title: Separation of hexane isomers in a metal-organic framework with triangular channels.
abstract: Metal-organic frameworks can offer pore geometries that are not available in zeolites or other porous media, facilitating distinct types of shape-based molecular separations. Here, we report Fe2(BDP)3 (BDP(2-) = 1,4-benzenedipyrazolate), a highly stable framework with triangular channels that effect the separation of hexane isomers according to the degree of branching. Consistent with the varying abilities of the isomers to wedge along the triangular corners of the structure, adsorption isotherms and calculated isosteric heats indicate an adsorption selectivity order of n-hexane > 2-methylpentane > 3-methylpentane > 2,3-dimethylbutane ≈ 2,2-dimethylbutane. A breakthrough experiment performed at 160°C with an equimolar mixture of all five molecules confirms that the dibranched isomers elute first from a bed packed with Fe2(BDP)3, followed by the monobranched isomers and finally linear n-hexane. Configurational-bias Monte Carlo simulations confirm the origins of the molecular separation.
authors.affiliation: Department of Chemistry, University of California-Berkeley, CA 94720, USA.
authors.forename: Zoey R
authors.initials: ZR
authors.lastname: Herm
authors.forename: Brian M
authors.initials: BM
authors.lastname: Wiers
authors.forename: Jarad A
authors.initials: JA
authors.lastname: Mason
authors.forename: Jasper M
authors.initials: JM
authors.lastname: van Baten
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Hudson
authors.forename: Pawel
authors.initials: P
authors.lastname: Zajdel
authors.forename: Craig M
authors.initials: CM
authors.lastname: Brown
authors.forename: Norberto
authors.initials: N
authors.lastname: Masciocchi
authors.forename: Rajamani
authors.initials: R
authors.lastname: Krishna
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Long