Crystal structures and conformations of 1-α-D-xylofuranosylcytosine and its protonated form (HCl salt)

1981 ◽  
Vol 59 (2) ◽  
pp. 238-245 ◽  
Author(s):  
Michael L. Post ◽  
Carol P. Huber ◽  
George I. Birnbaum ◽  
David Shugar
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Direct Method ◽  
Intramolecular Hydrogen Bonding ◽  
Protonated Form ◽  
X Ray Diffraction ◽  
Base Stacking ◽  
Torsion Angles ◽  
Cell Parameters ◽  
Intramolecular Hydrogen

The structures of 1-α-D-xylofuranosylcytosine, C9H13N3O5 (1), and its hydrochloride salt, C9H13N3O5•HCl (1•HCl), have been determined by X-ray diffraction from diffractometer data, using direct method techniques. Both compounds crystallize in the orthorhombic system with Z = 4. Space group and cell parameters are, for 1: P21212, a = 18.706, b = 8.127, c = 7.007 Å; and for 1 HCl::P21212, a = 16.800, b = 8.045, c = 8.897 Å. Refinement by block-diagonal least-squares calculations gave a final R of 0.033 on 873 reflections and 0.034 on 914 reflections for 1 and 1 HCl, respectively. The glycosyl torsion angles are in the anti domain, χCN = −25.1° (1) and −28.6° (1•HC1), and the sugar puckers are nearly pure [Formula: see text] and 3E (1•HCl) forms. The C(4′)—C(5′) rotamer is trans–gauche in both cases. No intramolecular hydrogen bonding occurs in the xylofuranosyl rings. Lattice packing in the crystal structures occurs via intermolecular hydrogen bonding, with base stacking in pairs about one of the 2-fold axes for the neutral form, and with no base-stacking interactions for the protonated form. The biological implications of the structure and conformation of α-nucleosides are examined.

Hétérocycles à fonction quinone. V. Réaction anormale de la butanedione avec la diamino-1,2 anthraquinone; structure cristalline de la naphto [2,3-f] quinoxalinedione-7,12 obtenue

1984 ◽  
Vol 62 (3) ◽  
pp. 526-530 ◽  
Author(s):  
Michel Baron ◽  
Sylviane Giorgi-Renault ◽  
Jean Renault ◽  
Patrick Mailliet ◽  
Daniel Carré ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Direct Method ◽  
Intramolecular Hydrogen Bonding ◽  
Unit Cell ◽  
Principal Characteristic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Dimensions ◽  
Intramolecular Hydrogen ◽  
Unit Cell Dimensions

Butanedione reacts on heating with 1,2-diaminoanthraquinone to give, not the expected 2,3-dimethyl-naphtho[2,3-f]quinoxaline-7,12-dione 3, but 2-(2-hydroxy-2-methyl-3-oxobutyl)-3-methylnaphtho[2,3-f]quinoxaline-7,12-dione 4a whose structure was established by X-ray diffraction. This compound crystallizes in the triclinic [Formula: see text] space group with unit cell dimensions of a = 9.091 (1), b = 16.966 (4), c = 12.375 (3) Å; α = 100.75 (2), β = 101.83 (2), γ = 100.29 (2)°, V = 1789 Å3, Z = 4. The structure was resolved by the direct method and refined to R = 0.039 for 3027 independent reflections. The overall conformation of the molecule is essentially planar. The principal characteristic is the presence of two cyclic arrangements caused by intramolecular hydrogen bonding. 2,3-Dimethylnaphtho[2,3-f]quinoxaline-7,12-dione is the intermediate in this reaction.

Two terphenyl-based diol hosts and corresponding solvent inclusions with dimethylformamide and acetonitrile

2015 ◽  
Vol 71 (9) ◽  
pp. 768-775
Author(s):  
Hendrik Klien ◽  
Wilhelm Seichter ◽  
Konstantinos Skobridis ◽  
Edwin Weber
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Solvent Molecule ◽  
Intramolecular Hydrogen Bonding ◽  
Host Lattice ◽  
Solvent Free ◽  
Guest Molecules ◽  
Solvent Molecules ◽  
Intramolecular Hydrogen ◽  
Supramolecular Aggregates

Having reference to an elongated structural modification of 2,2′-bis(hydroxydiphenylmethyl)biphenyl, (I), the two 1,1′:4′,1′′-terphenyl-based diol hosts 2,2′′-bis(hydroxydiphenylmethyl)-1,1′:4′,1′′-terphenyl, C44H34O2, (II), and 2,2′′-bis[hydroxybis(4-methylphenyl)methyl]-1,1′:4′,1′′-terphenyl, C48H42O2, (III), have been synthesized and studied with regard to their crystal structures involving different inclusions,i.e.(II) with dimethylformamide (DMF), C44H34O2·C2H6NO, denoted (IIa), (III) with DMF, C48H42O2·C2H6NO, denoted (IIIa), and (III) with acetonitrile, C48H42O2·CH3CN, denoted (IIIb). In the solvent-free crystals of (II) and (III), the hydroxy H atoms are involved in intramolecular O—H...π hydrogen bonding, with the central arene ring of the terphenyl unit acting as an acceptor. The corresponding crystal structures are stabilized by intermolecular C—H...π contacts. Due to the distinctive acceptor character of the included DMF solvent species in the crystal structures of (IIa) and (IIIa), the guest molecule is coordinated to the hostviaO—H...O=C hydrogen bonding. In both crystal structures, infinite strands composed of alternating host and guest molecules represent the basic supramolecular aggregates. Within a given strand, the O atom of the solvent molecule acts as a bifurcated acceptor. Similar to the solvent-free cases, the hydroxy H atoms in inclusion structure (IIIb) are involved in intramolecular hydrogen bonding, and there is thus a lack of host–guest interaction. As a result, the solvent molecules are accommodated as C—H...N hydrogen-bonded inversion-symmetric dimers in the channel-like voids of the host lattice.

Intramolecular Hydrogen Bonding and Intermolecular Dimerization in the Crystal Structures of Imidazole-4,5-dicarboxylic Acid Derivatives

2002 ◽  
Vol 2 (6) ◽  
pp. 653-664 ◽  
Author(s):  
Paul W. Baures ◽  
Jeremy R. Rush ◽  
Alexander V. Wiznycia ◽  
John Desper ◽  
Brian A. Helfrich ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Dicarboxylic Acid ◽  
Crystal Structures ◽  
Intramolecular Hydrogen Bonding ◽  
Intramolecular Hydrogen

Photochemical isomerization of 7-aryl-substituted 1H-Azepin-2(3H)-ones. Formation and X-ray structure determination of atropisomeric ketimines

1983 ◽  
Vol 36 (10) ◽  
pp. 2073 ◽  
Author(s):  
H Becker ◽  
BW Skelton ◽  
AH White
Keyword(s):  
Hydrogen Bonding ◽  
Structure Determination ◽  
Intramolecular Hydrogen Bonding ◽  
Phenolic Hydroxyl ◽  
X Ray Diffraction ◽  
X Ray ◽  
Photochemical Isomerization ◽  
Intramolecular Hydrogen

The structures of two isomeric 3,5-di-t-butyl-2-[(3,5-di-t-butyl-2-hydroxyphenyl){(Z)-methylimino}- methyl]cyclopent-2-en-1-ones, formed upon photoexcitation of 3,5-di-t-butyl-7-(3,5-di-t-butyl-2- hydroxyphenyl)-1-methyl-1H-azepin-2(3H)-one in methanol, have been established by X-ray diffraction, and are found to be examples of atropisomeric ketimines. In both isomers, the geometry of imino substitution is characterized by intramolecular hydrogen bonding with the phenolic hydroxyl.

Effects of intramolecular hydrogen bonding on the conformation and luminescence properties of dibenzoylpyridine-based thermally activated delayed fluorescence materials

2019 ◽  
Vol 7 (42) ◽  
pp. 13104-13110 ◽  
Author(s):  
Jayabalan Pandidurai ◽  
Jayachandran Jayakumar ◽  
Natarajan Senthilkumar ◽  
Chien-Hong Cheng
Keyword(s):  
Hydrogen Bonding ◽  
Crystal Structures ◽  
Linear Chain ◽  
Intramolecular Hydrogen Bonding ◽  
Delayed Fluorescence ◽  
Chain Conformation ◽  
Thermally Activated Delayed Fluorescence ◽  
Thermally Activated ◽  
Intramolecular Hydrogen ◽  
First Time

The crystal structures show a U shape for 26DAcBPy and 26DPXZBPy and a linear chain conformation for 25DAcBPy; for the first time, we reveal that the conformations are the result of intramolecular hydrogen bonding of these molecules.

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