Volumetric investigations of solute–solvent interactions of cytosine and their methyl-, methoxy-, and hydroxy-derivatives in methanol and N,N-dimethylformamide at 25 °C

Experimentally determined densities of cytosine and their methyl-, methoxy-, and hydroxy-derivatives at 25 °C in methanol and N,N-dimethylformamide are presented. The apparent molar volumes and then the partial molar volumes V20 were calculated. Together with previously obtained V20 for aqueous solutions of compounds studied: (1) the transfer functions ΔV2,tr0 water–methanol, water–N,N-dimethylformamide; (2) the contributions to V20 value which correspond to substitution on cytosine moiety of a hydrogen atom on a N, O, C atom by CH3 group and replacement of a hydrogen on N4 by an OH group were determined and discussed. Structural parameters: molecular accessible surface SM areas and their atomic partition SN, SO, SH(N,O), molecular volumes V2M of compounds studied were calculated. Its enables to determine the correlations between volumetric properties and structural parameters according to the model which is based on the assumptions that density of solvation shell α depends on polarity P and the structure of the hydrophobic compounds. The transfer functions ΔV2,tr0 water–methanol, water–N,N-dimethylformamide were also calculated and discussed.