相关概念视频
01:07Nuclear Overhauser Enhancement (NOE)
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Irradiation of a spin-active nucleus causes an increase or decrease in the signal intensity of neighboring nuclei that are not necessarily chemically bonded or involved in J-coupling. This phenomenon, called the Nuclear Overhauser Enhancement (NOE), results from through-space interactions between the nuclear spins. The NOE effect decreases with increasing internuclear distance and is generally not observed beyond 4 angstroms. In NOE, dipole-dipole interactions between neighboring...
617
03:02Colors and Magnetism
11.5K
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...
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...
11.5K
02:52Stereoisomerism
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Isomerism in Complexes
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
Isomers are different chemical species that have the same chemical formula.
Transition metal complexes often exist as geometric isomers, in which the same atoms are connected through the same types of bonds but with differences in their orientation in space. Coordination complexes with two different ligands in the cis and trans positions from a ligand of interest form isomers. For example, the octahedral [Co(NH3)4Cl2]+ ion has two isomers (Figure 1) In the cis...
11.7K
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
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01:26Variables Affecting Phosphorescence and Fluorescence
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Fluorescence and phosphorescence are essential phenomena in fields like analytical chemistry, biological imaging, and materials science, where they detect molecular properties and visualize cellular structures. Understanding the variables that influence these luminescent behaviors is crucial for maximizing accuracy and efficiency in their applications. These variables can broadly be grouped into chemical structure, solvent properties, and external conditions, each playing a distinct role in...
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01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
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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.
2.0K
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双核异质 Erbium 复合物用于改善分子基础的光在溶液中的上转化?
Inès Taarit1, Quentin Sommer1, Laure Guénée2
1Department of Inorganic and Analytical Chemistry, University of Geneva, 30 Quai E. Ansermet, CH-1211 Geneva 4, Switzerland.
Inorganic chemistry
|February 21, 2025
概括
研究人员使用一种新型联体合成了双核复合体,以增强激发状态吸收 (ESA) 以提高光线转换. 双核复合体显示出显著的上升转换,但没有观察到有益的交叉放松效应.
科学领域:
- 协调化学 协调化学
- 材料科学 材料科学 材料科学
- 光物理学的光学物理学
背景情况:
- 基于分子的兴奋状态吸收 (ESA) 对光向上转换技术至关重要.
- 交叉放松 (CR) 是提高ESA效率的一种潜在机制.
- 兰化物复合物是发光材料的有希望的候选物.
研究的目的:
- 通过CR合成和表征双核兰坦化物复合物,用于通过CR增强ESA.
- 为了研究合成的添加物的结构,热力学和光物理性质.
- 为了评估二核复合体的上转换性能.
主要方法:
- 一种二三酸多芳合体 (L4) 的合成及其与兰坦化物载荷的反应 [Ln(hfac) 3].
- 双核 adducts 的晶体结构的确定 [L4Ln2(hfac) 6].
- 用二甲和近红外 (NIR) 激发状态吸收 (ESA) 上转换测量的热力学研究.
主要成果:
- 与二核复合体组成的二维分子支架的形成[L4Er2(hfac) 6].
- 双核复合体表现出ESA光上转换与蓝绿色的排放.
- 双核添加物的上转换量子产量和亮度明显超过单核中间体,但与相关的单体添加物相比较.
结论:
- 合成的双核复合体显示出高效的光向上转换.
- 在双核复合体中没有观察到明确的有益交叉放松 (CR) 效应.
- 这项研究提供了对以兰他尼德为基础的上转换材料的结构性质关系的见解.