Heteroatom‐Doping Engineering of Fused Olympic Cations: Metal‐Free Modular Syntheses and NIR‐II Radicals with Mixed Aromatic/Antiaromatic Characters

Abstract

AbstractHeteroatom‐doping polycyclic aromatic hydrocarbons have attracted immense attention owing to their fascinating optoelectrical properties. However, precise heteroatom‐doping engineering and fabricating charged polycyclic aromatic scaffolds remain challenging and far from satisfactory. Herein, a new family of nitrogen and sulfur/oxygen dual‐doping fused Olympic heterocyclic cations (FPT/FPOs) are modularly synthesized employing an efficient and convenient metal‐free protocol. Tunable optical and redox properties can be achieved by rational structural editing. Compared with their half‐fused counterparts, FPTs and FPOs hold higher redox stability and can undergo single‐electron reduction to form delocalized neutral radicals, exhibiting NIR‐II absorptions around 1300–1400 nm and unexpected mixed aromatic/antiaromatic characters. It is anticipated that this line of research provides a new approach for heteroatom‐doping engineering and constructing novel charged π‐molecules, with deeper insights into their redox‐amphoteric features and aromaticity manipulation.