Understanding the Interface of Liquids with an Organic Crystal Surface from Atomistic Simulations and AFM Experiments

摘要

A strong ordering of solvent molecules in the solid—liquid interface of a typical and characteristic organic crystal (p-nitroaniline) is observed in state-of-the-art atomic force microscopy experiments. In the current work, we use both molecular dynamics (MD) simulations and experiments in different solvents to provide a detailed understanding of the nature of the solid—liquid interface. The strong ordering of solvent molecules at the surface of p-nitroaniline is confirmed in general, but the MD simulations point to several different possible surface reconstructions, offering different ordering of water on the surface. The calculated water density profiles and local surface hydration energies suggest a novel surface structure, which is in excellent agreement with the majority of experimental results and stands as a challenge for future diffraction techniques. Our joined theoretical and experimental study emphasizes the power of high-resolution techniques to probe the solid—liquid interface in 3D while demonstrating the importance of including systematic simulation approaches to confirm the details of the molecular structure and to increase our understanding of complex heterogeneous solid—liquid interfaces.