通过前所未有的异环合反应,通过导电型聚二烯的固态合成
Hong Meng1, Dmitrii F Perepichka, Michael Bendikov
1Department of Chemistry and Biochemistry and the Exotic Materials Institute, Microfabrication Lab, University of California, Los Angeles, California 90095-1569, USA.
Journal of the American Chemical Society
|December 5, 2003
概括
温和加热或长时间储存晶体的2,5-二-3,4-乙烯二氧化 (DBEDOT) 诱导固态聚合 (SSP) 形成高导电性聚-3,4-乙烯二氧化 (PEDOT). 这种方法在柔性塑料上产生导电性PEDOT薄膜.
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
- 有机电子 有机电子
背景情况:
- 聚3,4-乙烯二氧化烯 (PEDOT) 是一种高导电性聚合物,在有机电子中具有应用.
- 传统的PEDOT合成方法可能很复杂,可能不会产生最佳导电性或膜性质.
- 探索PEDOT的新型聚合路径对于提高其性能和适用性至关重要.
研究的目的:
- 为了研究2,5-dihalo-3,4-ethylenedioxythiophene (DHEDOT) 衍生物的固态聚合 (SSP).
- 通过SSP.确定实现高导电性PEDOT的最佳条件.
- 评估在柔性基板上制造导电PEDOT薄膜的可行性.
主要方法:
- 晶体DBEDOT,DCEDOT和DIEDOT经过长时间的储存和热处理.
- 固态NMR,FTIR,CV,Vis-NIR,ESR,DSC,显微镜和重力测量分析被用于表征.
- 使用X射线结构分析来了解二甲中的分子包装.
- 在得到的PEDOT材料和片上进行了导电性测量.
主要成果:
- 长时间储存或温和加热 (50-80°C) 的DBEDOT导致高导电性,添加PEDOT通过SSP.
- 对DCEDOT没有观察到SSP,对DIEDOT需要更高的温度 (>130°C).
- X射线分析显示了DBEDOT和DIEDOT中的短素-素距离,促进了SSP.
- 对于DBEDOT,观察到外热SSP反应 (14kcal/mol) 的激活能量为~26kcal/mol.
- SSP-PEDOT的导电率为20-80S/cm,通过兴奋剂进一步增强.
- 在柔性塑料表面上制造了高达20S/cm的导电性PEDOT薄膜.
结论:
- 固态聚合DBEDOT是一种有效的生产高导电性PEDOT的方法.
- 双二的分子结构和包装显著影响它们对SSP的倾向.
- 这种SSP方法为制造用于电子应用的柔性基板上的导电PEDOT薄膜提供了可行的途径.
相关概念视频
Thermal 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.
Thermal 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.
Photochemical 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
Cycloaddition Reactions: Overview
Cycloadditions are one of the most valuable and effective synthesis routes to form cyclic compounds. These are concerted pericyclic reactions between two unsaturated compounds resulting in a cyclic product with two new σ bonds formed at the expense of π bonds. The [4 + 2] cycloaddition, known as the Diels–Alder reaction, is the most common. The other example is a [2 + 2] cycloaddition.
[4+2] Cycloaddition of Conjugated Dienes: Diels–Alder Reaction
The Diels–Alder reaction is an example of a thermal pericyclic reaction between a conjugated diene and an alkene or alkyne, commonly referred to as a dienophile. The reaction involves a concerted movement of six π electrons, four from the diene and two from the dienophile, forming an unsaturated six-membered ring. As a result, these reactions are classified as [4+2] cycloadditions.
Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.


![Solid-phase Synthesis of [4.4] Spirocyclic Oximes](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F58508.jpg&w=3840&q=50)