Guest Transition Metals in Host Inorganic Nanocapsules: Single Sites, Discrete Electron Transfer, and Atomic Scale Structure
Guest Transition Metals in Host Inorganic Nanocapsules: Single Sites, Discrete Electron Transfer, and Atomic Scale Structure
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DOI：
10.1021/jacs.0c05264
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发表时间：
2020-08-26
影响因子：
15
通讯作者：
Neumann, Ronny
中科院分区：
文献类型：
--
作者：
Haviv, Eynat;Chen, Bo;Neumann, Ronny
具有广泛有机主体的主客体溶液化学是一个重要和成熟的研究领域，而无机主体的使用则是一个较新的研究领域。在最近的几个案例中，凯普莱型氧化钼基多孔、球形簇合物，简称为{Mo-132}，已被用作有机宾客的东道主。在这里，我们展示了第一排过渡金属(M=Mn，Fe和Co)的合成控制封装在内核上排列着磷酸阴离子的Keplerate簇中，{Mo132PO4}。用P-31核磁共振和Endor光谱对所合成的M-x(2+)主客体络合物进行了表征，证实了第一排过渡金属客体的包裹。磁化率测量表明，高达10当量的包覆金属之间几乎没有磁相互作用，这表明每个客体原子占据了一个单一的位置。利用球面和彩色双像差校正的电子显微镜结合能量过滤的透射电子显微镜(EFTEM)元素图谱，可以显示胶囊和区分胶囊骨架和被包裹的过渡金属的Mo原子。此外，利用可见光诱导XPS进行了化学分辨电学测量(CREM)，证实了M被成功地包裹在{Mo132PO4}中，并进一步显示了从M到Mo的光诱导电子转移。在未来，这种在主体{Mo-132}和过渡金属客体之间的定向电子转移可以被用作无机化合物的光引发开关和在受限空间中的单位光催化反应。
Host-guest solution chemistry with a wide range of organic hosts is an important and established research area, while the use of inorganic hosts is a more nascent area of research. In the recent past in a few cases, Keplerate-type molybdenum oxide-based porous, spherical clusters, shorthand notation {Mo-132}, have been used as hosts for organic guests. Here, we demonstrate the synthetically controlled encapsulation of first-row transition metals (M = Mn, Fe, and Co) within a Keplerate cluster that was lined on the inner core with phosphate anions, {Mo132PO4}. The resulting M-x(2+)subset of{Mo132PO4} host-guest complexes were characterized by P-31 NMR and ENDOR spectroscopy that substantiated the encapsulation of the first-row transition metal guest. Magnetic susceptibility measurements showed that the encapsulation of up to 10 equiv showed little magnetic interaction between the encapsulated metals, which indicated that each guest atom occupied a single site. Visualization of the capsules and differentiation of the Mo atoms of the capsule framework and the encapsulated transition metal were possible using spherical and chromatic double aberration-corrected electron microscopy combined with energy-filtered TEM (EFTEM) elemental maps. In addition, use of visible light-induced XPS for chemically resolved electrical measurements (CREM) confirmed the successful encapsulation of M within {Mo132PO4} and furthermore showed photoinduced electron transfer from M to Mo. In the future, such targeted electron transfer between host {Mo-132} and a transition metal guest could be used as photoinitiated switches using inorganic compounds and for single site photocatalytic reactions in confined space.