Switching of polymerization activity of cinnamoyl-alpha-cyclodextrin.
Cinnamoyl alpha-cyclodextrin (alpha-CD) has been found to initiate polymerization of delta-valerolactone (delta-VL) to give a polymer in high yield. By the presence of the cinnamoyl group, hydrogen bond was formed between the carbonyl oxygen of delta-VL and the hydroxyl group of CD to activate the monomer, which was observed by FT-IR measurements. However, the cinnamoyl group at the C(3)- and C(6)-positions of alpha-CD did not affect the polymerization ability. Only that of the C(2)-position showed high polymerization activity. The polymerization activity could be switched by the photoisomerization of the cinnamoyl group attached to the rim of alpha-CD. Specific monomer recognition and polymerization in the active site of the alpha-CD cavity was changed by the photoisomerization.
Osaki
Motofumi
M
Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan.
Takashima
Yoshinori
Y
Yamaguchi
Hiroyasu
H
Harada
Akira
A