Kostjukov Victor V
Physics Department, Sevastopol State University, Universitetskaya St., 33, Sevastopol, 299053, Crimea, Russian Federation.
J Mol Model. 2021 Oct 2;27(11):311. doi: 10.1007/s00894-021-04931-w.
The vibronic absorption spectra of OX170 dye in an aqueous solution using 40 hybrid functionals, the 6-31 + + G(d,p) basis set, and the SMD solvent model were calculated. It turned out that the long-range corrected ωB97XD functional provided the best agreement with the experiment in the positions of the main maximum and the short-wavelength shoulder. Calculations showed that this shoulder is vibronic and is not caused by a separate electronic transition. At the same time, the shoulder intensity in the calculated spectrum turned out to be lower than in the experimental one. Various parameters of the OX170 cation in the ground and excited states (IR spectra, atomic charges, dipole moments, and transition moment) were calculated. Maps of the distribution of electron density and electrostatic potential have been built. The influence of four strong hydrogen bonds of the dye with water molecules on the absorption spectrum was analyzed. It was shown that these bonds are strengthened upon OX170 excitation. It was found that explicit assignment of water molecules strongly bound to the dye leads to a redshift of the calculated spectrum by ≈15 nm as a whole, and worsened its shape. Photoexcitation of the dye leads to a noticeable polarization of only one of the four considered water molecules (associated with the endocyclic nitrogen atom in the central ring of the chromophore, the electron density on which increases the most).
使用40种杂化泛函、6-31++G(d,p)基组和SMD溶剂模型计算了OX170染料在水溶液中的振动吸收光谱。结果表明，长程校正的ωB97XD泛函在主峰和短波肩峰位置与实验结果吻合得最好。计算表明，该肩峰是振动所致，并非由单独的电子跃迁引起。同时，计算光谱中的肩峰强度低于实验光谱。计算了基态和激发态下OX170阳离子的各种参数（红外光谱、原子电荷、偶极矩和跃迁矩）。绘制了电子密度和静电势分布图。分析了染料与水分子的四个强氢键对吸收光谱的影响。结果表明，OX170激发后这些氢键增强。研究发现，明确指定与染料紧密结合的水分子会使计算光谱整体发生约15nm的红移，并使其形状变差。染料的光激发仅导致所考虑的四个水分子之一出现明显极化（与发色团中心环中的内环氮原子相关，其上的电子密度增加最多）。
