包埋芪的构象和荧光。

Conformations and fluorescence of encapsulated stilbene.

机构信息

Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou, Athens 116 35, Greece.

出版信息

J Am Chem Soc. 2012 Mar 7;134(9):4346-54. doi: 10.1021/ja211164b. Epub 2012 Feb 22.

DOI:10.1021/ja211164b

PMID:22289119

Abstract

Absorption and emission spectra of free and encapsulated stilbene in two different capsules were calculated using the DFT and the TDDFT methodology at the B3LYP, CAM-B3LYP, M06-2X, PBE0, and ωB97X-D/6-31G(d,p) levels of theory. The present work is directed toward the theoretical interpretation of recent experimental results on control of stilbene conformation and fluorescence in capsules [Ams, M. R.; et al. Beilstein J. Org. Chem. 2009, 5, 79]. The results of the calculations are in agreement with experiment and show that fluorescence of trans-stilbene persists in the large cage while it is quenched in the small one. It is found that the geometry of trans-stilbene in the ground as well as in the first excited singlet state is unaffected by encapsulation in the large cage, and consequently the absorption and emission spectra are similarly unaffected. In the small cage, the ground state of encapsulated trans-stilbene is distorted, with the two phenyl groups twisted, while the geometry of the excited state, after relaxation, lies at the conical intersection with the ground state. Consequently, there is no emission similar to that of free trans-stilbene, and the state decays nonradiatively to the ground state.

摘要

使用 DFT 和 TDDFT 方法，在 B3LYP、CAM-B3LYP、M06-2X、PBE0 和 ωB97X-D/6-31G(d,p) 理论水平上，计算了自由态和两种不同胶囊包裹态二苯乙烯的吸收和发射光谱。本工作旨在对胶囊中二苯乙烯构象和荧光控制的最新实验结果进行理论解释 [Ams, M. R.; et al. Beilstein J. Org. Chem. 2009, 5, 79]。计算结果与实验相符，表明反式二苯乙烯的荧光在大笼中保持不变，而在小笼中被猝灭。结果表明，在基态和第一激发单重态中，反式二苯乙烯的几何形状不受大笼包裹的影响，因此吸收和发射光谱也不受影响。在小笼中，包裹态反式二苯乙烯的基态发生扭曲，两个苯基基团扭转，而激发态的几何形状在弛豫后与基态相交于锥形交叉点。因此，没有类似于自由反式二苯乙烯的发射，该状态非辐射地衰减到基态。