Keto-enol tautomerism of the 4,5-dimethyl-2-(2′- hydroxyphenyl)imidazole in water solution: modeling equilibrium between neutral forms and accurate assignment of the absorption bands

Khrenova, M.G.; Kapusta, D.P.; Mulashkin, F.D.

Авторы: Khrenova Maria G., Kapusta Dmitry P., Mulashkin Fedor D.
Журнал: International Journal of Quantum Chemistry
Год издания: 2020
Издательство: John Wiley & Sons Inc.
Местоположение издательства: United States
DOI: 10.1002/qua.26577
Аннотация: Tautomerizarion between keto, cis- and trans-enol forms of the 4,5-dimethyl-2-(2′-hydroxyphenyl)imidazole (DMHI) is studied using molecular dynamics simulations with the QM/MM potentials. We applied the live solvent selection approach that presumes division of water molecules to either QM or MM subsystems on the fly depending on their distances from the chromophore. This allowed to treat a water shell around the chromophore at the QM level and to describe properly all chromophore-water interactions. According to the calculated Gibbs energy profiles the most stable is a keto form and a cis-enol form is ~ 1 kcal/mol higher. The trans-enol form is much higher in energy and should not be observed in experiment. Vertical S0,min-S1 excitation energies of all neutral tautomers were calculated at the XMCQDPT2 level: both enol forms have similar values ~ 4 eV and keto form is red-shifted, with the excitation energy of 3.3 eV. Thus, we conclude that two absorption bans in experimental absorption spectrum of DMHI in water solution are due to the presence of cis-enol and keto forms of the chromophore.
Добавил в систему: Мулашкин Фёдор Дмитриевич

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Keto-enol tautomerism of the 4,5-dimethyl-2-(2′- hydroxyphenyl)imidazole in water solution: modeling equilibrium between neutral forms and accurate assignment of the absorption bandsстатья

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