Evaluating Theoretical Solvent Models for Thermodynamic and Structural Descriptions of Dacarbazine–Cyclodextrin Complexes. The Theoretical and Conductometric Study

In this study, the influence of various implicit solvent models on the structural and thermodynamic properties of dacarbazine complexes with three cyclodextrins-α-CD, HP-β-CD, and HE-β-CD-was evaluated. The models considered were the polarizable continuum model (PCM), the conductor-like polarizable continuum model (CPCM), the solvation model based on density (SMD), and the Onsager model. Theoretical thermodynamic results were compared with experimental data obtained from conductometric studies. Our findings indicated that all three cyclodextrins form stable 1:1 inclusion complexes with dacarbazine. Among them, the complexes with HE-β-CD were the most thermodynamically stable. While the choice of solvent model had a minor impact on the structural properties of the complexes, it significantly affected thermodynamic parameters such as enthalpy, Gibbs free energy, and solvation free energy. The best agreement with experimental data-particularly for the Gibbs free energy of solvation-was observed when using the SMD model.