Liquid forms of pharmaceuticals (ionic liquids and deep eutectic solvents) offer a number of potential advantages over solid-state drugs; a key question is the role of intermolecular hydrogen bonding interactions in enabling membrane transport. Characterization is challenging since high sample viscosities, typical of liquid pharmaceutical formulations, hamper the use of conventional solution NMR at ambient temperature. Here, we report the application of magic-angle spinning (MAS) NMR spectroscopy to the deep eutectic pharmaceutical, lidocaine ibuprofen. Using variable temperature MAS NMR, the neat system, at a fixed molar ratio, can be studied over a wide range of temperatures, characterized by changing mobility, using a single experimental setup. Specific intermolecular hydrogen bonding interactions are identified by two-dimensional 1H-1H NOESY and ROESY MAS NMR experiments. Hydrogen-bonding dynamics are quantitatively determined by following the chemical exchange process between the labile protons by means of line-width analysis of variable temperature 1H MAS NMR spectra.

中文翻译：

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通过魔术角旋转NMR光谱揭示深共晶药物中的分子间氢键结构和动力学。

与固态药物相比，液态药物（离子液体和深共熔溶剂）具有许多潜在的优势；一个关键问题是分子间氢键相互作用在使膜运输中的作用。表征是具有挑战性的，因为液体药物制剂中典型的高样品粘度会妨碍在环境温度下使用常规溶液NMR。在这里，我们报告了魔角旋转（MAS）NMR光谱在深共晶药物利多卡因布洛芬中的应用。使用可变温度的MAS NMR，可以使用单个实验装置在固定的摩尔比下，在较宽的温度范围内研究纯系统，以改变迁移率为特征。通过二维1H-1H NOESY和ROESY MAS NMR实验确定特定的分子间氢键相互作用。氢键动力学是通过跟随可变质子之间的化学交换过程，通过可变温度1H MAS NMR谱线宽度分析来定量确定的。