2.3. LogP Measurement (Octanol/Water Partition Coefficient)

The octanol/water partition coefficient was measured using the flask shaking method [23]. After mixing octanol and water at a ratio of 1:1 and stirring vigorously, the mixture was allowed to stand for 24 h for equilibration. A 10 mM solution of each compound was added to the equilibrated octanol-water mixture and the mixture was shaken for 1 h. Centrifugation was performed at 2000× g to separate the octanol and the aqueous layers. The absorbance of each layer at 280 nm was measured and the concentration was calculated from the calibration curve of each compound. The concentration of each compound was converted into LogP_OW as follows: [compound concentration of octanol layer/compound concentration of water layer.]