Scholl Reaction of Perylene‐Based Polyphenylene Precursors under Different Conditions: Formation of Hexagon or Octagon?. Issue 32 (24th June 2021)

• Record Type: Journal Article
• Authors: Zou, Ya; Han, Yi; Wu, Shaofei; Hou, Xudong; Chow, Chi Hao Eugene; Wu, Jishan
• Is Part Of: Angewandte Chemie international edition. Volume 60:Issue 32(2021)
• Page Start: 17654
• Page End: 17663
• Publication Date: 2021-06-24
• Subjects: arenium ions -- perylene -- polycyclic aromatic hydrocarbon -- radical cations -- Scholl reaction; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202105427
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: A planar dibenzo‐peri‐hexacene derivative (2 ) was synthesized via FeCl3 ‐mediated Scholl reaction from a cyclopenta‐fused perylene (CP) based polyphenylene precursor (1 ). However, an unexpected octagon‐containing, negatively curved molecule (3 ) was obtained in nearly quantitative yield when 2, 3‐dichloro‐5, 6‐dicyano‐1, 4‐benzoquinone (DDQ) and methanesulfonic acid (MeSO3 H) were used. Similar results were observed when two smaller‐sized precursors containing one (4 ) or two CP units (5 ) were tested. X‐ray crystallographic analysis also revealed that there is no close π–π stacking between neighboring π‐conjugated skeletons. DFT calculations suggest a radical cation mechanism in the presence of FeCl3 while an arenium ion pathway for the DDQ/MeSO3 H mediated Scholl reaction, which can well explain the selective formation of hexagons and octagons under different conditions. The obtained compounds showed tunable optical and electrochemical properties. Abstract : We demonstrate that Scholl reaction of a bis‐perylene precursor gave either a planar polycyclic aromatic hydrocarbon (PAH) or a negatively curved PAH embedded with octagons, which can be explained by a radical cation or an arenium ion mechanism under different reaction conditions. The formed molecules show non‐aggregative features and exhibit high photoluminescence quantum yields.