In this thesis, a versatile toolbox of functionalized 5helicenes was developed and synthesized. Subsequently, they were employed as chiral tools in well-known research fields with the aim of investigating their applicability and their influence on the chemical and physical properties. Therefore, at first (Chapter 3) an adjustable route for the synthesis of 5helicene building blocks was optimized and its effectiveness was demonstrated by the synthesis of two dibromo-5helicenes as key precursors. Based on these molecules, a broad array of chiral tools was synthesized within a maximum of two subsequent synthetic steps. The helical compounds of our resulting toolbox combined enantiomeric stability and adjustable solubility with high functional compatibility. Their effectiveness and potential were underscored by application in four distinct projects. In the first project (Chapter 4), their performance as amplification tool of the chiroptical response within a multiple nhelicene framework was evaluated. Therefore, (M,M)-, (P,P)- and meso-Helical Diketones were synthesized, and their (chir)optical properties were investigated. Based on these HDks, a set of biradicaloid Helical Heptazethrenes was synthesized and the effect of their different conformation, namely enantiopure vs. meso-compound, on the chemical and physical properties was investigated (Chapter 5). A combination of kinetic stability studies, absorption and emission spectroscopy, EPR measurements, and detailed theoretical analysis provided a comprehensive view of their electronic behavior. In another project (Chapter 6), functionalized 5helicenes were combined with the aim to transfer the chirality of the individual subunits to the global structure and thus obtain an enhanced chiroptical response of nanometer-sized Helical Nanowires. In the last project of this work (Chapter 7), the influence of antiaromaticity on the magnetic transition dipole moment of the lowest energy transition was investigated.
Johannes Hennemann (2026) studied this question.