title: Macrocyclic Oligothiophene with Stereogenic [2.2]Paracyclophane Scaffolds: Chiroptical Properties from π-Transannular Interactions.
abstract: The enantiomers of a new cyclic oligothiophene, bridged by two pseudo-ortho[2.2]paracyclophanes, were synthesized as a new class of the chiral π-conjugated system. Single-crystal X-ray diffraction analysis revealed a twisted structure for these oligothiophenes induced by a torsion of the cyclophane moieties. The embedding oligothiophenes into the inherent planar chirality provided a significant enhancement in circular dichroism (CD) spectra thanks to the large magnetic/electric transition dipole moments. In the dicationic state, an intramolecular π dimer was formed due to the strong interactions of the oligothiophenes. We further recorded unprecedented wide ranges of CD spectra in 250-1800 nm region. The transitions are reasonably described by the exciton coupling of the oligothiophenes.
authors.affiliation: Department of Chemistry, Graduate School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Hasegawa
authors.affiliation: Department of Chemistry, Graduate School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
authors.forename: Kosuke
authors.initials: K
authors.lastname: Kobayakawa
authors.affiliation: Department of Chemistry, Graduate School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
authors.forename: Hideyo
authors.initials: H
authors.lastname: Matsuzawa
authors.affiliation: Department of Chemistry, Graduate School of Science and Engineering, Tokyo Metropolitan University, Hachioji, Tokyo, 192-0397, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Nishinaga
authors.affiliation: Department of Synthetic Chemistry and Biological Chemistry, Graduate School of Engineering, Kyoto University, Katsura, Nishikyo-ku, Kyoto, 615-8510, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Hirose
authors.affiliation: Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, 466-8555, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Sako
authors.affiliation: Department of Chemistry, Graduate School of Science, Kitasato University, 1-15-1 Kitasato, Minami-ku, Sagamihara, Kanagawa, 252-0373, Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Mazaki
keywords: chirality; cyclophanes; dimers; oligothiophenes; redox chemistry