Helical structures of N-alkylated poly(p-benzamide)s.
Helical structures of N-alkylated poly(p-benzamide)s.
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DOI：
10.1021/ja0455291
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发表时间：
2005-05
影响因子：
15
通讯作者：
Aya Tanatani;A. Yokoyama;I. Azumaya;Y. Takakura;C. Mitsui;M. Shiro;M. Uchiyama;A. Muranaka;N. Kobayashi;T. Yokozawa
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文献类型：
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作者：
Aya Tanatani;A. Yokoyama;I. Azumaya;Y. Takakura;C. Mitsui;M. Shiro;M. Uchiyama;A. Muranaka;N. Kobayashi;T. Yokozawa
采用链生长缩聚法合成了氮原子上带有手性侧链的聚（对苯酰胺）s1。聚酰胺具有明确的分子量和窄的多分散性。聚酰胺在几种有机溶剂(CH(3)CN、CHCl（3)和CH(3)OH）中的溶液表现出耦合振荡器的色散型CD信号，且比相应的单体大得多。CD信号依赖于聚酰胺的温度和分子量，但与溶剂无关。吸收光谱和CD光谱的激子模型分析清楚地说明了这些聚酰胺在溶液中的二级结构，即n -烷基化聚（对苯酰胺）s具有右手螺旋构象（(P)-螺旋）。在固体状态下，4-（甲氨基）苯甲酸低聚物的x射线晶体分析结果证实它们具有螺旋构象，每转3个单体单元。
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.