Novel side chain polypseudorotaxanes with cucurbit [7]uril (CB[7]) threaded onto the side chains are synthesized from a water-soluble polymer and CB [7] in water by simple stirring at room temperature. CB [7] beads could move from the hexyl groups to the benzyl and a part of viologen units in the side chains of polymer when the molar ratio of CB[7] to the monomer reaches from 1 to 2 as shown by 1 H NMR studies, and it is considered that the hydrophobic and charge-dipole interactions of CB [7] are the driving forces. The sizes of the polypseudorotaxanes with different molar ratio of CB[7] to 4VBVHeP in aqueous solution increase with increasing the molar ratio of CB[7] to 4VBVHeP as found by DLS and resonance light scattering, while the typical cyclic voltammograms and UV-vis data indicate that CB [7] are not threaded in the viologen units of P4VBVHeP, and the oxidation reduction characteristic of the polymer is remarkably affected by the addition of CB[7]. Cucurbit[7]uril (CB[7]), a water-soluble, barrel-shaped host, consists of 7 glycoluril groups and 14 methylene bridges at both ends. The two rims are formed by the glycoluril carbonyl oxygen, thereby, are negatively charged, and they develop ion-dipole interactions with cationic guests. 28,29 Recently, taking advantage of cucurbit[7]uril's structure, various mechanically interlocked molecules including rotaxanes and poly(pseudo)rotaxanes have been synthesized by Kim, [30][31][32][33][34][35][36][37][38][39] Kaifer, 40-42 and others. [43][44][45][46][47][48][49][50][51][52][53][54][55][56] We previously synthesized some side chain polypseudorotaxanes with viologen, and cucurbit[7]uril as a molecular bead have also been reported. 52This investigation expends our understanding about the movement on the side chains of polypseudorotaxanes. Herein, we synthesized novel water-soluble side chain polypseudoro-taxanes with CB[7], which could slippage on the side chains by adjusting the molar ratio of CB[7] to the monomer. The weight-average molar mass M w of the polymer was measured by multiangle laser light scattering, and the movement of CB[7] on the side chains of polypseudorotaxanes by adjusting the molar ratio of CB[7] to the monomer were studied by 1 H NMR. The average hydrodynamic radius (R h ), the oxidation reduction characteristics, and optical properties of the polypseudorotaxanes were studied by DLS, cyclic voltammograms, UV-vis, and resonance light scattering (RLS), respectively. CB[7] was prepared according to the literature. 29,30 4,4 0 -Dipyridyl (98%), pyridine (99%), 1,6-dibromohexane (99%), and 4-vinybenzyl chlorine (90%) were received from ACRO. Anhydrous acetonitrile (AR) and diethyl ether anhydrous (AR) were received from the Sinopharm Chemical Reagent (SCRC).
EXPERIMENTAL
MaterialSynthesis of 1-(6-Bromohexyl)pyridinium (HeP) 1,6-Dibromohexane (18.3 g, 0.075 mol) was dissolved in absolute ether (25 mL) and stirred for 10 min at room temperature. Pyridine (2.0 g, 0.025 mol) was slowly dripped to the solution of 1,6-dibromohexane, and the mixture was