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首页> 外文期刊>The journal of physical chemistry, C. Nanomaterials and interfaces >Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning ~(13)C and ~(29)Si NMR Enhanced by Dynamic Nuclear Polarization
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Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning ~(13)C and ~(29)Si NMR Enhanced by Dynamic Nuclear Polarization

机译：负载表面活性剂的介孔二氧化硅纳米粒子：动态核极化增强的低温魔角旋转〜（13）C和〜（29）Si NMR

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摘要

We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of ~(13)C and ~(29)Si 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 'H—'H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements ε_(on/off) of around 8. When the CTAB molecules are extracted, so that the radicals Can enter the mesopores, the enhancements increase to ε_(on/off) ≈ 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.
机译：我们显示动态核极化（DNP）可用于增强位于介孔有机/无机杂化材料中的〜（13）C和〜（29）Si核的NMR信号，距离被困的稳定自由基（TOTAPOL）几百纳米在周围的冰冻混乱的水中。使用介孔二氧化硅纳米粒子（MSN）进行了演示，该粒子被3-（N-苯基脲基）丙基（PUP）基团官能化，并填充有表面活性剂十六烷基三甲基溴化铵（CTAB）。 DNP增强的质子磁化通过'H-'H自旋扩散传输到中孔，并通过交叉极化转移到稀有自旋，产生大约8的信号增强ε_（on / off）。提取CTAB分子后，由于自由基可以进入中孔，两个原子核的增强都增加到ε_（on / off）≈30。带有和不带有表面活性剂的MSN中信号增强的定量分析基于一维质子自旋扩散模型。还研究了溶剂氘的作用。

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