The present work discusses a new 2D NMR method for characterizing the principal values and relative orientations of the electric field gradient and the chemical shift tensors of half-integer quadrupolar sites. The technique exploits the different contributions that quadrupolar and shielding interactions impart on the evolution of multiple-quantum and of single-quantum coherences, in order to ob...

Abstract The requirement for accelerated and quantitatively accurate screening of nuclear magnetic resonance spectra across the small molecules chemical compound space is two-fold: (1) a robust ‘local’ machine learning (ML) strategy capturing effect neighborhood on an atom’s ‘near-sighted’ property—chemical shielding; (2) reference dataset generated with state-of-the-art first-principles method...

Structural and magnetic properties of purine and pyrimidine nucleotides (CMP, UMP, dTMP, AMP, GMP, IMP) were studied at different levels of ab initio molecular orbital theory. These calculations were performed at the hartree-fock level and density functional B3LYP methods. Geometries were fully optimized by following Cs symmetry restrictions. The standard 6-31G** basis set which includes polari...

The unrivaled combination of speed, accuracy, and ease of use make CAE software that employs the BEM ideally suited for analyses involving shielding of MRI and NMR systems.

in this study the chemical properties of b6c4si and c16 clusters connected vitamin c have been investigated using density functional theory (dft). nmr parameters and homo- lumo gap energy are calculated by using density functional method (b3lyp) with 6-311g* basis set. calculations show that homo- lumo gap energy of vitamin c decreases after connecting to b6c4si or c16 cluster decreasing of hom...

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...

Conventional nuclear magnetic resonance spectroscopy is unable to distinguish between the two mirror-image forms (enantiomers) of a chiral molecule. This is because the NMR spectrum is determined by the chemical shifts and spin–spin coupling constants which – in the absence of a chiral solvent – are identical for the two enantiomers. We discuss how chirality may nevertheless be directly detecte...

The reaction between trans-PcSiCl2 (1) and the potassium salts of six fatty acids (2 a-2 f) led to the trans-PcSi[OOC(CH2)nCH3]2 compounds (3 a-3 f), which were characterised by elemental analysis, IR, UV/Vis and 1H, 13C, and 29Si NMR spectroscopy. From a detailed study of the NMR spectra, the strong anisotropic currents of the Pc macrocycle were found to have an effect on up to the sixth methy...

Linear diterpenes that are commonly found in brown algae are of high chemotaxonomic and ecological importance. This study reports bifurcatriol (1), a new linear diterpene featuring two stereogenic centers isolated from the Irish brown alga Bifurcariabifurcata. The gross structure of this new natural product was elucidated based on its spectroscopic data (IR, 1D and 2D-NMR, HRMS). Its absolute c...