Binding modes of cucurbituril and cucurbituril with a series of bis-pyridinium compounds
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Binding behaviors of cucurbituril (CB) and cucurbituril (CB) with a series of bis-pyridinium compounds N, N’-hexamethylenebis(1-alkyl-4-carbamoyl pyridinium bromide) (HBPB-n) (alkyl chain length, n = 6, 8 and 10) guests were investigated using 1H-NMR, ESI–MS and single crystal X-ray diffraction methods. The results show that CB and CB can form pseudorotaxanes with HBPB-n easily. When increasing the length of tail alkyl chain, the binding site of CB at guest molecules changed from the tail to the middle part, while CB remained located over the tail chain. As CB and CB were added in HBPB-8 aqueous solution, a pseudorotaxane was formed by the inclusion of the internal middle site in CB and the tail chain in CB.
KeywordsHost–guest system Cucurbit[n]uril Binding behavior Supramolecular chemistry Pseudorotaxane
N, N′-hexamethylenebis(1-alkyl-4-carbamoyl pyridinium bromide) (alkyl chain length, n)
We are grateful to the National Natural Science Foundation of China (No. 20972120) for financial support.
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