Macromolecular Chiral Amplification through a Random Coil to One-Handed Helix Transformation Induced by Metal Ion Coordination in an Aqueous Solution,Macromolecules

当前位置： X-MOL 学术 › Macromolecules › 论文详情

Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)

Macromolecular Chiral Amplification through a Random Coil to One-Handed Helix Transformation Induced by Metal Ion Coordination in an Aqueous Solution
Macromolecules ( IF 5.1 ) Pub Date : 2020-07-08 , DOI: 10.1021/acs.macromol.0c00533
Huajun Huang ₁ , Huimin Duan ₁ , Lijie Yin ₁ , Dongming Qi ₁ , Jiadan Xue ₂ , Yingjie Zhang ₃ , Jianping Deng ₃

Affiliation

Many inspiring achievements have been made in inducing chiral amplification in helical polymers; however, the induction of helical chirality in random coil polymers by the intermolecular noncovalent force in solutions so far is still an intractable task, which is almost only accomplishable in biopolymer systems. In this contribution, we found that a random coil poly(N-propargylamide) with an l- or d-alanine residue as the pendant (P-l(or -d)-ala-NH₂) can be induced to form a predominantly one-handed helical structure in an aqueous solution by complexing with metal ions, including Cu²⁺ and Ag⁺. The random coil to predominantly one-handed helix transformation and the chiral amplification therein were clearly evidenced by the remarkable red-shift of the UV–vis absorption peak, the occurrence of strong circular dichroism (CD), and the sharp increase in the absolute value of specific rotation. When Cu²⁺ was used as an inducer, the CD and UV–vis absorptions of P-l-ala-NH₂ were barely affected by heating and changing anions, demonstrating the high stability of the induced helical structure. The results obtained from CD, UV–vis, resonance Raman, Fourier transform infrared (FT-IR), and X-ray photoelectron spectroscopies and differential scanning calorimetry indicate that a contracted cis-cisoidal helical structure was formed in the polymer main chain through the generation of cis nearly square-planar complexes between each Cu²⁺ ion and the four nitrogens of two pendants. The metal ion coordination concurrently provided appropriate linkage among the pendants and reduced the pendant flexibility, thus endowing the main chain with helicity and triggering chiral amplification. Inspired by this mechanism, a universal and convenient methodology for preparing helical polymer/metal ion complexes and the corresponding chiral materials from random coil polymers may be established.

中文翻译：

通过水溶液中金属离子配位诱导的随机螺旋向单手螺旋转化的大分子手性扩增

在诱导螺旋聚合物中的手性扩增方面已经取得了许多令人鼓舞的成就。然而，迄今为止，溶液中的分子间非共价力在无规卷曲聚合物中诱导螺旋手性仍然是一项棘手的任务，几乎只能在生物聚合物系统中完成。在此贡献中，我们发现可以诱导以l-或d-丙氨酸残基为侧基的无规卷曲聚（N-炔丙基酰胺）（P- 1（或-d）-ala-NH ₂）通过与包括Cu ²⁺和Ag ⁺在内的金属离子络合，在水溶液中形成单螺旋结构。主要由单手螺旋转变和其中的手性放大组成的随机线圈通过明显的UV-vis吸收峰红移，强圆二色性（CD）的出现以及绝对值的急剧增加来清楚地证明特定旋转。若Cu ²⁺被用作诱导剂，在CD和UV-VIS P-的吸收升-Ala-NH ₂几乎不受加热和变化阴离子的影响，证明了诱导螺旋结构的高稳定性。从CD，UV-vis，共振拉曼光谱，傅立叶变换红外光谱（FT-IR）和X射线光电子能谱以及差示扫描量热法获得的结果表明，收缩的顺式-顺式螺旋结构通过聚合物主链形成。 Cu ²⁺之间的顺式近方平面复合物的生成离子和两个侧基的四个氮原子。金属离子配位同时提供了侧链之间的适当连接并降低了侧链的柔韧性，从而使主链具有螺旋性并引发手性扩增。受到这种机制的启发，可以建立一种通用且方便的方法，用于由无规卷曲聚合物制备螺旋聚合物/金属离子络合物和相应的手性材料。

更新日期：2020-07-28

点击分享查看原文

点击收藏

阅读更多本刊新发论文本刊介绍/投稿指南