TY - JOUR
T1 - Acid-base controllable molecular shuttles
AU - Ashton, Peter R.
AU - Ballardini, Roberto
AU - Balzani, Vincenzo
AU - Baxter, Ian
AU - Credi, Alberto
AU - Fyfe, Matthew C T
AU - Gandolfi, Maria Teresa
AU - Gómez-López, Marcos
AU - Martínez-Díaz, M. Victoria
AU - Piersanti, Arianna
AU - Spencer, Neil
AU - Fraser Stoddart, J.
AU - Venturi, Margherita
AU - White, Andrew J P
AU - Williams, David J.
PY - 1998/11/25
Y1 - 1998/11/25
N2 - Two novel [2]rotaxanes, comprised of a dibenzo[24]crown-8 (DB24C8) macroring bound mechanically to a chemical 'dumbbell' possessing two different recognition sites - viz., secondary dialkylammonium (NH2+) and 4,4'-bipyridinium (Bpym2+) units - have been synthesized by using the supramolecular assistance to synthesis provided by, inter alia, hydrogen bonding interactions. One of these rotaxanes bears a fluorescent and redox- active anthracene (Anth) stopper unit. NMR spectroscopy and X-ray crystallography have demonstrated that the DB24C8 macroring exhibits complete selectivity for the NH2+ recognition sites, i.e., that the [2]rotaxanes exist as only one of two possible translational isomers. Deprotonation of the rotaxanes' NH2+ centers effects a quantitative displacement of the DB24C8 macroring to the Bpym2+ recognition site, an outcome that can be reversed by acid treatment. The switching processes have been investigated by 1H NMR spectroscopy and, for the Anth-bearing rotaxane, by electrochemical and photophysical measurements. Furthermore, it is possible to drive the DB24C8 macroring from the dumbbell's Bpym2+ unit, in the deprotonated form of the Anth-bearing rotaxane, by destroying the stabilizing DB24C8-Bpym2+ charge- transfer interactions via electrochemical reduction. The photochemical and photophysical properties of this rotaxane (in both its protonated and deprotonated states) have also been investigated.
AB - Two novel [2]rotaxanes, comprised of a dibenzo[24]crown-8 (DB24C8) macroring bound mechanically to a chemical 'dumbbell' possessing two different recognition sites - viz., secondary dialkylammonium (NH2+) and 4,4'-bipyridinium (Bpym2+) units - have been synthesized by using the supramolecular assistance to synthesis provided by, inter alia, hydrogen bonding interactions. One of these rotaxanes bears a fluorescent and redox- active anthracene (Anth) stopper unit. NMR spectroscopy and X-ray crystallography have demonstrated that the DB24C8 macroring exhibits complete selectivity for the NH2+ recognition sites, i.e., that the [2]rotaxanes exist as only one of two possible translational isomers. Deprotonation of the rotaxanes' NH2+ centers effects a quantitative displacement of the DB24C8 macroring to the Bpym2+ recognition site, an outcome that can be reversed by acid treatment. The switching processes have been investigated by 1H NMR spectroscopy and, for the Anth-bearing rotaxane, by electrochemical and photophysical measurements. Furthermore, it is possible to drive the DB24C8 macroring from the dumbbell's Bpym2+ unit, in the deprotonated form of the Anth-bearing rotaxane, by destroying the stabilizing DB24C8-Bpym2+ charge- transfer interactions via electrochemical reduction. The photochemical and photophysical properties of this rotaxane (in both its protonated and deprotonated states) have also been investigated.
UR - http://www.scopus.com/inward/record.url?scp=0032567215&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0032567215&partnerID=8YFLogxK
U2 - 10.1021/ja982167m
DO - 10.1021/ja982167m
M3 - Article
AN - SCOPUS:0032567215
SN - 0002-7863
VL - 120
SP - 11932
EP - 11942
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 46
ER -