Abstract
We report the redox potentials of a set of organic aryl molecules, including quinones, juglone, tyrosine and tryptophan, calculated using a first principles molecular dynamics (FPMD) based method. The hybrid functional HSE06 reproduces the redox potentials spanning from -0.25 V to 1.15 V within an error of 0.2 V, whereas the errors with the BLYP functional are much larger (up to 0.7 V). It is found that the BLYP functional predicts consistently lower electron affinities/ionization potentials than HSE06 both in gas phase and in an aqueous solution. In water, the ionization potentials are significantly underestimated by BLYP due to the exaggeration of the mixing between the solute states and the valence band states of liquid water. Hybrid HSE06 markedly improves both the solute levels and water band positions, leading to accurate redox potentials. This study suggests that the current FPMD based method at the level of hybrid functionals is able to accurately compute the redox potentials of a wide spectrum of organic molecules.
Highlights
We report the redox potentials of a set of organic aryl molecules, including quinones, juglone, tyrosine and tryptophan, calculated using a first principles molecular dynamics (FPMD) based method
The hybrid functional HSE06 reproduces the redox potentials spanning from À0.25 V to 1.15 V within an error of 0.2 V, whereas the errors with the BLYP functional are much larger
This study suggests that the current FPMD based method at the level of hybrid functionals is able to accurately compute the redox potentials of a wide spectrum of organic molecules
Summary
Redox potential is a measure of the tendency of a species to gain electrons and is a key thermodynamic quantity for characterizing electron transfer reactions. Redox potentials can be calculated using firstprinciples molecular dynamics (FPMD), which treats solutes and solvents at the same quantum mechanical level and accounts for the atomic level details of dynamical solvent effects.[5] These can be important in many cases, for example, for the coordination spheres yielding drastic change upon reduction/ oxidation, wherein entropic contributions could be significant to free energies. Another example is that at the elevated T-P conditions relevant to the Earth’s interior, the solvent effects are hard to include in the implicit solvent protocols, because the models are usually parameterized for ambient conditions.[1]. Paper random phase approximation and a double hybrid functional have been found to compute accurate water band positions and redox potentials for the oxidizing species of OH and Cl.[20]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
