title: Dimensionality transformation through paddlewheel reconfiguration in a flexible and porous Zn-based metal-organic framework.
abstract: The reaction between Zn and a pyrene-based ligand decorated with benzoate fragments (H(4)TBAPy) yields a 2D layered porous network with the metal coordination based on a paddlewheel motif. Upon desolvation, the structure undergoes a significant and reversible structural adjustment with a corresponding reduction in crystallinity. The combination of computationally assisted structure determination and experimental data analysis of the desolvated phase revealed a structural change in the metal coordination geometry from square-pyramidal to tetrahedral. Simulations of desolvation showed that the local distortion of the ligand geometry followed by the rotation and displacement of the pyrene core permits the breakup of the metal-paddlewheel motifs and the formation of 1D Zn-O chains that cross-link adjacent layers, resulting in a dimensionality change from the 2D layered structure to a 3D structure. Constrained Rietveld refinement of the powder X-ray diffraction pattern of the desolvated phase and the use of other analytical techniques such as porosity measurements, (13)C CP MAS NMR spectroscopy, and fluorescence spectroscopy strongly supported the observed structural transformation. The 3D network is stable up to 425 °C and is permanently porous to CO(2) with an apparent BET surface area of 523(8) m(2)/g (p/p° = 0.02-0.22). Because of the hydrophobic nature, size, and shape of the pores of the 3D framework, the adsorption behavior of the structure toward p-xylene and m-xylene was studied, and the results indicated that the shape of the isotherm and the kinetics of the adsorption process are determined mainly by the shape of the xylene isomers, with each xylene isomer interacting with the host framework in a different manner.
authors.affiliation: Department of Chemistry, University of Liverpool, Liverpool L69 7ZD, UK.
authors.forename: Kyriakos C
authors.initials: KC
authors.lastname: Stylianou
authors.forename: Jeremy
authors.initials: J
authors.lastname: Rabone
authors.forename: Samantha Y
authors.initials: SY
authors.lastname: Chong
authors.forename: Romain
authors.initials: R
authors.lastname: Heck
authors.forename: Jayne
authors.initials: J
authors.lastname: Armstrong
authors.forename: Paul V
authors.initials: PV
authors.lastname: Wiper
authors.forename: Kim E
authors.initials: KE
authors.lastname: Jelfs
authors.forename: Sergey
authors.initials: S
authors.lastname: Zlatogorsky
authors.forename: John
authors.initials: J
authors.lastname: Bacsa
authors.forename: Alec G
authors.initials: AG
authors.lastname: McLennan
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Ireland
authors.forename: Yaroslav Z
authors.initials: YZ
authors.lastname: Khimyak
authors.forename: K Mark
authors.initials: KM
authors.lastname: Thomas
authors.forename: Darren
authors.initials: D
authors.lastname: Bradshaw
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Rosseinsky
mesh_terms: D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D009930:Organic Chemicals / Q000737:chemistry*; D013050:Spectrometry, Fluorescence; D015032:Zinc / Q000737:chemistry*
chemical_list: D009930:Organic Chemicals; D015032:Zinc