Tailor-Made helicity in polyaromatic systems

Abstract

This thesis was, and still is, the translation of a conceptual idea that took root years before its realization. As with many ideas that eventually get transcribed into actual molecular systems, it needed two things: a molecular design –and a name. For both existed a myriad of possibilities. But how to find a working title that reflects the topological beauty and simple elegance of the molecule? And how to address the general, underlying concept of a ladder with mismatched rails as an organic synthetic chemist? Eventually both were found: a molecular design involving six interlinked phenyl rings. And a name. Evelyne. The thesis is grouped around that concept chronologically, starting with the initial conceptual publication in Angewandte Chemie and the detailed synthetic aspects in the European Journal of Organic Chemistry. Besides the resolution of the synthetic maze, the structure as obtained by X-Ray diffraction analysis as well as the dynamic behavior is described therein. The ensuing publication from Chemistry – A European Journal expands on the concept, finding ways to fine-tune the shape of the helical structures by targeted changes in the structure. In a way, describing Evelyn’s daughters. Schwefelyn. And Selenyn. The supplementary information provided in the manuscripts have been added for the reader’s convenience at the very end, also chronologically ordered. Preceding these three manuscripts, the reader will find a review entitled “Strain Induced Helical Chirality in Polyaromatic Systems” which has been published in Chemical Society Reviews. This tutorial article explains the rise of helical shapes due to steric interactions with carefully selected examples. It gives a clear systematic overview over the different concepts used to induce helical chirality in small organic molecules – including the one realized in this thesis. It connects the thesis’ topic with the wider world of polyaromatic systems that become chiral due to steric interactions. The last publication included arises from a wonderful collaboration with the group of Prof. Dr. Willem Klopper at the Karlsruhe Institute of Technology, Germany. The excellent theoretical work by Angela Bihlmeier and experimental work by Jurgen Rotzler on the atropisomerizaion of alkyl bridged biphenyls was complemented by kinetic circular dichroism studies.