Dynamic nuclear magnetic resonance constants

A review is given of the application of Molecular Dynamics (MD) computer simulation to complex molecular systems. Three topics are treated in particular the computation of free energy from simulations, applied to the prediction of the binding constant of an inhibitor to the enzyme dihydrofolate reductase the use of MD simulations in structural refinements based on two-dimensional high-resolution nuclear magnetic resonance data, applied to the lac repressor headpiece the simulation of a hydrated lipid bilayer in atomic detail. The latter shows a rather diffuse structure of the hydrophilic head group layer with considerable local compensation of charge density. 

One of the most powerful tools in the study of carbocations is nuclear magnetic resonance (NMR) spectroscopy. This method yields direct information—through chemical shifts, coupling constants, and the temperature dependence of band shapes— about the structure and dynamics of carbocations. 

Conformational Dynamics Detected by Nuclear Magnetic Resonance NOE Values and ] Coupling Constants. 

Nuclear magnetic resonance (NMR) spectroscopy has proved to be a versatile and powerful experimental technique for structural and dynamical studies in chemistry and physics. Although the concentration of species, the temperature, and the magnetic field are often varied in NMR studies, the pressure is normally left constant at its ambient value. This is mainly because apparatus must be constructed specially for high-pressure measurements since it is not commercially available. None the less, there is increasing interest in the development of high-pressure NMR instrumentation. 

Spectral hole burning is an optical analog of the radio frequency saturation experiments in nuclear magnetic resonance (NMR) as introduced in the famous work by Bloembergen, Purcell, and Pound in 1948. The NMR saturation experiments are dynamic in nature, that is, the hole or the saturation dip relaxes with a rate constant as given by spin-lattice relaxation. The analogous experiment in the optical domain was performed for the first time by Szabo. In the optical domain, the relaxation processes... 

Nuclear magnetic resonance (NMR) spectroscopy is one of the most powerful and versatile methods for the elucidation of molecular structure and dynamics. It is also very well suited to study molecular complexes and their properties [1]. Therefore, it has been widely used for studying inclusion complexes formed by cyclodextrins (CyD) [2-4]. Some examples of the applications of NMR in conjunction with other techniques are presented in other chapters, in particular in Chapter 6. The success of NMR spectroscopy in this field is due to its ability to study complex chemical systems and to determine stoichiometry, association constants, and conformations of molecular complexes, as well as to provide information on their symmetry and dynamics. Furthermore, compared to other techniques, NMR spectroscopy provides a superior method to study complexation phenomena, because guest and host molecules are simultaneously observed at the atomic level. 

The pKbh+ is the dissociation constant of the conjugate acid (BH+) and BH+/B is the ionization ratio, which is generally measured by spectroscopic means [ultraviolet, nuclear magnetic resonance (NMR), and dynamic NMR]. Hammett s Ho scale is a logarithmic scale on which 100% sulfuric acid has an Ho value of -12.0. 

---