As expected, most optical modulations were generated by compounds bearing the catechol motif, whereas other molecules generated modest or no responses. Interestingly, the catechol motif was not a guarantee of the presence of a fluorescence modulation, and even within the catechol family of molecules, optical responses varied widely (Fig. ). This observation suggested that the heuristics described earlier are useful qualitative descriptors, but they do not fully capture the trends in optical responses. We therefore set out to identify molecular properties that could offer better quantitative explanation of the observed variability in optical responses. Towards this goal, we explored molecular correlates of optical modulation by assessing if certain physicochemical parameters of these molecules correlated with optical responses. To facilitate comparison and minimize contributions that might arise from significant differences in molecular structure and steric effects, we selected a subset of 18 compounds, each bearing a catechol motif with simple substituents at different positions on the aryl ring (Fig. ). We then investigated correlation between 12 different cheminformatic parameters of these molecules and the optical modulations generated by each. These properties included the strength of dipole moment, polarizability, LogP, and van der Waals surface area, among others. The analysis demonstrated a general lack of correlation between the experimentally measured optical responses and all 12 of the physicochemical attributes examined (Fig. and). The electrochemical properties of catecholamines have traditionally been exploited for their characterization and quantification using techniques such as amperometry, cyclic voltammetry, and liquid chromatography with tandem mass spectrometry. Similarly, optical modulations in some SWCNTbased sensors have been shown to be driven by the redox activities of their target analytes, with electrochemical mechanisms posited as the basis for fluorescence modulation. Given our observation of a wide range of optical responses even in compounds bearing simple catechol motifs, we set out to conduct a deeper exploration of whether the observed optical trends correlated with the electrochemical properties of the screened molecules. Specifically, we wanted to know if experimental optical responses correlated with reduction potentials in our selected subset of catechol compounds.