Faculty of Physics, "Alexandru Ioan Cuza" University, 700506 Iasi, Romania.
"Petru Poni" Institute of Macromolecular Chemistry, 700487 Iasi, Romania.
Int J Mol Sci. 2024 Apr 25;25(9):4682. doi: 10.3390/ijms25094682.
Investigation of chiroptical polymers in the solution phase is paramount for designing supramolecular architectures for photonic or biomedical devices. This work is devoted to the case study of poly(propylene oxide) (PPO) optical activity in several solvents: benzonitrile, carbon disulfide, chloroform, ethyl acetate, and -dioxane. To attain information on the interactions in these systems, rheological testing was undertaken, showing distinct variations of the rheological parameters as a function of the solvent type. These aspects are also reflected in the refractive index dispersive behavior, from which linear and non-linear optical properties are extracted. To determine the circular birefringence and specific rotation of the PPO solutions, the alternative method of the channeled spectra was employed. The spectral data were correlated with the molecular modeling of the PPO structural unit in the selected solvents. Density functional theory (DFT) computational data indicated that the torsional potential energy-related to the O1-C2-C3-O4 dihedral angle from the polymer repeating unit-was hindered in solvation environments characterized by high polarity and the ability to interact via hydrogen bonding. This was in agreement with the optical characterization of the samples, which indicated a lower circular birefringence and specific rotation for the solutions of PPO in ethyl acetate and -dioxane. Also, the shape of optical rotatory dispersion curves was slightly modified for PPO in these solvents compared with the other ones.
研究手性聚合物在溶液中的光学性质对于设计用于光子学或生物医学设备的超分子结构至关重要。这项工作致力于研究聚（环氧丙烷）（PPO）在几种溶剂中的光学活性：苯腈、二硫化碳、氯仿、乙酸乙酯和 -二氧六环。为了获得这些体系中相互作用的信息，进行了流变学测试，结果表明流变学参数随溶剂类型的变化而有明显的变化。这些方面也反映在折射率色散行为中，从中提取了线性和非线性光学性质。为了确定 PPO 溶液的圆二色性和比旋光度，采用了通道谱的替代方法。光谱数据与 PPO 结构单元在选定溶剂中的分子建模相关联。密度泛函理论（DFT）计算数据表明，与聚合物重复单元中 O1-C2-C3-O4 二面角相关的扭转势能在具有高极性和通过氢键相互作用能力的溶剂环境中受到阻碍。这与样品的光学特性一致，表明 PPO 在乙酸乙酯和 -二氧六环中的溶液具有较低的圆二色性和比旋光度。此外，与其他溶剂相比，PPO 在这些溶剂中的旋光色散曲线的形状也略有改变。
