Radically enhanced molecular recognition

Ali Trabolsi, Niveen M. Khashab, Albert C. Fahrenbach, Douglas C. Friedman, Michael T. Colvin, Karla K. Coti, Diego S. Benítez, Ekaterina Tkatchouk, John Carl Olsen, Matthew E. Belowich, Raanan Carmieli, Hussam Khatib, William Andrew III Goddard, Michael R. Wasielewski, Fraser Fraser Raser Stoddart

Research output: Contribution to journalArticlepeer-review

247 Scopus citations


The tendency for viologen radical cations to dimerize has been harnessed to establish a recognition motif based on their ability to form extremely strong inclusion complexes with cyclobis(paraquat-p-phenylene) in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chemistry, extending its practice beyond the traditional reliance on neutral and charged guests and hosts. In particular, transporting the concept of radical dimerization into the field of mechanically interlocked molecules introduces a higher level of control within molecular switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochemical potentials. In a tristable [2]rotaxane composed of a cyclobis(paraquat-p-phenylene) ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidation, it moves from the tetrathiafulvalene to the dioxynaphthalene, and on reduction, to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication. © 2010 Macmillan Publishers Limited. All rights reserved.
Original languageEnglish (US)
Pages (from-to)42-49
Number of pages8
JournalNature Chemistry
Issue number1
StatePublished - Dec 17 2009

Bibliographical note

KAUST Repository Item: Exported on 2020-10-01

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Chemistry(all)


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