金属からポリオキシメタレートへの電荷移転分子クロモフォアの合成と特徴付け
Chongchao Zhao1, Zhuangqun Huang, William Rodríguez-Córdoba
1Department of Chemistry and Cherry L. Emerson Center for Scientific Computation, Emory University, Atlanta, Georgia 30322, USA.
Journal of the American Chemical Society
|November 19, 2011
まとめ
研究者は,共振性W-O-Re結合を持つ,ポリオキソメタラートで支えられた新しいレニウム複合体を合成した. この複合体は,強い可視光吸収を示し,刺激時に急速な電子移転を経験します.
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
- フォトケミストリー フォトケミストリー
背景:
- ポリオキソメタラート (POM) は,調節可能な電子および構造的特性を有する多用途の無機クラスターです.
- レーニウム複合体は,光物理学的および触媒的応用で知られている.
- POMと移行金属を組み合わせると,ユニークな機能を持つ新しい材料が生成されます.
研究 の 目的:
- ウェルズ・ダウソンのポリオキソメタラートで支えられた新しいレニウム複合体を合成し,特徴づけること.
- 光物理学的性質,特に可視光吸収と電子伝送のダイナミクスを調査する.
- 機能材料における共振性W-O-Re結合の可能性を調査する.
主な方法:
- [P(4)W(35)O(124){Re(CO)(3)}(2)](16-) 複合体の合成について
- X線結晶学を用いた特徴化.
- スペクトル解析 (UV-Vis吸収) とコンピュータモデリング.
- 可視領域と中部IR領域における一時的吸収測定.
主要な成果:
- POMによるレニウム複合体の合成と構造確認が成功しました.
- 470 nmでの高可視光吸収率 (ε = 4000 M−1 cm−1) の観測は,Re(I) からPOMへの電荷伝送 (MPCT) バンドに属している.
- 超高速 (<50 fs) の分子内電子移転は,MPCTトランジションの光学刺激により,Re(I) センターからPOMリガンドへ.
結論:
- 合成された複合体は,MPCT帯による有意な可視光吸収を示しています.
- 光刺激は,レニウムからポリオキシメタレートへの急速な電子移転を誘発する.
- この研究は,光駆動プロセスのためのPOMでサポートされた金属複合体の可能性を実証しています.
関連する概念動画
02:51Metal-Ligand Bonds
The hemoglobin in the blood, the chlorophyll in green plants, vitamin B-12, and the catalyst used in the manufacture of polyethylene all contain coordination compounds. Ions of the metals, especially the transition metals, are likely to form complexes.
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
In these complexes, transition metals form coordinate covalent bonds, a kind of Lewis acid-base interaction in which both of the electrons in the bond are contributed by a donor (Lewis base) to an electron acceptor (Lewis acid). The Lewis acid in...
00:39Complexometric Titration: Overview
Complexometric titration involves the formation of a complex by reacting a metal ion with one or more ligands. A visual indicator often detects the end point of a complexometric titration. It is added to the metal solution before the titration, forming a stable metal–indicator complex and imparting color to the solution. As the titration approaches the equivalence point, the excess of the added ligand displaces the indicator from the metal–indicator complex, releasing the free indicator. The...
01:23Properties of Organometallic Compounds
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.
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.
00:56Extraction: Advanced Methods
Metal ions can be separated from one another by complexation with organic ligands–the chelating agent– to form uncharged chelates. Here, the chelating agent must contain hydrophobic groups and behave as a weak acid, losing a proton to bind with the metal. Since most organic ligands used in this process are insoluble or undergo oxidation in the aqueous phase, the chelating agent is initially added to the organic phase and extracted into the aqueous phase. The metal-ligand complex is formed in...
01:19Complexation Equilibria: The Chelate Effect
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...