Sulfur‐Doped Heptagon Embedded Polycyclic Aromatic Hydrocarbons as Non‐Benzenoid Derivatives of Pentacene

Abstract

ABSTRACT Incorporating heteroatoms and non‐benzenoid rings—such as pentagons or heptagons—into polycyclic aromatic frameworks represents a key approach for designing advanced optoelectronic materials. In this work, two novel pentacene derivatives, DSH‐1 and DSH‐2, were synthesized by embedding sulfur‐doped heptagons into the conjugation backbone via efficient Ullmann coupling and acid‐catalyzed Friedel–Crafts reactions as the key steps. Single‐crystal analysis shows that DSH‐1 adopts a curved bow‐shaped structure, integrating an oxygen‐doped pentagon and two sulfur‐doped heptagons to form a unique 7‐5‐7 system. In contrast, DSH‐2 features a 7‐6‐7 system and displays a Z‐shaped conformation. Because of their difference in conformation, DSH‐1 exhibits a significantly red‐shifted absorption, superior thermal stability, and tighter intermolecular interactions, and shows p‐type semiconducting property with charge mobility of 0.25 cm 2 V −1 s −1 . Because of the nonplanar configuration of these two molecules, the sulfur atoms can act as anchoring groups in the single‐molecule conductance characterization. In addition, DSH‐1 can be oxidized to a radical cation DSH‐1 •+ with red‐shifted absorption around 650 nm and high stability, resulting from the enhanced aromaticity of the sulfur‐doped heptagon rings after oxidation.