The integration of the indoloindolizine framework into polycyclic systems significantly influences the reactivity of these compounds. The most remarkable attribute observed, particularly when compared with acenes, is the enhanced stability against photooxidation. The majority of the compounds we investigated exhibited notable resilience, remaining stable in solution under exposure to sunlight and air for days. In a controlled experiment, where solutions of these compounds were aerated and subjected to 254 nm UV light irradiation, the indoloindolizines demonstrated stability that surpassed traditional organic electronic benchmarks -such as tetracene and rubrene -by at least an order of magnitude (Section ). This shows the potential of indoloindolizine-based materials in extending the durability and performance of organic electronic devices. Furthermore, the indole-type nature of indoloindolizines is manifested in their reactivity. In electrophilic substitution, I6 reacts exclusively at the pyrrole C-H position (position 9 of indoloindolizine moiety, Figure ). Such high regioselectivity of these reactions can also be explained by aromatic stabilization energy where the positive charge localizes in the transition state on the ring that is already less aromatic, which in this case is the pyrrole ring. This again is backed by the Glidewell-Lloyd rules. Hence, compound I6 gave the corresponding aldehyde I6a under Vilsmeier-Haack reaction conditions. Additionally, I6 undergoes bromination with N-bromosuccinimide, producing the C9-brominated indoloindolizine I6b with a high yield. Expanding the scope of our reactivity investigation, I6 was also subjected to an azo coupling reaction with 4-bromophenyldiazonium salt, affording the cis-azo-indoloindolizine I6c. Interestingly, I6c does not switch under light irradiation, presumably because of the large steric hindrance imposed by the adjacent TIPS-acetylene group. Furthermore, we expanded the synthetic scope of this new class of compounds by attaching TMS-acetylene to I8b under Sonogashira cross-coupling conditions giving I8e, which shows that I8b can readily be functionalized at this position with a broad range of substituents via cross-coupling chemistry.