55%, respectively, when roots were not colonized, while the reductions were only 12% and 31%, respectively, with mycorrhizal association. In addition, the emergence of tassels and silks was earlier in M+ plants than in M– plants under drought conditions. Mycorrhizal response was more pronounced under both well-watered and drought conditions in C0 than in the C8 cultivar. The overall results suggest that AM inoculation affects host plant nutritional status and growth and thereby alters the reproductive behaviour of maize under drought conditions.
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