Switching of polymerization activity of cinnamoyl-alpha-cyclodextrin.

Motofumi Osaki, Yoshinori Takashima, Hiroyasu Yamaguchi, Akira Harada

Index: Org. Biomol. Chem. 7(8) , 1646-51, (2009)

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Abstract

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.