Refolding Foldamers:  Triazene-Arylene Oligomers That Change Shape with Chemical Stimuli LiuSimin ZavalijPeter Y. LamYiu-Fai IsaacsLyle 2007 We describe the preparation of five triazene-arylene oligomers (<b>3</b>, <b>4</b>, <b>7</b>, <b>8</b>, and <b>11</b>) and investigations of their folding properties in aqueous solution. These oligomers contain four 2-fold rotors and populate a conformational ensemble comprising at least 10 states. Extensive 1D and 2D NMR studies as well as X-ray crystallography establish that the presence of three members of the cucurbit[<i>n</i>]uril family (CB[<i>n</i>]), CB[10], CB[7], and CB[8], results in the selective population of the (a,a,a,a)-, (a,s,s,a)-, and (a,a,a,s)-conformers. As a result of the high affinity and highly selective binding properties of the CB[<i>n</i>] family, it is possible to fold a single foldamer strand (<b>3</b>) into the CB[8]·(a,a,a,s)-<b>3</b> conformer by the addition of CB[8], then unfold and refold it into the CB[7]·(a,s,s,a)-<b>3</b>·CB[7] conformer by addition of CB[7] and 3,5-dimethylaminoadamantane (<b>17</b>), then unfold and refold it again into the CB[10]·(a,a,a,a)-<b>3</b> conformer by addition of CB[10]·CB[5] and aminoadamantane (<b>18</b>). The transformation of CB[8]·(a,a,a,s)-<b>3</b> into CB[7]·(a,s,s,a)-<b>3</b>·CB[7] proceeds through the intermediacy of CB [8]·(a,a,s,a)-<b>3</b>·CB[7], which enhances the rate of dissociation of strand <b>3</b> from CB[8].