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1981 (1)
1Author    PeterM. Kaiser®, Reinhard Nesper, Karl-Friedrich Tebbe, Herbert Witzel»-Requires cookie*
 Title    Pyridin-4-on-Nueleosid + : Stabilisierung der Struktur im Kristall und in wäßriger Lösung Pyridine-4-on Nucleoside: Stabilisation of the Structure in the Crystal and in Aqueous Solution  
 Abstract    C10H13NO5 • H2O is monoclinic, space group P2i with a = 773.7 pm, b = 814.6 pm, c= 932.6 pm, ß = 109.36° at 143 K, Z = 2. The crystal structure has been refined to R =0.031 with 1340 counter reflections. Features of this nucleoside include an orientation of the base at the glycosidic bond N(l)-C(l') in the anii-range (52.5°), a ribosyl moiety in the C(2')-endo(S) conformation and in contrast to many other nucleosides a trans arrange-ment at C(4')-C(5'). This unusual conformation is stabilized by a distinct H-bonding scheme including the water molecule and the oxygen of the adjacent pyridin-4-on ring system. NMR data indicate on the other side that in solution the conformation of the nucleoside is anti/g + similar to that of other pyrimidine nucleosides. The 5'-OH group replaces the water molecule in the crystal. The preferred anti position of the base cannot be explained by an interaction of H(2,6) of the base with the 5'-OH group or the C(4) oxygen. Both protons which couple with H(3,5) coalesce in a single sharp doublet. Water entropy seems to be the decisive factor for the stabilization of the anti/g+ conformation in aqueous solution. 
  Reference    Z. Naturforsch. 36b, 1632—1639 (1981); eingegangen am 3. Juli 1981 
  Published    1981 
  Keywords    Pyridine-4-on Nucleoside, X-ray, NMR Spectra, Conformational Differences, Water Entropy 
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 TEI-XML for    default:Reihe_B/36/ZNB-1981-36b-1632.pdf 
 Identifier    ZNB-1981-36b-1632 
 Volume    36