Mechanical bonds and topological effects in radical dimer stabilization

Marco Frasconi, Takashi Kikuchi, Dennis Cao, Yilei Wu, Wei Guang Liu, Scott M. Dyar, Gokhan Barin, Amy A. Sarjeant, Charlotte L. Stern, Raanan Carmieli, Cheng Wang, Michael R. Wasielewski, William A. Goddard, J. Fraser Stoddart

Research output: Contribution to journalArticlepeer-review

40 Scopus citations


While mechanical bonding stabilizes tetrathiafulvalene (TTF) radical dimers, the question arises: what role does topology play in catenanes containing TTF units? Here, we report how topology, together with mechanical bonding, in isomeric [3]- and doubly interlocked [2]catenanes controls the formation of TTF radical dimers within their structural frameworks, including a ring-in-ring complex (formed between an organoplatinum square and a {2+2} macrocyclic polyether containing two 1,5-dioxynaphthalene (DNP) and two TTF units) that is topologically isomeric with the doubly interlocked [2]catenane. The separate TTF units in the two {1+1} macrocycles (each containing also one DNP unit) of the isomeric [3]catenane exhibit slightly different redox properties compared with those in the {2+2} macrocycle present in the [2]catenane, while comparison with its topological isomer reveals substantially different redox behavior. Although the stabilities of the mixed-valence (TTF2)•+ dimers are similar in the two catenanes, the radical cationic (TTF•+)2 dimer in the [2]catenane occurs only fleetingly compared with its prominent existence in the [3]catenane, while both dimers are absent altogether in the ring-in-ring complex. The electrochemical behavior of these three radically configurable isomers demonstrates that a fundamental relationship exists between topology and redox properties.

Original languageEnglish (US)
Pages (from-to)11011-11026
Number of pages16
JournalJournal of the American Chemical Society
Issue number31
StatePublished - Aug 6 2014


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