Multivariate CuBTC Metal–Organic Framework with Enhanced Selectivity, Stability, Compatibility, and Processability

Abstract

A novel, mixed-linker metal−organic framework (MOF) was synthesized, and the resulting macromolecular assembly had enhanced activity and stability in comparison to the isostructural CuBTC (aka HKUST-1). Mixtures of 5-aminoisophthalic acid (AIA) and 1,3,5-benzenetricarboxylic acid (BTC) were combined at different ratios to incorporate aryl amine groups into the MOF that were readily amenable to postsynthetic modification. As one example, the amine groups were reacted with decanoyl chloride (DC) through the formation of amide linkages, which overcame a major shortcoming of CuBTC by stabilizing the MOF toward ammonia vapor during breakthrough experiments and to liquid water for over 24 h. Furthermore, the MOF modified with DC exhibited ∼70% increases in CO₂/N₂ and CO₂/H₂O selectivity at flue gas relevant conditions relative to CuBTC. The modified MOFs had increased compatibility with polyacrylonitrile, poly(styrene-block-isoprene-block-styrene), and poly(styrene-block-ethylene-ranbutylene-block-styrene) polymers, which made them ideal for incorporation in polymer fibers and composite films and reduced defects generally associated with polymer−nanoparticle systems. Finally, the AIA and DC-modified MOFs had significantly enhanced moisture stability relative to unmodified CuBTC. Overall, this facile modification route provides the framework for higher-performance materials in applications such as filtration, gas storage, and flue gas scrubbing, among many others.