Feldman Haim, Iron Mark A, Fixler Dror, Moshkov Sergei, Zurgil Naomi, Afrimzon Elena, Deutsch Mordechai
Physics Department, The Biophysical Interdisciplinary Schottenstein Center for the Research and Technology of the Cellome, Bar Ilan University, 5290002, Ramat Gan, Israel.
Computational Chemistry Unit, Department of Chemical Research Support, Weizmann Institute of Science, 7610001, Rehovot, Israel.
Photochem Photobiol Sci. 2021 Nov;20(11):1397-1418. doi: 10.1007/s43630-021-00096-w. Epub 2021 Oct 5.
A common perception exists that glycerol provides an inert-like environment modifying viscosity and index of refraction by its various concentrations in aqueous solution. Said perception is herein challenged by investigating the effects of the glycerol environment on the spectroscopic properties of fluorescein, as a representative fluorophore, using steady-state and time-resolved techniques and computational chemistry. Results strongly suggest that the fluorescence quantum yield, measured fluorescence lifetime (FLT), natural lifetime and calculated fluorescence lifetime are all highly sensitive to the presence of glycerol. Glycerol was found to impact both the ground and first excited states of fluorescein, quenching and modifying both absorption and emission spectra, affecting the fundamental electrical dipoles of the ground and first excited singlet states, and lowering FLT and quantum yield. Furthermore, the Stern-Volmer, Lippert-Mataga, Perrin and Strickler-Berg relations indicate that glycerol acts upon fluorescein in aqueous solution as a quencher and alters the fluorescein geometry. Predictions made by computational chemistry impressively correspond to experimental results, both indicating changes in the properties of fluorescein at around 35% v/v aqueous glycerol, a clear indication that glycerol is not an innocent medium. This study proposes the Strickler-Berg relation as a means of detecting non-negligible effects of a hosting medium on its host fluorophore. These new insights on the molecular structures, the interactions between glycerol and its host fluorophore, and the effects of one on the other may be essential for understanding fundamental phenomena in chemistry and related fields.
人们普遍认为，甘油在水溶液中的不同浓度会提供一种类似惰性的环境，改变溶液的粘度和折射率。本文通过使用稳态和时间分辨技术以及计算化学方法，研究甘油环境对作为代表性荧光团的荧光素光谱性质的影响，对上述观点提出了挑战。结果有力地表明，荧光量子产率、测量的荧光寿命（FLT）、自然寿命和计算得到的荧光寿命对甘油的存在都高度敏感。研究发现甘油会影响荧光素的基态和第一激发态，猝灭并改变吸收光谱和发射光谱，影响基态和第一激发单重态的基本电偶极矩，并降低FLT和量子产率。此外，斯特恩 - 沃尔默、利珀特 - 马塔加、佩林和斯特里克勒 - 伯格关系式表明，甘油在水溶液中对荧光素起猝灭剂的作用，并改变荧光素的几何结构。计算化学做出的预测与实验结果惊人地相符，两者均表明在约35% v/v的甘油水溶液中荧光素的性质发生了变化，这清楚地表明甘油并非一种惰性介质。本研究提出将斯特里克勒 - 伯格关系式作为一种检测主体介质对其主体荧光团不可忽略影响的方法。这些关于分子结构、甘油与其主体荧光团之间的相互作用以及彼此间影响的新见解，对于理解化学及相关领域的基本现象可能至关重要。
