Isotopic Perturbations in Aromatic Character and New Annulene Conformers

本项目将探讨环烯的构象和芳香性之间的相互作用。具体地说，环烯的sigma框架的形态会因内部质子被氘原子取代而受到干扰。发生的pi离域变化将由核磁共振波谱监测。测量氘化环烯和质子化环烯及其各自离子的相对环电流将有助于深入了解sigma和pi框架在芳族和反芳族特征方面的相对重要性。通过这个RUI奖，有机和大分子化学项目支持伊利诺伊州立大学Cheryl D. Stevenson教授的研究。史蒂文森教授的研究将探索一种被化学家称为芳香性的现象，芳香性不是指一种嗅觉特征，而是指一种情况，即由于其键合电子的特定排列，特定分子的稳定性比预期的要高。为了进行这项研究，将合成被称为环烯的大环状分子，并在分子内的特定位置加入氢的同位素。氢的同位素氘会根据它在成键电子中的位置以及是否满足芳香性的条件而表现出特定的行为。分子尺度的核磁共振将被用来探测氘原子。

This project will explore the interplay between conformation and aromaticity in annulenes. Specifically, the morphology of the sigma framework of annulenes will be perturbed via replacement of the internal protons with deuterium atoms. The changes in pi-delocalization that takes place will be monitored by NMR spectroscopy. Measurements of the relative ring currents in deuterated and protiated annulenes and their respective dianions will lead to insight into the relative importance of the sigma and pi frameworks in terms of aromatic and antiaromatic character.With this RUI Award, the Organic and Macromolecular Chemistry Program supports the research of Professor Cheryl D. Stevenson of Illinois State University. Professor Stevenson's research will explore a phenomenon known to chemists as aromaticity, referring not to an olfactory characteristic but to a circumstance whereby the stability of a particular molecule is greater than expected due to a specific arrangement of its bonding electrons. In order to carry out this study, large ring-like molecules known as annulenes will be synthesized and an isotope of hydrogen incorporated at specific locations within the molecule. This hydrogen isotope, deuterium, will display certain behavior depending upon its location among the bonding electrons as well as whether the conditions for aromaticity are met. A molecular-scale MRI known as NMR will be used to probe the deuterium atoms.