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

Abstract

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 V 2 0 were calculated. Together with previously obtained V 2 0 for aqueous solutions of compounds studied: (1) the transfer functions Δ V 2,tr 0 water–methanol, water– N, N-dimethylformamide; (2) the contributions to V 2 0 value which correspond to substitution on cytosine moiety of a hydrogen atom on a N, O, C atom by CH 3 group and replacement of a hydrogen on N 4 by an OH group were determined and discussed. Structural parameters: molecular accessible surface S M areas and their atomic partition S N, S O, S H(N,O), molecular volumes V 2 M 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 Δ V 2,tr 0 water–methanol, water– N, N-dimethylformamide were also calculated and discussed.