Isotopic Perturbations in Aromatic Character and New Annulene Conformers

本计画将探讨轮烯的构象与芳香性之间的相互影响。 具体地，轮烯的σ框架的形态将通过用氘原子替换内部质子而被扰动。 将通过NMR光谱监测发生的π-离域的变化。 测量氘代和质子化轮烯及其各自的二价阴离子的相对环电流将有助于深入了解sigma和pi框架在芳香族和反芳香族特征方面的相对重要性。史蒂文森，伊利诺伊州州立大学。 史蒂文森教授的研究将探索化学家称为芳香性的现象，指的不是嗅觉特征，而是由于其键合电子的特定排列，特定分子的稳定性大于预期的情况。 为了进行这项研究，将合成称为轮烯的大型环状分子，并在分子内的特定位置掺入氢的同位素。 这种氢同位素氘，将根据其在成键电子中的位置以及是否满足芳香性的条件而显示出某些行为。 一种被称为NMR的分子级MRI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.