Synthesis and Photophysical Properties of a Water‐Soluble Tetrabenzotetraaza[8]Circulene Derivative With Long Lifetime Phosphorescence

ABSTRACT [8]Circulenes, a class of intriguing polycyclic aromatic hydrocarbons, have garnered considerable attention due to their aesthetically pleasing structures. Despite their unique structural features, the applications of these rigid π‐conjugated systems remain far from fully explored due to the inherent challenges in functionalizing them. In this study, we report the synthesis of a water‐soluble tetrabenzotetraaza[8]circulene derivative ( 3 ) through the introduction of four 2,5,8,11‐tetraoxatridecane substituents. The optical properties of 3 were systematically studied in THF/water mixtures, revealing its water‐fraction‐dependent fluorescence. At 77 K, compound 3 exhibits distinctive phosphorescence with an exceptionally long lifetime of 2.08 s and a phosphorescence quantum yield of 12.3%, both among the highest values of reported hetero[8]circulenes. Additionally, 3 displays a pronounced yellow‐green afterglow luminescence that persists for 7.6 s, underscoring its potential for persistent emission applications. This study presents an effective method to modulate the optoelectronic properties of hetero[8]circulene derivatives, offering new opportunities for hetero[8]circulenes as promising functional materials.