Comprehensive models of non-covalent aromatic interactions

分子间微弱的吸引力决定了物质的许多性质。例子包括熔化温度、加热时的膨胀程度、硬度和抗断裂性。南卡罗来纳大学的Ken D. Shimizu教授致力于开发精确测量和预测分子间吸引力的方法。该项目为研究生和本科生提供研究培训，特别是通过与女子学院的教员及其学生合作。该项目还支持开发一个教育网站，旨在通过基于问题的方法教授本科生有机化学。该项目由大分子、超分子和纳米化学项目支持，目标是开发能够准确预测芳香表面非共价相互作用能的模型，如堆叠、边对面和CH-pi相互作用。这个项目的创新之处在于使用专门设计的分子来测量这些相互作用。“分子平衡”的多功能性使研究更广泛的分子表面和环境以及直接比较它们的吸引力或排斥力成为可能。首先，利用“分子平衡”收集实验测量的相互作用的庞大数据库。“平衡”在分子内芳香族相互作用形成和破坏的两种构象状态之间翻转。因此，构象比提供了这些弱相互作用的敏感和准确的测量。其次，评估了芳香相互作用中各个贡献力的重要性和大小。特别令人感兴趣的是分散和疏溶剂项，因为它们在溶液中的作用尚不清楚。最后，采用多元方法，使用多个分子和溶剂描述符来开发更准确的预测模型，并评估贡献力的相对强度。

The weak attractive forces between molecules determine many properties of matter. Examples include melting temperature, degree of expansion upon heating, hardness, and resistance to breaking. Prof. Ken D. Shimizu of the University of South Carolina aims to develop methods to accurately measure and predict these attractive forces between molecules. This project provides research training for graduate and undergraduate students, in particular via collaboration with a faculty member at a women's college and her students. The project also supports the development of an educational website targeted at teaching undergraduate students organic chemistry via a problem based approach. The goal of this project supported by the Macromolecular, Supramolecular and Nanochemistry Program is to develop models that can accurately predict the non-covalent interaction energies of aromatic surfaces such as stacking, edge-to-face, and CH-pi interactions. An innovative aspect of this project is the use of specifically designed molecules to measure these interactions. The versatility of the 'molecular balances' enables the study of a broader range of molecular surfaces and environments and the direct comparison of their attractive or repulsive forces. First, an expansive database of experimentally measured interactions is collected using a 'molecular balance'. The 'balance' flips between two conformational states in which an intramolecular aromatic interaction is formed and broken. Thus, the conformational ratio provides a sensitive and accurate measure of these weak interactions. Second, the importance and magnitude of individual contributing forces to the aromatic interactions is evaluated. Of particular interest are the dispersion and solvophobic terms as their role in solution is still unclear. Finally, a multivariate approach is employed using multiple molecular and solvent descriptors to develop a more accurate predictive model and also to assess the relative strengths of the contributing forces.