邻位甲基红水溶液的光谱性质随pH值的变化:含时密度泛函理论计算与实验研究（英文）

发布时间：2018-04-22 01:04

本文选题：邻位甲基红 + 紫外/可见吸收光谱　；参考：《物理化学学报》2016年01期

【摘要】：探明影响甲基红光谱性质的各种因素,有助于拓宽偶氮苯衍生物在有机光电器件中的应用。采用密度泛函理论和实验相结合的方法研究了溶液酸碱性和溶剂水对邻位甲基红水溶液光谱的影响。溶液pH从13.1逐渐降低至0.5,邻位甲基红水溶液的最大吸收波长从430 nm红移至520 nm。在不同酸碱条件下,主要有三种物种共存于甲基红水溶液中,它们分别是双质子化的甲基红o-H_2MR+(强酸性条件下),单质子化的甲基红oHMR(弱酸条件下)和碱性甲基红o-MR (碱性条件下),通过密度泛函理论计算研究了三种不同形式的电子结构特征。采用含时密度泛函理论计算了甲基红偶极跃迁允许的最低激发能,分别采用连续介质模型和分子簇模型研究水溶剂对甲基红电子结构和光谱性质的影响。在酸性条件下,o-H_2MR+和o-HMR分子内氢键导致π共轭体系平面性增强,因而光谱红移。而在碱性条件下,溶剂对o-MR 的光谱有显著影响:极性o-HMR和o-MR 与水分子的偶极偶极相互作用导致光谱进一步红移。
[Abstract]:The investigation of various factors affecting the spectral properties of methyl red is helpful to broaden the application of azobenzene derivatives in organic optoelectronic devices. The effects of solution acidity and alkalinity and solvent water on the spectra of o-methyl-red aqueous solution were studied by means of density functional theory and experiments. The pH of the solution gradually decreased from 13.1 to 0.5, and the maximum absorption wavelength of orthomethyl red solution shifted from 430 nm to 520 nm. Under different acid-base conditions, there are mainly three species coexisting in methyl red aqueous solution. They are diprotonated methyl red o-H_2MR (strong acid condition), monoprotonated methyl red o H MRs (weak acid condition) and alkaline methyl red o-MR (basic condition). Three different forms are studied by density functional theory (DFT). The electronic structure characteristics of. The lowest allowable excitation energy of methyl red dipole transition is calculated by time-dependent density functional theory. The influence of water solvent on the electronic structure and spectral properties of methyl red is studied by means of continuum model and molecular cluster model, respectively. In acidic conditions, the intramolecular hydrogen bonds of o-H2MR and o-HMR lead to the enhancement of the planarity of 蟺 -conjugated system, and thus the redshift of the spectra. Under alkaline conditions, the solvent has a significant effect on the spectra of o-MR ~ (2 +): the dipolar dipole interaction of polar o-HMR and o-MR ~ (2 +) with water molecules leads to a further redshift of the spectra.
【作者单位】：南京大学化学与化工学院南京大学理论与计算化学研究所;
【基金】：supported by the National Natural Science Foundation of China(21290192,21273102)~~
【分类号】：O645

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