Issue 7, 2014

An ExBox [2]catenane


A donor–acceptor [2]catenane, in which an extended tetracationic cyclophane is mechanically interlocked by a porphyrin-containing macrocycle, was synthesised using a template-directed protocol and alkene metathesis as the ring-closing step. In the ground state of this [2]catenane, the porphyrin ring resides inside the cavity of the cyclophane on account of favourable charge-transfer interactions between the electron-rich porphyrin and the electron-deficient cyclophane. The [2]catenane can act as a push-button molecular switch where the co-conformations of the [2]catenane can be controlled either chemically or electrochemically. Addition of acid protonates the porphyrin ring and a relative circumrotational motion of the macrocycle positions the charged porphyrin ring outside the cavity of the cyclophane. The switch can be reset to its ground-state co-conformation by the addition of base. Electrochemical reduction of the extended bipyridinium units of the cyclophane decreases the strength of the donor–acceptor interactions in the [2]catenane, leading to a loss of recognition between the mechanically interlocked rings. The chemical and electrochemical switching mechanisms are both reversible.

Graphical abstract: An ExBox [2]catenane

Supplementary files

Article information

Article type
Edge Article
13 Feb 2014
31 Mar 2014
First published
04 Apr 2014

Chem. Sci., 2014,5, 2724-2731

An ExBox [2]catenane

M. Juríček, J. C. Barnes, N. L. Strutt, N. A. Vermeulen, K. C. Ghooray, E. J. Dale, P. R. McGonigal, A. K. Blackburn, A. Avestro and J. F. Stoddart, Chem. Sci., 2014, 5, 2724 DOI: 10.1039/C4SC00488D

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