The Molecular Structure of Dimethoxymethane, CH3-O-CH2-O-CH3, in the Gas Phase.

Astrup, E. E.; Støgård, Jan; Dale, Johannes; Daasvatn, Kari; Kristiansen, Per Olav; Swahn, Carl‐Gunnar

doi:10.3891/acta.chem.scand.27-3271

Cited by 61 publications

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“…Table1 displays molecular energies (relative to the lowest energy conformer, namely the gg conformer) for 1 and 2 . The lowest energy of the 1 gg conformer agrees with the available experimental information14–17 and all the previously reported computational studies 17–26. G2 relative energies calculated in this work are also in good agreement with those reported in the chemical literature for 1 17–26 and 2 27, 28…”

Section: Resultssupporting

confidence: 91%

“…Both the experimental bond distances and valence angles of compound 1 (the one where accurate experimental geometries are available) are quite closely reproduced by either HF, B3LYP, or MP2 calculations (supplementary information). If compared with electron diffraction data ( r g values),14, 15, 36 B3LYP calculations seem to overestimate the bond distances, with the notable exception of the CH 3 O bond distance in 1 . Nevertheless, the assumptions introduced in the analysis of the experimental radial distribution curve15, 36 make this comparison meaningless.…”

Section: Resultsmentioning

confidence: 92%

“…Over the past three decades, dimethoxymethane (1) has been the focus of several experimental14–17 and theoretical17–26 studies, as a model for the anomeric effect. Electron diffraction,14, 15 microwave,16 and X‐ray diffraction17 studies indicate that in the gas phase 1 exists solely in the gg conformation (Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

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Distribution and cellular localization of insulin‐regulated aminopeptidase in the rat central nervous system

Fernando¹,

Larm²,

Albiston³

et al. 2005

J of Comparative Neurology

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Central infusions of angiotensin IV enhance spatial learning, memory retention and retrieval, neurotransmitter release, and long-term potentiation via interaction with a specific, high-affinity binding site. This site was recently purified and identified as the insulin-regulated aminopeptidase (IRAP). This enzyme was previously characterized as the marker protein of specialized insulin-responsive vesicles containing GLUT4 in muscle and adipose tissue. The present study provides the first comprehensive description of IRAP distribution in the adult rat brain. By using immunohistochemistry, IRAP was found to be highly expressed in selected olfactory regions, in septal and hypothalamic nuclei, throughout the hippocampal formation and cerebral cortex, and in motor and motor associated nuclei. IRAP was expressed exclusively in neurons in these regions. At the cellular level, IRAP was localized within cell bodies, excluding the nucleus, in a punctate vesicular pattern of expression. IRAP-positive immunoreactivity was also found in some proximal processes but was not detected in synaptic nerve terminals. The neurochemical composition of IRAP-containing neurons was further characterized by dual-label immunohistochemistry. IRAP was expressed in cholinergic cell bodies of the medial septum, a source of cholinergic projections to the hippocampus and cerebral cortex. The distribution of IRAP in motor and motor-associated nuclei; the colocalization of the enzyme with potential in vivo substrates, oxytocin and vasopressin in the hypothalamus; and the colocalization with GLUT4 in selected nuclei all suggest diverse physiological roles for IRAP in the rat central nervous system.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 92%

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Distribution and cellular localization of insulin‐regulated aminopeptidase in the rat central nervous system

Fernando¹,

Larm²,

Albiston³

et al. 2005

J of Comparative Neurology

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“…Of particular interest is the variation of the C-O bonds in the anhydro ring, in which the two external bonds of the C-O-C-O-C sequence are longer than the internal bonds, as shown in Table 3. These differences are of the same order of magnitude as observed in the gas electron diffraction study of dimethoxymethane CHa-O--CH2-O-CH 3 (Astrup, 1973) and in methyl pyranosides and the glycosidic linkages in di-and trisaccharides, where they have been associated with the 'anomeric effect' by Jeffrey, Pople & Radom (1974). This is therefore another example of differences in bond character due to the back donation of oxygen rr-type lone-pair electrons, originally pointed out by Romers, Altona, Buys & Havinga (1969).…”

Section: Molecular Conformation and Structuresupporting

confidence: 69%

The crystal structure of 3-amino-1,6-anhydro-3-deoxy-β-D-glucopyranose by neutron diffraction

Noordik¹,

Jeffrey²

1977

Acta Crystallogr B Struct Sci

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The crystal structure of 3-amino-l,6-anhydro-3-deoxy-/~-D-glucopyranose, C6H llNO4, has been determined from neutron diffraction data. The space group is P2~212~, Z=4, a= 7.804(8), b= 14.671 (16), c = 6.236 (8) A. The structure was solved by direct methods with MULTAN and refined anisotropically against Fo 2 to an R(F 2) value of 0-056. The molecular conformation has the amino group and the anhydro ring on the same side of a distorted ~C4 pyranose ring. The distortion is in the direction of a sofa conformation with the ring O out of plane. There are significant differences in the ring C-O bond lengths, which are similar to those observed in the methyl pyranosides. There is only one strong hydrogen bond in the crystal structure, OH • • • NH 2 at 1.760 A. The NH. • • O hydrogen bonds are weaker, at 2.212 and 2.258 ~,, and the N-H bonds are shorter, at 1.000 and 1.019 A, than generally found in the amino acid structures.

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“…21-30 (1.3) and 31-40 (0.0085), respectively. The three angle cards are for atom types 6- [1][2][3][4][5][6] in the usual format with a bending constant of 0.46. The natural angles are 99.9, 97.0, and 102.2 for types 1, 2, and 3, respectively.…”

Section: Appendix Input Data For the M ( 8 2 ) Programmentioning

confidence: 99%

A molecular mechanics treatment of the anomeric effect

Nørskov-Lauritsen

Allinger

1984

J Comput Chem

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The tendency of C-0 bond lengths to change as a function of the torsional angles at an acetal carbon has been included in a new version of the molecular mechanics program ~~2 ( 8 2 ) , based on the observed behavior of molecules of this class as indicated by ab initio calculations and experimental structural data. The experimental geometries and energies are reasonably well reproduced.The molecular mechanics or empirical force field method has been widely used for determining molecular structures and energies during the last severalHydrocarbons and most of the common types of monofunctionalized molecules can be treated with reasonable accuracy and reliability? For polyfunctional molecules the results are generally also quite good if the functions are separated by three or more carbons, but molecules that contain close or adjacent functional groups have not been studied in much detail. Since the interactions between close functional groups are likely to be strong, the results for molecules containing such an organization are not expected to be very good at present. We are currently making an effort to better deal with the interactions between close functional groups, and the present article is concerned with one special interaction of this class which occurs when geminal oxygens (or other electronegative atoms) are present.This particular pattern of functionalization leads to what is usually called the anomric effect, because it was first recognized as something peculiar to the anomeric carbon (C-1) of ~u g a r s .~ The observation was that an axial methoxyl at the anomeric carbon tended to be more stable than its equatorial counterpart, contrary to the results expected from steric effects. The anomeric effect has been studied theoretically in considerable detail and can be quantita-*Presented at the Molecular Mechanics Symposium, Indianapolis, Indiana, June 23-24,1983.Permanent address: Department of Chemistry, University of Georgia, Athens, GA 30602. Correspondence should be hrected to this author at this address.tively summarized as follows. The structure has an important kind of resonance form:which involves donation of a lone pair of electrons on one oxygen into the carbon oxygen bond region as shown, with a bond breaking and removal of negative charge by the other oxygen. For this resonance to be most effective, the lone pair on 0-2 must lie in the plane defined by atoms 2-3-4 (assuming tetrahedral hybridization). If the lone pair lies out of the latter plane, the resonance is suppressed. There are two lone pairs on each oxygen, so the effect needs to be considered for each of the four different lonepair-oxygen combinations. While the usual steric interactions are minimized by having the torsion angles about the 2-3 and 3-4 bonds either 60" or 180" (+& torsional term), this resonance effect leads to the most effective energy lowering when those angles are 90" (-V, torsion term). In addition, the dipole-dipole interactions in the molecule (which in the MM2 program are between the C-0 bonds and the 0-lone pair...

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The Molecular Structure of Dimethoxymethane, CH3-O-CH2-O-CH3, in the Gas Phase.

Cited by 61 publications

References 0 publications

Distribution and cellular localization of insulin‐regulated aminopeptidase in the rat central nervous system

Distribution and cellular localization of insulin‐regulated aminopeptidase in the rat central nervous system

The crystal structure of 3-amino-1,6-anhydro-3-deoxy-β-D-glucopyranose by neutron diffraction

A molecular mechanics treatment of the anomeric effect

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