title: Enantiomer-selective and helix-sense-selective living block copolymerization of isocyanide enantiomers initiated by single-handed helical poly(phenyl isocyanide)s.
abstract: Rigid-rodlike right (P)- and left (M)-handed helical polyisocyanides (P-poly-L-1 and M-poly-L-1) prepared by the living polymerization of an enantiomerically pure phenyl isocyanide bearing an L-alanine pendant with a long n-decyl chain (L-1) with the mu-ethynediyl Pt-Pd catalyst were found to block copolymerize L-1 and D-1 in a highly enantiomer-selective manner while maintaining narrow molecular weight distributions. The M-poly-L-1 preferentially copolymerized L-1 over the antipode D-1 by a factor of 6.4-7.7, whereas the D-1 was preferentially copolymerized with P-poly-L-1 composed of the same L-1 units, but possessing the opposite helicity by a factor of 4.0. Circular dichroism and high-resolution atomic force microscopy revealed that the enantiomer-selective block copolymerizations proceed in an extremely high helix-sense-selective fashion, and the preformed helical handedness determines the overall helical sense of the polyisocyanides irrespective of the configuration of the monomer units of the initiators during the block copolymerizations. The block copolymers are rigid-rod helical polymers with a narrow molecular weight distribution and exhibit a lyotropic smectic liquid crystalline phase.
authors.affiliation: Department of Molecular Design and Engineering, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya 464-8603, Japan.
authors.forename: Zong-Quan
authors.initials: ZQ
authors.lastname: Wu
authors.forename: Kanji
authors.initials: K
authors.lastname: Nagai
authors.forename: Motonori
authors.initials: M
authors.lastname: Banno
authors.forename: Kento
authors.initials: K
authors.lastname: Okoshi
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Onitsuka
authors.forename: Eiji
authors.initials: E
authors.lastname: Yashima
mesh_terms: D003486:Cyanides / Q000138:chemical synthesis*; D015394:Molecular Structure; D011108:Polymers / Q000138:chemical synthesis*; D013237:Stereoisomerism
chemical_list: D003486:Cyanides; D011108:Polymers