This affinity for water, at least for acidic compounds, was further demonstrated using the CH_strength descriptor (Figure ). This descriptor, calculated by Jazzy, predicts the hydrogenbond donor strength in carbon atoms. The smaller CH_strength values indicate that for entries with d3 < 0. Similarly, for basic compounds, higher values of the ATSc3 descriptor are associated with the consideration of the P I app for modeling pH-dependent lipophilic profiles on basic molecules (Figure ). This descriptor is related to the high molecular polarizability, which agrees with the pattern of small molecules in the presence of polar atoms such as nitrogen. Therefore, the apparent ionic partition effect should be considered for these small, rigid, and unsaturated molecules, which present a significant proportion of ionic species in the aqueous phase. It has been previously shown that the P I app of molecules may mechanistically occur via a simple ion-transfer reaction. 140 Thus, it is more plausible that small and compact molecules have a more prominent P I app because of the lower energetic cost of transferring to the cavity of the ion they replace.