Since the number of fragments differs from the default library, the same number was selected from the remaining libraries. A workflow in KNIME 4.7.7 was implemented to compute the different stages of the filtering. Fragments H2O, NH3, and HCl were not considered. The first stage was to choose all fragments with MW less than 300 Da, according to the Rule of Three (RO3) . This was done with the RDKit Descriptor Calculation node.