RUI:Targeted Structural Diversity and Assessments in Quasiracemates

点击翻译按钮获取中文摘要

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.