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

几十年来，核磁共振波谱对化合物，特别是手性化合物的构型和构象的测定主要是对J偶联和NOE的评价。90年代末，残留偶极耦合(RDC)等各向异性核磁共振参数开始被应用于生物分子的结构解析[1]，后来又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，对于他们的测量来说，防止分析物各向同性翻滚的各向异性环境是必要的。这可以通过拉伸的聚合物凝胶或通过溶致液晶(LLC)相来实现。[2]这些所谓的取向介质中的一些是以光学活性形式制备的，旨在对手性分析物的对映体区分取向(有时称为DOE：差序效应)，以最终确定它们的绝对构型。本课题组围绕这一课题在三个方面进行了初步研究：(I)开发氧化石墨烯液晶作为有机溶剂中通用的和可调的排列介质(由雷新祥和韩孙进行)；[3](Ii)开发聚乙炔和聚胍作为对映异向排列介质(由Michael Regglin进行)；[4](Iii)发展利用分子动力学模拟确定聚乙炔相绝对构型的方法(由HanSun和Michael Regglin进行)。所提出的比例将旨在将强烈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 mg！)通过一个长期成立的中德研究小组。这两个目标都可能通过将氧化石墨烯的良好性质与聚芳基乙炔提供的性质相结合来实现。为了达到最终目标，确定绝对构型，韩孙将凭借她在聚合物/分析物相互作用建模方面的专业知识做出贡献。

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.