نتایج جستجو برای: nmr shielding
تعداد نتایج: 67435 فیلتر نتایج به سال:
LiCl and LiNO3 water solutions in the presence of small amounts of 3-helium have been investigated by means of multinuclear resonance spectroscopy. The resulting concentration dependences of the 3He, 6,7Li+, NO3 and 35Cl− resonance radiofrequencies are reported in the infinite limit. This data along with new theoretical corrections of shielding lithium ions was analyzed by a known NMR relations...
in this research, we studied the structure, properties and nmr parameters of interaction f2 gas with pristine and 3c-doped (8, 0) zigzag models of boron phosphide nanotubes (bpnts). in order to reach these aims, we considered four different configurations for adsorption of f2gas on the outer and inner surfaces of bpnts. the structures of all models were optimized by using density functional the...
A complementary approach that combines NMR measurements, analysis of X-ray and neutron powder diffraction data and advanced quantum mechanical calculations was employed to study the α-polymorph of L-polylactide. Such a strategy, which is known as NMR crystallography, to the best of our knowledge, is used here for the first time for the fine refinement of the crystal structure of a synthetic pol...
The spin-rotation and nuclear magnetic shielding constants are analysed for both nuclei in the HCl molecule. Nonrelativistic ab initio calculations at the CCSD(T) level of approximation show that it is essential to include relativistic effects to obtain spin-rotation constants consistent with accurate experimental data. Our best estimates for the spin-rotation constants of (1)H(35)Cl are CCl = ...
Through-space isotropic NMR shielding values of a perpendicular diatomic hydrogen probe moved in a 0.5 Å grid 2.5 Å above several polycyclic aromatic/antiaromatic ring and aromatic/aromatic hydrocarbons were computed with Gaussian 03 at the GIAO HF/6-31G(d,p) level. Combinations of benzene fused with cyclobutadiene, with the tropylium ion, and with the cyclopentadienyl anion were investigated. ...
in this work, we have studied binding of clonidine drug (c9h9cl2n3) with zigzag single walled carbonnanotubes (swcnt) (5, 0) by theoretical methods of theory using gaussian 09 software package.binding energies, nmr parameters and homo- lumo gap energy were calculated. results frombinding energies indicate that it is possible thermodynamically to bind clonidine drug to swcnt.the calculated nmr p...
Cryptophane cages serve as host molecules to a Xe atom. Functionalization of cryptophane-A has permitted the development of Xe as a biosensor. Synthetic routes used to prepare cryptophanes result in racemic mixtures of the chiral cages. In the preparation of a tethered cryptophane-A cage for biosensor applications, some achiral and chiral substituents such as left-handed amino acids have been u...
The four aldopentoses ribose, arabinose, xylose, and lyxose were evaluated to test their suitability as linear linkers for the formation of intrinsically chiral covalent organic boronic ester networks. Based on X-ray crystal structures of the reaction products with phenylboronic acid, arabinose and xylose formed boronic acid diesters. Lyxose and ribose formed monoesters under the conditions emp...
The p53 tumor-suppressor gene encodes a nuclear phosphoprotein with cancer- inhibiting properties. The most probable cancerous mutations occur as point mutations in exons 5 up to 8 of p53, as a base pair substitution that encompasses CUA and GAT sequences. As DNA drug design represents a direct genetic treatment of cancer, in the research reported computational drug design was carried out to ex...
The ordering properties of an anisotropic liquid crystal can be studied by recording 13C NMR spectra at different temperatures for a number of rigid solutes. The traditional difficulty in analyzing 13C data comes from the scarcity of experimental information about the carbon shielding tensors and from their limited transferability among different solutes. We show that these obstacles can be ove...
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