Confinement can have a drastic influence over the structure and properties of water. For example, water confined in pores narrower than 1 nm has significantly different dielectric constant and ionization potential compared to bulk water, which can profoundly change its ability to solvate ions and stabilize charged species. We have recently discovered a new class of bis-guanidinium receptors that persistently self-assemble with oxoanion-water clusters from competitive aqueous solutions into crystalline salts of extremely low aqueous solubilities, thereby providing a simple and effective separation approach for this class of anions via selective crystallization. Along these lines, we seek to understand the factors determining the anion selectivities and aqueous solubilities of these crystals, such as guanidinium-anion hydrogen bonding and anion hydration under the confinement and constraints of the crystal lattice. While the complete understanding of these crystalline systems remains our long-standing goal, we already applied them to solving real-world problems such as sulfate removal from seawater, in the context of scale prevention in oil field and desalination operations, and CO<sub>2</sub> capture from ambient air by carbonate crystallization, with relevance to climate change mitigations.<br/><br/>

Confinement of anion-water clusters in guanidine crystals

255th National Meeting (2018)

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