title: Diindeno-fusion of an anthracene as a design strategy for stable organic biradicals.
abstract: The consequence of unpaired electrons in organic molecules has fascinated and confounded chemists for over a century. The study of open-shell molecules has been rekindled in recent years as new synthetic methods, improved spectroscopic techniques and powerful computational tools have been brought to bear on this field. Nonetheless, it is the intrinsic instability of the biradical species that limits the practicality of this research. Here we report the synthesis and characterization of a molecule based on the diindeno[b,i]anthracene framework that exhibits pronounced open-shell character yet possesses remarkable stability. The synthetic route is rapid, efficient and possible on the gram scale. The molecular structure was confirmed through single-crystal X-ray diffraction. From variable-temperature Raman spectroscopy and magnetic susceptibility measurements a thermally accessible triplet excited state was found. Organic field-effect transistor device data show an ambipolar performance with balanced electron and hole mobilities. Our results demonstrate the rational design and synthesis of an air- and temperature-stable biradical compound.
authors.affiliation: Department of Chemistry &Biochemistry and the Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1253, USA.
authors.forename: Gabriel E
authors.initials: GE
authors.lastname: Rudebusch
authors.affiliation: Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071 Malaga, Spain.
authors.forename: José L
authors.initials: JL
authors.lastname: Zafra
authors.affiliation: Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala 751 23, Sweden.
authors.forename: Kjell
authors.initials: K
authors.lastname: Jorner
authors.affiliation: Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Kotaro
authors.initials: K
authors.lastname: Fukuda
authors.affiliation: Department of Chemistry &Biochemistry and the Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1253, USA.
authors.forename: Jonathan L
authors.initials: JL
authors.lastname: Marshall
authors.affiliation: Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071 Malaga, Spain.
authors.forename: Iratxe
authors.initials: I
authors.lastname: Arrechea-Marcos
authors.affiliation: Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071 Malaga, Spain.
authors.forename: Guzmán L
authors.initials: GL
authors.lastname: Espejo
authors.affiliation: Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071 Malaga, Spain.
authors.forename: Rocío
authors.initials: R
authors.lastname: Ponce Ortiz
authors.affiliation: Instituto de Ciencia Molecular, Universidad de Valencia, 46980 Paterna, Valencia, Spain.
authors.forename: Carlos J
authors.initials: CJ
authors.lastname: Gómez-García
authors.affiliation: CAMCOR, University of Oregon, Eugene, Oregon 97403-1433, USA.
authors.forename: Lev N
authors.initials: LN
authors.lastname: Zakharov
authors.affiliation: Department of Materials Engineering Science, Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Nakano
authors.affiliation: Department of Chemistry - BMC, Uppsala University, Box 576, Uppsala 751 23, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Ottosson
authors.affiliation: Department of Physical Chemistry, University of Malaga, Campus de Teatinos s/n, 229071 Malaga, Spain.
authors.forename: Juan
authors.initials: J
authors.lastname: Casado
authors.affiliation: Department of Chemistry &Biochemistry and the Materials Science Institute, University of Oregon, Eugene, Oregon 97403-1253, USA.
authors.forename: Michael M
authors.initials: MM
authors.lastname: Haley
mesh_terms: D000873:Anthracenes / Q000138:chemical synthesis* / Q000737:chemistry*; D002625:Chemistry, Organic; D018360:Crystallography, X-Ray; D004583:Electrons; D005609:Free Radicals / Q000737:chemistry*; D008280:Magnetics; D008958:Models, Molecular; D015394:Molecular Structure; D013696:Temperature
chemical_list: D000873:Anthracenes; D005609:Free Radicals; C034020:anthracene