Synthesis and Late-Stage Functionalization of pH-Sensitive Quinacridine and Diazaoxatriangulene Fluorophores

After the isolation of a new class of highly stable cationic [4]helicenes and triangulenes in the early 2000s, the scientific community has driven many efforts for the development of effective preparation methods of this type of derivatives. In this context, a new family of pH-sensitive diaza[4]helicenes was synthesized in 2014 by using tetramethoxyacridinium as substrate and hydrazine as nucleophile. The work of this PhD has been focused on the use of such derivatives as common precursors for the synthesis of different helicene and triangulene based chromophores. For instance, the (chir)optical properties of quinacridines were enhanced after nitration or Vilsmeier-Haack formylation reactions, and further derivatization led to the formation of a BODIPY-like class of fluorophores. Furthermore, neutral quinacridines proved to be excellent substrates for Ru(II)- and Rh(II)-catalyzed regioselective C–H insertion reactions with 2-diazomalonates as carbene precursors. Finally, the behavior of pH-sensitive diazaoxatriangulenes as fluorescent probes was studied in HeLa cells.