カロテノイドの2光子の興奮した最初のシングレット状態からの異常なリラックス経路
Yoonsoo Pang1, Garth A Jones, Matthew A Prantil
1Department of Chemistry, University of California, Berkeley, and Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720-1460, USA.
Journal of the American Chemical Society
|January 29, 2010
まとめ
研究者は,一時的吸収とDFT計算を使用してカロテノイドを研究しました. 彼らは長寿種を特定し,おそらくカロテノイドと溶媒の間の電荷伝送複合体であり,そのユニークな赤外線と可視吸収特性を説明しました.
科学分野:
- フォトケミストリーとスペクトロスコピー
- コンピューティング・ケミストリー
- カロテノイド科学 カロテノイド科学
背景:
- カロテノイドは,複雑な興奮状態のダイナミクスを持つ重要な色素です.
- 以前の研究では,光刺激後のカロテノイドで長生きする種が観察されましたが,その性質は不明でした.
- これらの一時的な種を理解することは,カロテノイドの光物理的経路を明らかにするために非常に重要です.
研究 の 目的:
- カロテノイド8'-アポ-ベータ-カロテン-8'-アルと7',7'-ディシアノ-7'-アポ-ベータ-カロテンにおける長寿種の分子同一性を調査する.
- 実験的スペクトロスコピクデータを理論的計算と相関させる.
- 観察された遷移種の形成のメカニズムと構造的特徴を明らかにする.
主な方法:
- 暫定的な赤外線および可視吸収スペクトロスコピーは,興奮状態の種を監視するために使用されました.
- 光化学的プロセスを開始するために,2光子の刺激が使用されました.
- B3LYP/6-31G (d) レベルの理論を用いた密度関数理論 (DFT) の計算を行い,潜在エネルギー表面,同位体,スペクトル特性をモデル化しました.
主要な成果:
- 独特の赤外線吸収 (~1510 cm−1) と可視吸収 (760 nmを中心に) を有する長生き種が観察されました.
- この種はビート指数分解運動 (16 psと140270 ps) を示し,緩やかな成分は溶媒の極性に依存した.
- DFTの計算は,実験上の赤外線スペクトルと,カロテノイドカチオンラジカルの計算されたスペクトルの間で強い類似性を示したが,可視スペクトルは完全に一致しなかった.
結論:
- 実験的および理論的データから,長寿種は単純な単体カチオン基ではないことを示唆しています.
- 興奮したカロテノイドと溶媒分子の間に形成された電荷伝送複合体は,観察された長寿種の起源として提案されています.
- この発見は,溶液中のカロテノイドの複雑な光化学に関する新しい洞察を提供します.
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