![[(DPEPhos)(bcp)Cu]PF6: A General and Broadly Applicable Copper-Based Photoredox Catalyst](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59739.jpg&w=3840&q=50)
可逆铜 (II) /I) 电化学电位切换由可见光诱导的协调环旋转驱动
Michihiro Nishikawa1, Kuniharu Nomoto, Shoko Kume
1Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.
Journal of the American Chemical Society
|May 29, 2012
概括
这项研究引入了一种新型的铜复合体,通过光燃料分子旋转将光能转化为电子信号. 该系统通过利用双稳态和电化学电位变化来证明可重复的信号提取.
科学领域:
- 协调化学 协调化学
- 摄影化学的使用.
- 分子电子学分子电子学
背景情况:
- 内部分子连接体旋转可以与金属复合体中的电子状态相结合.
- 为了利用光能进行分子切换,需要高效的能量转换机制.
研究的目的:
- 开发一种金属复杂系统,通过光燃料的分子内旋转来提取电子信号.
- 为了研究一个铜复合体中电子转移和分子运动之间的关系.
主要方法:
- 一个铜 (I) 复合物的合成,其中包含一个胺基衍生物和一个二胺基连接体.
- 在可变温度下使用循环电压计进行电化学分析.
- 研究氧化还原和旋转反应动力学和热力学.
主要成果:
- 铜复合体表现出与联结体旋转相关的双稳态,由铜氧化状态控制.
- 带旋转在铜 (I) 状态下被结,但在低温下在铜 (II) 状态下活跃.
- 光和热可以驱动旋转,导致显著的电化学电位转移 (0.14V).
- 通过铜的中间体确定了一条绕过路径,通过铜的中间体进入一个转移性铜 (I) 状态.
结论:
- 开发的铜复合体代表了从光燃料分子旋转中反复提取电子信号的第一个系统.
- 这项工作提供了一个基于光能转换和电化学电位移的新分子信号系统.
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.
01:17Thermal 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.
03:02Colors and Magnetism
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human eye.
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.
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...