Polyaluminum Keggin structures and larger clusters have a number of applications in water treatment, clay pillaring, active pharmaceutical ingredients (APIs), and serve as model molecules to study mineral surfaces. However, only a few aluminum Keggin structures have been isolated which can be partially attributed to their metastable nature. In fact, small perturbations in aluminum concentration, temperature, pH, or a number of other factors can cause significant structural transformations leading to polydispersity, completely different structure moieties, degradation into aluminum chloride monomers or precipitation as bulk aluminum hydroxide. In this work, we report the unprecedented stabilization of one of the more common Keggin aluminum clusters, Keggin Al13-mer, in alkaline pH environments (i.e., pH &gt; 9) by utilizing a combination of CaCl2 and L-arginine. Electronic structure calculations were employed and demonstrate favorable energies for binding configurations between calcium and L-arginine at ratios present in the high pH system. The discovery of soluble cationic polyaluminum clusters at pH &gt; 7 unlocks a new realm of synthesis, mechanism, and application of aluminum clusters.

Stabilization of cationic aluminum hydroxide clusters in high pH environments with a CaCl2/L-arginine matrix

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.