title: Cethrene: A Helically Chiral Biradicaloid Isomer of Heptazethrene.
abstract: We report the synthesis and properties of "cethrene", the only helically chiral isomer of heptazethrene with a biradicaloid singlet ground state. Cethrene gives a well-resolved EPR spectrum at room temperature and its structure was confirmed by 2D NMR and absorption spectroscopies. Our experiments and calculations show that the helical twist affects its electronic properties and decreases the singlet-triplet energy gap when compared to that of planar heptazethrene. Cethrene undergoes an intramolecular cyclization within several hours at room temperature.
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Prince
authors.initials: P
authors.lastname: Ravat
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Šolomek
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Michel
authors.identifier: http://orcid.org/0000-0002-6107-2310
authors.initials: M
authors.lastname: Rickhaus
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Daniel
authors.initials: D
authors.lastname: Häussinger
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Neuburger
authors.affiliation: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Baumgarten
authors.affiliation: Department of Chemistry, University of Basel, St. Johanns-Ring 19, 4056, Basel, Switzerland. michal.juricek@unibas.ch.
authors.forename: Michal
authors.identifier: http://orcid.org/0000-0001-5595-431X
authors.initials: M
authors.lastname: Juríček
keywords: biradicaloids; cethrene; chirality; helical structures; zethrene