Nuclear Magnetic Resonance Studies of Molecular Structure and Dynamics

该研究计划描述了一个程序，以调查的材料的详细结构和动力学是对科学界的根本兴趣。广泛的材料将被研究，包括混合钙钛矿，是太阳能电池的基石，天然产品和药物，是重要的医学，过渡金属配合物，其中一些催化化学反应和具有重要的工业应用。我们研究材料结构和动力学的主要实验工具是核磁共振波谱学，这是核磁共振成像的通用工具。我们研究的许多天然产物，例如姜黄素，都有很强的氢键，这在决定它们的分子结构和分子性质方面起着重要作用。在这些具有分子内氢键的分子中，我们最近观察到氘同位素对固态核磁共振化学位移的影响，我们相信这有可能提供关于氢原子位置的详细信息，这些信息很难通过x射线衍射获得。我们正在与理论家一起计算具有非对称双阱势面系统的精确势能和零点能量。有趣的是，美国食品和药物管理局已经批准了第一种氘标记药物，tetrabenazine-d6，用于人类使用。

The research proposal describes a program to investigate the detailed structure and dynamics of materials that are of fundamental interest to the scientific community. A wide range of materials will be investigated including hybrid perovskites that are building blocks of solar cells, natural products and pharmaceuticals that are important in medicine, and transition metal complexes, some of which catalyze chemical reactions and have important industrial applications. Our principal experimental tool for investigating the structure and dynamics of materials is nuclear magnetic resonance spectroscopy, a general tool upon which MRI, magnetic resonance imaging, is based. Many of the natural products that we examine, e.g., curcumin, have strong hydrogen bonds that play a fundamental role in determining their molecular structure and hence their molecular properties. In these molecules with intramolecular hydrogen bonds we have very recently observed deuterium isotope effects on NMR chemical shifts in the solid state that we believe have the potential to provide detailed information about the positions of hydrogen atoms, information difficult to obtain by X-ray diffraction. We are working with theoreticians to compute accurate potentials and zero-point energies for systems with unsymmetrical double-well potential surfaces. It is interesting to point out that the US FDA has approved the first deuterium-labeled drug, tetrabenazine-d6, for human use. We have extensive experience working with methylammonium lead iodide, a compound that belongs to a class of compounds known as organic-inorganic hybrid perovskites. Although we started working with this material in 1985, not long after it was first prepared by Weber, it was not until 2009 that it was realized that this material could be used to convert solar energy into electrical energy. In 2009, the efficiency of converting solar energy to electrical energy was approximately 3.8 %, but now, by careful control of the preparation procedures, efficiencies in excess of 22% have been achieved. Today, we join many research groups scrutinizing related organic-inorganic perovskite materials as possible candidates for solar energy applications. From the recent literature, it seems clear that the cation and halide ion dynamics significantly influences the performance of these materials. We plan to use mechanochemical synthetic methods to prepare several lead mixed-halide perovskites and characterize both the cation and anion dynamics using solid-state NMR.