Issue 10, 2011

Sulfur-containing amide-based [2]rotaxanes and molecular shuttles

Abstract

We report on the synthesis, structure and properties of [2]rotaxanes prepared by the assembly of benzylic amide macrocycles around a series of amide and sulfide-/sulfoxide-/sulfone-containing threads. The efficacy of rotaxane formation is related to the hydrogen bond accepting properties of the various sulfur-containing functional groups in the thread, with the highest yields (up to 63% with a rigid vinyl spacer in the template site) obtained for sulfoxide rotaxanes. X-Ray crystallography of a sulfoxide rotaxane, 5, shows that the macrocycle adopts a highly symmetrical chair-like conformation in the solid state, with short hydrogen bonds between the macrocycle isophthalamide NH-protons and the amide carbonyl and sulfoxide S–O of the thread. In contrast, in the X-ray crystal structures of the analogous sulfide (4) and sulfone (6) rotaxanes, the macrocycle adopts boat-like conformations with long intercomponent NH⋯O[double bond, length as m-dash]SO and NH⋯S hydrogen bonds (in addition to several intercomponent amideamide hydrogen bonds). Taking advantage of the different hydrogen bonding modes of the sulfur-based functional groups, a switchable molecular shuttle was prepared in which the oxidation level of sulfur determines the position of the macrocycle on the thread.

Graphical abstract: Sulfur-containing amide-based [2]rotaxanes and molecular shuttles

Supplementary files

Article information

Article type
Edge Article
Submitted
30 May 2011
Accepted
21 Jun 2011
First published
14 Jul 2011

Chem. Sci., 2011,2, 1922-1928

Sulfur-containing amide-based [2]rotaxanes and molecular shuttles

A. Altieri, V. Aucagne, R. Carrillo, G. J. Clarkson, D. M. D'Souza, J. A. Dunnett, D. A. Leigh and K. M. Mullen, Chem. Sci., 2011, 2, 1922 DOI: 10.1039/C1SC00335F

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