The crystal structure of alloxan

Bolton, W.

doi:10.1107/s0365110x6400041x

Cited by 69 publications

(42 citation statements)

References 3 publications

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“…As a remarkable example, the crystal structure of alloxan (pyrimidine-2,4,5,6-tetraone) [17] (Figure 2) features an array of short, almost orthogonal intermolecular C=O···C=O contacts with distances of about 2.8 and C=O···C angles in the range between 1558 and 1638, rather than form the hydrogenbonded structure one would expect, given the existence of two acidic NH units per molecule.…”

Section: A Survey Of the Literaturementioning

confidence: 97%

Orthogonal Multipolar Interactions in Structural Chemistry and Biology

2005

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The past few decades of molecular recognition studies have greatly enhanced our knowledge on apolar, ion-dipole, and hydrogen-bonding interactions. However, much less attention has been given to the role that multipolar interactions, in particular those with orthogonal dipolar alignment, play in organizing a crystal lattice or stabilizing complexes involving biological receptors. By using results from database mining, this review attempts to give an overview of types and structural features of these previously rather overlooked interactions. A number of illustrative examples of these interactions found in X-ray crystal structures of small molecules and protein-ligand complexes demonstrate their propensity and thus potential importance for both, chemical and biological molecular recognition processes.

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Section: A Survey Of the Literaturementioning

confidence: 97%

Orthogonal Multipolar Interactions in Structural Chemistry and Biology

2005

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“…However, there is a growing body of literature that is concerned with non-covalent interactions of the >C(8+)--O(8-) dipole © 1998 International Union of Crystallography Printed in Great Britain -all rights reserved that are not mediated by hydrogen. Bolton (1963Bolton ( , 1964Bolton ( , 1965 showed that intermolecular N--H...O hydrogen bonds did not occur in the crystal structure of alloxan, the extended structure being determined instead by intermolecular carbonyl...carbonyl interactions. Later, Bernstein et aL (1974) identified a tendency for quinonoidal carbonyl groups to interact either through C--H.…”

Section: Introductionmentioning

confidence: 99%

Carbonyl–Carbonyl Interactions can be Competitive with Hydrogen Bonds

Allen

Baalham

Lommerse

et al. 1998

Acta Crystallogr B Struct Sci

388

386

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The geometries and attractive energies of carbonylcarbonyl interactions have been investigated using crystallographic data and ab initio molecular-orbital calculations. Analysis of crystallographic data for 9049 carbon-substituted >C~O groups shows that 1328 (15%) form contacts with other >C~O groups, in which d(C...O) < 3.6,~. Three common interaction motifs are observed in crystal structures: (a) a slightly sheared antiparallel motif (650 instances) involving a pair of short C...O interactions, together with (b) a perpendicular motif (116 instances) and (c) a highly sheared parallel motif (130 instances), which both involve a single short C...O interaction. Together, these motifs account for 945 (71%) of the observed interactions. Ab-initio-based molecular-orbital calculations (6-31G** basis sets), using intermolecular perturbation theory (IMPT) applied to a bis-propanone dimer model, yield an attractive interaction energy of -22.

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“…These are connected by aryl-C-H … F interactions, also about a centre of inversion, leading to a 24-membered {…FC5NC4H}2 synthon, as well as very weak methyl-C-H … π(aryl) contacts. This association has the result that supramolecular layers are formed in the ac-plane, 75.17(7); 75.17 (7) 81.38 (6 The crystal packing indices (packing efficiency) were calculated [32] for 1.MeOH and 1, and were 69.8 and 66.3%, respectively. Clearly, the inclusion of the solvent methanol molecules in 1.MeOH reduces the amount of free space in the crystal structure.…”

Section: Molecular Packing In Unsolvatedmentioning

confidence: 99%

“…Rather than the formation of the what might be anticipated amide-N-H…O(carbonyl) hydrogen bonds, the most prominent intermolecular interactions, i.e. points of contact between molecules, are dipolar C=O … C=O contacts [7]. Such C=O … C=O contacts have been recognised for some time as being important in the molecular packing of both organic [8] and metalorganic crystal structures [9].…”

Section: Introductionmentioning

confidence: 99%

“…Such C=O … C=O contacts have been recognised for some time as being important in the molecular packing of both organic [8] and metalorganic crystal structures [9]. In the case of alloxan [7], global crystal packing considerations, correlated with the shape of the molecule, have been cited as being an overriding factor in determining the ultimate molecular packing in the crystal [10]. Herein, the crystal structure determination of 2,6-bis(4-fluorophenyl)-3,5-dimethylpiperidin-4-one (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Hydrogen bonding in 2,6-bis(4-fluorophenyl)-3,5-dimethylpiperidin-4-one methanol solvate

Suresh¹,

Vijayakumar

Kumar

et al. 2016

Zeitschrift Für Kristallographie - Crystalline Materials

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Hydrogen bonding in 2,6-bis(4-fluorophenyl)-3,5-dimethylpiperidin-4-one methanol solvate 72S.docx 30.10.2017 1 (21) Hydrogen bonding in a piperidin-4-one Keywords: Piperidin-4-one / conformation / DFT / crystal structure analysis / X-ray diffraction Abstract. The crystal structure analysis of a 2,6-diaryl 4-piperidone derivative, isolated as a mono-methanol solvate, reveals that both the piperidone and the methanol molecule lie on a crystallographic mirror plane. A chair conformation is found for the piperidone ring with the aryl and methyl groups in equatorial positions. The most prominent feature of the molecular packing is the formation of supramolecular zigzag chains mediated by amine-N-H…O(methanol) and hydroxyl-O-H…N(amine) hydrogen bonds, i.e. the methanol molecule serves as a bridge between piperidone molecules. The molecular structure is compared with that determined in an unsolvated form and the gas-phase equilibrium structure, obtained using density-functional theory (DFT); differences relate, in the main, to the relative dispositions of the aryl rings. An analysis of the Hirshfeld surfaces of the experimental structures indicates very similar relative contributions with the notable exception being the contribution by O…H/H…O which at 13.7% in the methanol solvate is greater than 8.5% in the unsolvated form.

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The crystal structure of alloxan

Cited by 69 publications

References 3 publications

Orthogonal Multipolar Interactions in Structural Chemistry and Biology

Orthogonal Multipolar Interactions in Structural Chemistry and Biology

Carbonyl–Carbonyl Interactions can be Competitive with Hydrogen Bonds

Hydrogen bonding in 2,6-bis(4-fluorophenyl)-3,5-dimethylpiperidin-4-one methanol solvate

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