曲的多环芳香分子是对hexabenzocoronene的π-异电子
Jiye Luo1, Xiaomin Xu, Renxin Mao
1Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
Journal of the American Chemical Society
|July 26, 2012
概括
研究人员通过修改六enzocoronene (HBC) 和六zoperylene (HBP) 结构,合成了新的曲π分子,包括形和扭曲的符合性分子. 这些分子表现出独特的电子特性和结构性行为,为有机半导体设计提供了新的途径.
科学领域:
- 有机化学 有机化学
- 材料科学 材料科学 材料科学
- 超分子化学 超分子化学
背景情况:
- 平面多环芳,如六enzocoronene (HBC) 是有机电子的基础.
- 控制分子几何学,特别是π系统平面性,对于调整电子和光物理性质至关重要.
- 引入非平面性可以导致新的分子架构和功能.
研究的目的:
- 为了合成和描述新型曲线π分子的异电子到hexabenzocoronene (HBC).
- 研究由嵌入的七个成员环或固体拥挤引起的非平面性对分子结构,刚性和构造的影响.
- 探索这些曲线分子的结构-属性关系,包括π-π相互作用和半导体行为.
主要方法:
- 在六烯基支架上合成具有基组的新型曲π分子 (1, 2a, b).
- 使用光谱和晶体学技术进行结构性表征.
- 研究热异构化,热力学和适配体的动力学.
- 薄膜晶体管的制造和表征,以评估半导体性能.
主要成果:
- 成功合成了一种形分子 (1) 和六二烯衍生物 (2a,b) 的扭曲/反折合体.
- 分子1表现出硬度,尽管曲率中等,而衍生品2a,b显示出形态同质性 (扭曲与反折叠).
- 2b的扭曲同位素作为p型半导体起作用,而分子1由于缺乏π-π相互作用而具有绝缘性.
- π面的曲率会影响边界分子轨道能量水平和分子间相互作用.
结论:
- 分子曲率显著影响有机半导体中的π-π相互作用和电子特性.
- 曲线π系统的设计提供了一种控制分子包装和电荷运输的策略.
- 了解形态动态和π堆叠对于开发下一代有机电子材料至关重要.
相关概念视频
01:18Aromatic 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...
01:13Five-Membered Heterocyclic Aromatic Compounds: Overview
Heterocyclic aromatic compounds are cyclic compounds that are aromatic and have one or more heteroatoms—atoms other than carbon, in the ring. Depending upon the number of atoms present in the ring, they can be either five or six-membered. Examples of five-membered heterocyclic aromatic compounds include pyrrole, furan, thiophene, and imidazole. Pyrrole consists of one nitrogen atom having one lone pair of electrons. Furan and thiophene have one oxygen and one sulfur heteroatom, respectively.
01:18Aromatic Hydrocarbon Anions: Structural Overview
Neutral hydrocarbons like cyclopentadiene with an odd number of carbon atoms and one intervening CH2 group in the ring are not aromatic. Cyclopentadiene with 4 π electrons does not satisfy the 4n + 2 π electron rule. Additionally, the intervening CH2 group is sp3 hybridized and lacks a vacant p orbital, thereby interrupting the overlap of p orbitals in a continuous manner and preventing the delocalization of π electrons throughout the ring.
Due to the absence of continuous overlap of p...
Due to the absence of continuous overlap of p...
01:18Frost Circles for Different Conjugated Systems
The inscribed polygon method is consistent with Hückel’s 4n + 2 rule and helps to learn whether the given cyclic compound is aromatic or not. The compound is stable and aromatic if every bonding molecular orbital (MO) is completely filled with a pair of electrons. However, if the non-bonding or antibonding orbitals are filled with electrons, the compound is unstable and not aromatic. Consider the Frost circle diagrams for cycloalkenes containing 4 to 8 carbons.
01:20Criteria 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.
01:18Structure of Benzene: Molecular Orbital Model
According to the molecular orbital (MO) model, benzene has a planar structure with a regular hexagon of six sp2 hybridized carbons. As shown in Figure 1, each carbon is bonded to three other atoms with C–C–C and H–C–C bond angles of 120°. The C–H bond length is 109 pm, and the C–C bond length is 139 pm which is midway between the single bond length of sp3 hybridized carbons (154 pm) and sp2 hybridized carbons (133 pm).