Photo-responsive pseudo[n]rotaxanes based on disparate hetero-macrocycle host combination

A series of novel photo-responsive pseudorotaxanes employing three different hetero-macrocycles combination, α-cyclodextrin (α-CD), cucurbit[7]uril (CB[7]) and p-sulfonatocalix[4]arene (SC4), as hosts were obtained. The shuttling of α-CD on the dumbbell can be reversibly driven by alternating irradiation with different lights. 1H NMR, 2D NOSEY experiments, and MALDI-TOF MS measurement are used to demonstrate the formation of the pseudorotaxanes. UV–vis absorption and induced circular dichroism measurements were carried out to illustrate the reversible photo-responsive properties of the pseudorotaxanes as well.