Universität Leipzig, Wilhelm-Ostwald-Institut für Physikalische und Theoretische Chemie, Linnéstraße 2, 04103, Leipzig, Germany.
Northwestern University, Department of Chemical and Biological Engineering, 2145 Sheridan Road, Evanston, Illinois, 60208, United States.
Chemphyschem. 2021 Nov 18;22(22):2336-2341. doi: 10.1002/cphc.202100489. Epub 2021 Sep 23.
The dynamics of carbon dioxide in third generation (i. e., flexible) Metal-Organic Frameworks (MOFs) can be experimentally observed by C NMR spectroscopy. The obtained line shapes directly correlate with the motion of the adsorbed CO , which in turn are readily available from classical molecular dynamics (MD) simulations. In this article, we present our publicly available implementation of an algorithm to calculate NMR line shapes from MD trajectories in a matter of minutes on any current personal computer. We apply the methodology to study an effect observed experimentally when adsorbing CO in different samples of the pillared layer MOF Ni (ndc) (dabco) (ndc=2,6-naphthalene-dicarboxylate, dabco=1,4-diazabicyclo-[2.2.2]-octane), also known as DUT-8(Ni). In C NMR experiments of adsorbed CO in this MOF, small (rigid) crystals result in narrower NMR line shapes than larger (flexible) crystals. The reasons for the higher mobility of CO inside the smaller crystals is unknown. Our ligand field molecular mechanics simulations provide atomistic insight into the effects visible in NMR experiments with limited computational effort.
通过 C NMR 光谱可以在第三代（即柔性）金属有机骨架（MOF）中观察到二氧化碳的动力学。所获得的谱线形状直接与吸附 CO 的运动相关，而后者可以从经典分子动力学（MD）模拟中轻松获得。在本文中，我们展示了我们公开提供的一种算法，该算法可以在任何当前的个人计算机上在几分钟内从 MD 轨迹计算 NMR 谱线形状。我们应用该方法研究了当在不同的支柱层 MOF Ni(ndc)(dabco)（ndc=2,6-萘二甲酸酯，dabco=1,4-二氮杂二环[2.2.2]-辛烷），也称为 DUT-8（Ni）中吸附 CO 时实验中观察到的一种效应。在该 MOF 中吸附 CO 的 C NMR 实验中，较小（刚性）晶体的 NMR 谱线形状比较大（柔性）晶体更窄。较小晶体中 CO 更高迁移率的原因尚不清楚。我们的配体场分子力学模拟以有限的计算工作量提供了对 NMR 实验中可见效应的原子见解。
