Molecular Interactions and Binding Free Energy of Polydopamine and Methylene Blue: A DFT Study (original) (raw)

Polydopamine (PDA) is a kind of mussel-inspired material. It has been applied as a coating and an adsorbent material. As an adsorbent, the PDA microspheres were used to remove methylene blue (MB) in aqueous solution. It was reported that the efficiency of the PDA adsorbent depends on the pH of the solution. Furthermore, in a pH range of 3 - 10, the hydroxyl and amine functional groups of PDA can be either protonated or deprotonated. The change of the net charge of PDA can affect the intermolecular interactions between PDA and MB. It was proposed that both of the electrostatic and p-p interactions should be dominant in the acidic and basic solutions. Therefore, the structural properties and intermolecular interactions of the PDA-MB complex should be investigated. Such an investigation can be useful for the improvement of the PDA microspheres for the other dyes. To get insight into the roles of PDA structure and its role as an interesting adsorbent for MB, the PDA-MB complex formation...