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27Al NMR diffusometry of Al13 Keggin nanoclusters
Magnetic Resonance in Chemistry ( IF 1.9 ) Pub Date : 2021-09-18 , DOI: 10.1002/mrc.5218 Trent R Graham 1 , Jaehun Chun 1 , Gregory K Schenter 1, 2 , Xin Zhang 1 , Sue B Clark 1, 2 , Carolyn I Pearce 1, 3 , Kevin M Rosso 1
Magnetic Resonance in Chemistry ( IF 1.9 ) Pub Date : 2021-09-18 , DOI: 10.1002/mrc.5218 Trent R Graham 1 , Jaehun Chun 1 , Gregory K Schenter 1, 2 , Xin Zhang 1 , Sue B Clark 1, 2 , Carolyn I Pearce 1, 3 , Kevin M Rosso 1
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Although nanometer-sized aluminum hydroxide clusters (i.e., ϵ-Al13, [Al13O4(OH)24(H2O)12]7+) command a central role in aluminum ion speciation and transformations between minerals, measurement of their translational diffusion is often limited to indirect methods. Here, 27Al pulsed field gradient stimulated echo nuclear magnetic resonance (PFGSTE NMR) spectroscopy has been applied to the AlO4 core of the ϵ-Al13 cluster with complementary theoretical simulations of the diffusion coefficient and corresponding hydrodynamic radii from a boundary element-based calculation. The tetrahedral AlO4 center of the ϵ-Al13 cluster is symmetric and exhibits only weak quadrupolar coupling, which results in favorable T1 and T2 27Al NMR relaxation coefficients for 27Al PFGSTE NMR studies. Stokes–Einstein relationship was used to relate the 27Al diffusion coefficient of the ϵ-Al13 cluster to the hydrodynamic radius for comparison with theoretical simulations, dynamic light scattering from literature, and previously published 1H PFGSTE NMR studies of chelated Keggin clusters. This first-of-its-kind observation proves that 27Al PFGSTE NMR diffusometry can probe symmetric Al environments in polynuclear clusters of greater molecular weight than previously considered.
中文翻译：
Al13 Keggin 纳米团簇的 27Al NMR 扩散法
尽管纳米级氢氧化铝簇（即 ε-Al 13、[Al 13 O 4 (OH) 24 (H 2 O) 12 ] 7+）在铝离子形态形成和矿物之间的转化中发挥着核心作用，但测量它们的平移扩散通常仅限于间接方法。在这里，27 Al 脉冲场梯度受激回波核磁共振 (PFGSTE NMR) 光谱已应用于ε-Al 13的 AlO 4核心集群与扩散系数和相应的流体动力学半径的补充理论模拟来自基于边界元的计算。ε-Al 13簇的四面体AlO 4中心是对称的并且仅表现出弱四极耦合，这导致对27 Al PFGSTE NMR研究有利的T 1和T 2 27 Al NMR弛豫系数。斯托克斯-爱因斯坦关系用于将ε-Al 13簇的27 Al 扩散系数与流体动力学半径联系起来，以便与理论模拟、文献中的动态光散射和先前发表的1进行比较 螯合 Keggin 簇的 H PFGSTE NMR 研究。这一首创的观察结果证明，27 Al PFGSTE NMR 扩散法可以探测分子量比之前考虑的更大的多核簇中的对称 Al 环境。
更新日期：2021-09-18
中文翻译：
Al13 Keggin 纳米团簇的 27Al NMR 扩散法
尽管纳米级氢氧化铝簇（即 ε-Al 13、[Al 13 O 4 (OH) 24 (H 2 O) 12 ] 7+）在铝离子形态形成和矿物之间的转化中发挥着核心作用，但测量它们的平移扩散通常仅限于间接方法。在这里，27 Al 脉冲场梯度受激回波核磁共振 (PFGSTE NMR) 光谱已应用于ε-Al 13的 AlO 4核心集群与扩散系数和相应的流体动力学半径的补充理论模拟来自基于边界元的计算。ε-Al 13簇的四面体AlO 4中心是对称的并且仅表现出弱四极耦合，这导致对27 Al PFGSTE NMR研究有利的T 1和T 2 27 Al NMR弛豫系数。斯托克斯-爱因斯坦关系用于将ε-Al 13簇的27 Al 扩散系数与流体动力学半径联系起来，以便与理论模拟、文献中的动态光散射和先前发表的1进行比较 螯合 Keggin 簇的 H PFGSTE NMR 研究。这一首创的观察结果证明，27 Al PFGSTE NMR 扩散法可以探测分子量比之前考虑的更大的多核簇中的对称 Al 环境。
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