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A Light-Driven Pseudo[4]rotaxane Encoded by Induced Circular Dichroism in a Hydrogel

Authors


  • H.T. acknowledges the support by the NSFC/China (50673025, 90401026), the National Basic Research 973 Program (2006CB806205), and the Scientific Committee of Shanghai. Supporting Information is available online from Wiley InterScience or from the author.

Abstract

A light-driven pseudo[4]rotaxane 1, based on α-cyclodextrin (α-CyD) and cucurbit[7]uril (CB[7]), is prepared in an easy and convenient manner. The reference pseudo[2]rotaxane 2 and pseudo[3]rotaxane 2′ are obtained via the insertion of α-CyD and CB[7] onto the dumbbell 3, thus including an azobenzene unit and two viologen moieties, respectively. The CyD macrocycle in pseudo[4]rotaxane 1 can be photochemically stimulated to shuttle accompanied with obvious induced circular dichroism (ICD) signals. The ICD performances of these pseudorotaxanes, including ICD in aqueous solution, variable-temperature ICD, ICD in confected hydrogel systems and in solid-state films, are investigated for their conformational identification. The photo-driven shuttling of the CyD macrocycle in pseudo[4]rotaxane 1 is easier than in the CyD-based pseudo[2]rotaxane 2, especially in non-solution media. This can be attributed to the space exploitation of CB[7]-included parts, which aid the movement of α-CyD.

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