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

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 amide–amide 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.

Bibliographic Details

Main Authors:	Altieri, Andrea, Aucagne, Vincent, Carrillo Fumero, Romen, Clarkson, Guy J., D'Souza, Daniel M., Dunnett, Jennifer A., Leigh, David A., Mullen, Kathleen M.
Other Authors:	Engineering and Physical Sciences Research Council (UK)
Format:	artículo biblioteca
Language:	English
Published:	Royal Society of Chemistry (UK) 2011-07-14
Subjects:	[2]rotaxanes, Sulfur-containing, Shuttles,
Online Access:	http://hdl.handle.net/10261/212897 http://dx.doi.org/10.13039/501100000266 http://dx.doi.org/10.13039/100008054
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