Semi-empirical methods in RedOx potential calculations of substituted aromatic compounds: Parameterizations, solvation models, approximation by frontier molecular orbital energies

• Published in: Electrochimica acta 2019-01, Vol.294, p.423-430
• Main Authors: Vakulin, I.V., Bugaets, D.V., Zilberg, R.A., Maistrenko, V.N.
• Format: Article
• Language: English
• Subjects: AM1; Approximation; Aromatic compounds; Calculation accuracy; Chemical compounds; Diphenols; Electroactive compounds; Electrode potentials; Functional groups; HOMO; LUMO; Mathematical analysis; Mathematical models; Molecular orbitals; Molecules; Organic chemicals; Parameterization; Phenols; Phenols and quinones; PM7; RM1; Solvation; Solvation model; Standard RedOx potentials; Substituted anilines
• ISSN: 0013-4686; 1873-3859
• DOI: 10.1016/j.electacta.2018.09.126

The accuracy of standard RedOx potential calculation in water solution by semi-empirical approximations (AM1, PM7 and RM1) with various continual solvation models (COSMO, PCM, SM5.2 and SM5C) was considered. On a wide set of electroactive compounds (121 pcs.) we showed that errors of E0RedOx calculation decrease among PM7 > AM1 > RM1 and COSMO > PCM > SM5.2 > SM5C. However parameterization is more important than solvation model, thus PCM/RM1 is more accurate than SM5C/AM1. The accuracy of RedOx potential calculation depends on the electroactive functional group. PCM/RM1 demonstrates the best accuracy on anilines, approaching to ab initio methods SM5.42R/BPW91/DZVP//BPW91/cc-pVDZ (MADPCM/RM1(anilines) = 0.09 vs MADSM5.42R/BPW91/DZVP//BPW91/cc-pVDZ (anilines) = 0.09). For O-containing molecules accuracy of E0RedOx calculation was worse, MADPCM/RM1(phenols) = 0.92 and MADPCM/RM1(diphenols) = 0.68. Calculated values can be correlated by the equation E0RedOx (calc) = 0.2671*E0RedOx(PCM/RM1) + 0.2430. MO energies provided by PCM/RM1 can be used for ERedOx approximation. The routine equation ERed/Ox = −0,1494* EHOMO (X) −0,1416 * ELUMO (X) EMO2 - 0,5602 (R = 0,7420) has good correlation and is more practical, than the best equation ERed/Ox = −0,1752 * EHOMO (X+∗) −0,1653* ELUMO (X) EMO2 −1,0146 (R = 0,7762), because only one calculation of electroactive compound X is needed.