Helical structures of N-alkylated poly(p-benzamide)s.
Poly(p-benzamide)s 1 bearing a chiral side chain on the nitrogen atom were synthesized by chain-growth polycondensation methodology. The polyamides exhibited well-defined molecular weights with narrow polydispersities. Solutions of the polyamides in several organic solvents (CH(3)CN, CHCl(3), and CH(3)OH) showed dispersion type CD signals characteristic of coupled-oscillator and much larger as compared with the corresponding monomer. The CD signals were dependent on the temperature and molecular weight of the polyamides but independent of the solvent, as far as examined. An exciton model analysis of the absorption and CD spectra provided a clear-cut picture for the secondary structure of these polyamides in solution that the N-alkylated poly(p-benzamide)s possess a right-handed helical conformation ((P)-helix). In the solid states, the results of X-ray crystallographic analysis of 4-(methylamino)benzoic acid oligomers substantiated that they have a helical conformation with three monomer units per turn.
Tanatani
Aya
A
Synthesis and Control, PRESTO, Japan Science and Technology Agency (JST), Department of Applied Chemistry, Kanagawa University, Rokkakubashi, Kanagawa-ku, Yokohama 221-8686, Japan.
Yokoyama
Akihiro
A
Azumaya
Isao
I
Takakura
Yoshinori
Y
Mitsui
Chikashi
C
Shiro
Motoo
M
Uchiyama
Masanobu
M
Muranaka
Atsuya
A
Kobayashi
Nagao
N
Yokozawa
Tsutomu
T