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首页> 外文学位 >Off-resonance NMR on nitrogen-15 in guanosine and phase cycling of quadrupolar nmr on oxygen-17 in silica.
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Off-resonance NMR on nitrogen-15 in guanosine and phase cycling of quadrupolar nmr on oxygen-17 in silica.

机译：鸟苷中氮15的非共振NMR和二氧化硅中氧17的四极核磁共振的相循环。

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摘要

Nuclear magnetic resonance in the solid state provides a wealth of inter- and intramolecular interactions that can be utilized to provide useful physical information. Chemical shift, dipolar, J-coupling, and quadrupolar interactions are all present in the solid state and provide complementary information on molecular structure and dynamics. In this work, dipolar, J-coupling, and quadrupolar interactions are studied. Lee-Goldburg off-resonance excitation is employed on a sample of 15N enriched guanosine to determine inter and intramolecular nitrogen-hydrogen distances and the scalar J-coupling constant. Satellite transition magic angle spinning is employed on an 17O enriched sample in silica to experimentally study phase cycling effects.;Lee-Goldburg decoupling on guanosine is employed to determine scalar coupling in 15N bonded to 1H in guanosine. Experimental results are compared to theoretically predicted results. Results show scaling factors of 0.47 +/- 0.03 and 0.39 +/- 0.13 compared to theoretical values of 0.58. Also, a hydrogen bond shift in the resonance frequencies is postulated.;Lee-Goldburg cross polarization on guanosine is used to probe inter-nuclear distances of 15N bonded to 1H in guanosine. Results are compared to x-ray crystal structures where positions of protons are energetically optimized. Simulation of experimental results is also used to compare x-ray bond lengths to Lee-Goldburg cross polarization results. The Lee-Goldburg results for N-H and N-H2 bonds show stronger agreement with simulation than x-ray results. Differences in distances range from 0.01 to 0.05 A N-H hydrogen bond distances are also compared.;Finally, phase cycling effects are studied in satellite transition magic angle spinning experiments on 17O in silica. Results show that a variety of phase cycles for the final pulse in the pulse sequence can be employed to give quantitatively the same result. On the other hand, phase cycles for the first and second pulses may significantly alter the spectrum, showing more coherences for smaller numbers of phase cycles.
机译：固态的核磁共振提供了大量的分子间和分子内相互作用，可用于提供有用的物理信息。化学位移，偶极，J耦合和四极相互作用都以固态存在，并提供有关分子结构和动力学的补充信息。在这项工作中，研究了偶极，J耦合和四极相互作用。 Lee-Goldburg非共振激发用于富含15N鸟嘌呤的样品，以确定分子间和分子内氮氢距离和标量J耦合常数。在富含17 O的二氧化硅样品中采用卫星跃迁幻角旋转技术来实验研究相循环效应。在鸟嘌呤上，Lee-Goldburg鸟嘌呤的解偶联用于测定与1H结合的15N中的标量耦合。将实验结果与理论预测结果进行比较。结果显示比例因子为0.47 +/- 0.03和0.39 +/- 0.13，而理论值为0.58。此外，还假定了共振频率中的氢键移位。鸟嘌呤上的Lee-Goldburg交叉极化用于探测鸟嘌呤中与1H键合的15N的核间距离。将结果与X射线晶体结构进行比较，在X射线晶体结构中，质子的位置得到了优化。实验结果的模拟还用于比较x射线键长与Lee-Goldburg交叉极化的结果。与X射线结果相比，N-H和N-H2键的Lee-Goldburg结果显示出与仿真更强的一致性。还比较了距离差异在0.01到0.05 A之间的N-H氢键距离。最后，在卫星跃迁魔术角旋转实验中研究了二氧化硅在17O上的相循环效应。结果表明，可以使用脉冲序列中最终脉冲的各种相周期来定量给出相同的结果。另一方面，第一和第二脉冲的相位周期可能会显着改变频谱，对于较少数量的相位周期显示出更多的相干性。

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  • 作者

    Malave, Peter Lorenzo.;

  • 作者单位

    Tufts University.;

  • 授予单位 Tufts University.;
  • 学科 Chemistry Inorganic.;Chemistry Physical.;Physics Radiation.
  • 学位 Ph.D.
  • 年度 2011
  • 页码 91 p.
  • 总页数 91
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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