Using muon-spin spectroscopy, we study the exceptional dynamical properties of rotating molecular struts engineered within a Zn-based metal–organic framework at cryogenic temperatures, where the internal motions of almost any other organic substance are quenched. Muon-spin spectroscopy is particularly suited for this aim, as the experimental evidence suggests several implantation sites for the muons, among which at least one directly onto the rotating moiety. The dynamics of the molecular rotors are characterized by the exceptionally low activation energy E_A ∼ 30 cal mol^–1. At the same time, we evidence a highly unusual temperature dependence of the dipolar interaction of muons with nuclear magnetic moments on the rotors, suggesting a complex influence of the rotations on the muon implantation and diffusion.

中文翻译：

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金属有机框架中的分子转子：超快速旋转木马上的介子。

利用μ自旋光谱学，我们研究了低温条件下在基于Zn的金属-有机框架中工程化的旋转分子撑杆的出色动力学特性，几乎所有其他有机物质的内部运动都被抑制了。on子自旋光谱特别适合于此目的，因为实验证据表明该ons子有多个植入位点，其中至少一个直接位于旋转部分上。分子转子的动态特性的特征在于非常低的活化能ê_甲〜30 CAL摩尔^-1。同时，我们证明了介子与转子上的核磁矩的偶极相互作用的极不寻常的温度依赖性，表明旋转对介子注入和扩散的复杂影响。