Highly Twisted 1,2:8,9-Dibenzozethrenes: Synthesis, Ground State, and Physical Properties

• Published in: ChemPlusChem (Weinheim, Germany) Vol. 79; no. 11; pp. 1549 - 1553
• Main Authors: Sun, Zhe, Zheng, Bin, Hu, Pan, Huang, Kuo-Wei, Wu, Jishan
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 01.11.2014; WILEY‐VCH Verlag; Wiley
• Subjects: amphoteric redox behavior; biradical; Chemistry; Chemistry, Multidisciplinary; cyclodimerization; density functional calculations; Physical Sciences; polycycles; Science & Technology; density functional calculations; ZETHRENE; POLYCYCLIC AROMATIC-HYDROCARBONS; cyclodimerization; amphoteric redox behavior; PHOTOPHYSICAL PROPERTIES; INDEX; OPEN-SHELL; biradical; polycycles
• ISSN: 2192-6506; 2192-6506
• DOI: 10.1002/cplu.201402127

Two soluble and stable 1,2:8,9‐dibenzozethrene derivatives (3 a,b) are synthesized through a palladium‐catalyzed cyclodimerization reaction. X‐ray crystallographic analysis shows that these molecules are highly twisted owing to congestion at the cove region. Broken‐symmetry DFT calculations predict that they have a singlet biradical ground state with a smaller biradical character and a large singlet–triplet energy gap; these predictions are supported by NMR and electronic absorption measurements. They have small energy gaps and exhibit far‐red/near‐infrared absorption/emission and amphoteric redox behaviors. Twisted zethrene! Highly twisted 1,2:8,9‐dibenzozethrenes are synthesized and isolated in crystalline form (see figure). They are found to have a small biradical character with a small energy gap, showing NIR emission and amphoteric redox behavior.