A Radically Configurable Six-State Compound

• Published in: Science (American Association for the Advancement of Science) Vol. 339; no. 6118; pp. 429 - 433
• Main Authors: Barnes, Jonathan C., Fahrenbach, Albert C., Cao, Dennis, Dyar, Scott M., Frasconi, Marco, Giesener, Marc A., Benítez, Diego, Tkatchouk, Ekaterina, Chernyashevskyy, Oleksandr, Shin, Weon Ho, Li, Hao, Sampath, Srinivasan, Stern, Charlotte L., Sarjeant, Amy A., Hartlieb, Karel J., Liu, Zhichang, Carmieli, Raanan, Botros, Youssry Y., Choi, Jang Wook, Slawin, Alexandra M. Z., Ketterson, John B., Wasielewski, Michael R., Goddard, William A., Stoddart, J. Fraser
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for the Advancement of Science 25.01.2013; The American Association for the Advancement of Science
• Subjects: Atomic and molecular physics; Chemical reactions; Configurable; Crystallography; Crystals; Depersonalization; Dimers; Electrolysis; Electron resonance and relaxation; Electrons; Exact sciences and technology; Fragmentation; Free radicals; Manganese; Molecular properties and interactions with photons; NMR; Nuclear magnetic resonance; Organic Chemistry; Organic compounds; Oxidation; Physics; Protons; Rings (mathematics); Signals; Spectroscopy; Spectrum analysis; Topology; Valence; Vapor phases; Electronic structure; Frontier orbital; Organic free radical; Inclusion compounds; Theoretical study; Density functional method; Dimerization; EPR spectra; Pi electron system
• ISSN: 0036-8075; 1095-9203
• DOI: 10.1126/science.1228429

Most organic radicals possess short lifetimes and quickly undergo dimerization or oxidation. Here, we report on the synthesis by radical templation of a class of air- and water-stable organic radicals, trapped within a homo[2]catenane composed of two rigid and fixed cyclobis (paraquat-p-phenylene) rings. The highly energetic octacationic homo[2]catenane, which is capable of accepting up to eight electrons, can be configured reversibly, both chemically and electrochemically, between each one of six experimentally accessible redox states (0, 2+, 4+, 6+, 7+, and 8+) from within the total of nine states evaluated by quantum mechanical methods. All six of the observable redox states have been identified by electrochemical techniques, three (4+, 6+, and 7+) have been characterized by x-ray crystallography, four (4+, 6+, 7+, and 8+) by electron paramagnetic resonance spectroscopy, one (7+) by superconducting quantum interference device magnetometry, and one (8+) by nuclear magnetic resonance spectroscopy.