title: Stereoisomerism, crystal structures, and dynamics of belt-shaped cyclonaphthylenes.
abstract: The chemistry of a belt-shaped cyclic array of aromatic panels, a so-called "nanohoop," has increasingly attracted much interest, partly because it serves as a segmental model of single-wall carbon nanotubes with curved sp(2)-carbon networks. Although the unique molecular structure of nanohoops is expected to deepen our understanding in curved π-systems, its structural chemistry is still in its infancy despite structural variants rapidly accumulated over the past several years. For instance, structural characteristics that endow the belt shapes with rigidity, an important structural feature relevant to carbon nanotubes, have not been clarified to date. We herein report the synthesis and structures of a series of belt-shaped cyclonaphthylenes. Random synthesis methods using three precursor units with different numbers of naphthylene panels allowed us to prepare 6 congeners consisting of 6 to 11 naphthylene panels, and relationships between the rigidity and the panel numbers, i.e., molecular structures, were investigated. Fundamental yet complicated stereoisomerism in the belt-shaped structures was disclosed by mathematical methods, and dynamics in the panel rotation was revealed by dynamic NMR studies with the aid of theoretical calculations.
authors.affiliation: Isobe Degenerate π-Integration Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Aoba-ku, Sendai 980-8577, Japan; Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan;
authors.forename: Zhe
authors.initials: Z
authors.lastname: Sun
authors.affiliation: Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan;
authors.forename: Takuya
authors.initials: T
authors.lastname: Suenaga
authors.affiliation: Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan;
authors.forename: Parantap
authors.initials: P
authors.lastname: Sarkar
authors.affiliation: Isobe Degenerate π-Integration Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Aoba-ku, Sendai 980-8577, Japan; Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan;
authors.forename: Sota
authors.initials: S
authors.lastname: Sato
authors.affiliation: Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan; Mathematical Institute, Tohoku University, Aoba-ku, Sendai 980-8578, Japan;
authors.forename: Motoko
authors.initials: M
authors.lastname: Kotani
authors.affiliation: Isobe Degenerate π-Integration Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Aoba-ku, Sendai 980-8577, Japan; Advanced Institute for Materials Research, Tohoku University, Aoba-ku, Sendai 980-8577, Japan; Department of Chemistry, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan isobe@m.tohoku.ac.jp.
authors.forename: Hiroyuki
authors.identifier: 0000-0001-8907-0694
authors.initials: H
authors.lastname: Isobe
keywords: carbon nanotubes; crystal structures; dynamic structures; macrocycles; stereoisomerism