نتایج جستجو برای: nmr chemical shielding
تعداد نتایج: 435629 فیلتر نتایج به سال:
The stable configurations, electronic structure and magnetic properties of B16N16, B8C24, Al and P inserted (BC3)8 was studied by performing density functional theory (DFT) calculations of the NMR parameters. The results indicate that B8C24 has semiconductivity property and be effectively modified by inserti...
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 fullerene structures of C20cage and bowl,C20H10 and their N-doped structures as C20cage NH,C20bowl NH, C20H10NH, C20H10N and their isomers are optimized using the MPW1PW91/6-31G level of the theory. Magnetic shielding tensors of 14N and 13C atoms are calculated by the same level of the theory. Results show that doping an N atom on fullerenes affects differently on the chemical shielding of ...
Density functional theory calculations were applied to investigate 13C Chemical Shielding (CS) tensors in cryptolepine (1) and its sulfur (2) and oxygen (3) isosteres. The results showed that the CS of carbon nuclei in these compounds may be divided into three types. First, carbons type α,are those directly bonded to X (X= NH, S, O) and σ 33 shielding component of these carbons are deshield...
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...
In the present work a set of formal relations connecting different approaches to calculate relativistic effects on magnetic molecular properties are proven. The linear response (LR) within the elimination of the small component (ESC), Breit Pauli, and minimal-coupling approaches are compared. To this end, the leading order ESC reduction of operators within the minimal-coupling four-component ap...
A series of molybdate, MoO4(2-), salts have been studied using solid-state 95Mo NMR spectroscopy at applied magnetic field strengths of 11.75, 17.63 and 21.14 T. In contrast to previous investigations, the principal components of the Mo shielding and EFG tensors have been obtained, as well as their relative orientations. At the fields employed, the anisotropic Mo shielding and quadrupolar inter...
A new pulse sequence for high-resolution solid-state heteronuclear double-quantum MAS NMR spectroscopy of dipolar-coupled spin-12 nuclei is introduced. It is based on the five-pulse sequence known from solution-state NMR, which is here applied synchronously to both spin species. The heteronuclear double-quantum (HeDQ) spinning-sideband patterns produced by this experiment are shown to be sensit...
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