2,2'-ビピリミジン・ラジカル・ブリッジド・ディランタニド・コンプレックスにおける交換結合と磁気緩解に対する置換効果
Colin A Gould, Edward Mu, Veacheslav Vieru1
1Theory of Nanomaterials Group, Katholieke Universiteit Leuven, Celestijnenlaan 200F, 3001 Leuven, Belgium.
Journal of the American Chemical Society
|December 16, 2020
まとめ
研究者は代替剤を変化させることで 根性ブリッジされたランタニド複合体における磁気結合を調整した. ガドリニウム複合体におけるより強い結合は,ディスプロシウム単分子磁石における磁気緩和のためのより高いエネルギーバリアをもたらした.
科学分野:
- 協調化学
- 材料科学
- マグネティズム
背景:
- 強化された性質を持つ単分子磁石 (SMM) の設計には,関連する化合物の体系的な研究が必要です.
- 強力な磁気結合を持つ多核ランタニド複合体は,高度な磁気材料にとって不可欠ですが,あまり研究されていません.
- ラジカルブリッジされたランタニド複合体は 調節可能な磁気特性を有する.
研究 の 目的:
- ダイランタニド複合体を合成し 磁気的に特徴づけること
- ブリッジングリガンド置換剤が磁気交換カップリングに与える影響を調査する.
- ディスプロシウムベースの単分子磁石の性能と磁気結合を相関させる.
主な方法:
- ブリッジング 2,2'-ビピリミジン・リガンドの様々な置換剤によるディランタニド複合塩の合成.
- 磁気感受性とリラックスダイナミクスの測定を含む磁気特性.
- 磁気交換コップリング定数 (J) とエネルギーバリア (U_eff) の分析
主要な成果:
- ガドリニウム複合体における磁気交換結合定数 (J_Gd-rad) は,置換素を修正することで−2.7から−11.1cm−1まで調節可能であった.
- 電子を取り除く置換物質は交換結合を強化し,電子を寄付するグループはそれを弱めた.
- より強いJ_Gd-radは,より大きな熱的障壁 (U_eff),より高い温度磁気ヒステレス,およびディスプロシウムアナログのより遅いリラックスと相関する.
結論:
- ディスプロシウムSMMにおけるU_effと,対応するガドリニウム複合体におけるJ_Gd-radの間の線形相関が確立された.
- このモデルは,電子構造と 根性ブリッジ分子のための設計原理の洞察を提供します.
- この発見は,より高い動作温度を持つSMMの設計のための明確な基準を提供します.
さらに関連する動画
04:51Author Spotlight: Functionalizing Metal-Organic Frameworks: Advancements, Challenges, and the Power of Post-Synthetic Ligand Exchange
Published on: June 23, 2023
3.8K
07:24Hyperspectral Imaging as a Tool to Study Optical Anisotropy in Lanthanide-Based Molecular Single Crystals
Published on: April 14, 2020
18.1K
関連する概念動画
01:27π Electron Effects on Chemical Shift: Overview
1.4K
An applied magnetic field causes loosely bound π-electrons in organic molecules to circulate, producing a local or induced diamagnetic field over a large spatial volume. As the molecules tumble in solution, the field generated by π-electrons in spherical substituents results in a zero net field. However, the net field generated by π-electrons in non-spherical substituents is not zero. The effect of this induced field depends on the orientation of the molecule with respect to B0,...
1.4K
01:14π Electron Effects on Chemical Shift: Aromatic and Antiaromatic Compounds
1.5K
In aromatic compounds, such as benzene, the circulation of (4n + 2) π-electrons sets up a diamagnetic or diatropic ring current around the perimeter of the molecule. This current induces a magnetic field that opposes the external field inside the ring and reinforces it on the outside. The protons in benzene are deshielded and exhibit high chemical shifts in the range 6.5–8.5 ppm. The shielding effect at the center of the ring is evident in complex aromatic molecules, such as...
1.5K
01:20Spin–Spin Coupling: Two-Bond Coupling (Geminal Coupling)
1.3K
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...
1.3K
02:42Valence Bond Theory
10.3K
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...
10.3K
01:19Complexation Equilibria: The Chelate Effect
894
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...
894
03:02Colors and Magnetism
13.0K
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...
13.0K