一种具有螺旋功能的多开关聚二烯:了解光电和电化学控制
Klaudia Wagner1, Robert Byrne, Michele Zanoni
1ARC Centre of Excellence for Electromaterials Science and Intelligent Polymer Research Institute, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.
Journal of the American Chemical Society
|March 23, 2011
概括
合成了一种新型的酸替代聚二烯,通过酸异构化和聚合物氧化表现出多种彩色状态. 实现了对聚合物特性的电化学控制,导电率达到0.4 S cm(-1).
科学领域:
- 材料科学 材料科学 材料科学
- 聚合物化学 聚合物化学
- 电化学 电化学 电化学
背景情况:
- 聚二是电活性聚合物,在有机电子学中具有应用.
- 螺旋是光色和电色分子,可以经历可逆异体化.
- 将这些材料结合起来,可能会产生具有可调节性质的新型功能性聚合物.
研究的目的:
- 为了合成和表征一种新型的化替代聚二烯.
- 为了研究新聚合物的电化学和光谱电化学行为.
- 了解螺旋异构化和聚合物骨干电化学之间的相互作用.
主要方法:
- 用尼特罗斯皮洛替代的聚二烯单体和聚合物的合成.
- 电化学聚合和循环电压测量研究.
- 光谱电化学,扫描电子显微镜 (SEM) 和原子力显微镜 (AFM).
主要成果:
- 目标聚合物的成功合成,呈现多种彩色状态.
- 电化学氧化导致了螺旋的不可逆转的环开通,使其变成梅洛.
- 墨氨酸的形成在电化学上是不可逆转的,但可以通过光化学再生.
- 电化学氧化影响了螺旋的异构化效率,使得财产控制.
- SEM/AFM显示,螺旋的异体化到平面色素的结果是更光滑的薄膜.
- 独立的聚合物薄膜的导电性为0.4 S cm(-1).
结论:
- 合成的酸替代聚二烯提供可调节的电色特性.
- 电化学和光化学刺激可以控制聚合物的异构和性质.
- 这种材料显示出在电色设备和传感器中的应用潜力.
相关概念视频
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.