show that for electron donating groups, HOMOP and HOMOX have a strong orbital interaction, and the resultant energy splitting opens a large energy gap that raises the energy level of the HOMO of the overall molecule, making it relatively easier to oxidize. In contrast, for electron withdrawing groups, HOMOP -HOMOX interactions are insignificant, and HOMOP -LUMOX interactions are important for setting the HOMO level of the overall molecule, lowering the HOMO level of the substituted molecule relative to the parent molecule (i.e., benzene-1,2-diol), thus making the molecule more difficult to oxidize. Using this theoretical framework, Yamabe et al. show a strong linear correlation between the experimentally determined reduction potentials of substituted benzene-1,2-diols and computationally determined HOMO levels (eHOMO). This correlation highlights that the electron donating or withdrawing character of substituents and computationally obtained eHOMO levels are excellent predictors of reduction potentials for substituted benzene-1,2-diols. This study therefore enabled extending the correlation analysis between optical response and electrochemical properties to a broader range of the screened analytes where reduction potentials had not have been experimentally determined but could be reasonably approximated with substituent inductive constants or computationally determined eHOMO values.