RUI:Targeted Structural Diversity and Assessments in Quasiracemates

在材料研究部固态和材料化学计划的支持下，Kraig Wheeler(化学)和Diana Schepens(数学)合作合成并表征了独特的材料家族，这些材料在分子晶体中可预测地排列。虽然许多导致分子相互作用的结构细节是已知的，但也存在一些化学特征，这些特征通过定义不明确或弱接触而产生不太容易管理的基序，这些基序对整个分子识别过程同样关键。分子形状就是这样的结构特征之一，也是本次研究的重点。这项研究的目的是了解如何利用有机小分子的形状在晶体中构建可预测的分子组装。这项工作的发现提供了有关分子形状空间的必要信息，这些信息可用于功能材料的设计。此外，鉴于所研究的小分子有机化合物独特的分子识别特征和计算机辅助发现方法的发展，从这些研究中获得的知识有助于更全面地了解大类化合物的自组装过程。该项目通过惠特沃斯大学实验和计算机辅助研究的实践经验，支持对一批本科生和高中生的培训，惠特沃斯大学是一所以本科生为主的机构。外展工作还包括支持夏季X射线结晶学会议，来自全国各地的与会者在会上为他们正在进行的教学和研究计划接受必要的培训。技术总结这个跨学科的项目结合了实验固态有机化学和数学拓扑学，以研究对映体如何接近地组装成能量有利的晶体组装。本研究通过构建双分子化合物的准外消旋体方法探索分子形状对分子识别过程的结构边界。使用苯甲酰氨基酸分子支架制备了由已知有机前体组成的手性构建块。虽然准对映体材料的研究现在已经发展到一门成熟的科学，但组装准对映体对的密切细节仍然相对未知。这个项目探索了通过强氢键增加晶格稳定性如何导致材料具有更大的准对映体成分的结构变化。目标系统的行为有望为分子识别图谱提供关键的洞察力。结晶学、视频辅助热显微镜、量热和晶格能计算被用来评估这些材料形成准外消旋材料的能力。这项研究还开发了用于确定准对映体成分对的形状、空间差异和反转对称度的电子方法，这将为准外消旋预测提供诊断工具。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-Technical SummaryWith the support of the Solid State and Materials Chemistry Program in the Division of Materials Research, the collaboration between Kraig Wheeler (Chemistry) and Diana Schepens (Mathematics) synthesizes and characterizes unique families of materials that align predictably in molecular crystals. While many structural details responsible for molecular interactions are known, there also exist chemical features that produce less manageable motifs via ill-defined or weak contacts that are no less critical to the overall molecular recognition process. Molecular shape is one such structural feature and the focus of this investigation. The goal of this research is to understand how the shape of small organic molecules can be used to advantage to construct predictable molecular assemblies in crystals. Findings from this work supply necessary information about the shape space of molecules that is transferable to the design of functional materials. In addition, given the unique molecular recognition profiles of the small organic compounds under study and the development of computer-aided discovery methods, the knowledge gained from these studies contributes to a more comprehensive understanding of the self-assembly process for broad classes of compounds. This project supports the training of a cohort of undergraduate and high school students through hands-on experiences in experimental and computer-assisted research at Whitworth University, a predominantly undergraduate institution. Outreach efforts also include support for a summer X-ray crystallography conference, where participants from across the country receive essential training for their ongoing teaching and research programs.Technical SummaryThis interdisciplinary project combines experimental solid-state organic chemistry and math topology to examine how near enantiomers assemble into energetically favorable crystalline assemblies. The research explores the structural boundaries of molecular shape to the molecular recognition process by using the quasiracemate approach for constructing bimolecular compounds. Chiral building blocks formulated from known organic precursors are prepared using benzoyl amino acid molecular scaffolds. Though the study of quasiracemic materials has now progressed to an established science, the intimate details of assembling pairs of quasienantiomers remain relatively unknown. This project explores how increasing crystal lattice stabilization via strong hydrogen bonds leads to materials with a greater structural variation of the quasienantiomeric components. The behavior of the target systems is expected to offer critical insight into molecular recognition profiles. Crystallographic, video-assisted thermomicroscopy, calorimetric, and lattice energy calculations are utilized to assess the ability of these materials to form quasiracemic materials. This study also develops in silico methods for determining the shape space differences and degree of inversion symmetry of pairs of quasienantiomeric components that will provide diagnostic tools for quasiracemate prediction.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.