Size-complementary effects of PEG diamine 1,1’-disubstituted ferrocene on incorporations of β- and γ-cyclodextrins and syntheses of poly(pseudo)rotaxanes with lower coverages therefrom

Poly(ethylene glycol) diamine 1,1’-disubstituted ferrocene was utilized as a size-com-plementary site to synthesize lower coverage pseudopolyrotaxanes (pPRs) from self-assemblies with β- and γ-cyclodextrins (CDs). After end-capping β-CD pPRs using N-(triphenylmethyl)glycine (Trt-Gly-OH), an exact β-CD [3]polyrotaxane (PR) was created. However, an unexpected γ-CD [2]PR and a predictive chain folded stranded γ-CD pPR were identified from end-capped γ-CD pPRs. After end-capping a β-CD pPR self-assembled from β-CDs with amine terminated PEG containing ferrocene as a site-complementary site using Trt-Gly-OH, an exact β-CD [3]PR is invariably created. However, an unexpected γ-CD [2]PR and a predictive chain folded stranded γ-CD pPR are identified from end-capping γ-CD pPRs with Trt-Gly-OH.