Determination of the lipophilicity parameters R-M0 and log P of new azaphenothiazines by reversed-phase thin-layer chromatography

The lipophilicity parameters (R-M0 and log P-TLC) of three types of azaphenothiazines 1-3 were determined by reversed-phase thin-layer chromatography on RP-18 silica plates with acetone-aqueous TRIS (tris(hydroxymethyl)aminomethane) buffer as the mobile phase. The R-M values were linearly dependent on the concentration of acetone, and extrapolated to 0% of acetone, gave the lipophilicity parameter R-M0. The parameter R-M0 and specific hydrophobic surface area b were significantly intercor-related showing a congeneric class of azaphenothiazines 1-3. The parameter log P-TLC was determined from the R-M0 values by use of a calibration curve obtained for five standards. The determined parameters were discussed in the terms of structure lipophilicity relationships and compared with data obtained from seven calculation programs.