Macromolecular-metal complexes induced by Co(II) with polymer and flexible ligands for ammonia uptake compared with MOFs

Abstract

MOFs are considered as potential adsorbents for their outstanding properties, but it’s troublous for reversible ammonia adsorption or the collapse of MOFs’ framework. Macromolecular-metal complexes (MMCs) are proposed to efficient and reversible NH3 uptake at the first time with the consideration of the same coordinated unit to MOFs but with entropic advantage to assist the reversibility. In this work, the MMCs are developed with the construction of stable porous macromolecular-Co(II) networks and competitive flexible ligands to target the high capacity of 19.5 mmol/g under STP and reversibility of MMCs. The efficient NH3 uptake of MMCs was proposed to the coordination of NH3 with Co(II) along with the hydrogen bonding interaction with flexible ligand and the physical adsorption for the porosity of MMCs, meanwhile, the invariable macromolecular-Co(II) networks protect MMCs from collapse and comfine the flexible ligand. The comfined ligand would compete with NH3 to coordinate with Co(II), which promotes the release of NH3 and the reversibility of MMCs. The development of MMCs in this work provides a potential and competitive choice for NH3 storage as well as other special applications for the tunable structure trough regulating the macromolecule, metallic center, and ligand.