Quantitative characterization of weak interactions

弱相互作用的定量表征

• 批准号: 1213329
• 负责人: A. Alan Pinkerton
• 金额: $ 50万
• 依托单位: University of Toledo
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-08-15 至 2016-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1213329&HistoricalAwards=false
• 关键词: Quantitative; characterization; weak; interactions

Through this award, funded by the Chemical Structure, Dynamics, and Mechanisms Program of the Division of Chemistry, Prof. A. Alan Pinkerton and Dr. Elizabeth Zhurova from the University of Toledo, will quantitatively characterize important weak interactions between atoms or molecules in the solid state using advanced, high resolution, X-ray crystallographic techniques. The electron density distribution will be determined from the intensities of the X-rays scattered from single crystals, and quantified by fitting the parameters of an atom-centered multipole expansion to the observed data. A range of intra- and inter-molecular interactions that have been previously identified from structural data, many with "non-bonded" distances significantly below the sum of the Van der Waals radii, will be studied. Currently potential interactions between 20 different atom pairs have been identified for 20 different molecular solids. Information from this study will provide new insight into a wide spectrum of scientific areas such as materials design/crystal engineering and biological ligand-receptor binding/cell signaling. Properties of all materials are intimately related to the distribution of electrons between the atoms and molecules. For example, diamond and graphite are composed entirely of carbon atoms, but have vastly different properties, diamond being very hard, and graphite being a soft lubricant. This is easily understood as the distribution of electrons in diamond leads to strong covalent bonds in three dimensions, whereas graphite is strongly bonded in two dimensions, and weakly bonded in the third. The importance of strong chemical bonds has been recognized by generations of chemists, and their characterization by theory and experiment is the material for text books. The importance of weak interactions, with the exception of hydrogen bonds, has not been systematically studied using X-ray diffraction techniques until now, and represents a new investigative direction in chemistry. This pursuit will allow graduate students and postdoctoral fellows to acquire specialized training in cryogenics, and in high resolution X-ray crystallography. The new methods for cryogenic data collection and analysis, followed by workshops to train others, will push the limits of what is experimentally obtainable. This project will also be integrated into an outreach program to introduce high school students to the science of crystallography.

通过该奖项，由化学划分的化学结构，动力学和机制计划资助，托莱多大学的A. Alan Pinkerton教授和Elizabeth Zhurova博士将定量地表征原子或分子之间重要的弱相互作用。使用高级，高分辨率，X射线晶体学技术的固态。 电子密度分布将从散布在单晶体的X射线的强度上确定，并通过将原子中心的多极扩展的参数拟合到观察到的数据中来量化。先前从结构数据中鉴定出的一系列范围的分子间相互作用，许多具有“非键入”距离的距离将显着低于范德华半径的总和。目前已经确定了20种不同的分子固体之间的20种不同原子对之间的潜在相互作用。这项研究的信息将为广泛的科学领域提供新的见解，例如材料设计/晶体工程和生物配体受体结合/细胞信号传导。所有材料的性质与原子和分子之间电子的分布密切相关。 例如，钻石和石墨完全由碳原子组成，但具有巨大的特性，钻石非常坚硬，石墨是一种软润滑剂。 这很容易理解为钻石中电子的分布会导致三个维度的强共价键，而石墨在二维中强烈键合，在第三个维度上键弱。几代化学家已经认识到强大的化学键的重要性，其理论和实验的表征是教科书的材料。 除氢键外，弱相互作用的重要性尚未系统地研究X射线衍射技术，并且代表了化学方面的新调查方向。这种追求将使研究生和博士后研究员获得低分辨率X射线晶体学的专业培训。低温数据收集和分析的新方法，然后是培训其他人的研讨会，将推动可获得实验的限制。该项目还将集成到一个外展计划中，以向高中生介绍晶体学科学。