![Cercosporin-Photocatalyzed [4+1]- and [4+2]-Annulations of Azoalkenes Under Mild Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F60786.jpg&w=3840&q=50)
ディニトロアントラセンの結晶から結晶への光誘導反応は,アントラキノンに反応する
Tommaso Salzillo1, Ivano Bilotti, Raffaele Guido Della Valle
1Dipartimento di Chimica Fisica e Inorganica and INSTM-UdR Bologna, University of Bologna, I-40136 Bologna, Italy.
Journal of the American Chemical Society
|October 9, 2012
まとめ
この研究は,ラマン光譜を用いて9,10-ディニトロアントラセン (DNO(2) A) がアントラキノン (AQ) に変換される方法を明らかにしています. この研究は,光,結晶構造の変化,この光化学反応中の機械的ストレスの間の関連性を明らかにしています.
科学分野:
- 固体化学 固体化学
- フォトケミストリー フォトケミストリー
- スペクトル顕微鏡検査です.
背景:
- 固体における光化学反応には,複雑な構造的および化学的な変化が伴う可能性があります.
- これらの変換を分子レベルで理解することは,固体反応の制御に極めて重要です.
- ラーマン光譜は,分子振動と格子ダイナミクスの両方を探査するための強力なツールです.
研究 の 目的:
- 9,10-ジニトロアントラゼン (DNO(2) A) とアントラキノン (AQ) の光化学反応機構を調査する.
- 分子変換と結晶構造の同時変化を相関させるため.
- 光反応に及ぼす機械的張力と高圧の影響を調査する.
主な方法:
- 格子フォノンラマンスペクトロスコーピーは,結晶構造の修正を監視するために使用されます (10-150cm(-1)).
- 内分子ラマン活性モードは,反応物質 (DNO(2) A) と産物 (AQ) の振動変化を追跡する.
- 2GPaまでの高圧実験で反応抑制を研究する.
主要な成果:
- DNOからAQの光反応中の分子と結晶構造の変化を同時に検出する.
- 衝突する光子によって誘発されるマクロスコープの機械的緊張 (曲げ,展開) の観察.
- 1GPa以上で観測された光反応阻害.
- 理論的なモデリングにより,特定の格子変形経路が特定されました.
結論:
- ラーマン光譜は,固体状態の光化学反応機構に対する顕微鏡の洞察を提供します.
- 光の吸収,分子再配置,およびマクロスコープの機械的な効果の間に直接的なリンクが存在する.
- 高圧は,固体状態の光化学的変換を大幅に変化させ,または阻害することができます.
さらに関連する動画
関連する概念動画
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
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.
01:26Photochemical Electrocyclic Reactions: Stereochemistry
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
01:29The Photochemical Reaction Center
Reaction centers are pigment-protein complexes that initiate energy conversion from photons to chemical entities. Therefore, photochemical reaction center is a more appropriate term that describes these complexes. The Nobel laureates Robert Emerson and William Arnold provided the first experimental evidence of photochemical reaction centers by demonstrating the participation of nearly 2,500 chlorophyll molecules for the release of just one molecule of oxygen. Despite thousands of photosynthetic...
01:12Cycloaddition Reactions: MO Requirements for Photochemical Activation
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.
01:27Cyclohexenones via Michael Addition and Aldol Condensation: The Robinson Annulation
Robinson annulation is a base-catalyzed reaction for the synthesis of 2-cyclohexenone derivatives from 1,3-dicarbonyl donors (such as cyclic diketones, β-ketoesters, or β-diketones) and α,β-unsaturated carbonyl acceptors. Named after Sir Robert Robinson, who discovered it, this reaction yields a six-membered ring with three new C–C bonds (two σ bonds and one π bond).
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.