Localization of Guest Molecules in Nanopores by Pulsed EPR Spectroscopy
Localization of Guest Molecules in Nanopores by Pulsed EPR Spectroscopy
复制标题
通过脉冲 EPR 光谱定位纳米孔中的客体分子
DOI：
10.1021/acs.jpcc.7b10758
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发表时间：
2018
影响因子：
3.7
通讯作者：
M. Drescher
中科院分区：
文献类型：
--
作者：
A. Pivtsov;M. Wessig;V. Klovak;S. Polarz;M. Drescher
客体分子在介孔主体材料中在分子尺度上的定位对于多相催化、色谱、药物递送和不同生物医学应用中的应用是至关重要的。在这里，我们提出了第一次精确定位不同的客体分子内的介孔有机硅材料UKON 2a的孔径为6 nm。我们利用顺磁探针分子4-氨基-2，2，6，6-四甲基哌啶-1-氧基（4-氨基-TEMPO）和4-羧基-TEMPO与氘代策略相结合。应用一组不同的脉冲电子顺磁共振方法的互补，我们获得的信息的空间分布和局部浓度的维度通过双电子-电子共振实验，相对于孔壁的客体分子的取向通过电子自旋回波包络调制光谱，和客体分子和孔壁之间的距离通过电子核双共振光谱。这允许定位客体分子，并表明它们在纳米孔中的空间分布强烈依赖于它们的极性。
The localization of guest molecules at the molecular scale in mesoporous host materials is crucial for applications in heterogeneous catalysis, chromatography, drug delivery, and in different biomedical applications. Here, we present for the first time the precise localization of different guest molecules inside the mesoporous organosilica material UKON2a with a pore size of 6 nm. We exploited paramagnetic probe molecules 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-amino-TEMPO) and 4-carboxy-TEMPO in combination with a deuteration strategy. Applying a complementary set of different pulsed electron paramagnetic resonance methods, we obtained information about the dimensionality of the spatial distribution and local concentration via double electron–electron resonance experiments, orientation of the guest molecules with respect to the pore walls via electron spin echo envelope modulation spectroscopy, and about the distance between guest molecules and pore walls via electron nuclear double resonance spectroscopy. This allowed localizing the guest molecules and shows that their spatial distribution in nanopores strongly depends on their polarity.