Synthesis and Characterization of Electron-Deficient Perfluorinated Tetrathia[8]Circulene via Sequential Coupling Reactions.

Abstract

Tetrathia[8]circulene is a heteroaromatic framework consisting of an eight-membered ring fused with four thiophene and four benzene units, whose electronic properties are highly tunable by peripheral substituents. Herein, we report the synthesis of a perfluorinated tetrathia[8]circulene bearing hexafluorocyclopentene rings via sequential Suzuki-Miyaura and C─H/C─Cl coupling reactions. Single-crystal X-ray diffraction analysis revealed a highly planar π-conjugated core with dense F···F contacts, leading to a two-dimensional layered and one-dimensional columnar packing structure. UV-vis absorption spectroscopy and cyclic voltammetry demonstrated that the electron-withdrawing hexafluorocyclopentene units substantially lower the LUMO energy level, resulting in a reduced HOMO-LUMO gap and enhanced electron-accepting character. Density functional theory calculations further supported these findings by correlating the perfluoroalkyl annulation with frontier orbital stabilization and excited-state properties.