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The Neighboring Component Effect in a Tristable [2]Rotaxane

Wang, Yuping and Cheng, Tao and Sun, Junling and Liu, Zhichang and Frasconi, Marco and Goddard, William A., III and Stoddart, J. Fraser (2018) The Neighboring Component Effect in a Tristable [2]Rotaxane. Journal of the American Chemical Society, 140 (42). pp. 13827-13834. ISSN 0002-7863.

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The redox properties of cyclobis(paraquat-p-phenylene) cyclophane (CBPQT^(4+)) renders it a uniquely variable source of recognition in the context of mechanically interlocked molecules, through aromatic donor-acceptor interactions in its fully oxidized state (CPBQT^(4+)) and radical- pairing interactions in its partially reduced state (CBPQT^(2(•+))). Although it is expected that the fully reduced neutral state (CBPQT^((0))) might behave as a p-donating recognition unit, resulting in a dramatic change in its binding properties when compared with the other two redox states, its role in rotaxanes has not yet been investigated. To address this challenge, we report herein the synthesis of a tristable [2]rotaxane in which a CBPQT^(4+) ring is mechanically interlocked with a dumbbell component containing five recognition sites—(i) one, a bipyridinium radical cation (BIPY^((•+))) located centrally along the axis of the dumbbell, straddled by (ii) two tetrafluorophenylene units linked to (iii) two triazole rings. In addition to the selective recognition between (iv) the CBPQT^(4+) ring and the triazole units, and (v) the CBPQT^(2(•+)) ring and the reduced BIPY^((•+)) unit in the dumbbell component, investigations in solution have now confirmed the presence of additional noncovalent bonding interactions between the CBPQT^((0)) ring, acting as a donor in its neutral state towards the two tetrafluorophenylene acceptors in the dumbbell component. The unveiling of this piece of molecular recognition in a [2]rotaxane is reminiscent of the existence in much simpler, covalently linked, organic molecules of neighboring group participation (anchimeric assistance giving way to transannular interactions) in small-, medium-, and large-membered rings.

Item Type:Article
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URLURL TypeDescription Information
Wang, Yuping0000-0002-9315-2358
Cheng, Tao0000-0003-4830-177X
Liu, Zhichang0000-0003-3412-512X
Frasconi, Marco0000-0003-2010-175X
Goddard, William A., III0000-0003-0097-5716
Stoddart, J. Fraser0000-0003-3161-3697
Additional Information:© 2018 American Chemical Society. Received: August 8, 2018; Published: September 25, 2018. This research is part (Project 34-945) of the Joint Center of Excellence in Integrated Nano-Systems (JCIN) at King Abdulaziz City for 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. The computational resources are from Extreme Science and Engineering Discovery Environment, which is supported by National Science Foundation Grant ACI-1548562. The authors declare no competing financial interest.
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King Abdulaziz City for Science and Technology (KACST)34-945
Northwestern UniversityUNSPECIFIED
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Record Number:CaltechAUTHORS:20180926-083241549
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Official Citation:Neighboring Component Effect in a Tri-stable [2]Rotaxane. Yuping Wang, Tao Cheng, Junling Sun, Zhichang Liu, Marco Frasconi, William A. Goddard, III, and J. Fraser Stoddart. Journal of the American Chemical Society 2018 140 (42), 13827-13834. DOI: 10.1021/jacs.8b08519
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89947
Deposited By: Tony Diaz
Deposited On:26 Sep 2018 17:45
Last Modified:25 Oct 2018 16:25

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