Improta Roberto, Barone Vincenzo
Dipartimento di Chimica, Università Federico II, Complesso Universitario Monte S. Angelo, Via Cintia, I-80126 Napoli, Italy.
J Am Chem Soc. 2004 Nov 10;126(44):14320-1. doi: 10.1021/ja0460561.
Here we present the first computations of fluorescence spectra in aqueous solution at an accurate quantum mechanical level. From a methodological point of view, our study shows that by only taking into account both bulk effects and explicit solvent molecules it is possible to reproduce solvent effects on the energy and the intensities of the electronic spectra, especially for what concerns pi/pi* transition. The computed absorption and fluorescence spectra are in a good agreement with the available experimental results. The energy ordering between the lowest energy n-pi* and the pi/pi* transitions in uracil strongly depends on the nature of the embedding medium. The geometry of the first solvation shell is remarkably sensitive to the specific electronic state, suggesting that solvent degrees of freedom can act as S1/S2 coupling modes.
在此,我们展示了在精确量子力学水平下对水溶液中荧光光谱的首次计算。从方法学的角度来看,我们的研究表明,仅通过考虑体相效应和明确的溶剂分子,就有可能重现溶剂对电子光谱能量和强度的影响,特别是对于π/π跃迁而言。计算得到的吸收光谱和荧光光谱与现有的实验结果吻合良好。尿嘧啶中最低能量的n-π和π/π*跃迁之间的能量顺序强烈依赖于嵌入介质的性质。第一溶剂化层的几何结构对特定电子态非常敏感,这表明溶剂自由度可以作为S1/S2耦合模式。