期刊
CHEMICAL SCIENCE
卷 4, 期 7, 页码 2735-2743出版社
ROYAL SOC CHEMISTRY
DOI: 10.1039/c3sc50835h
关键词
-
资金
- Ministerios de Ciencia e Innovacion y de Economia y Competitividad [CTQ2009-08632, CTQ2012-33436, CTQ2012-31381]
- Xunta de Galicia [PGIDIT09CSA029209PR, CN2011/037]
The elasticity (stretched/compressed) and helical sense (clockwise/anticlockwise) of a dynamic helical poly(phenylacetylene) (PPA), bearing (R)-alpha-methoxytrifluorophenyl acetic acid (MTPA) pendants [poly-(R)-1], can be selectively controlled by the donor and the polar character of the solvent. The basis for this effect lies on the presence in the pendants of two independently tuneable bonds: (O=)C-C(-O) and (H-)N-C(=O). An increase in polarity shifts the conformational equilibrium of the (O=)C-C(-O) bond in favour of the most polar synperiplanar (sp) conformer, that is more sterically demanding, thus forcing the polymer to invert its helix. A donor solvent associates with the (H-)N-C(=O) bond favouring the shift to the cis form of the amide and inducing both the elongation of the polymer chain and the inversion of the helical sense (visualized as UV-Vis bathochromic shift and CD inversion respectively). This ability of poly-(R)-1 to respond to donor/polar properties occurs in solution as well as in film state. Poly(R)-1 presents in CHCl3 identical helical sense for both the internal (polyene backbone) and for the external (described by the pendants) helices (3/1 clockwise), while in THE their senses are opposite (internal anticlockwise; external 2/1 clockwise), as proven by DSC.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据