Synthesis and Secondary Structure of Polyacetylenes Carrying Diketopiperazine Moieties. The First Example of Helical Polymers Stabilized by s-cis-Amide-Based Hydrogen Bonding
Synthesis and Secondary Structure of Polyacetylenes Carrying Diketopiperazine Moieties. The First Example of Helical Polymers Stabilized by s-cis-Amide-Based Hydrogen Bonding
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DOI：
10.1021/ma8023552
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发表时间：
2009-01
期刊：
影响因子：
5.5
通讯作者：
Kayo Terada;T. Masuda;F. Sanda
中科院分区：
文献类型：
--
作者：
Kayo Terada;T. Masuda;F. Sanda
以L-苯丙氨酸为原料，合成了新型光学活性的含二酮基哌嗪的苯乙炔，并在铑催化剂作用下聚合，以较好的产率制得了数均相对分子质量大于10000的聚合物。CD和UV-−-Vis光谱表明，聚合物在二甲基甲酰胺中为螺旋结构，在三氯甲烷中为无规卷曲结构。在CHCl3中向聚合物溶液中加入不同的羧酸，如三氟乙酸，促进了螺旋的形成。分子力学计算表明，最稳定的构象是氨基之间伴随着串联氢键链的右旋螺旋。
Novel optically active phenylacetylenes having diketopiperazine were synthesized from l-phenylalanine and polymerized with a rhodium catalyst to obtain the polymers with number-average molecular weights over 10 000 in good yields. The CD and UV−vis spectra of the polymers indicated that they took helical structures with predominantly one-handed screw sense in DMF, while random coil structures in CHCl3. Addition of various carboxylic acids such as trifluoroacetic acid to the polymer solution in CHCl3 promoted the helical formation. Molecular mechanics calculation suggested that the most stable conformer was a right-handed helix accompanying tandem hydrogen-bonding strands between the amide groups.