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Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry

Fahrenbach, Albert C. and Barnes, Jonathan C. and Li, Hao and Benitez, Diego and Basuray, Ashish N. and Fang, Lei and Sue, Chi-Hau and Barin, Gokhan and Dey, Sanjeev K. and Goddard, William A., III and Stoddart, J. Fraser (2011) Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry. Proceedings of the National Academy of Sciences of the United States of America, 108 (51). pp. 20416-20421. ISSN 0027-8424. PMCID PMC3251067.

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In donor–acceptor mechanically interlocked molecules that exhibit bistability, the relative populations of the translational isomers—present, for example, in a bistable [2]rotaxane, as well as in a couple of bistable [2]catenanes of the donor–acceptor vintage—can be elucidated by slow scan rate cyclic voltammetry. The practice of transitioning from a fast scan rate regime to a slow one permits the measurement of an intermediate redox couple that is a function of the equilibrium that exists between the two translational isomers in the case of all three mechanically interlocked molecules investigated. These intermediate redox potentials can be used to calculate the ground-state distribution constants, K. Whereas, (i) in the case of the bistable [2]rotaxane, composed of a dumbbell component containing π-electron-rich tetrathiafulvalene and dioxynaphthalene recognition sites for the ring component (namely, a tetracationic cyclophane, containing two π-electron-deficient bipyridinium units), a value for K of 10 ± 2 is calculated, (ii) in the case of the two bistable [2]catenanes—one containing a crown ether with tetrathiafulvalene and dioxynaphthalene recognition sites for the tetracationic cyclophane, and the other, tetrathiafulvalene and butadiyne recognition sites—the values for K are orders (one and three, respectively) of magnitude greater. This observation, which has also been probed by theoretical calculations, supports the hypothesis that the extra stability of one translational isomer over the other is because of the influence of the enforced side-on donor–acceptor interactions brought about by both π-electron-rich recognition sites being part of a macrocyclic polyether.

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Goddard, William A., III0000-0003-0097-5716
Stoddart, J. Fraser0000-0003-3161-3697
Additional Information:© 2011 National Academy of Sciences. Freely available online through the PNAS open access option. Edited by Jack Halpern, University of Chicago, Chicago, IL, and approved September 19, 2011 (received for review June 20, 2011). Published online before print November 30, 2011. We acknowledge the World Class University Program (R-31-2008-000-10055-0) in Korea for supporting this research. We also thank the National Science Foundation for the award of a Graduate Research Fellowship (to A.C.F.). W.A.G. and J.F.S. acknowledge support by the Microelectronics Advanced Research Corporation and its Focus Center Research Program on Functional Engineered Nano Architectonics. Computational facilities (W.A.G.) were funded by grants from the Army Research Office Defense University Research Instrumentation Program and the Office of Naval Research Defense University Research Instrumentation Program. Author contributions: A.C.F. and J.F.S. designed research; A.C.F., J.C.B., H.L., and D.B. performed research; A.C.F., A.N.B., G.B., and S.K.D. contributed new reagents/analytic tools; A.C.F., J.C.B., D.B., A.N.B., L.F., C.-H.S., and W.A.G. analyzed data; and A.C.F., J.C.B., D.B., W.A.G., and J.F.S. wrote the paper.
Funding AgencyGrant Number
World Class University program of KoreaR31-2008-000-10055-0
NSF Graduate Research FellowshipUNSPECIFIED
Microelectronics Advanced Research CorporationUNSPECIFIED
Focus Center Research Program on Functional Engineered Nano ArchitectonicsUNSPECIFIED
Army Research Office-Defense University Research Instrumentation Program (ARO-DURIP)UNSPECIFIED
Office of Naval Research-Defense University Research Instrumentation Program (ONR-DURIP)UNSPECIFIED
Subject Keywords:density functional theory; donor-acceptor molecules; electrochemistry; isomerism; switches
Issue or Number:51
PubMed Central ID:PMC3251067
Record Number:CaltechAUTHORS:20120113-130051638
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Official Citation:Albert C. Fahrenbach, Jonathan C. Barnes, Hao Li, Diego Benítez, Ashish N. Basuray, Lei Fang, Chi-Hau Sue, Gokhan Barin, Sanjeev K. Dey, William A. Goddard III, and J. Fraser Stoddart Measurement of the ground-state distributions in bistable mechanically interlocked molecules using slow scan rate cyclic voltammetry PNAS 2011 108 (51) 20416-20421; published ahead of print November 30, 2011, doi:10.1073/pnas.1109795108
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28787
Deposited By: Ruth Sustaita
Deposited On:13 Jan 2012 23:46
Last Modified:03 Oct 2019 03:35

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