Sublimation of Molecular Crystals: Prediction of Sublimation Functions on the Basis of HYBOT Physicochemical Descriptors and Structural Clusterization

Quantitative structure-property relationship (QSPR) models on the basis of HYBOT physicochemical descriptors (molecular polarizability, the sum of all H-bond acceptor, and the sum of H-bond donor factors in a molecule) have been developed to predict sublimation enthalpies and Gibbs energies of molecular crystals. The experimental database analyzed includes 1766 values of sublimation enthalpies and 965 values of Gibbs energies. Fragmentation of the training sets for structurally similar groups/clusters both for enthalpies and Gibbs energies has been carried out using Tanimoto similarity coefficients T-c with the restriction of 0.5 <= T-c <= 1. According to this approach, any thermodynamic function, Y-(i) (where Y = Delta G(sub)(298), Delta H-sub(298), Delta S-sub(298)), has been calculated on the basis of experimental values of the same function of structurally closely related compounds (nearest neighbors, nn), Y-(nn), and the difference in their relevant physicochemical descriptors, Delta Y: Y-(i) = Y-(nn) + Delta Y. The value of unknown thermodynamic function has been calculated as a mean value from the values obtained for each of the elements in a cluster.