About the seminar:

Chemistry under nanoconfinement exhibits fundamentally different behavior compared to bulk systems, such as altered thermodynamic properties and molecular dynamics. Understanding these confined environments is critical for applications ranging from drug delivery and water purification to catalysis. While we can observe the initial and final states in these processes, the dynamic behavior of individual molecules within nanoconfined spaces remains poorly understood. This presentation discusses recent work utilizing anodic aluminum oxide (AAO) membranes as a practical model system to investigate confinement effects on molecular transport. Employing fluorescence correlation spectroscopy (FCS), the diffusion of rhodamine B (RhB) was observed through individual AAO pores, enabling direct observation of single molecule dynamics in one-dimensional nanoconfinement. The measurements reveal bimodal diffusion behavior that was absent in bulk solution: a fast diffusion component that, while exhibiting behaviors similar to that of bulk RhB diffusion, exhibits reduced mobility attributable to electrostatic interactions between the charged dye and AAO pore walls accompanied by hydrodynamic drag from an immobile water layer adsorbed at the pore-solution interface, and a slow diffusion component arising from reversible adsorption-desorption events at the pore surface. These findings demonstrate how nanoconfinement alters transport mechanisms available to molecular species, highlighting the relationship between geometric constraints, interfacial interactions, and molecular dynamics in nanoscale environments.