title: Isolable zwitterionic pyridinio-semiquinone pi-radicals. Mild and efficient single-step access to stable radicals.
abstract: A rational design based on the proton-coupled electron transfer (PCET) concept allows us to structurally characterize for the first time isolable, air- and moisture-stable semiquinone radicals in a zwitterionic neutral form. The presence of an alkoxy and the bulky pyridinio substituents causes only a minor perturbation of either the redox potentials or the spectral UV-vis characteristics of the semiquinone core but significantly stabilizes the new radicals.
authors.affiliation: Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
authors.forename: Chenyi
authors.initials: C
authors.lastname: Yi
authors.forename: Carmen
authors.initials: C
authors.lastname: Blum
authors.forename: Shi-Xia
authors.initials: SX
authors.lastname: Liu
authors.forename: Tony D
authors.initials: TD
authors.lastname: Keene
authors.forename: Gabriela
authors.initials: G
authors.lastname: Frei
authors.forename: Antonia
authors.initials: A
authors.lastname: Neels
authors.forename: Silvio
authors.initials: S
authors.lastname: Decurtins
mesh_terms: D016227:Benzoquinones / Q000138:chemical synthesis* / Q000737:chemistry / Q000145:classification*; D018360:Crystallography, X-Ray; D008968:Molecular Conformation; D015394:Molecular Structure; D010084:Oxidation-Reduction; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet
chemical_list: D016227:Benzoquinones; D011725:Pyridines; C025232:semiquinone radicals