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Donor-Acceptor Oligorotaxanes Made to Order

Basu, Subhadeep and Coskun, Ali and Friedman, Douglas C. and Olson, Mark A. and Benítez, Diego and Tkatchouk, Ekaterina and Barin, Gokhan and Yang, Jeffrey and Fahrenbach, Albert C. and Goddard, William A., III and Stoddart, J. Fraser (2011) Donor-Acceptor Oligorotaxanes Made to Order. Chemistry-A European Journal, 17 (7). pp. 2107-2119. ISSN 0947-6539.

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Five donor–acceptor oligorotaxanes made up of dumbbells composed of tetraethylene glycol chains, interspersed with three and five 1,5-dioxynaphthalene units, and terminated by 2,6-diisopropylphenoxy stoppers, have been prepared by the threading of discrete numbers of cyclobis(paraquat-p-phenylene) rings, followed by a kinetically controlled stoppering protocol that relies on click chemistry. The well-known copper(I)-catalyzed alkyne–azide cycloaddition between azide functions placed at the ends of the polyether chains and alkyne-bearing stopper precursors was employed during the final kinetically controlled template-directed synthesis of the five oligorotaxanes, which were characterized subsequently by ^1H NMR spectroscopy at low temperature (233 K) in deuterated acetonitrile. The secondary structures, as well as the conformations, of the five oligorotaxanes were unraveled by spectroscopic comparison with the dumbbell and ring components. By focusing attention on the changes in chemical shifts of some key probe protons, obtained from a wide range of low-temperature spectra, a picture emerges of a high degree of folding within the thread protons of the dumbbells of four of the five oligorotaxanes—the fifth oligorotaxane represents a control compound in effect— brought about by a combination of C-H···O and π–π stacking interactions between the p-electron-deficient bipyridinium units in the rings and the π-electron-rich 1,5-dioxynaphthalene units and polyether chains in the dumbbells. The secondary structures of a foldamer-like nature have received further support from a solid-state superstructure of a related [3]pseudorotaxane and density functional calculations performed thereon.

Item Type:Article
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URLURL TypeDescription
Coskun, Ali0000-0002-4760-1546
Goddard, William A., III0000-0003-0097-5716
Stoddart, J. Fraser0000-0003-3161-3697
Additional Information:© 2011 Wiley. Received: September 6, 2010. Article first published online: 27 Jan 2011. This research was supported in the beginning by the National Science Foundation (NSF) under grant CHE-0924620 and subsequently by the Non-Equilibrium Energy Research Center (NERC), which is an Energy Frontier Research Center (EFRC) funded by the US Department of Energy (DOE) of Basic Energy Sciences under Award Number DESC0000989. G.B. thanks the International Center for Diffraction Data for the award of a 2011 Ludo Frevel Crystallography Scholarship.
Funding AgencyGrant Number
Department of Energy (DOE)DE-SC0000989
Subject Keywords:folding; noncovalent bonding interactions; oligomers; rotaxanes; template-directed syntheses
Issue or Number:7
Record Number:CaltechAUTHORS:20110328-100709966
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:23124
Deposited By: Ruth Sustaita
Deposited On:29 Mar 2011 15:28
Last Modified:09 Mar 2020 13:18

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