In 2016, as a basis of this PhD dissertation, our group published a study reporting the late-stage regioselective functionalization of dimethoxyquinacridinium (DMQA). In that report, many functional groups were introduced on the DMQA scaffold and the resulting (chir)optical properties of newly prepared compounds were studied. Yet, access to some desired derivatives remained elusive. Via two herein, synthetic strategies (Seyferth-Gilbert homologation and Sandmeyer reaction) applied on derivatives of cationic diaza [4]helicenes, two new key DMQA derivatives; iodo and ethynyl were prepared . With these molecules in hand, new routes to further post-functionalization were now reachable. This PhD. has mainly focused on their use as common precursors in synthesis of various series of [4]helicene compounds (partially also on functionalized triangulenes) and on follow-up investigations of their structural, electronic and (chir)optical properties.