title: Molecular design and synthesis of artificial double helices.
abstract: This account describes novel artificial double helices recently developed by our group. We have designed and synthesized the double helices consisting of two complementary, m-terphenyl-based strands that are intertwined through chiral amidinium-carboxylate salt bridges. Due to the chiral substituents on the amidine groups, the double helices adopted an excess one-handed helical conformation in solution as well as in the solid state. By extending the modular strategy, we have synthesized double helices bearing Pt(II) linkers, which underwent the double helix-to-double helix transformations through the chemical reactions of the Pt(II) complex moieties. In addition, artificial double-stranded metallosupramolecular helical polymers were constructed by combining the salt bridges and metal coordination. In contrast to the design-oriented double helices based on salt bridges, we have serendipitously developed a spiroborate-based double helicate bearing oligophenol strands. The optical resolution of the helicate was successfully attained by a diastereomeric salt formation. We have also unexpectedly found that oligoresorcinols consisting of a very simple repeating unit self-assemble into double helices with the aid of aromatic interactions in water. Furthermore, a bias in the twist sense of the double helices can be achieved by incorporating chiral substituents at both ends of the strands.
authors.affiliation: Yashima Super-structured Helix Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency (JST), Creation Core Nagoya 101, 2266-22 Shimoshidami, Moriyama-ku, Nagoya 463-0003, Japan.
authors.forename: Yoshio
authors.initials: Y
authors.lastname: Furusho
authors.forename: Eiji
authors.initials: E
authors.lastname: Yashima
mesh_terms: D000578:Amidines / Q000138:chemical synthesis / Q000737:chemistry*; D002942:Circular Dichroism; D046911:Macromolecular Substances / Q000138:chemical synthesis / Q000737:chemistry*; D008958:Models, Molecular; D008968:Molecular Conformation; D009944:Organoplatinum Compounds / Q000138:chemical synthesis / Q000737:chemistry; D010984:Platinum / Q000737:chemistry*; D013056:Spectrophotometry, Ultraviolet; D013730:Terphenyl Compounds / Q000138:chemical synthesis / Q000737:chemistry*
chemical_list: D000578:Amidines; D046911:Macromolecular Substances; D009944:Organoplatinum Compounds; D013730:Terphenyl Compounds; D010984:Platinum