A dynamic and electrostatic potential prediction of the prototropic tautomerism between imidazole 3-oxide and 1-hydroxyimidazole in external electric field.
J Mol Model
; 25(11): 330, 2019 Oct 28.
Article
en En
| MEDLINE
| ID: mdl-31659461
In order to obtain an optimum scheme for separating the proton-transfer tautomer, a dynamic investigation into the effect of the external electric field on the proton-transfer tautomeric conversion in imidazole 3-oxide and 1-hydroxyimidazole was carried out at the M06-2X/6-311++G** and CCSD(T)/6-311++G(2d,p) level, accompanied by the analysis of the surface electrostatic potentials. The results show that, for both the forward reaction "imidazole 3-oxide â N-hydroxyimidazole free radical â 1-hydroxyimidazole" and its reverse reaction processes, the fields parallel to the NâO or N-OH bond axis affect the barrier heights and rate constants considerably more than those parallel to the other orientations. As the field strength is increased along the orientation from the O to N atom, the chemical equilibrium moves toward the direction for the formation of 1-hydroxyimidazole, while the amount of imidazole 3-oxide is increased with the increased field strength along the opposite orientation. In the fields along the orientation consistent with the dipole moment, the electrostatic potentials and their variances "abnormally" increase for the transition states with the NâO bond in comparison with those in no field (they decrease generally), which enhances the nucleophilicity of the coordination O atom and the electrophilicity of the activated H atom. The analyses of the AIM (atoms in molecules) and NICS (nucleus-independent chemical shift) were used to explain the above anomaly. Graphical Abstract Electrostatic potentials and their variances "abnormally" increase in the external electric field, which greatly affects tautomeric conversion.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Tipo de estudio:
Prognostic_studies
/
Risk_factors_studies
Idioma:
En
Revista:
J Mol Model
Asunto de la revista:
BIOLOGIA MOLECULAR
Año:
2019
Tipo del documento:
Article
País de afiliación:
China
Pais de publicación:
Alemania