Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization

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• 作者：Olivier Lafon ; Aany S. Lilly Thankamony ; Takeshi Kobayashi ; Diego Carnevale ; Veronika Vitzthum ; Igor I. Slowing ; Kapil Kandel ; Herv茅 Vezin ; Jean-Paul Amoureux ; Geoffrey Bodenhausen ; Marek Pruski
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：January 24, 2013
• 年：2013
• 卷：117
• 期：3
• 页码：1375-1382
• 全文大小：427K
• 年卷期：v.117,no.3(January 24, 2013)
• ISSN：1932-7455

文摘

We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of ¹³C and ²⁹Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via ¹H鈥?sup>1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements 蔚_on/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to 蔚_on/off 鈮?30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.