当前位置: X-MOL 学术J. Phys. Chem. A › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Predicting Keto–Enol Equilibrium from Combining UV/Visible Absorption Spectroscopy with Quantum Chemical Calculations of Vibronic Structures for Many Excited States. A Case Study on Salicylideneanilines
The Journal of Physical Chemistry A ( IF 2.9 ) Pub Date : 2018-05-16 00:00:00 , DOI: 10.1021/acs.jpca.8b03389
Freddy Zutterman 1 , Orian Louant 1 , Gabriel Mercier 2 , Tom Leyssens 2 , Benoît Champagne 1
Affiliation  

Salicylideneanilines are characterized by a tautomer equilibrium, between an enol and a keto form of different colors, at the origin of their remarkable thermochromic, solvatochromic, and photochromic properties. The enol form is usually the most stable but appropriate choice of substituents and conditions (solvent, crystal, host compound) can displace the equilibrium toward the keto form so that there is a need for fast prediction of the keto:enol abundance ratio. Here we demonstrate the reliability of a combined theoretical–experimental method, based on comparing simulated and measured UV/visible absorption spectra, to determine this keto/enol ratio. The calculations of the excitation energies, oscillator strengths, and vibronic structures of both enol and keto forms are performed for all excited states absorbing in the relevant (visible and near-UV) wavelength range at the time-dependent density functional theory level by accounting for solvent effects using the polarizable continuum model. This approach is illustrated for two salicylideneaniline derivatives, which are present, in solution, under the form of keto–enol mixtures. The results are compared to those of chemometric analysis as well as ab initio predictions of the reaction free enthalpies.

中文翻译:

通过将紫外线/可见光吸收光谱与许多激发态的振动结构的量子化学计算相结合来预测酮基-烯醇平衡。水杨基苯胺类药物的个案研究

水杨基苯胺的特征在于互变异构体平衡,其在不同颜色的烯醇和酮形式之间,源于其显着的热致变色,溶剂变色和光致变色特性。烯醇形式通常是最稳定但最合适的取代基选择,条件(溶剂,晶体,主体化合物)可使平衡向酮形式转移,因此需要快速预测酮:烯醇丰度比。在这里,我们通过比较模拟和测量的UV /可见光吸收光谱,确定该酮/烯醇比,证明了理论与实验相结合的方法的可靠性。激发能,振荡器强度的计算,通过使用可极化连续谱模型考虑溶剂效应,对所有吸收在相关(可见光和近紫外)波长范围内的激发态在依赖于时间的密度泛函理论水平下进行了烯醇和酮形式的振动结构。对于两种水杨基苯胺衍生物,以酮-烯醇混合物形式存在于溶液中,说明了该方法。将结果与化学计量分析以及从头开始预测反应的自由焓。
更新日期:2018-05-16
down
wechat
bug