New Chiral Alignment Media based on Helically Chiral Synthetic Polymers and Graphene Oxides and Applications to Stereochemistry Elucidation

几十年来，一般化合物，特别是手性化合物的构型和构象的核磁共振光谱测定主要是对j偶联和noe的评价。90年代末，残余偶极偶联（rdc）等各向异性核磁共振参数开始应用于生物分子[1]的结构解析，后来被用于有机结构的测定。rdc是非常强大的全局参数，因为它们包含角度和距离信息而不需要参数化。然而，对于他们的测量，各向异性的环境，防止分析物从各向同性翻滚，是必要的。这可以通过拉伸聚合物凝胶或溶致液晶（LLC）相来实现其中一些所谓的对准介质已被制备成光学活性形式，目的是对手性分析物的对映体区分取向（有时称为DOE：微分顺序效应），最终确定它们的绝对构型。本课组围绕这一课题进行了三个方面的初步研究：(i)开发氧化石墨烯液晶作为有机溶剂中通用和可调谐的定向介质（由雷鑫祥和孙涵主持）；[3] （ii）开发聚乙炔和多胍作为对映体分化对准介质（由Michael Reggelin主持）；[4] （iii）利用MD模拟方法发展了聚乙炔相的绝对构型测定（由Han Sun和Michael Reggelin进行）。提出的建议旨在通过一个长期建立的中德研究小组，将强大的对映体区分效应转移到其他定向系统，并最大限度地减少每次测量所需的聚合物量（约120毫克！）。通过将氧化石墨烯的优良性能与聚芳基乙炔的优良性能结合起来，这两个目标都有可能实现。为了达到最终目标，确定绝对构型，孙涵将在聚合物/分析物相互作用建模方面贡献她的专业知识。

For many decades, the NMR-spectroscopic determination of the configuration and conformation of compounds in general and chiral compounds in particular was dominated by the evaluation of J-couplings and NOEs. At the end of the 90s, anisotropic NMR-parameters such as residual dipolar couplings (RDCs) started to being applied for struc-ture elucidation of biomolecules[1] and were later adopted in organic structure determination. RDCs are very powerful global parameters because they contain angular and distance information without the need for parametrization. How-ever, for their measurement an anisotropic environment preventing the analyte from tumbling isotropically, is neces-sary. This can be achieved either by stretched polymer gels or by lyotropic liquid crystalline (LLC) phases.[2] Some of these so called alignment media have been prepared in optically active form aiming at enantiomer differentiating orientation (sometimes called DOE: differential order effect) of chiral analytes to finally determine their absolute configuration. Preliminary studies around this topic have been conducted on three aspects in our groups: (i) develop-ment of graphene oxide liquid crystals as versatile and tunable alignment media in organic solvents (Conducted by Xinxiang Lei and Han Sun);[3] (ii) development of polyacetylenes and polyguanidines as enantiodifferentiating align-ment media (Conducted by Michael Reggelin);[4] (iii) methods development of absolute configurational determination in polyacetylene phases using MD simulations (Conducted by Han Sun and Michael Reggelin). The presented pro-posal will aim at transfering the strong enantiomer differentiating effect to other orienting systems and minimizing the amount of polymer needed per measurement (ca. 120 mg!) through a long-term established Sino-German research group. Both goals may possibly be attained by combining the favorable properties of graphene oxide with the ones offered by the polyarylacetylenes. To reach the final goal, the determination of absolute configurations, Han Sun will contribute with her expertise in modeling the polymer/analytes interactions.