Molecular Modeling of Textile Dye Adsorption in Cyclodextrin Metal-Organic Frameworks

This study examines the adsorption behavior of textile dyes Crystal Violet (CV), Methylene Blue (MB), and Congo Red (CR) within cyclodextrin-based metal-organic frameworks (CD-MOFs) using simulated annealing and molecular dynamics simulations. The lowest-energy configurations revealed that CV is predominantly trapped within the central cavity of CD-MOF, stabilized by strong hydrogen bonding between cyclodextrin moieties and the amine group of CV. The adsorption energy of -74.84 kJ mol -1 suggests strong interaction, indicative of chemisorption-like behavior. MB and CR, in contrast, were primarily adsorbed within the side cavities of CD-MOF, exhibiting adsorption energies of -47.55 kJ mol -1 and -718.17 kJ mol -1 , respectively. The stability of these dye-CD-MOF complexes was confirmed by molecular dynamics, with low root-mean-square deviations (RMSD) and consistent radii of gyration over 10 ns simulations. Electrostatic and van der Waals interactions played a critical role in maintaining dye entrapment, ensuring prolonged retention within the MOF structure. These results highlight the potential of CD-MOFs as effective adsorbents for dye removal in wastewater treatment, with strong and stable dye-MOF interactions preventing desorption and ensuring efficient pollutant capture.