title: Highly tunable molecular sieving and adsorption properties of mixed-linker zeolitic imidazolate frameworks.
abstract: Nanoporous zeolitic imidazolate frameworks (ZIFs) form structural topologies equivalent to zeolites. ZIFs containing only one type of imidazole linker show separation capability for limited molecular pairs. We show that the effective pore size, hydrophilicity, and organophilicity of ZIFs can be continuously and drastically tuned using mixed-linker ZIFs containing two types of linkers, allowing their use as a more general molecular separation platform. We illustrate this remarkable behavior by adsorption and diffusion measurements of hydrocarbons, alcohols, and water in mixed-linker ZIF-8(x)-90(100-x) materials with a large range of crystal sizes (338 nm to 120 μm), using volumetric, gravimetric, and PFG-NMR methods. NMR, powder FT-Raman, and micro-Raman spectroscopy unambiguously confirm the mixed-linker nature of individual ZIF crystals. Variation of the mixed-linker composition parameter (x) allows continuous control of n-butane, i-butane, butanol, and isobutanol diffusivities over 2-3 orders of magnitude and control of water and alcohol adsorption especially at low activities.
authors.forename: Kiwon
authors.initials: K
authors.lastname: Eum
authors.forename: Krishna C
authors.initials: KC
authors.lastname: Jayachandrababu
authors.forename: Fereshteh
authors.initials: F
authors.lastname: Rashidi
authors.forename: Ke
authors.initials: K
authors.lastname: Zhang
authors.affiliation: ‡School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
authors.forename: Johannes
authors.initials: J
authors.lastname: Leisen
authors.affiliation: §Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332-0405, United States.
authors.forename: Samuel
authors.initials: S
authors.lastname: Graham
authors.forename: Ryan P
authors.initials: RP
authors.lastname: Lively
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Chance
authors.forename: David S
authors.initials: DS
authors.lastname: Sholl
authors.affiliation: ‡School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia 30332-0400, United States.
authors.forename: Christopher W
authors.initials: CW
authors.lastname: Jones
authors.forename: Sankar
authors.initials: S
authors.lastname: Nair
mesh_terms: D000327:Adsorption; D000438:Alcohols / Q000302:isolation & purification; D002073:Butanes / Q000302:isolation & purification; D004058:Diffusion; D057927:Hydrophobic and Hydrophilic Interactions; D007093:Imidazoles / Q000737:chemistry*; D008958:Models, Molecular; D058608:Nanopores / Q000648:ultrastructure; D049329:Nanostructures / Q000737:chemistry*; D016062:Porosity; D014867:Water / Q000032:analysis; D017641:Zeolites / Q000737:chemistry*
chemical_list: D000438:Alcohols; D002073:Butanes; D007093:Imidazoles; D014867:Water; D017641:Zeolites; C046888:butane; C029899:imidazole