Interaction between drug molecule and inverse spinel surfaces in aqueous solution: Insights from DFT and DMC simulation

In this work, Hartree-Fock (HF), Density function theory (DFT) and dynamical Monte Carlo (DMC) simulations were executed to give information about the adsorption mechanism of clofibric acid (CA) on Mg2TiO4 and Ba2TiO4. Results show that the adsorption efficiency is closely related to global and local quantum chemical parameters. Electronic properties including HOMO-LUMO analysis and NBO charge transfer analysis reveal that the ionic form (CAion) is a more reactive and less stable than the neutral CA molecule. DMC results show that both forms of the drug are adsorbed almost parallel to the surfaces. Mg2TiO4 exhibited high adsorption energy toward the acidic form (-35.056 kcal/mol). From the results, dynamic descriptors show that both forms are adsorbed more strongly on the Mg2TiO4 surface compared to the Ba2TiO4 surface. The short distances between the adsorbates and the adsorbents suggest a chemisorption. Furthermore, the interaction energy values are negative which implies a spontaneous process.