نتایج جستجو برای: nmr shielding tensor

تعداد نتایج: 110240  

Journal: :Physical chemistry chemical physics : PCCP 2011
Matti Hanni Perttu Lantto Juha Vaara

Nuclear spin relaxation provides detailed dynamical information on molecular systems and materials. Here, first-principles modeling of the chemical shift anisotropy (CSA) relaxation time for the prototypic monoatomic (129)Xe gas is carried out, both complementing and predicting the results of NMR measurements. Our approach is based on molecular dynamics simulations combined with pre-parametrize...

Journal: :Dalton transactions 2015
Jamal Dabachi Monique Body Jens Dittmer Franck Fayon Christophe Legein

The structures of the β- and t-LaOF phases have been refined from XRPD patterns. For both phases, (19)F and (139)La solid-state NMR spectra recorded at high magnetic fields show the presence of a single F and a single La local environment, indicating a full anionic ordering in these oxyfluoride compounds. DFT calculations of the (19)F and (139)La chemical shielding tensors and of the (139)La EF...

Journal: :journal of physical & theoretical chemistry 2005
h. aghaie m. monajjemi gh. ghassemi m. kia

we have evaluated the nmr shielding tensors for a:t,g:c,a:u in watson-crick, and u-quartet. we have computed nmr shielding tensors at b31yp level by using 6-31g(d) basis set. we have compute anisotropy and asymmetry in a:t,g:c,a:u and u-quartet. the nmr shielding tensors were calculated using the giao method. the natural bonding orbital analysis (nbo) were performed. nbo calculation have been ...

Journal: :Journal of the American Chemical Society 2004
Cynthia J Jameson

We report, for the first time, a theoretical prediction of the (129)Xe nuclear magnetic resonance chemical shift tensor of xenon atom in a single crystal of silicalite at near-zero occupancy and the temperature dependence of the Xe NMR chemical shift tensor for the polycrystalline silicalite at maximum occupancy. The former is a measure of the sensitivity of the Xe tensor components to the loca...

Gh. Ghassemi H. Aghaie M. Kia M. Monajjemi

We have evaluated the NMR shielding tensors for A:T,G:C,A:U in Watson-crick, and U-quartet. We have computed NMR shielding tensors at B31YP level by using 6-31G(d) basis set. We have compute anisotropy and asymmetry in A:T,G:C,A:U and U-quartet. The NMR shielding tensors were calculated using the GIAO method. The natural bonding orbital analysis (NBO) were performed. NBO calculation have been ...

Journal: :physical chemistry research 2015
afshan mohajeri akbar omidvar

magnesium oxide nanoclusters have attracted much attention due to their potential applications to catalysis and novel optoelectronic materials. in the present study, we have studied the electronic and magnetic properties of the stoichiometric magnesium oxide nanoclusters (mgo)n  for n = 2-20. although the binding energy increases with the size of the cluster, it  reaches the asymptotic limit of...

2013
Salvatore Mamone Maria Concistrè Ivo Heinmaa Marina Carravetta Ilya Kuprov Gary Wall Mark Denning Xuegong Lei Judy Y-C Chen Yongjun Li Yasujiro Murata Nicholas J Turro Malcolm H Levitt

We present a solid-state NMR study of H2 molecules confined inside the cavity of C70 fullerene cages over a wide range of temperatures (300 K to 4 K). The proton NMR spectra are consistent with a model in which the dipole-dipole coupling between the ortho-H2 protons is averaged over the rotational/translational states of the confined quantum rotor, with an additional chemical shift anisotropy δ...

Journal: :Journal of the American Chemical Society 2005
Kevin W Waddell Eduard Y Chekmenev Richard J Wittebort

15N shielding tensors were determined for the central peptide groups in GGV, AGG, and APG by single-crystal NMR. We find that the angle between the downfield component (delta11) and the N-H or the N-C(delta) (pro) bonds is in the range of 20-23 degrees and in accord with previous solid-state NMR measurements. However, AGG, unlike APG or GGV, has a distorted peptide plane, and delta11 lies appro...

Journal: :journal of physical and theoretical chemistry 0
neda ahmadinejad young research arezoo tahan 2semnan branch, islamic azad university, semnan, iran mostafa talebi tari1 young researchers and elite club, yadegar-e-imam khomeini(rah) , shahr-e-rey- branch, islamic azad university, tehran, iran

abstractl density functional theory (dft) was used to investigate the effects of intra-moecular interactions and implicit water molecules on the relative stability and the nmr shielding tensors of hallucinogenic harmine in the monomeric and dimeric states. results represented that the relative stability and the nmr shielding tensors are dependent on the resonance interactions and chemical envir...

Zeinab Ahmadi

Xylometazoline is a drug which is used as a topical nasal decongestant. It is applied directly into the nose, either as a spray or as drops. Xylometazoline is an imidazole derivative which is designed to mimic the molecular shape of adrenaline. It binds to alpha-adrenergic receptors in the nasal mucosa. Due to its sympathomimetic effects, it should not be used by people with high blood pressure...

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