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Preparation of high densitivity and resolution solid state NMR probe for transition metal nuclei

高密度、高分辨率过渡金属核固态核磁共振探针的制备

基本信息

批准号：
05554026
负责人：
KITAGAWA Susumu
金额：
$ 6.4万
依托单位：
Tokyo Metropolitan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1994
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-05554026/
关键词：
Solid State NMR High Sensitivity Probe Ag NMR Low Frequency Probe CPMAS ワイドバンドパワーアンプ

项目摘要

There are many useful nuclei in low resonance frequency region. However, few studies of their solid state NMR spectra have been reported because of their low sensitivity. In order to overcome the difficulties in measurements of high resolution solid state MAS NMR spectra, We have prepared a high sensitive probe for nuclei having low resonance frequency (low-gamma) and half-integer spin. Especially, Ag-109 NMR probe is useful for material science of silver compounds. The important points to prepare the probe are as follows. (1) According to Hartman-Hahn condition, the CP time is much longer than that in usual C-13 experiments, 50-100 ms. In addition to this, the applied field is much stronger than that of C-13 case. Thus, the probe should work against high power for long time. (2) To fill larger amount of sample in a bullet sample tube, the coil diameter is enlarged. (3) The probe circuits are improved in response to the above conditions. On these basis we have prepared a probe and succeeded in measuring Ag-109 spectra of various silver compounds with high sensitivity. The CPMAS conditions was checked by using [Ag(2,9-phenanthroline)2]PF6. The plots of signal intensity vs. contact time were obtained for practical use. The maximum intensity was obtained at a contact time, t=50 ms.The spectra were measured for various Ag compounds from mononuclear to coordination polymers. We found that[Ag(dihydroxybenzoquinone dianion)]n is the best compound to obtain a strong signal within a short time due to its shortest distance of 109Ag...1H.In addition to the know-how for the measurements we have completed chemical shifts scheme depending on donor atoms of ligands. The shift ranges from 0 ppm to 1000 ppm. the origin of the chemical shift was also discussed by using linear type silver compounds of pyridine derivatives. The shift trend shows that sigma-andpi-mechanism are competing.

在低共振区有许多有用的原子核。然而，由于它们的灵敏度较低，对它们的固体核磁共振谱的研究报道很少。为了克服高分辨固态MAS核磁共振谱测量的困难，我们研制了一种高灵敏度的低共振频率(低伽马)、半整数自旋的原子核探针。特别是Ag-109核磁共振探头在银化合物的材料科学中具有重要的应用价值。准备探头的要点如下。(1)根据Hartman-Hahn条件，CP时间比通常的C-13实验要长得多，为50-100ms。此外，外场比C-13的场强得多。因此，探头应在高功率下工作较长时间。(2)为了在子弹样管中填充更大的样品量，需要增大线圈直径。(3)针对上述情况对探头电路进行了改进。在此基础上，我们制备了探针，并成功地高灵敏度地测量了各种银化合物的Ag-109光谱。用[Ag(2，9-邻菲咯啉)2]PF6考察CPMAS条件。给出了信号强度与接触时间的关系曲线，以供实际使用。在接触时间t=50ms时获得最大强度。测量了从单核到配位聚合物的各种银化合物的光谱。我们发现[Ag(二羟基苯醌二阴离子)]n是在短时间内获得强信号的最佳化合物，因为它的最短距离为109Ag...1H。除了测量的诀窍之外，我们还完成了依赖于配体施主原子的化学位移方案。移位的范围从0ppm到1000ppm。用线性吡啶类银化合物对化学位移的来源进行了讨论。这种转变趋势表明，西格玛和皮尼机制是相互竞争的。