Institute of Organic Chemistry and Biochemistry, Flemingovo nam. 2, 166 10 Prague, Czech Republic.
Langmuir. 2016 Jun 14;32(23):5755-64. doi: 10.1021/acs.langmuir.6b01187. Epub 2016 May 31.
A combined experimental and computational approach was used to investigate the spectroscopic properties of anisole in aqueous solutions and at the ice-air interface in the temperature range of 77-298 K. The absorption, diffuse reflectance, and emission spectra of ice samples containing anisole prepared by different techniques, such as slow freezing (frozen aqueous solutions), shock freezing (ice grains), or anisole vapor deposition on ice grains, were measured to evaluate changes in the contaminated ice matrix that occur at different temperatures. It was found that the position of the lowest absorption band of anisole and its tail shift bathochromically by ∼4 nm in frozen samples compared to liquid aqueous solutions. On the other hand, the emission spectra of aqueous anisole solutions were found to fundamentally change upon freezing. While one emission band (∼290 nm) was observed under all circumstances, the second band at ∼350 nm, assigned to an anisole excimer, appeared only at certain temperatures (150-250 K). Its disappearance at lower temperatures is attributed to the formation of crystalline anisole on the ice surface. DFT and ADC(2) calculations were used to interpret the absorption and emission spectra of anisole monomer and dimer associates. Various stable arrangements of the anisole associates were found at the disordered water-air interface in the ground and excited states, but only those with a substantial overlap of the aromatic rings are manifested by the emission band at ∼350 nm.
采用实验与计算相结合的方法，研究了苯甲醚在水溶液中和冰-气界面上的光谱性质，温度范围为 77-298 K。测量了不同技术制备的含有苯甲醚的冰样品的吸收、漫反射和发射光谱，这些技术包括缓慢冷冻（冷冻水溶液）、冲击冷冻（冰粒）或苯甲醚蒸气在冰粒上沉积，以评估不同温度下污染冰基质的变化。结果发现，与液态水溶液相比，苯甲醚的最低吸收带及其尾部在冷冻样品中向长波方向移动约 4nm。另一方面，发现水相苯甲醚溶液的发射光谱在冷冻后发生了根本变化。虽然在所有情况下都观察到一个发射带（约 290nm），但第二个在 350nm 左右的带，归因于苯甲醚激基复合物，仅在某些温度（150-250K）下出现。其在较低温度下的消失归因于冰表面上结晶苯甲醚的形成。DFT 和 ADC(2)计算用于解释苯甲醚单体和二聚体配合物的吸收和发射光谱。在无序的水-气界面上发现了各种苯甲醚配合物的稳定排列，在基态和激发态下，但只有那些芳环有显著重叠的排列，才会表现出约 350nm 的发射带。
