Cucurbit[6]uril dimer induces supramolecular polymerisation of a cationic polyethylene glycol derivative

2014-05-19T14:54:17Z (GMT) by James B. Wittenberg Lyle Isaacs
<div><p>Recently, we reported the synthesis of two new dimeric cucurbit[6]uril compounds (<b>1</b> and <b>2</b>). Herein, we describe the ability of compound <b>1</b> to undergo supramolecular polymerisation when combined with polyethylene glycol (PEG) derived divalent guests <b>3</b><sub>MW</sub> (MW = 300, 1000, 3350, 10,000). Interestingly, we find that the shorter PEG-derived guests <b>3</b><sub>300</sub>, <b>3</b><sub>1000</sub> and <b>3</b><sub>3350</sub> lead to low degrees of oligomerisation based on the diffusion coefficients obtained by diffusion-ordered spectroscopy measurements. In contrast, when <b>1</b> was combined with the longest PEG-derived guest <b>3</b><sub>10,000</sub>, we observed the formation of a supramolecular polymer with a degree of oligomerisation of at least 36. We observe that the supramolecular polymer <b>1</b><sub><i>n</i></sub><b>·</b>(<b>3</b><sub>10,000</sub>)<i>n</i> undergoes a slow decrease in its degree of oligomerisation to 22 over the course of 14 days controlled by the slow dissociation rate constant of the hexanediammonium unit of <b>3</b><sub>10,000</sub> from the CB[6]-sized cavity of <b>1</b>.</p></div>