作为化学键的相互转换观察到的动态旋转-旋转相互作用
Katsuya Mutoh1, Shota Toshimitsu1, Yoichi Kobayashi2
1Department of Chemistry, Aoyama Gakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa 252-5258, Japan.
Journal of the American Chemical Society
|August 24, 2021
概括
这项研究探讨了双光色分子中的动态自旋相互作用,揭示了多个自旋系统如何通过阶段性光色反应和键重组演变. 了解这些复杂的行为是开发具有合作自旋特性的新有机多基的关键.
科学领域:
- 有机化学
- 材料科学
- 摄影化学
背景情况:
- π 结合的有机分子中的比拉迪卡洛因对于理解化学键和独特的光学,电学和磁性属性至关重要.
- 灵活的比拉迪卡洛伊德中的动态旋转互动与分子结构变化相关,为结构-属性关系提供了洞察力.
- 之前关于动态旋转行为的研究仅限于双旋转系统.
研究的目的:
- 研究具有多个自旋相互作用的双光色分子的渐进光色特性.
- 阐明这些复杂系统中的动态旋转互动和键重组.
- 将单基双体理解为有机多基和散装材料中的合作旋转行为.
主要方法:
- 使用双脉冲激光闪光光学分析来研究渐进的光色反应.
- 通过单光子吸收和热异构化分析了二基和形形式的生成.
- 研究未配对旋转对不同形结构的形成的影响.
主要成果:
- 一个光子的光色反应产生一个o-比基形式,它以o-形形式变异.
- 进一步的光激发导致在p位置的不配对旋转,影响p-形或bis-形的形成.
- 通过与o-biradicals的抗铁磁相互作用观察到p-quinoidal形式的偏好形成,并从o-quinoidal形式生成bis.
结论:
- 这项研究证明了具有多个旋转中心的双光色分子中的阶段性光色和动态旋转互动.
- 这些发现加深了对单基双体及其在制造有机多基体方面的理解.
- 这项研究为设计具有可控合作旋转行为的材料铺平了道路.
更多相关视频
相关概念视频
01:26Photochemical Electrocyclic Reactions: Stereochemistry
2.0K
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
2.0K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.2K
Two NMR-active nuclei bonded to a central atom can be involved in geminal or two-bond coupling. Geminal coupling is commonly seen between diastereotopic protons in chiral molecules and unsymmetrical alkenes, among others.
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
The central atom need not be NMR-active because its electrons are affected by the electron polarization of the spin-active atoms. However, spin information is transmitted less effectively than in one-bond coupling, and 2J values are usually weaker than 1J values. The energy of...
1.2K
01:22Spin–Spin Coupling: Three-Bond Coupling (Vicinal Coupling)
1.2K
Vicinal or three-bond coupling is commonly observed between protons attached to adjacent carbons. Here, nuclear spin information is primarily transferred via electron spin interactions between adjacent C‑H bond orbitals. This generally favors the antiparallel arrangement of spins, so 3J values are usually positive.
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
The extent of coupling depends on the C‑C bond length, the two H‑C‑C angles, any electron-withdrawing substituents, and the dihedral angle between the...
1.2K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.6K
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.
2.6K
01:25Deactivation Processes: Jablonski Diagram
1.1K
Luminescence, the emission of light by a substance that has absorbed energy, is a process that involves the interaction of molecules with light. The energy-level diagram, or Jablonski diagram, is a graphical representation of these interactions, illustrating the various states and transitions a molecule can undergo. In a typical Jablonski diagram, the lowest horizontal line represents the ground-state energy of the molecule, which is usually a singlet state. This state represents the energies...
1.1K
01:08Spin–Spin Coupling Constant: Overview
1.1K
In bromoethane, the three methyl protons are coupled to the two methylene protons that are three bonds away. In accordance with the n+1 rule, the signal from the methyl protons is split into three peaks with 1:2:1 relative intensities. The methylene protons appear as a quartet, with the relative intensities of 1:3:3:1.
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
Qualitatively, any spin plus-half nucleus polarizes the spins of its electrons to the minus-half state. Consequently, the paired electron in the hydrogen–carbon bond must...
1.1K