Liu Hai-Bo, Yu Daun, Shin Sung Chul, Park Hyoung-Ryun, Park Jong Keun, Bark Ki-Min
Department of Chemistry and Research Institute of Life Science, Gyeongsang National University, Chinju, Korea.
Photochem Photobiol. 2009 Jul-Aug;85(4):934-42. doi: 10.1111/j.1751-1097.2009.00550.x.
The characteristic fluorescence properties of quercetin-3-O-rhamnoside (QCRM) and quercetin-3-O-rutinoside (QCRT) were studied in CH3OH-H2O and CH3CN-H2O mixed solvents. Although QCRM and QCRT are known as nonfluorescent molecules, significant fluorescence emissions were discovered at 360 nm in CH3OH and CH3CN when they were promoted to the second excited state. The emission band is broad and structureless and the intensity decreases quickly as the H2O composition in the solvent increases. When the amount of H2O exceeds 60% in both mixed solvents, this emission disappears due to the formation of the distorted excited state. This state will be formed due to the strong intermolecular hydrogen bonding between the polar groups of solute and H2O. As the composition of CH3OH or CH3CN in solvent becomes large, the number of molecules having several intramolecular hydrogen bonding increases. Some of these molecules will be changed to a fluorescent species during the decay process, after excitation. The theoretical calculation further supports these results. The change of the lifetimes, quantum yields, and radiative and nonradiative rate constants of molecules was also examined as a function of solvatochromic parameters for CH3OH-H2O and CH3CN-H2O.
在甲醇 - 水和乙腈 - 水混合溶剂中研究了槲皮素 - 3 - O - 鼠李糖苷（QCRM）和槲皮素 - 3 - O - 芦丁糖苷（QCRT）的特征荧光性质。尽管QCRM和QCRT被认为是非荧光分子，但当它们被激发到第二激发态时，在甲醇和乙腈中于360 nm处发现了显著的荧光发射。发射带宽且无结构，并且随着溶剂中水的组成增加，强度迅速降低。当两种混合溶剂中水的含量超过60%时，由于扭曲激发态的形成，这种发射消失。这种状态将由于溶质的极性基团与水之间强烈的分子间氢键而形成。随着溶剂中甲醇或乙腈的组成增加，具有多个分子内氢键的分子数量增加。其中一些分子在激发后的衰变过程中会转变为荧光物种。理论计算进一步支持了这些结果。还研究了分子的寿命、量子产率以及辐射和非辐射速率常数随甲醇 - 水和乙腈 - 水溶剂化显色参数的变化。
