title: Asymmetric anionic polymerization of 2,7-bis(4-t-butylphenyl)fluoren-9-ylmethyl methacrylate and photoinduced structural transition of the obtained polymer.
abstract: 2,7-Bis(4-t-butylphenyl)fluoren-9-ylmethyl methacrylate (BBPFMMA) was synthesized as a new candidate of a bulky monomer suitable for asymmetric anionic polymerization (IUPAC nomenclature: asymmetric helix-chirogenic polymerization) leading to a preferred-handed helical, optically active polymer. The new monomer was polymerized using the complex of 9-fluorenyllithium and (S)-(+)-1-(2-pyrrolidinylmethyl)pyrrolidine in toluene at -78 °C. As opposed to the original intention to obtain a polymethacrylate, the monomer seemed to undergo structural transition (decomposition) giving 2,7-bis(4-t-butylphenyl)dibenzofulvene and the obtained polymer was most probably a terpolymer of BBPFMMA, 2,7-bis(4-t-butylphenyl)dibenzofulvene, and methacrylic acid. The obtained polymer showed circular dichroism (CD) spectra, indicating that chirality had been introduced to the copolymer chain during the course of polymerization. On photo irradiation, the polymer underwent a structural transition involving a remarkable decrease in apparent molecular weight measured by size-exclusion chromatography (SEC) and changes in FT-IR spectral patterns. However, the CD spectrum of the polymer was not obviously altered by irradiation, indicating that polymer chirality is not affected by light.
authors.affiliation: Division of Biotechnology and Macromolecular Chemistry, Faculty of Engineering, Hokkaido University, Sapporo 060-8628, Japan.
authors.forename: Kento
authors.initials: K
authors.lastname: Watanabe
authors.forename: Takeshi
authors.initials: T
authors.lastname: Sakamoto
authors.forename: Tamaki
authors.initials: T
authors.lastname: Nakano
mesh_terms: D000838:Anions; D002845:Chromatography / Q000379:methods; D002942:Circular Dichroism; D003517:Cyclopentanes / Q000737:chemistry; D005449:Fluorenes / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008689:Methacrylates / Q000737:chemistry*; D008956:Models, Chemical; D008968:Molecular Conformation; D010777:Photochemistry / Q000379:methods; D010782:Photolysis; D058105:Polymerization; D011108:Polymers / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013237:Stereoisomerism; D013696:Temperature; D014466:Ultraviolet Rays
chemical_list: D000838:Anions; D003517:Cyclopentanes; D005449:Fluorenes; D008689:Methacrylates; D011108:Polymers; C017332:fulvene; C008384:methacrylic acid