Guangzheng Gao, F. Sanda, T. Masuda
May 8, 2003
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Journal
Macromolecules
Abstract
The present study deals with the copolymerization of an amino acid-based acetylene, N-(tert-butoxycarbonyl)-l-alanine N‘-propargylamide (l-1A) with the optical isomer (d-1A), achiral hexanoic acid N-propargylamide (2A), and pivalic acid N-propargylamide (3A), and chiroptical properties of the copolymers. The copolymerization catalyzed by (nbd)Rh+[η6-C6H5B-(C6H5)3] afforded copolymers with number-average molecular weights over 104 in good yields. Nonlinear relationships were observed in the specific rotation and CD and UV−vis spectroscopies with respect to the l-1A content in feed. For instance, poly(l-1A-co-d-1A)s incorporated with 12.5% of either optical isomer (75% ee) exhibited almost the same optical properties as those of the homopolymers. Chiral amplification was observed in the copolymerization of l-1A with the achiral monomers. The specific rotation of poly(l-1A-co-2A) with 45% l-1A unit was practically the same as that of poly(l-1A). The copolymers of l-1A and 3A with an l-1A content in feed as l...