Ammonia Capture within Zirconium Metal–Organic Frameworks: Reversible and Irreversible Uptake

-oxo. Ammonia adsorption occurs via both reversible and irreversible processes. The latter are of particular interest for protection and mitigation. Notably, the unexpected dissociative adsorption occurs only with nodes that have been fully dehydrated and irreversibly structurally distorted via thermal pre-treatment-a finding that is supported by density functional theory calculations. Differentiating and ranking the relative importance of the many modes of adsorption was facilitated, in part, by the availability of variants of NU-1000 that replace the majority of terminal aqua and hydroxo ligands with nonstructural formate ligands, auxiliary ditopic linkers, or both. The study provides insights into the chemical basis for both reversible and irreversible uptake of ammonia by Zr-MOFs and related compounds. The unexpectedly rich variety of sorption motifs suggest the criteria for designing or choosing MOFs that are optimal for specific ammonia-centric applications.