Thermodynamic investigations of cytosine and its methyl, methoxy and hydroxy derivatives. Enthalpies of solvation in methanol and N, N -dimethylformamide

Abstract

Abstract The enthalpies of solution Δ sol H m ∞ of cytosine, 1-methylcytosine, 1,5-dimethylcytosine, 1-methyl-N 4 -hydroxycytosine, 1,5-dimethyl-N 4 -hydroxycytosine, 1-methyl-N 4 -methoxycytosine, 1,5-dimethyl-N 4 -methoxycytosine in methanol and in N, N - dimethylformamide were determined and discussed with previously obtained data of the enthalpy of sublimation Δ s g H m , partial molar volumes V 0 2 and structural parameters {e.g. molecular accessible surface areas S M and their atomic partition S N , S O , S H(N,O) , molecular volumes V M 2 } for compounds investigated. The enthalpies of solvation Δ solv H m , the transfer enthalpies of solution Δ tr H m , water-methanol, water- N, N -dimethylformamide and enthalpies of interaction Δ int H m were calculated. Correlation between the enthalpy of solvation, volumetric and structural parameters was elaborated. It was demonstrated that the enthalpy of solvation and transfer enthalpy of solution correlate with surface accessible areas as well as with volumetric properties characterized by parameter β, corresponding to the difference between the partial molar and molecular volumes of compounds studied.