نتایج جستجو برای: nmr chemical shielding

تعداد نتایج: 435629  

Journal: :Journal of the American Chemical Society 2002
Haihong Sun Lori K Sanders Eric Oldfield

We have used ab initio quantum chemical techniques to compute the (13)C(alpha) and (13)C(beta) shielding surfaces for the 14 amino acids not previously investigated (R. H. Havlin et al., J. Am. Chem. Soc. 1997, 119, 11951-11958) in their most popular conformations. The spans (Omega = sigma(33) - sigma(11)) of all the tensors reported here are large ( approximately 34 ppm) and there are only ver...

Journal: :Chemistry 2006
Avital Steinberg Miriam Karni David Avnir

Molecular symmetry is a key parameter which dictates the NMR chemical shielding anisotropy (CSA). Whereas correlations between specific geometrical features of molecules and the CSA are known, the quantitative correlation with symmetry--a global structural feature--has been unknown. Here we demonstrate a CSA/symmetry quantitative relation for the first time: We study how continuous deviation fr...

M. Monajjemi M. Sheikhi

In this research, the Magnetite nanoparticles (Fe304) were prepared by coprecipitation of Fe- andGinger is a well known spice and flavoring agent which has also been used in traditional medicine inmany countries. Ginger contains essential oils including gingerol and zingiberene. It also containspungent principles such as zingerone, and shogaol. In the paper six theoretical methods were used toc...

Journal: :Physical chemistry chemical physics : PCCP 2011
Jérôme Cuny Kateryna Sykina Bruno Fontaine Laurent Le Pollès Chris J Pickard Régis Gautier

Solid-state (95)Mo nuclear magnetic resonance (NMR) properties of molybdenum hexacarbonyl have been computed using density functional theory (DFT) based methods. Both quadrupolar coupling and chemical shift parameters were evaluated and compared with parameters of high precision determined using single-crystal (95)Mo NMR experiments. Within a molecular approach, the effects of major computation...

2011
Jérôme Cuny Kateryna Sykina Bruno Fontaine Laurent Le Pollès Chris J. Pickard Régis Gautier

Solid-state Mo nuclear magnetic resonance (NMR) properties of molybdenum hexacarbonyl have been computed using density functional theory (DFT) based methods. Both quadrupolar coupling and chemical shift parameters were evaluated and compared with parameters of high precision determined using single-crystal Mo NMR experiments. Within a molecular approach, the effects of major computational param...

Journal: :Journal of chemical theory and computation 2016
Peter B Karadakov Kate E Horner

Differences in nuclear isotropic magnetic shieldings give rise to the chemical shifts measured in NMR experiments. In contrast to existing NMR experimental techniques, quantum chemical methods are capable of calculating isotropic magnetic shieldings not just at nuclei, but also at any point in the space surrounding a molecule. Using s-trans-1,3-butadiene, ethane, ethene, and ethyne as examples,...

In this research, geometrical structures of armchair single walled boron nitride nanotube (SWBNNT) and armchair single walled aluminum nitride nanotube (SWAlNNT) were optimized by Density Functional Theory (DFT) in the gas phase, both having the same length of 5 angstrom and n=9, m=9. B3LYP/6-31G* level of theory have been used to determine and compare electronic properties, n...

In this research, geometrical structures of armchair single walled boron nitride nanotube (SWBNNT) and armchair single walled aluminum nitride nanotube (SWAlNNT) were optimized by Density Functional Theory (DFT) in the gas phase, both having the same length of 5 angstrom and n=9, m=9. B3LYP/6-31G* level of theory have been used to determine and compare electronic properties, n...

Journal: :Physical chemistry chemical physics : PCCP 2015
Jouni Karjalainen Juha Vaara Michal Straka Perttu Lantto

Applications of liquid crystals (LCs), such as smart windows and the ubiquitous display devices, are based on controlling the orientational and translational order in a small volume of LC medium. Hence, understanding the effects of confinement to the liquid crystal phase behaviour is essential. The NMR shielding of (129)Xe atoms dissolved in LCs constitutes a very sensitive probe to the details...

Journal: :journal of physical & theoretical chemistry 2012
e. pournamdari m. monajjemi

bcn compounds have been researched theoretically and experimentally widely. in this paper, weintroduce the theoretical prediction of ternary b-c-n compounds. nmr spectroscopy was employedextensively to study these ternary nanostructures. we discuss the utilization of chemical shiftinformation as well as ab initio calculations of nuclear shielding for h20134c9n4 structuredetermination. we calcul...

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