奥利戈3-基thiophene (3HT) s (3HT) n 的热和结构特性,n = 4-36
Felix Peter Vinzenz Koch1, Martin Heeney, Paul Smith
1Department of Materials, Eidgenössische Technische Hochschule (ETH) Zürich , Wolfgang-Pauli-Strasse 10, 8093 Zurich, Switzerland.
Journal of the American Chemical Society
|August 21, 2013
概括
奥利戈3-基thiophene) 呈现两个固态结构,具有不同的热性能. 处理条件可以控制这些多态之间的转换,影响材料的行为.
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
- 固态物理 固态物理
背景情况:
- 区域常规的基基基基 (3HT) 是研究聚基基基基 (P3HT) 的模型化合物.
- 了解它们的固态结构和热特性对于开发有机电子材料至关重要.
研究的目的:
- 为了研究不同链长度 (n=4-36) 的基3-基thiophene的热和结构特性.
- 识别不同的固态多态及其热力学和运动性质.
- 探索这些多态体之间的相互转换及其与P3HT的相关性.
主要方法:
- 单分散的合成,区域常规的基基基基基基基) s.
- 差分扫描热量计 (DSC) 用于热分析 (融温度,融热量).
- 用X射线衍射 (XRD) 或类似的技术来描述固态结构.
- 控制的加工处理以诱导多态互转换.
主要成果:
- 确定了两种不同的固态多态 (Form I和Form II),它们在六侧链互数字化上有所不同.
- 与I型 (~298°C) 相比,II型具有显著较低的化温度 (~116°C) 和较高的化度.
- 从热力学偏好的II形式到动力学偏好的I形式的交叉发生在n=12.
- 在10 ≤ n ≤ 21的范围内的Oligo(3-hexylthiophene) 可以通过加工在多态体之间可逆转换.
结论:
- 这项研究揭示了对基3-基烯多态性的关键见解,突出了链条长度和加工的影响.
- 这些发现提供了对P3HT相关的结构-财产关系的基本理解.
- 通过处理对多态的控制为调整有机半导体设备的性能提供了潜力.
相关概念视频
Aromatic Hydrocarbon Cations: Structural Overview
Cycloheptatriene is a neutral monocyclic unsaturated hydrocarbon that consists of an odd number of carbon atoms and an intervening sp3 carbon in the ring. The three double bonds in the ring correspond to 6 π electrons, which is a Huckel number, and therefore satisfies the criteria of 4n + 2 π electrons. However, the intervening sp3 carbon disrupts the continuous overlap of p orbitals. As a result, cycloheptatriene is not aromatic.
Removing one hydrogen from the intervening CH2 group with both...
Removing one hydrogen from the intervening CH2 group with both...
Criteria for Aromaticity and the Hückel 4n + 2 Rule
Like benzene, cyclobutadiene and cyclooctatetraene are cyclic compounds with alternate single and double bonds. However, their chemical behavior differs from benzene, as they are unstable and not aromatic. So, what are the structural characteristics of unsaturated compounds categorized as aromatic?
For the first time, Eric Hückel, a German chemical physicist, derived a set of structural features for a compound to be classified as aromatic. This is now known as Hückel’s rule or the 4n + 2 rule.
For the first time, Eric Hückel, a German chemical physicist, derived a set of structural features for a compound to be classified as aromatic. This is now known as Hückel’s rule or the 4n + 2 rule.
Structure and Nomenclature of Thiols and Sulfides
Thiols and sulfides are sulfur analogs of alcohols and ethers, respectively, where the sulfur atom takes the place of the oxygen atom. Thus, thiols are generally represented as RSH, where R is an alkyl substituent and —SH is the functional group. On the other hand, in sulfides, the central sulfur atom is bonded to two hydrocarbon groups on either side. Depending upon the type of group, sulfides can be either symmetrical or asymmetrical. Both thiols and sulfides display a bent geometry, similar...
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.
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.
π Molecular Orbitals of 1,3-Butadiene
Conjugated dienes have lower heats of hydrogenation than cumulated and isolated dienes, making them more stable. The enhanced stabilization of conjugated systems can be understood from their π molecular orbitals.
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...
The simplest conjugated diene is 1,3-butadiene: a four-carbon system where each carbon is sp2-hybridized and has an unhybridized p orbital that contains an unpaired electron. According to molecular orbital theory, atomic orbitals combine to form molecular orbitals such that the number...


