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Quantum Mechanical and Experimental Validation that Cyclobis(paraquat-p-phenylene) Forms a 1:1 Inclusion Complex with Tetrathiafulvalene

Hartlieb, Karel J. and Liu, Wei-Guang and Fahrenbach, Albert C. and Blackburn, Anthea K. and Frasconi, Marco and Hafezi, Nema and Dey, Sanjeev K. and Sarjeant, Amy A. and Stern, Charlotte L. and Goddard, William A., III and Stoddart, J. Fraser (2016) Quantum Mechanical and Experimental Validation that Cyclobis(paraquat-p-phenylene) Forms a 1:1 Inclusion Complex with Tetrathiafulvalene. Chemistry: a European Journal, 22 (8). pp. 2736-2745. ISSN 0947-6539.

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The promiscuous encapsulation of π-electron-rich guests by the π-electron-deficient host, cyclobis(paraquat-p-phenylene) (CBPQT^(4+)), involves the formation of 1:1 inclusion complexes. One of the most intensely investigated charge-transfer (CT) bands, assumed to result from inclusion of a guest molecule inside the cavity of CBPQT^(4+), is an emerald-green band associated with the complexation of tetrathiafulvalene (TTF) and its derivatives. This interpretation was called into question recently in this journal based on theoretical gas-phase calculations that reinterpreted this CT band in terms of an intermolecular side-on interaction of TTF with one of the bipyridinium (BIPY^(2+)) units of CBPQT^(4+), rather than the encapsulation of TTF inside the cavity of CBPQT^(4+). We carried out DFT calculations, including solvation, that reveal conclusively that the CT band emerging upon mixing TTF with CBPQT^(4+) arises from the formation of a 1:1 inclusion complex. In support of this conclusion, we have performed additional experiments on a [2]rotaxane in which a TTF unit, located in the middle of its short dumbbell, is prevented sterically from interacting with either one of the two BIPY^(2+) units of a CBPQT^(4+) ring residing on a separate [2]rotaxane in a side-on fashion. This [2]rotaxane has similar UV/Vis and ^1H NMR spectroscopic properties with those of 1:1 inclusion complexes of TTF and its derivatives with CBPQT^(4+). The [2]rotaxane exists as an equimolar mixture of cis- and trans-isomers associated with the disubstituted TTF unit in its dumbbell component. Solid-state structures were obtained for both isomers, validating the conclusion that the TTF unit, which gives rise to the CT band, resides inside CBPQT^(4+).

Item Type:Article
Related URLs:
URLURL TypeDescription
Liu, Wei-Guang0000-0002-6633-7795
Frasconi, Marco0000-0003-2010-175X
Sarjeant, Amy A.0000-0002-1993-0406
Goddard, William A., III0000-0003-0097-5716
Stoddart, J. Fraser0000-0003-3161-3697
Additional Information:© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim. Received: June 2, 2015; First published: 19 January 2016. This research is part (project 34-945) of the Joint Center of Excellence in Integrated Nano-Systems (JCIN) at the King Abdulaziz City of Science and Technology (KACST) and Northwestern University (NU). The authors would like to thank both KACST and NU for their continued support of this research. W.G.L. and W.A.G. acknowledge support from the US National Science Foundation (EFRI-1332411 and DMR-1436985). A.C.F. acknowledges support from a National Science Foundation (NSF) Graduate Research Fellowship. A.K.B. acknowledges Fulbright New Zealand for a Fulbright Graduate Award and the New Zealand Federation of Graduate Women for a Postgraduate Fellowship award.
Funding AgencyGrant Number
King Abdulaziz City for Science and Technology (KACST)UNSPECIFIED
Northwestern UniversityUNSPECIFIED
NSF Graduate Research FellowshipUNSPECIFIED
Fulbright New ZealandUNSPECIFIED
New Zealand Federation of Graduate WomenUNSPECIFIED
Subject Keywords:DFT calculations; donor–acceptor systems; rotaxanes; tetrathiafulvalene
Issue or Number:8
Record Number:CaltechAUTHORS:20160122-100323999
Persistent URL:
Official Citation:K. J. Hartlieb, W.-G. Liu, A. C. Fahrenbach, A. K. Blackburn, M. Frasconi, N. Hafezi, S. K. Dey, A. A. Sarjeant, C. L. Stern, W. A. Goddard, J. F. Stoddart, Chem. Eur. J. 2016, 22, 2736
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63882
Deposited By: Tony Diaz
Deposited On:22 Jan 2016 20:52
Last Modified:22 Apr 2020 19:35

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