The results of a solid-state (11)B NMR study of a series of 10 boronic acids and boronic esters with aromatic substituents are reported. Boron-11 electric field gradient (EFG) and chemical shift (CS) tensors obtained from analyses of spectra acquired in magnetic fields of 9.4 and 21.1 T are demonstrated to be useful for gaining insight into the molecular and electronic structure about the boron...

The chemical shielding is the most familiar and universal parameter in the field of nuclear magnetic resonance (NMR). It may be calculated or measured experimentally; it may be studied by gas phase, liquid phase, or solid phase NMR, as well as by quantum mechanical methods. This chapter will introduce NMR both from a theoretical and an experimental standpoint, and quantum theory. The following ...

Calculations of NMR parameters (the absolute shielding constants and the spin-spin coupling constants) for 5(12), 5(12)6(2) and 5(12)6(4) cages enclathrating CH4, C2H6 and C3H8 molecules are presented. The DFT/B3LYP/HuzIII-su3 level of theory was employed. The (13)C shielding constants of guest molecules are close to available experimental data. In two cases (the ethane in 5(12) and the propane...

We report solid-state 25Mg NMR, X-ray crystallographic, and quantum-mechanical calculation results for bis(pyridine)(5,10,15,20-tetraphenylporphyrinato)magnesium(II), Mg(TPP)·Py2. Mg(TPP)·Py2 crystallizes in the triclinic form, in the space group P1. The unit cell parameters are: a = 9.6139(13) Å, b = 11.0096(16) Å, c = 11.8656(15) Å; α = 102.063(3)°, β = 103.785(3)°, γ = 114.043(2)°; Z = 1. Th...

α-amylase has been studied extensively from various sides. this enzyme is used in many industries .many applications of this enzyme have encouraged us for greater attempts on the study of α-amylase and to search for more effective processes. in this investigation, the structure of nanotube - catalytic site of bacillus subtilis α- amylase was optimized by hyperchem 7.0 and then it was investigat...

The olefinic carbon chemical shift tensors of trans-stilbene-R,â-C2 (1) and (trans-stilbene-R,â-C2)[bis(triphenylphosphine)]platinum(0) (2) have been characterized by solid-state 13C NMR spectroscopy. Analyses of the 13C NMR spectra obtained for stationary powder samples of 1 and 2 at 4.7 and 9.4 T yield the principal components of the carbon chemical shift tensors. The presence of a homonuclea...

as drug delivery systems nanoparticulan widely investigated because of many advantages such as smaller size,controlled drug release potential targeting ability, enhancement of therapeutic efficacy and reduction oftoxicity. so, carbon nanotubes have recently received considerable attention as alternative drug delivery carrierin this study we investigate interaction of tamoxifen with open-end of ...

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...

Aseries of uni- and multidimensional variants of the dipolar exchange-assisted recoupling (DEAR) NMR experiment is described and applied to determinations of (13)C-(14)N dipolar local field spectra in amino acids and dipeptides. The DEAR protocol recouples nearby nuclei by relying on differences in their relative rates of longitudinal relaxation, and has the potential to give quantitative geome...

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...