Enhanced Solid-State NMR Correlation Spectroscopy of Quadrupolar Nuclei Using Dynamic Nuclear Polarization

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• 作者：Daniel Lee ; Hiroki Takahashi ; Aany S. L. Thankamony ; Jean-Philippe Dacquin ; Michel Bardet ; Olivier Lafon ; Ga毛l De Pa毛pe
• 刊名：The Journal of the American Chemical Society
• 出版年：2012
• 出版时间：November 14, 2012
• 年：2012
• 卷：134
• 期：45
• 页码：18491-18494
• 全文大小：245K
• 年卷期：v.134,no.45(November 14, 2012)
• ISSN：1520-5126

文摘

By means of a true sensitivity enhancement for a solid-state NMR spectroscopy (SSNMR) experiment performed under dynamic nuclear polarization (DNP) conditions, corresponding to 4鈥? orders of magnitude of time savings compared with a conventional SSNMR experiment, it is shown that it is possible to record interface-selective ²⁷Al鈥?sup>27Al two-dimensional dipolar correlation spectra on mesoporous alumina, an advanced material with potential industrial applications. The low efficiency of cross-polarization and dipolar recoupling for quadrupolar nuclei is completely negated using this technique. The important presence of pentacoordinated Al has not only been observed, but its role in bridging interfacial tetra- and hexacoordinated Al has been determined. Such structural information, collected at low temperature (103 K) and 9.4 T with the use of DNP, would have been impossible to obtain under standard conditions, even using a higher magnetic field. However, here it is demonstrated that this information can be obtained in only 4 h. This work clearly opens a new avenue for the application of SSNMR to quadrupolar nuclei and notably the atomic-scale structure determination of catalysis materials such as mesoporous alumina.