Issue 11, 2017

Influence of axle length on the rate and mechanism of shuttling in rigid H-shaped [2]rotaxanes

Abstract

A series of [2]rotaxane molecular shuttles was prepared containing a dibenzo[24]crown-8 (DB24C8) wheel and a rigid H-shaped axle with varying track lengths between recognition sites; from 7.4 to 20.3 Å as defined by 1–4 phenyl rings or a naphthyl group. The rate of shuttling was measured by variable temperature 1H NMR spectroscopy for neutral compounds and EXSY experiments for dicationic species. The rates were found to be independent of the length of the axle, except when the distance between the two recognition sites might be short enough (n = 1) to allow the crown ether to simultaneously interact with both recognition sites providing a short-cut mechanism which could lower the energy barrier. This notion is supported by DFT calculations and solid-state characterization of model compounds that mimic possible transition states.

Graphical abstract: Influence of axle length on the rate and mechanism of shuttling in rigid H-shaped [2]rotaxanes

Supplementary files

Article information

Article type
Edge Article
Submitted
25 8 2017
Accepted
22 9 2017
First published
25 9 2017
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2017,8, 7718-7723

Influence of axle length on the rate and mechanism of shuttling in rigid H-shaped [2]rotaxanes

G. Gholami, K. Zhu, G. Baggi, E. Schott, X. Zarate and S. J. Loeb, Chem. Sci., 2017, 8, 7718 DOI: 10.1039/C7SC03736H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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