Analytical ultracentrifugation (AUC) is a powerful and information-rich technique for directly characterizing the molecular weight, size, shape, dispersity, and association behavior of species in their native solution environment, spanning a broad molecular weight range of ~ 100 Da to 100 MDa. Unlike many orthogonal methods, AUC does not require immobilization, labeling, or assumptions regarding sample homogeneity. With recent advances in instrumentation and data analysis software, AUC enables more accurate and reliable characterization of diverse solution systems, including biomacromolecules, colloids, surfactants, and polymers. Owing to their uniform and well-defined molecular weights, sizes, and shapes, molecular clusters are particularly well suited for AUC studies. In this work, we investigate molecular cluster solutions using AUC, highlighting its significant potential in this field. Even relatively simple AUC experiments can provide detailed and quantitative insights into molecular cluster systems, including hydration shell thickness, intermolecular distances in dimers, and adsorption of organic ligands such as amino acids.

An emerging method for effectively improving the catalytic activity of metal oxide hybrids involves the creation of metal oxide interfaces for facilitating the activation of reagents. Here, we demonstrate that bilayer vesicles formed from a hexavanadate cluster functionalized with two alkyl chains are highly efficient catalysts for the oxidation of 3, 3′, 5, 5′-tetramethylbenzidine (TMB) with H₂O₂ at room temperature, a widely used model reaction mimicking the activity of peroxidase in biological catalytic oxidation processes. Driven by hydrophobic interactions, the double-tailed hexavanadate-headed amphiphiles can self-assemble into bilayer vesicles and create hydrophobic domains that segregate the TMB chromogenic substrate. The reaction of TMB with H₂O₂ takes place at the interface of the hydrophilic and hydrophobic domains, where the reagents also make contact with the catalytic hexavanadate clusters, and it is approximately two times more efficient compared with the reactions carried out with the corresponding unassembled systems. Moreover, the assembled vesicular system possesses affinity for TMB comparable to that of reported noble metal mimic nanomaterials, as well as a higher maximum reaction rate.