Tyrosine-based poly(m-phenyleneethynylene-p-phenyleneethynylene)s. Helix folding and responsiveness to a base
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- 作者：Ruiyuan Liu ; Hiromitsu Sogawa ; Masashi Shiotsuki ; Toshio Masuda ; Fumio S ; a
- 关键词：Amino acid ; Helix ; Poly(phenyleneethynylene)
- 刊名：Polymer
- 出版年：2010
- 出版时间：14 May 2010
- 年：2010
- 卷：51
- 期：11
- 页码：2255-2263
- 全文大小：1544 K
文摘
The Sonogashira–Hagihara polymerization of 3′,5′-diiodo-N-α-tert-butoxycarbonyl-l-tyrosine methyl ester (1) and 3′,5′-diiodo-N-α-tert-butoxycarbonyl-O-methyl-l-tyrosine methyl ester (2) with para-diethynylbenzene (3) was carried out to obtain optically active poly(m-phenyleneethynylene-p-phenyleneethynylene)s [poly(1) and poly(2)] with Mn’s ranging from 9900 to 15,000 in 80–87 % yields. Poly(1) exhibited intense CD signals in DMSO and THF, but did not in CH2Cl2, indicating that it took a predominantly one-handed helical conformation in the former two solvents. On the other hand, there was no evidence for poly(2) to take a helical structure in these solvents. Poly(1) turned the CD sign at 390 nm from plus to minus in DMSO/H2O = 9/1 (v/v) by the addition of NaOH. Alkaline hydrolysis of ester moieties of poly(1) and poly(2) gave the corresponding polymers having carboxy groups [poly(1a) and poly(2a)]. Poly(1a) and poly(2a) increased the CD intensity by the addition of NaOH.