Thermodynamic study of sublimation, solubility and solvation of bioactive derivatives of hydrogenated pyrido[4,3-b]indoles

Abstract

The saturated vapor pressure of 5 biologically active compounds of the series of hydrogenated pyrido[4,3-b]indoles were measured using the transpiration method in the temperature range of (427.15–461.15) K. Based on the experimental data the thermodynamic functions of sublimation were calculated. The sublimation enthalpies of the compounds vary from 143.1 to 167.3 kJ·mol−1. It has been shown that the thermodynamic functions of sublimation can be estimated by the space clusterization approach for the studied and structurally related compounds The diagram approach has been used to study the effect of the chemical nature of substituents on sublimation, dissolution and solvation of the compounds in solvents modelling different biological media: buffer pH 7.4, 1-octanol and n-hexane. It has been established that structural modification of the molecules through the introduction of a fluorine atom into the indole fragment reduces the sublimation and solvation terms of the Gibbs energy of dissolution in buffer pH 7.4 and hexane, improving the solubility.