## 3 Results
### Lipophilicity  
It is well known that chromatographic methods allow for establishing the experimental lipophilicity. In this research, the standardization procedure with six reference substances covering the range of lipophilicity of 0.46-3.80 was used. As a result, their log P values were highly correlated with their R\({}_{\mathrm{M}0}\) values in four organic modifiers, namely, acetone, acetonitrile, 1,4-dioxane, and methanol solvent systems, and appropriate calibration curves for further lipophilicity study were obtained:  
1. acetone: log P\({}_{\mathrm{EXP}}\) = 1.250R\({}_{\mathrm{M}0}\) - 0.256; \(r^{2}\) = 0.7265
2. acetonitrile: log P\({}_{\mathrm{EXP}}\) = 2.563R\({}_{\mathrm{M}0}\) - 2.402; \(r^{2}\) = 0.8984
3.1,4-dioxane: log P\({}_{\mathrm{EXP}}\) = 0.902R\({}_{\mathrm{M}0}\) + 0.662; \(r^{2}\) = 0.9457
4. methanol: log P\({}_{\mathrm{EXP}}\) = 1.101R\({}_{\mathrm{M}0}\) - 0.242; \(r^{2}\) = 0.9821  
The obtained coefficients of determination (\(r^{2}\)) for the mentioned equations were above 0.89 for three organic modifiers (i.e., acetonitrile, 1,4-dioxane, and methanol). Moreover, the \(r^{2}\) values were rather high (>0.72) for all organic modifiers used, including acetone. Similarly, for six reference compounds, the correlations between the R\({}_{\mathrm{F}}\) and R\({}_{\mathrm{M}0}\) values for **2**-**6** and **8**-**16** were sufficiently high (\(r^{2}\)\(\geq\) 0.91) for all solvents used. In addition, even better correlations (i.e., \(r^{2}\)\(\geq\) 0.98 for 12 or 11 compounds) were obtained for acetonitrile, acetone, and 1,4-dioxane solvent systems, providing accuracy for further lipophilicity determination (Table 2). Experimental lipophilicity (log P\({}_{\mathrm{EXP}}\)) of the synthesized 14 hydrazide-hydrazones (**2**-**6** and **8**-**16**) was calculated on the basis of the above calibration equations and respective R\({}_{\mathrm{M}0}\) values (Table 3). Generally, the highest log P\({}_{\mathrm{EXP}}\) values were calculated for the methanol-water solvent systems, except for compounds **4** and **13**, while the lowest values were obtained for acetonitrile, except for compound **14**. As far as more detailed differences were concerned, the highest log P\({}_{\mathrm{EXP}}\) values were calculated for compounds **2**-**4** containing monochloro(phenyl) substituents in _ortho-_, _meta-_, or _para-_positions. This was observed for all solvent systems used in our experiments. Thus, it can be stated that the position of the chloride atom in a phenyl ring did not affect the lipophilicity of these three derivatives (**2**-**4**). On the contrary, clearly seen differences were observed for dimethoxyphenyl-substituted hydrazide-hydrazones (compounds **12**-**14**). Between them, compound **13**, with a 2,4-dimethoxyyphenyl substituent, showed the highest log P values for all solvent systems used in our experiments, illustrating the importance of positional isomerism in the lipophilicity of these compounds. At the same time, two chlorophenyl substituted derivatives (i.e., **2** and **3**) showed higher log P values than similar fluorophenyl-substituted compounds (**5** and **6**). When compounds **8** and **10** were compared, the 4-hydroxy-3-iodo-5-methoxyphenyl-substituted hydrazide-hydrazone (**10**) was found to be more lipophilic than compound **8** with a 4-hydroxy-5-ethoxyphenyl substituent. This was observed for almost all solvent systems used in the present study (i.e., for the mixtures with acetonitrile, 1,4-dioxane, and methanol). Bearing in mind all the tested hydrazide-hydrazones (**2**-**6** and **8**-**16**), the lowest lipophilicity was shown for compound **15** substituted with the 5-nitro-2-furyl moiety.