A key finding from the study by Yamabe et al. is that electron donating groups raise the eHOMO values of benzene-1,2-diols, making them easier to oxidize. Accordingly, we first extended our correlation analysis between optical modulation and reduction potentials to the 18-compound subset library (Fig. ). Here, we used the Hammett constant of each substituent as a correlate for reduction potential. The analysis unveiled a robust correlation between experimentally measured optical modulations and the Hammett values of each substituent. Specifically, electron donating substituents produced stronger optical modulations (Fig. , fig. , fig. ). Moreover, for the same substituent X, Yamabe et al. demonstrated that the atomic orbital coefficients at the para-positions (4 or 5) are larger than the meta-/ortho-positions (3 or 5), leading to more robust orbital interactions that strongly modulate HOMO levels. For instance, placement of an -OH group at the para-position of benzene-1,2-diol (C) significantly increases electron density in the aryl compared to placement at the meta-/ortho-position (MM), making the molecule more easily oxidizable (fig. ). Notably, the optical responses we measured correlated well with such subtle differences between isomers of the same compound (fig. ) and in compounds that differed in just one functional group (fig. ). Because Yamabe's framework ultimately implicates eHOMO values as correlates for reduction potentials, it allowed us to extend this analysis to molecules in our library lacking a simple catechol motif or for which Hammett values could not be found, but for which overall HOMO values can be computed.