title: Refolding foldamers: triazene-arylene oligomers that change shape with chemical stimuli.
abstract: We describe the preparation of five triazene-arylene oligomers (3, 4, 7, 8, and 11) 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[n]uril family (CB[n]), 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[n] family, it is possible to fold a single foldamer strand (3) into the CB[8].(a,a,a,s)-3 conformer by the addition of CB[8], then unfold and refold it into the CB[7].(a,s,s,a)-3.CB[7] conformer by addition of CB[7] and 3,5-dimethylaminoadamantane (17), then unfold and refold it again into the CB[10].(a,a,a,a)-3 conformer by addition of CB[10].CB[5] and aminoadamantane (18). The transformation of CB[8].(a,a,a,s)-3 into CB[7].(a,s,s,a)-3.CB[7] proceeds through the intermediacy of CB [8].(a,a,s,a)-3.CB[7], which enhances the rate of dissociation of strand 3 from CB[8].
authors: Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, USA.
authors: Simin
authors: S
authors: Liu
authors: Peter Y
authors: PY
authors: Zavalij
authors: Yiu-Fai
authors: YF
authors: Lam
authors: Lyle
authors: L
authors: Isaacs
mesh_terms: D018360:Crystallography, X-Ray; D010455:Peptides / Q000737:chemistry*; D011487:Protein Conformation; D017510:Protein Folding; D014226:Triazenes / Q000737:chemistry*
chemical_list: D010455:Peptides; D014226:Triazenes