The NMR Chemical Shift: Insight into Structure and Environment

摘要: Publisher Summary This chapter discusses the nuclear shielding surfaces in simple systems: The systems discussed are diatomic molecules to focus on variation with bond length H 2 O, NH 3 , PH and CH 4 consider angles lengths. variations Φ, Ψ, x explored various model peptides, finally remote stretches. Following intramolecular surfaces, intermolecular atom-atom pairs, atom-ion, atom-molecule pairs clusters of three or more, including up 5 16 polar solvent molecules, is chapter. effects electric fields field gradients considered separately. origin temperature dependence, isotope shifts, shifts density solvent, hydrogen-bonding also shown this At present, only small fragments networks have been treated quantum-mechanically, such as [SiO ] -4 unit represent silicates. Approaches complex systems, proteins, developed provide new insight into interdependence structure. However, other ionic covalent solids, so far at empirical level.