Anab initio interpretation in gas phase and aqueous solution of the generalized anomeric effect in R?O?CR2?NR2 (R = H, CH3)

Carballeira, Luís; Prez-Juste, Ignacio

doi:10.1002/(sici)1096-987x(20000430)21:6<462::aid-jcc5>3.0.co;2-z

Cited by 20 publications

(12 citation statements)

References 42 publications

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“…A different explanation (hereafter referred as hyperconjugative model) considers the stabilization arises from the delocalization of one Y lone pair into the anti‐bonding orbital C‐Z9 that takes place when the lp YCZ unit adopts an antiperiplanar arrangement. However, Natural Bond Orbital (NBO) studies have shown that other orbital and bond‐antibond interactions, as well as steric and electrostatic effects have to be taken into account, with relative importance that depends on the system under consideration 7, 10–12. Despite that numerous anomeric units have been studied, there is no doubt that, probably because the anomeric effect was first discovered in carbohydrates,13 ROCOR′ has been the objective of the largest number of works and can be considered as the most characteristic anomeric moiety.…”

Section: Introductionmentioning

confidence: 99%

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: Introductionmentioning

confidence: 99%

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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“…Studies are now underway to examine this further. These include an AIM analysis (24) of the electron density, as has been done previously (25)(26)(27); an NBO analysis (28) to examine the role of the suspected orbital interactions (29)(30)(31)(32)(33)(34); and a bond energy analysis (35)(36)(37), which, to our knowledge, has never been used for the examination of the anomeric effect but should reveal results about steric, electrostatic, and electronic effects similar to other energy decomposition methods (38)(39)(40). As well, experiments are underway to examine all possible permutations within the two subsets.…”

Section: Discussionmentioning

confidence: 99%

A theoretical analysis of the conformational behaviour of substituted methylenecyclohexanes

Mawhinney¹,

Muchall²,

Lessard³

2003

Can. J. Chem.

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The use of the PBE0 hybrid density functional theory method in conjunction with the COSMO solvation model allowed us to reproduce, both qualitatively and quantitatively, the experimentally observed conformational compositions of 2-substituted and 2,7-disubstituted methylenecyclohexanes. An analysis revealed several different interactions that influence the overall equilibrium. It was found that the endo (general) anomeric effect plays a significant role in the equilibrium and that the "unsaturation effect" possibly comprises two effects.Key words: conformational analysis, methylenecyclohexanes, anomeric effect, unsaturation effect.

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“…Modern methods for the analysis of wave functions, like natural bond orbitals (NBO), or even methods based on valence bond (VB) theories and the analysis of electron densities, like the quantum theory of atoms in molecules (QTAIM), , have been also applied to account for the origin of the anomeric effect. NBO analysis has been generally found to support the presence of n → σ* B–X interactions combined with other terms, whose relative importance depends upon the molecular system. − However, the VB results provide strong evidence that the n → σ* B–X interactions are not responsible for the anomeric effect and that it is better interpreted in terms of electrostatic interactions. In the same vein, the still scarce QTAIM studies − on this point also reveal facts that are not in line with the SM interpretation.…”

Section: Introductionmentioning

confidence: 98%

Anomeric Effect in Halogenated Methanols: A Quantum Theory of Atoms in Molecules Study

2013

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The quantum theory of atoms in molecules (QTAIM) has been used to analyze the gauche conformational preference of fluoromethanol and chloromethanol. The analysis of the total atomic population and localization and delocalization indices show trends that are not in line with the hyperconjugative explanation. Energy terms arising from the QTAIM partitioning have been obtained for fluoromethanol, revealing that (i) C-O interaction plays the most significant role in stabilizing the gauche rotamer and (ii) the summation of exchange terms (the only ones that could be related to hyperconjugation) has a smaller weight than electrostatic ones in the energy balance among gauche, anti, and syn conformations; however, they are far from being negligible.

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Anab initio interpretation in gas phase and aqueous solution of the generalized anomeric effect in R?O?CR2?NR2 (R = H, CH3)

Cited by 20 publications

References 42 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

A theoretical analysis of the conformational behaviour of substituted methylenecyclohexanes

Anomeric Effect in Halogenated Methanols: A Quantum Theory of Atoms in Molecules Study

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