Building and testing correlations for the estimation of one‐electron reduction potentials of a diverse set of organic molecules

Abstract

We describe and evaluate a method for computationally predicting reduction potentials of a diverse group of organic molecules by linearly correlating calculated lowest unoccupied molecular orbital energies with ground state reduction potentials measured in acetonitrile. The approach is shown to provide a unique combination of extreme computational simplicity and excellent accuracy across a diverse range of organic structures and a wide window of reduction potentials. A disparate set of molecules (74 compounds belonging to six distinct structural families, comprised of molecules containing C, H, N, O, F, Cl, and Br, with functional groups including esters, ketones, halides, nitriles, quinones, alkenes, arenes, heteroarenes, and pyridinium and higher benzologs, all containing conjugated pi systems, spanning a 3.5‐V range of reduction potentials) was used to build the correlations. This methodology was found to be computationally inexpensive compared with other approaches and to permit the useful prediction of reduction potentials of additional molecules of diverse structural types not included in the families used to determine the correlation parameters. The effects of varying the basis set used in the B3LYP electronic structure calculations and including solvent (compared with calculations in gas phase) were also examined. It was found that the inclusion of a continuum solvent model in the calculations was required for accurate results, particularly when including cationic species in the correlations (although when only neutral molecules were examined, reasonable results could even be obtained in vacuo). Several of the best correlations were used to predict the reduction potentials of seven much larger and structurally diverse chromophores that were not included in the correlation data set. Strong correlations (r2 values > 0.99) with very good predictive abilities (root mean square deviation < 60 mV) were found. This extremely simple and computationally efficient entirely closed‐shell methodology is proven robust and useful for the design of new molecules capable of participating in redox processes, including electron transfer reactions. Copyright © 2015 John Wiley & Sons, Ltd.

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

“…The main reason for the low R 2 values for calculations in the gas phase is likely the fact that our experimental potentials correspond to the reduction process of neutral molecules as well as molecular cations under aqueous conditions. We found similar poor correlations (R 2 < 0.65) in a previous work [31] when the set of experimental potentials were for reduction processes of both neutral and charged molecules. Simulations of reduction processes of charged molecules without including solvation effects (gas phase calculations) fail to reproduce the measured potentials.…”

“…The calculation of the redox potential of organic molecules in solutions is crucial for the rational design of such technologies. Various methodologies are currently employed to calculate redox potential in solutions: i) the Born-Haber thermodynamic cycle (BHTC) [24][25][26][27], ii) the S0-D0 energy difference approximation (EDA) [28][29][30], and iii) the molecular orbital energy approximation (MOEA) [28,31,32]. In the BHTC method, the redox potential is calculated from the standard free energy of product and reactants in a redox half-reaction.…”

“…However, the EDA and MOEA methods have been shown to work for a diverse set of molecules in a given solvent [27][28][29][30][31][32][33]. For example, Gillmore et al [29,30] and Méndez-Hernández et al [31,32] have reported strong correlations for a set of 74 diverse molecules in acetonitrile using the EDA and MOEA methodologies, respectively. The great advantage of the MOEA method is that once the correlation model is available only a minimal computational effort is required to obtain an unknown redox potential, which becomes crucial for high-throughput screening.…”

N‐doped cycloparaphenylenes: Tuning electronic properties for applications in thermally activated delayed fluorescence

“…All the calculations reported here were done with the G09 package, using Gabedit, Multiwfn, and the NANCY_EX package for post‐processing of the results. To model the electrostatic effects arising in solution, and, thus, to truly compare whenever possible with the set of experimental results mostly performed in acetonitrile or in dichloromethane (DCM), for charged nanohoops we employ the conductor‐like polarization continuum model (CPCM) according to recent recommendations, while the neutral compounds are treated by the standard PCM model . The cost‐effective basis set 6‐31G* was fixed for most of the calculations reported here.…”

Development of a chromatographic method to study oxidative potential of airborne particulate matter

“…This data is used in many fields: from battery research (Palacín, 2009) to enology (Danilewicz et al, 2019). In addition, quantum mechanical methods allow reduction potentials in water to be calculated theoretically; such 25 techniques have already been used on atmospherically relevant compounds such as quinones (Lynch et al, 2012;Guerard and Arey, 2013;Marenich et al, 2014;Méndez-Hernández et al, 2015). In the biochemical literature, the Nernst equation has been frequently used to calculate the reduction potential of antioxidant redox couples such as GSH/GSSG (Schafer and Buettner, 2001).…”