Chemistry of open-shell π-extended azacorannulenes

Abstract

Open-shell aromatic molecules have garnered attention due to their applications in various fields. Designing such molecules by incorporating non-hexagonal structures or hetero atoms into the π-surface of aromatic molecules is an effective approach. This thesis investigates multiple analogs of open-shell aromatic molecules based on the azacorannulene skeleton. Chapter 1 provides a general introduction to the development of carbon-centered radical chemistry from the perspective of fragment molecules of carbon-defective graphene, highlighting the significance of organic open-shell molecules. Chapter 2 discusses the synthesis and properties of monoradical molecules, modified by incorporating one carbon into azapentabenzocorannulene, and the isolation of a single crystal of the rare tropyl radical form. Chapter 3 presents open-shell molecules with two sp2 carbons added to azacorannulene, featuring a small singlet-triplet gap and a singlet ground state. Chapter 4 details the synthesis of diazapentabenzocorannulenium cation, which incorporates another nitrogen atom in the central pyrrole ring of the corannulene structure and serves as a potential precursor to diazapentabenzocorannulene radical. This cation molecule itself exhibits high affinity for water despite its large π-surface. These carbon-defective modifications enable the design of functional open-shell molecules. Chapter 5 describes the conclusion and perspective of this research.