Hartree-Fock (HF) and Density Functional Theory (DFT) methods employed to study the effect of conformational change on the 13C chemical shifts of 6-mono axial and equatorial substituted and 6,7-di axial-axial, equatorial-equatorial and axial-equatorial substitutedderivatives of 5,6,7,8-tetrahydrodibenzo[a,c]cyclo-octene. The geometry of the conformers have been optimized...

Density functional theory (DFT) calculations of the magnetic shielding in solid state nuclear magnetic resonance (NMR) experiments provide an important contribution for the understanding of the experimentally observed chemical shifts. In this work we focus on the relation between atomic and orbital character of the valence and conduction band wave functions and the S NMR shielding in sulfides a...

The series of methyl halides, CH(3)X (X = F, Cl, Br, and I), is prototypic for demonstrating the s.c. normal halogen dependence of light-atom nuclear magnetic resonance shielding constants in the presence of halogen atoms of varying electronegativity. We report a systematic experimental and first-principles theoretical study of the (13)C and (1)H shielding tensors in this series. The experiment...

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...

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...

The present work introduces a new three-dimensional nuclear magnetic resonance ~3D NMR! experiment for the analysis of half-integer quadrupolar nuclei in solids. The method is based on the multi-rank expansion of the high-field NMR Hamiltonian governing the central transition of these spins in terms of irreducible spherical tensor elements. This approach leads to a temporal spin evolution given...

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...

A wide range of novel supramolecular (three-dimensional) heterometallic compounds, synthesized at the University of Hamburg, have been studied by magic-angle spinning NMR using 1 C, N, Sn and 2 0 7 Pb nuclei. Typical examples are [(Me3Sn)3Co(CN)<5]oo and [(Me3Sn)4Fe(CN)6Joo. The systems are insoluble and often not in forms suitable for single-crystal Xray work. The NMR results are therefore vit...

A series of 11 oxovanadium(V) complexes mimicking the active site of vanadium haloperoxidases have been investigated by (51)V magic angle spinning NMR spectroscopy and density functional theory (DFT). The MAS spectra are dominated by the anisotropic quadrupolar and chemical shielding interactions; for these compounds, C(Q) ranges from 3 to 8 MHz, and delta(sigma) is in the range 340-730 ppm. Th...

geometrical structure, nuclear magnetic resonance (n1,1it) chemical shielding tensors, and chemical shiftsof silicon and carbon nucler are investigated for twn infinite size zigzag and armchair single-walled siliconcarbide nanotabes (sicnts). geometrical structures of sients, sit bonds and bond angles of st and cvertices in both zigzag and armchair nanotubes, indicate that bond lengths are appr...