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相关概念视频

Thermal Electrocyclic Reactions: Stereochemistry01:17

Thermal Electrocyclic Reactions: Stereochemistry

2.0K
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.
2.0K
Complexation Equilibria: The Chelate Effect01:19

Complexation Equilibria: The Chelate Effect

468
In complexation reactions, metal atoms or cations interact with ligands to form donor-acceptor adducts called metal complexes. Ligands that bind through one donor site are monodentate, ligands with two donor sites are bidentate, and those with more than two donor sites are polydentate ligands. For example, ethylene diamine is a bidentate ligand that binds through two nitrogen donor atoms, forming a five-membered ring. EDTA is a polydentate ligand that binds through four oxygen and two nitrogen...
468
Directing Effect of Substituents: meta-Directing Groups01:09

Directing Effect of Substituents: meta-Directing Groups

4.5K
Substituents on the benzene ring that direct an incoming electrophile to undergo substitution at the meta position are called meta directors. All meta directors either have a positive charge on the atom directly bonded to the ring or a partial positive charge. These groups function by withdrawing electrons from the ring through inductive and resonance effects. Consider the carbocation intermediates formed upon the addition of an electrophile on nitrobenzene at the...
4.5K
ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH301:11

ortho–para-Directing Activators: –CH3, –OH, –⁠NH2, –OCH3

5.8K
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
5.8K
Properties of Organometallic Compounds01:23

Properties of Organometallic Compounds

956
Organometallic compounds are compounds that contain a carbon–metal bond. Carbon belongs to an organyl group like alkyl, aryl, allyl, or benzyl groups. The metal can be from Group I or Group II of the periodic table, a transition metal, or a semimetal.
956
Complexation Equilibria: Factors Influencing Stability of Complexes01:09

Complexation Equilibria: Factors Influencing Stability of Complexes

345
In complexation reactions, metal cations are the electron pair acceptors, and the ligands are the electron pair donors. The stability of the metal complexes depends primarily on the complexing ability of the central metal ion and the nature of the ligands. Generally, the complexing ability of the metal ion depends on the size and charge of the ion. As the metal ion size increases, the stability of the metal complexes decreases, provided that the valency of the metal ion and the ligands remain...
345

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Updated: Jun 9, 2025

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
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通过静电相互作用指导有机金属环链平衡.

Rujia Hou1, Yuhong Gao1, Yuan Guo1

  • 1Interdisciplinary Materials Research Center, School of Materials Science and Engineering, Tongji University, Shanghai 201804, People's Republic of China.

ACS nano
|October 30, 2024
PubMed
概括
此摘要是机器生成的。

研究人员通过操纵静电相互作用来控制表面上的动态共价化学. 这一突破允许创建可适应的纳米结构,弥合共价化学和超分子化学.

关键词:
密度函数理论密度函数理论动态共价化学 动态共价化学在表面的化学物质.环链平衡是指环链的平衡.扫描道显微镜扫描道显微镜

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Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs
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相关实验视频

Last Updated: Jun 9, 2025

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
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科学领域:

  • 超分子化学 超分子化学
  • 协价化学 协价化学 协价化学
  • 材料科学 材料科学 材料科学

背景情况:

  • 动态共价化学提供了独特的特性,如适应性和自我愈合.
  • 目前的方法通常依赖于内部因素,限制对纳米结构动态的外部控制.
  • 使用外部刺激指导基于表面的动态共价化学仍然是一个重大挑战.

研究的目的:

  • 在表面上可控地指导共价有机金属结构的环链平衡.
  • 通过外部相互作用实现表面动态共价化学.
  • 了解控制动态共价聚合物的亚分子机制.

主要方法:

  • 使用超高真空 (UHV) 条件进行表面研究.
  • 调节分子间静电相互作用以控制共价纳米结构动力学.
  • 在有机金属结构中研究环链平衡.

主要成果:

  • 通过静电相互作用证明了环链平衡的可控操纵.
  • 在超高温条件下实现了表面动态共价化学.
  • 在亚分子层面揭示了共价聚合物的动态机制.

结论:

  • 通过外部静电相互作用成功指导了表面动态共价化学.
  • 弥合了超分子和共价化学之间的差距.
  • 铺平了制造适应性聚合物纳米结构的道路,以响应外部条件.