A combined DFT-MD study on the adsorption behavior of allicin on silver-organic framework surfaces

This research explores the adsorption characteristics of allicin (ALC) molecules on the metal-organic framework (MOF) designated as AgH₈C₆N₃O₂, or Ag-MOF, focusing on three different surface orientations: 100, 010, and 001. The binding strength of ALC molecules on different facets of the Ag-MOF was systematically evaluated by using density functional theory with D3 dispersion corrections (DFT-D3) and molecular dynamics (MD) simulations. Results revealed that on the (001) surface, the molecule labelled as configuration D (001-D) demonstrated a binding energy (E_bin) of -0.894 eV. This value reflects a significantly stronger binding affinity relative to other configurations, with configuration A (001-A) showing - 0.697 eV, configuration B (001-B) at -0.732 eV, and configuration C (001-C) measuring - 0.816 eV. This stronger interaction, assessed via the PBE-D3 functional, suggests that ALC (particularly 001-D) preferentially binds more robustly to the (001) facet through physisorption, whereas interactions on the (010) and (100) surfaces are comparatively weaker in adsorption process. Significant variations in the dipole moment were observed upon ALC adsorption onto the (001) surface, which could enhance its solubility. We used Time-Dependent Density Functional Theory (TDDFT) to analyze UV-Vis spectra, finding a modest red shift in the absorption peak when ALC was adsorbed onto the (001) surface, compared to the spectrum of the pristine MOF surface. Infrared (IR) spectra calculations for both ALC and the ALC-adsorbed MOF closely matched experimental data, validating the computational approaches. MD simulations, spanning 20 to 80 picoseconds, demonstrated that ALC interacts effectively with the porous surface of the MOF, highlighting its suitability for adsorption. The theoretical analysis revealed that the electronic structure of the Ag-MOF changes when ALC molecules are adsorbed onto it. These findings offer valuable insights into the properties of ALC when adsorbed onto Ag-MOFs, providing a foundation for further exploration of their role in biomedical applications.