Topological Analysis of Fluorinated Dimethyl Ethers and Their Protonated Forms

Vila, Antonio; Mosquera, Ricardo A.

doi:10.1021/jp002725v

Cited by 25 publications

(28 citation statements)

References 37 publications

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“…Thus, in 1 tg the transfer of electron population from hydrogens to more powerful attractors produces a decrease of the energy in the charge acceptors, C 1 , O 3 , and C 5 , (−79 kJ mol −1 ) that surpasses the destabilizations experienced by the donors, H 7 and H 12 , (34 kJ mol −1 ). A leading role of the modifications experienced by the electron population of hydrogens was also found when studying processes such as protonation,75–77 dimerization,78 or adduct formation 79, 80…”

Section: Resultsmentioning

confidence: 82%

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: Resultsmentioning

confidence: 82%

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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“…The torsional barrier to internal rotation about the C-O bond in both PFDME and DME has been previously studied using Hartree-Fock ab initio theory [5,17,18]. Previous studies have focused on the geometrical and atomic charge aspects of a broad range of these perfluoro materials, including perfluoro-dimethyl, diethyl and methyl-isopropyl ethers [17,[19][20][21][22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Torsional Energy Barriers in Dimethyl Ether and Perfluoro-Dimethyl Ether: Electronic Structure Contributions

et al. 2011

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The optimized geometries, torsional energy barriers and atomic charge in dimethyl ether and perfluorodimethyl ether have been investigated with density functional theory (dft) molecular orbital calculations. The optimized dimethyl ether (DME) and perfluoro-dimethyl ether (PFDME) geometries have been obtained and are in good agreement with experimental results. The torsional energy barriers for both the DME and PFDME have been calculated by incrementally increasing the dihedral angle and performing a full-geometry optimization. The DME and PFDME barriers have been compared, and the geometries of the transition states for both molecules are given. The net atomic charges of both the optimized and transition state species are calculated for both DME and PFDME and shown to be consistent with a stereoelectronic effect (anomeric) that mixes an anti-bonding C-H-centered molecular orbital and an oxygen lone pair. The effects of this antiperiplanar electronic interaction are discussed, and the calculated torsion energy barriers are justified using a simplified second-order bonding model.

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“…In both cases, the charges on the H and F atoms bonded to the C 1 and C 5 carbons decrease. Notice an absence of correlation between the PAs and the charges on the excess proton, similar to that of protonated fluorethers or the negative charges on the CO groups, similar to that of protonated aliphatic aldehydes and ketones …”

Section: Resultsmentioning

confidence: 97%

Methyl Formate and Its Mono and Difluoro Derivatives: Conformational Manifolds, Basicity, and Interaction with HF Theoretical Investigation

Zeegers‐Huyskens

Kryachko

2011

J. Phys. Chem. A

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The conformational manifolds, scenarios of protonation, and hydrogen bond propensity of methyl formate and its mono and difluoro derivatives, which possess two oxygen atoms with different basicities, are studied at the B3LYP/6-311++G(3df,3pd) computational level. The optimized geometries of the title molecules, their energetics, and relevant harmonic vibrational frequencies, mainly of the ν(CH) mode of the H-C═O group, are of a primary focus. The Natural Bond Orbital analysis is invoked to obtain the second-order intra- or intermolecular hyperconjugation energies, occupations of antibonding orbitals, and hybridization of the carbon atoms. It is demonstrated that the Z conformers (and their rotamers) of the three title molecules are characterized by a higher stability compared to the E ones. The stabilities depend on the intramolecular hyperconjugative interaction and on the attraction or repulsion nonbonded interaction. The proton affinity of the carbonyl oxygen exceeds, by 15-20 kcal·mol(-1), that of the methoxy oxygen. Fluorine substitution causes a moderate lowering of the proton affinity of the oxygens. Protonation on the oxygen atoms yields a contraction of the C-H bond and large concomitant blue shift of the ν(CH) vibration. These changes are mainly determined by a lowering of the occupation of the corresponding σ*(CH) orbitals. The esters under consideration are probed on the interaction with the HF molecule. The complexes that are formed under this interaction on the oxygen of the H-C═O group are stronger than those formed on the oxygen belonging to the methoxy one. It is deduced that the hydrogen bond energies show a linear dependence on the proton affinities of the corresponding oxygen atoms. Hydrogen-bonded complexes of moderate strength are also formed, while HF interacts with the fluorine atoms of the fluorinated esters.

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Topological Analysis of Fluorinated Dimethyl Ethers and Their Protonated Forms

Cited by 25 publications

References 37 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

Torsional Energy Barriers in Dimethyl Ether and Perfluoro-Dimethyl Ether: Electronic Structure Contributions

Methyl Formate and Its Mono and Difluoro Derivatives: Conformational Manifolds, Basicity, and Interaction with HF Theoretical Investigation

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