title: Controlled dynamic helicity of a folded macrocycle based on a bisterephthalamide with a twofold Z-shaped structure.
abstract: Dynamic helicity in a folded macrocycle and control of the helical preference are described. We designed macrocycle 1 with a dual mode of folding through the integration of two flexible units that are arranged twice to form a cyclic structure. As a folding unit, we used a terephthalamide skeleton and a Z-shaped hydrocarbon: the former acted as a control unit to induce a preference of a particular sense of dynamic helicity and the latter was just a spacer. A terephthalamide unit provided a binding site for capturing a ditopic hydrogen-bonding guest when it adopted helically folded syn forms (M/P). Thus, only the terephthalamide unit controlled the helical sense of dynamic helicity in a folded macrocycle through the supramolecular transmission of chirality upon complexation with a chiral ditopic guest. In addition, chirality on a host could also contribute to the control of the helical preference in a folded macrocycle, which led to exceptionally enhanced chiroptical signals.
authors.affiliation: Department of Chemistry, Faculty of Science, Hokkaido University, Sapporo (Japan). katoono@sci.hokudai.ac.jp.
authors.forename: Ryo
authors.initials: R
authors.lastname: Katoono
authors.forename: Keiichi
authors.initials: K
authors.lastname: Kusaka
authors.forename: Kenshu
authors.initials: K
authors.lastname: Fujiwara
authors.forename: Takanori
authors.initials: T
authors.lastname: Suzuki
keywords: chirality; helical structures; host-guest systems; hydrogen bonds; macrocycles