Radically Enhanced Molecular Recognition

by Trabolsi, A., Khashab, N., Fahrenbach, A. C., Friedman, D. C., Colvin, M. T., Coti, K. K., Benitez, D., Tkatchouk, E., Olsen, J.-C., Belowich, M. E., Carmielli, R., Khatib, H. A., Goddard, W. A., III, Wasielewski, M. R., Stoddart, J. F.
Year: 2010


Trabolsi, A.; Khashab, N.; Fahrenbach, A. C.; Friedman, D. C.; Colvin, M. T.; Coti, K. K.; Benitez, D.; Tkatchouk, E.; Olsen, J.-C.; Belowich, M. E.; Carmielli, R.; Khatib, H. A.; Goddard, W. A., III; Wasielewski, M. R.; Stoddart, J. F. Radically Enhanced Molecular Recognition. Nat. Chem. 2010, 2, 42-49


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 in its diradical dicationic redox state. This previously unreported complex involving three bipyridinium cation radicals increases the versatility of host-guest chem., 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 mech. interlocked mols. introduces a higher level of control within mol. switches and machines. Herein, we report that bistable and tristable [2]rotaxanes can be switched by altering electrochem. potentials. In a tristable [2]rotaxane composed of a ring and a dumbbell with tetrathiafulvalene, dioxynaphthalene and bipyridinium recognition sites, the position of the ring can be switched. On oxidn., it moves from the tetrathiafulvalene to the dioxynaphthalene, and on redn., to the bipyridinium radical cation, provided the ring is also reduced simultaneously to the diradical dication.


Radically Molecular Recognition