Theoretical evaluation of solvent effects on the conformational and tautomeric equilibria of 2-(2′-hydroxyphenyl)benzimidazole and on its absorption and fluorescence spectra
Theoretical evaluation of solvent effects on the conformational and tautomeric equilibria of 2-(2′-hydroxyphenyl)benzimidazole and on its absorption and fluorescence spectra
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DOI：
10.1021/jp984773
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发表时间：
1999-06-10
影响因子：
2.9
通讯作者：
Luque, FJ
中科院分区：
文献类型：
--
作者：
Forés, M;Duran, M;Luque, FJ
采用蒙特卡罗模拟和连续模型计算的方法研究了溶剂对2-（2′-羟基苯基）苯并咪唑及其酮互变异构体三个烯醇构象基态自由能差的影响。与实验数据一致，计算表明，反式烯醇和酮的形式被极性溶剂稳定，导致与封闭的顺式烯醇构象在水中的构象和互变异构平衡，这是极性溶剂中唯一的单一物种。蒙特卡罗模拟也被用来检验溶剂对封闭的顺式烯醇结构的吸收带和由光诱导分子内质子转移产生的酮形式的荧光带的影响。与实验光谱一致，随着溶剂极性和氢键容量的增加，封闭的顺式烯醇和酮的吸收和荧光带最大值分别发生蓝移。
The effect of the solvent on the ground state free energy differences of three enol conformers of 2-(2'-hydroxyphenyl)benzimidazole and its keto tautomer has been examined by means of Monte Carlo simulations and continuum model calculations. In agreement with the experimental data, calculations show that the trans enol and keto forms are stabilized by polar solvents, leading to a conformational and tautomeric equilibrium with the closed cis enol conformer in water, the only single species in apolar solvents. Monte Carlo simulations have also been used to examine the influence of the solvent on the absorption band of the closed cis enol structure and the fluorescence band of the keto form generated by photoinduced intramolecular proton transfer. In concordance with the experimental spectra, absorption and fluorescence band maxima for the closed cis enol and keto forms, respectively, are found to be blue-shifted with increasing polarity and hydrogen bonding capacity of the solvent.