To highlight the changes of physicochemical properties during transfer learning, we selected the fraction of sp 3 -hybridized carbon atoms (Fsp3) as an illustrative example since Fsp3 values typically differ between synthetic and natural compounds . During transfer learning, the Fsp3 distribution approximated the transfer learning set distribution (Fig. ). This finding confirms that transfer learning from a small set of structurally similar compounds enables the model to implicitly capture relevant physicochemical properties.