在双分子光诱导电子转移中控制封闭和开放金属复合物的逃产率的因素
Alexia Ripak1, Ana Karem Vega Salgado1, Danillo Valverde2
1Molecular Chemistry, Materials and Catalysis (MOST), UCLouvain, Institut de la Matière Condensée et des Nanosciences (IMCN), Place Louis Pasteur 1/L4.01.02, B-1348 Louvain-la-Neuve, Belgium.
Journal of the American Chemical Society
|July 30, 2024
概括
在11种溶剂中研究了光敏剂的脱产量. (III) 复合物显示出最高的产量,表明它们在光氧化催化中的潜力,而铁 (III) 复合物显示出最高的产量.
科学领域:
- 光化学和光物理
- 催化剂
- 物理化学
背景情况:
- 了解激发状态电子转移对于开发高效的光催化剂至关重要.
- 双基对重组对反应结果产生重大影响.
- 溶剂效应在控制电荷分离和重组动态方面发挥着至关重要的作用.
研究的目的:
- 为了研究不同溶剂中的各种金属光敏剂 (Fe (III),Ru (II),Ir (III)) 的逃产量.
- 阐明光敏剂电子结构 (封闭外与开放外) 和溶剂介电性质对子逃逸产量的影响.
- 为优化光催化剂性能提供指导方针.
主要方法:
- 使用六种不同的光敏感剂 (Fe(III),Ru(II),Ir(III)) 和三聚胺作为电子捐赠物的逃产量的实验研究.
- 溶剂极性 (11 种溶剂) 的系统变化以探测介电效应.
- 对自旋动力学 (系统间交叉) 和电荷重组路径的分析.
主要成果:
- (III) 光敏剂的脱率最高 (0.67-1),表明其具有极好的光催化潜力.
- (II) 和 (II) 光敏剂的产量中等至良好 (分别为0.65和0.38左右).
- 铁 (III) 光敏剂在高压电常数溶剂中表现出低产量 (<0.1),但在低压电常数溶剂中显著增加 (高达0.58),这归因于闭复合体中的自旋禁止重组与开复合体中的自旋允许重组.
结论:
- 逃生产量高度依赖于光敏剂的电子配置和溶剂环境.
- 由于自旋禁止重组,封闭外光敏化剂 (Ir(III,Ru(II)) 产生高逃脱效率,独立于溶剂介电效应.
- 开光敏感剂 (Fe(III)) 显示溶剂依赖的产量,为光电还原催化在低电介质中的调反应提供了机会.
相关概念视频
01:26Photochemical Electrocyclic Reactions: Stereochemistry
1.8K
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
1.8K
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
2.3K
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.
2.3K
01:09Complexation Equilibria: Factors Influencing Stability of Complexes
353
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...
353
01:19Complexation Equilibria: The Chelate Effect
491
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...
491
02:58Crystal Field Theory - Octahedral Complexes
26.3K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
26.3K
02:45E2 Reaction: Kinetics and Mechanism
10.1K
SN2 substitutions and E2 eliminations of alkyl halides proceed via a concerted pathway. While the nucleophile attacks the alpha carbon in SN2 reactions, it functions as a strong base and abstracts a beta hydrogen in the E2 mechanism. The rate-limiting transition state in E2 elimination reactions is characterized by partially broken carbon–hydrogen and carbon–halogen bonds and a partially formed pi bond between the alpha and beta carbons. The beta hydrogen and halide are eliminated...
10.1K