在 perylenediimides 中进入三重激发状态
Aaron A Rachford1, Sébastien Goeb, Felix N Castellano
1Department of Chemistry and Center for Photochemical Sciences, Bowling Green State University, Bowling Green, Ohio 43403, USA.
Journal of the American Chemical Society
|February 14, 2008
概括
研究人员开发了新的 ((II) 复合物与PDI部分,访问PDI三重组组,同时保持着染料特性. 这些复合体表现出灭的光,并表现出明显的三重状态寿命.
科学领域:
- 协调化学 协调化学
- 光物理学的光学物理学
- 材料科学 材料科学 材料科学
背景情况:
- 二胺 (PDI) 染料以出色的坚固性和光吸收性而闻名.
- 访问PDI的三重状态对于光动力学疗法和有机电子等应用至关重要.
- 以前的方法常常会损害PDI染料的理想性质.
研究的目的:
- 为了合成新的 (II) 复合物,其中包括PDI部分.
- 调查这些Pt(II) -PDI复合物的光物理性质,重点是三重状态访问.
- 为了保持PDI染料固有的坚固性和吸光特性.
主要方法:
- 通过乙化物桥梁连接PDI单元的三个新的Pt (II) 复合物的合成和结构特征.
- 纳米秒激光闪光光分解研究激发状态动态.
- 使用 thioxanthone 的三重状态敏感化实验.
主要成果:
- 成功合成和表征了Pt (II) -PDI复合体.
- PDI的单一状态光在与Pt ((II)) 结合时被定量灭.
- 跨复合体的短暂吸收光谱相似,具有明显的单指数三重生命周期 (246 ns,1.0 μs,710 ns).
- 通过敏感化实验证实了三重组状态的分配.
结论:
- 建立了一个在Pt(II) 综合体中访问PDI三重组分组的策略.
- 合成的复合物保持了理想的PDI染料特性.
- 这项研究为潜在的应用提供了对Pt(II) -PDI系统光物理学的见解.
相关概念视频
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
01:26Thermal 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.
01:18Aromatic 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...
01:17Thermal 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.
01:34Woodward–Hoffmann Selection Rules and Microscopic Reversibility
Electrocyclic reactions, cycloadditions, and sigmatropic rearrangements are concerted pericyclic reactions that proceed via a cyclic transition state. These reactions are stereospecific and regioselective. The stereochemistry of the products depends on the symmetry characteristics of the interacting orbitals and the reaction conditions. Accordingly, pericyclic reactions are classified as either symmetry-allowed or symmetry-forbidden. Woodward and Hoffmann presented the selection criteria for...
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
Some cycloaddition reactions are activated by heat, while others are initiated by light. For example, a [2 + 2] cycloaddition between two ethylene molecules occurs only in the presence of light. It is photochemically allowed but thermally forbidden.