title: Octazethrene and Its Isomer with Different Diradical Characters and Chemical Reactivity: The Role of the Bridge Structure.
abstract: The fundamental relationship between structure and diradical character is important for the development of open-shell diradicaloid-based materials. In this work, we synthesized two structural isomers bearing a 2,6-naphthoquinodimethane or a 1,5-naphthoquinodimethane bridge and demonstrated that their diradical characters and chemical reactivity are quite different. The mesityl-or pentafluorophenyl-substituted octazethrene derivatives OZ-M/OZ-F and their isomer OZI-M (with mesityl substituents) were synthesized via an intramolecular Friedel-Crafts alkylation followed by oxidative dehydrogenation strategy from the key building blocks 4 and 11. Our detailed experimental and theoretical studies showed that both isomers have an open-shell singlet ground state with a remarkable diradical character (y0 = 0.35 and 0.34 for OZ-M and OZ-F, and y0 = 0.58 for OZI-M). Compounds OZ-M and OZ-F have good stability in an ambient environment, while OZI-M has high reactivity and can be easily oxidized to a dioxo product 15, which can be correlated to their different diradical characters. Additionally, we investigated the physical properties of OZ-M, OZ-F, and 15.
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, 117543 Singapore.
authors.forename: Pan
authors.initials: P
authors.lastname: Hu
authors.affiliation: Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 120-749, Korea.
authors.forename: Sangsu
authors.initials: S
authors.lastname: Lee
authors.affiliation: Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 120-749, Korea.
authors.forename: Kyu Hyung
authors.initials: KH
authors.lastname: Park
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, 117543 Singapore.
authors.forename: Soumyajit
authors.initials: S
authors.lastname: Das
authors.affiliation: Department of Materials Science & Engineering, National University of Singapore , 119260 Singapore.
authors.forename: Tun Seng
authors.initials: TS
authors.lastname: Herng
authors.affiliation: Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Théo P
authors.initials: TP
authors.lastname: Gonçalves
authors.affiliation: Division of Physical Science and Engineering and KAUST Catalysis Center, King Abdullah University of Science and Technology (KAUST) , Thuwal 23955-6900, Kingdom of Saudi Arabia.
authors.forename: Kuo-Wei
authors.initials: KW
authors.lastname: Huang
authors.affiliation: Department of Materials Science & Engineering, National University of Singapore , 119260 Singapore.
authors.forename: Jun
authors.initials: J
authors.lastname: Ding
authors.affiliation: Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University , Seoul 120-749, Korea.
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
authors.affiliation: Department of Chemistry, National University of Singapore , 3 Science Drive 3, 117543 Singapore.
authors.forename: Jishan
authors.initials: J
authors.lastname: Wu