10.1021/ol900559p.s001 Chenyi Yi Chenyi Yi Carmen Blum Carmen Blum Shi-Xia Liu Shi-Xia Liu Tony D. Keene Tony D. Keene Gabriela Frei Gabriela Frei Antonia Neels Antonia Neels Silvio Decurtins Silvio Decurtins Isolable Zwitterionic Pyridinio-semiquinone π-Radicals. Mild and Efficient Single-Step Access to Stable Radicals American Chemical Society 2009 concept PCET Zwitterionic Efficient radical characteristic Access Isolable time isolable perturbation semiquinone core zwitterionic transfer presence pyridinio substituents causes electron Stable Radicals redox potentials UV alkoxy Mild 2009-06-04 00:00:00 Dataset https://acs.figshare.com/articles/dataset/Isolable_Zwitterionic_Pyridinio_semiquinone_Radicals_Mild_and_Efficient_Single_Step_Access_to_Stable_Radicals/2852575 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.