Linear correlation models for the redox potential of organic molecules in aqueous solutions

Abstract

In this study we use the molecular orbital energy approximation (MOEA) and the energy difference approximation (EDA) to build linear correlation models for the redox potentials of 53 organic compounds in aqueous solutions. The molecules evaluated include nitroxides, phenols and amines. Both the MOEA and EDA methods yield similar correlation models, however the MOEA method is less computationally expensive. Correlation coefficients (R 2) below 0.3 and mean absolute errors above 0.25 V were found for correlation models built without solvent effects. When explicit water molecules and a continuum solvent model are added to the calculations, correlation coefficients close to 0.8 are reached and mean absolute errors below 0.18 V are obtained. The incorporation of solvent effects is necessary for good correlation models, particularly for redox processes of charged molecules in aqueous solutions. A comparison of the correlation models from different methodologies is provided.

High throughput selection of organic cathode materials

“…The regression provides an R 2 value of 0.86 (see Table S2 and Figure S1), which is lower than the value reported in previous publications 33–35,66 . This might be caused by two main reasons: First, previous publications use higher levels of theory, typically hybrid functionals coupled with at least double zeta basis sets.…”

Benchmarking computational methods to calculate the octanol/water partition coefficients of a diverse set of organic molecules

“…to be essential to reproduce some experimental results [30][31][32] and this could further improve the correlations, although some reports claim the contrary. 29…”

Local reactivity descriptors to decipher the electrochemical hydrogenation of unsaturated carboxylic acids

“…Therefore, we expected that the onset potential for ECH should be correlated with the energy of the molecule's LUMO based on Koopman's theorem, as reported in a similar fashion for other electrochemical reactions. [36][37][38] Building on this concept, we computed the LUMO energies for ccMA, SA, and their respective ECH reaction intermediates.…”

“…Linear correlations have been established between molecules' lowest unoccupied molecular orbital (LUMO) energies, electron affinities, and redox potentials. [36][37][38] However, the tools available do not provide information on the reactivity of individual redox sites within a molecule.…”