![Measuring the Spin-Lattice Relaxation Magnetic Field Dependence of Hyperpolarized [1-13C]pyruvate](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F59399.jpg&w=3840&q=50)
テトラエドール複合体[Co(SPh) ]4−2−4におけるゼロフィールドでのゆっくりとした磁気放松
Joseph M Zadrozny1, Jeffrey R Long
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|December 7, 2011
まとめ
四面体コバルト複合体は単一分子磁石の振る舞いを示し,低温では温度に依存しないリラックス,高温では熱的に活性化された振る舞いを示しています. 希釈の研究は,分子間相互作用が量子トンネリングを媒介することを明らかにしています.
科学分野:
- 無機化学 無機化学とは
- マテリアルサイエンス 材料科学
- 量子物理学とは,量子物理学のことです.
背景:
- 単分子磁石 (SMM) は,高密度データストレージと量子コンピューティングの開発に不可欠です.
- 磁気リラクゼーションのダイナミクスと,SMMの行動に影響を与える要因を理解することは,その実用的な応用に不可欠です.
- テトラエドール調整環境を持つコバルト複合体は,その電子特性により,SMMの潜在的な候補である.
研究 の 目的:
- テトラエドール複合体のPh(4) P(+) 塩の単分子磁石の振る舞いを調査する [Co(SPh) ((4)) ((2-).
- 温度依存と量子トンネリングを含む磁気リラックスメカニズムを解明する.
- 観測された磁気特性における分子間相互作用の役割を決定する.
主な方法:
- [Co ((SPh)) ((4))) ((2-)) 複合体の合成と特徴付け.
- ダイナミックな磁気特性を探査するために,磁気感受性の測定を行う.
- 適用された磁場の下での可変温度磁気の研究.
- 同型亜鉛複合マトリックスを用いた希釈実験.
主要な成果:
- [Co (((SPh)) ((4))) ((2-)) 複合体は,S = 3/2の基底状態と軸性ゼロフィールド分割 (D = -70 cm ((-1)) との単分子磁石の振る舞いを示す.
- 磁気緩和は,非常に低い温度では温度に関係なく,量子トンネリングの兆候であり,2.5 K (U(eff) = 21(1) cm(-1), τ(0) = 1.0(3) × 10(-7) s) 以上のアレニウスの行動に従っています.
- 適用された磁場 (1 kOe) は,より広い温度範囲でアレニウスの行動を促進します.
- 希釈の研究は,分子間二極相互作用が低温量子トンネリング経路を媒介することを示唆しています.
結論:
- [Co ((SPh)) ((4))) ((2-)) 複合体は単一分子磁石として機能します.
- 量子トンネリングは,低温で重要なリラックス経路であり,分子間相互作用の影響を受ける可能性が高い.
- SMMの性能を最適化し,実用的なアプリケーションのためのトンネリングを抑制するために,分子設計に関するさらなる研究が必要です.
さらに関連する動画
09:25NMR 15N Relaxation Experiments for the Investigation of Picosecond to Nanoseconds Structural Dynamics of Proteins
Published on: November 1, 2024
06:53Magnetometric Characterization of Intermediates in the Solid-State Electrochemistry of Redox-Active Metal-Organic Frameworks
Published on: June 9, 2023
関連する概念動画
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.
01:23Atomic Nuclei: Nuclear Relaxation Processes
In the absence of an external magnetic field, nuclear spin states are degenerate and randomly oriented. When a magnetic field is applied, the spins begin to precess and orient themselves along (lower energy) or against (higher energy) the direction of the field. At equilibrium, a slight excess population of spins exists in the lower energy state. Because the direction of the magnetic field is fixed as the z-axis, the precessing magnetic moments are randomly oriented around the z-axis. This...
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...
01:28Atomic Nuclei: Types of Nuclear Relaxation
Nuclear relaxation restores the equilibrium population imbalance and can occur via spin–lattice or spin–spin mechanisms, which are first-order exponential decay processes.
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...
In spin–lattice or longitudinal relaxation, the excited spins exchange energy with the surrounding lattice as they return to the lower energy level. Among several mechanisms that contribute to spin–lattice relaxation, magnetic dipolar interactions are significant. Here, the excited nucleus transfers energy to a nearby...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Tetrahedral Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
02:58Crystal Field Theory - Octahedral Complexes
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...