Side-chain polypseudorotaxanes by threading cucurbit[6]uril onto N′-3-vinylbenzyldiaminobutane dihydrochloride: synthesis, characterization, and properties

A pseudorotaxane monomer consisting of cucurbit[6]uril (CB[6]) and N′-3-vinylbenzyldiaminobutane dihydrochloride (3VBCB) was prepared in aqueous solution. This monomer was then polymerized using potassium persulfate as the initiator to give side-chain polypseudorotaxanes (P3VBCB). The CB[6] “beads” were localized on butyl units in side chains of P3VBCB. The hydrodynamic radius distribution of P3VBCB increased as the concentration of P3VBCB or NaCl increased. Interestingly, it was possible to control the threading and dethreading of CB[6] onto the side chains of P3VBCB by adding Ba2+ and SO4 2−. P3VBCB also showed pH-responsive behavior. Significantly, applying P3VBCB caused the T m of λ-DNA to decrease from 59.5 °C to 38 °C by damaging the double-helix structure of λ-DNA.