All QC calculations were performed with Gaussian, applying the PM6 method for all SQC calculations. All QC calculations were set up with the B3LYP functional and 6-31G** basis set, as well as an implicit benzene solvent environment through the CPCM model. These settings have been selected after benchmarking results for alizarin and purpurin (see section S2.1 of the ESI). Settings related to the hyperparameter grid initialization of the ArchOnML package, as well as the definitions of the descriptors used for this study can be found in the ESI in sections S2.6