## 3 Results
### Lipophilicity  
It is well known that chromatographic methods allow fast and reproducible determination of experimental lipophilicity. In our research, we applied the standardization procedure with six reference substances (range of lipophilicity of 0.62-3.80) [34]. Their logP values were in high correlation with their R\({}_{\rm M0}\) values in three organic modifiers, i.e., acetonitrile, 1,4-dioxane and methanol solvent systems (Table 2). On the basis of this fact, the appropriate calibration curves for a further lipophilicity study were calculated:  
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Compound** & \multicolumn{4}{c}{**Acetonitrile-Water**} & \multicolumn{4}{c}{**1/4-Dioxane-Water**} & \multicolumn{4}{c}{**Methanol-Water**} \\ \cline{2-13}
**No** & **R\({}_{\rm M0}\)** & \(S\) & \(\mathbf{r^{2}}\) & \(\varphi\) & **R\({}_{\rm M0}\)** & \(S\) & \(\mathbf{r^{2}}\) & \(\varphi\) & **R\({}_{\rm M0}\)** & \(S\) & \(\mathbf{r^{2}}\) & \(\varphi\) \\ \hline
**2** & 2.7793 & \(-\)0.04 & 0.9722 & 70.86 & 3.1301 & \(-\)0.05 & 0.9803 & 64.17 & 4.0434 & \(-\)0.05 & 0.9931 & 83.00 \\ \hline
**3** & 3.1071 & \(-\)0.04 & 0.9792 & 76.11 & 3.7815 & \(-\)0.06 & 0.9717 & 67.54 & 4.8978 & \(-\)0.06 & 0.9913 & 87.08 \\ \hline
**4** & 2.4385 & \(-\)0.04 & 0.9849 & 68.03 & 3.2336 & \(-\)0.05 & 0.9927 & 61.91 & 3.9436 & \(-\)0.05 & 0.9862 & 80.80 \\ \hline
**5** & 2.8437 & \(-\)0.04 & 0.9872 & 73.71 & 3.8941 & \(-\)0.06 & 0.9997 & 65.10 & 4.7399 & \(-\)0.06 & 0.9886 & 84.77 \\ \hline
**6** & 2.9758 & \(-\)0.04 & 0.9918 & 74.58 & 3.9957 & \(-\)0.06 & 0.9955 & 65.42 & 4.7418 & \(-\)0.04 & 0.9983 & 86.00 \\ \hline
**7** & 3.1485 & \(-\)0.04 & 0.9863 & 76.34 & 4.0481 & \(-\)0.06 & 0.9978 & 66.01 & 4.8895 & \(-\)0.05 & 0.9913 & 87.24 \\ \hline
**8** & 3.3686 & \(-\)0.04 & 0.9747 & 79.02 & 4.0034 & \(-\)0.06 & 0.9846 & 68.82 & 5.0271 & \(-\)0.06 & 0.9979 & 88.90 \\ \hline
**9** & 2.0621 & \(-\)0.04 & 0.9916 & 58.52 & 2.4781 & \(-\)0.04 & 0.9939 & 58.01 & 3.1511 & \(-\)0.04 & 0.9866 & 76.25 \\ \hline
**10** & 2.1722 & \(-\)0.04 & 0.9873 & 61.40 & 2.6718 & \(-\)0.05 & 0.9926 & 59.00 & 3.5089 & \(-\)0.04 & 0.9943 & 78.19 \\ \hline
**11** & 2.1966 & \(-\)0.04 & 0.9834 & 62.39 & 2.4623 & \(-\)0.04 & 0.9957 & 58.57 & 3.3256 & \(-\)0.06 & 0.9932 & 77.28 \\ \hline
**12** & 2.3122 & \(-\)0.04 & 0.9858 & 62.26 & 2.7184 & \(-\)0.05 & 0.9985 & 60.10 & 3.3190 & \(-\)0.06 & 0.9913 & 78.44 \\ \hline \hline \end{tabular}  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline
**Compound** & \multicolumn{4}{c}{**Acetonitrile-Water**} & \multicolumn{4}{c}{**1/4-Dioxane-Water**} & \multicolumn{4}{c}{**Methanol-Water**} \\ \cline{2-13}
**No** & **R\({}_{\rm M0}\)** & \(S\) & \(\mathbf{r^{2}}\) & \(\varphi\) & **R\({}_{\rm M0}\)** & \(S\) & \(\mathbf{r^{2}}\) & \(\varphi\) & **R\({}_{\rm M0}\)** & \(S\) & \(\mathbf{r^{2}}\) & \(\varphi\) \\ \hline
**2** & 2.7793 & \(-\)0.04 & 0.9722 & 70.86 & 3.1301 & \(-\)0.05 & 0.9803 & 64.17 & 4.0434 & \(-\)0.05 & 0.99  
The obtained coefficients of determination (\(r^{2}\)) for the mentioned equations were above 0.90 for three organic modifiers (i.e., acetonitrile, 1,4-dioxane and methanol). Similarly, for our six reference compounds, the correlations between the R\({}_{\rm F}\) and R\({}_{\rm M0}\) values were sufficiently high (\(r^{2}\geq 0.97\)) with all solvents used.  
Better correlations (i.e., \(r^{2}\geq 0.99\) for compounds **7** or **16**) were calculated for methanol and 1,4-dioxane solvent systems, providing accuracy for further lipophilicity determination (Table 2).  
The logP\({}_{\rm EXP}\) values (experimental lipophilicity) of the fifteen tested substances **2-16** were calculated on the basis of the above calibration equations and respective R\({}_{\rm M0}\) values (Table 3).