<sup>15</sup>N Nuclear Magnetic Resonance Spectroscopy. Changes in Nuclear Overhauser Effects and <i>T</i><sub>1</sub> with Viscosity
作者:Alexander Wei、Mary Katherine Raymond、John D. Roberts
DOI:10.1021/ja963263v
日期:1997.3.1
A procedure is described for probing changes in ^(15)N T_1 relaxation rates and nuclearOverhausereffects (NOE) with viscosity as a function of temperature. The large freezing-point depression and high viscosities of 8.8 M dimethyl sulfoxide (DMSO)−water solutions allowed study of the molecular motions of several ammonium salts, amides, and heterocycles on the pico- to nanosecond time scale. Dipole−dipole
描述了一种用于探测 ^(15)N T_1 弛豫率和核奥弗豪瑟效应 (NOE) 变化的程序,其中粘度随温度变化。8.8 M 二甲基亚砜 (DMSO)-水溶液的冰点下降幅度大且粘度高,可以在皮秒到纳秒的时间尺度上研究几种铵盐、酰胺和杂环的分子运动。偶极-偶极相互作用为铵盐提供了主要的弛豫形式,但化学位移各向异性 (CSA) 在酰胺和杂环的弛豫中也起着重要作用。对于吡啶,CSA 是一个特别重要的机制,吡啶在 8.8 M DMSO-水中的屏蔽各向异性估计约为 325 ppm。