title: Naphthalene- and anthracene-based aromatic foldamers with iminodicarbonyl linkers: their stabilities and application to a chiral photochromic system using retro [4 + 4] cycloaddition.
abstract: A circular dichroism (CD) spectral study on chiral aromatic chain imides possessing anthracene and naphthalene moieties with bulky N substituents showed that their helical chirality based on folding remained for a reasonably long time without racemization in solution. Racemization due to conformational equilibration occurred very slowly, requiring over 1 week at ambient temperature. Their CD spectra both in solution and in the solid state gave similar CD signals, suggesting retention of helicity observed in the solid state even after dissolving. As an application of this novel chiral folding of aromatic chain imides, a chiral photochromic system was investigated based on the photo [4 + 4] cycloaddition and its thermal cycloreversion of an anthracene-naphthalene system. The foldamer possessing an anthracene moiety in the center connected with two naphthalene moieties below and above it by iminodicarbonyl linkers was prepared for this purpose. Induced CD was observed for the foldamer with (S)-1-(1-naphthyl)ethyl substituents at the imide nitrogen atoms. Chiral photochromic cycles were monitored by CD spectral measurement.
authors.affiliation: Faculty of Pharmaceutical Sciences at Kagawa Campus, Tokushima Bunri University, Sanuki, Kagawa 769-2193, Japan.
authors.forename: Hyuma
authors.initials: H
authors.lastname: Masu
authors.forename: Ikuko
authors.initials: I
authors.lastname: Mizutani
authors.forename: Takako
authors.initials: T
authors.lastname: Kato
authors.forename: Isao
authors.initials: I
authors.lastname: Azumaya
authors.forename: Kentaro
authors.initials: K
authors.lastname: Yamaguchi
authors.forename: Keiki
authors.initials: K
authors.lastname: Kishikawa
authors.forename: Shigeo
authors.initials: S
authors.lastname: Kohmoto
mesh_terms: D009281:Naphthalenes / Q000737:chemistry*
chemical_list: D009281:Naphthalenes; C031721:naphthalene