Reconciling the discrepancies between crystallographic porosity and guest access as exemplified by Zn-HKUST-1.

There are several compounds for which there exists a disconnect between porosity as predicted by crystallography and porosity measured by gas sorption analysis. In this paper, the Zn-based analogue of Cu(3)(btc)(2) (HKUST-1), Zn(3)(btc)(2) (Zn-HKUST-1; btc = 1,3,5-benzenetricarboxylate) is investigated. Conventional analysis of Zn-HKUST-1 by powder X-ray diffraction and gas sorption indicates retention of crystalline structure but negligible nitrogen uptake at 77 K. By using positron annihilation lifetime spectroscopy, a densified surface layer preventing the entry of even small molecular species into the crystal framework is revealed. The material is shown to have inherent surface instability after solvent removal, rendering it impermeable to molecular guests irrespective of handling and processing methods. This previously unobserved surface instability may provide insight into the failure of other microporous coordination polymers to exhibit significant porosity despite crystal structures indicative of regular, interconnected, microporous networks.

[1]  D. Ruthven,et al.  The nature of surface barriers on nanoporous solids explored by microimaging of transient guest distributions. , 2011, Journal of the American Chemical Society.

[2]  Hae‐Kwon Jeong,et al.  Heteroepitaxial Growth of Isoreticular Metal−Organic Frameworks and Their Hybrid Films , 2010 .

[3]  A. Matzger,et al.  Microporous coordination polymers as selective sorbents for liquid chromatography. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[4]  Omar K Farha,et al.  Supercritical processing as a route to high internal surface areas and permanent microporosity in metal-organic framework materials. , 2009, Journal of the American Chemical Society.

[5]  Ian D. Williams,et al.  A chemically functionalizable nanoporous material (Cu3(TMA)2(H2O)3)n , 1999 .

[6]  Chengdu Liang,et al.  A microporous metal-organic framework for gas-chromatographic separation of alkanes. , 2006, Angewandte Chemie.

[7]  Felix Baitalow,et al.  Main-group and transition-element IRMOF homologues. , 2010, Journal of the American Chemical Society.

[8]  A. Yee,et al.  Determination of Pore Size in Mesoporous Thin Films from the Annihilation Lifetime of Positronium , 2001 .

[9]  Zhigang Xie,et al.  Freeze drying significantly increases permanent porosity and hydrogen uptake in 4,4-connected metal-organic frameworks. , 2009, Angewandte Chemie.

[10]  A. Matzger,et al.  Dramatic tuning of carbon dioxide uptake via metal substitution in a coordination polymer with cylindrical pores. , 2008, Journal of the American Chemical Society.

[11]  B. Rieger,et al.  Paddle-Wheel Zinc Carboxylate Clusters as Building Units for Metal-Organic Frameworks , 2007 .

[12]  R. Snurr,et al.  Using molecular simulation to characterise metal-organic frameworks for adsorption applications. , 2009, Chemical Society reviews.

[13]  U. Mueller,et al.  Metal–organic frameworks—prospective industrial applications , 2006 .

[14]  A. Matzger,et al.  Metal-dependent phase selection in coordination polymers derived from a C(2V)-symmetric tricarboxylate. , 2010, Inorganic chemistry.

[15]  Byeong Kwon Park,et al.  Metal-directed supramolecular assembly of metal(II) benzoates (M = Co, Ni, Cu, Zn, Mn, and Cd) with 4,4'-bipyridine: Effects of metal coordination modes and novel catalytic activities , 2009 .

[16]  Ulrich Müller,et al.  Industrial applications of metal-organic frameworks. , 2009, Chemical Society reviews.

[17]  Lili Wen,et al.  Structures, Photoluminescence, and Photocatalytic Properties of Six New Metal−Organic Frameworks Based on Aromatic Polycarboxylate Acids and Rigid Imidazole-Based Synthons , 2009 .

[18]  A. Matzger,et al.  Beryllium benzene dicarboxylate: the first beryllium microporous coordination polymer , 2009 .

[19]  A. Micke,et al.  A Nonequilibrium Surface Barrier for Sorption Kinetics of p-Ethyltoluene on ZSM-5 Molecular Sieves , 1994 .

[20]  Omar K Farha,et al.  Metal-organic framework materials as catalysts. , 2009, Chemical Society reviews.

[21]  S. Kitagawa,et al.  Soft secondary building unit: dynamic bond rearrangement on multinuclear core of porous coordination polymers in gas media. , 2011, Journal of the American Chemical Society.

[22]  Krista S. Walton,et al.  Applicability of the BET method for determining surface areas of microporous metal-organic frameworks. , 2007, Journal of the American Chemical Society.

[23]  D. D. De Vos,et al.  Separation of styrene and ethylbenzene on metal-organic frameworks: analogous structures with different adsorption mechanisms. , 2010, Journal of the American Chemical Society.

[24]  D. Gidley,et al.  POSITRON ANNIHILATION AS A METHOD TO CHARACTERIZE POROUS MATERIALS , 2006 .

[25]  S. J. Tao.  Positronium Annihilation in Molecular Substances , 1972 .

[26]  D. Vos,et al.  Silica–MOF Composites as a Stationary Phase in Liquid Chromatography , 2010 .

[27]  A. Matzger,et al.  Evolution of Nanoscale Pore Structure in Coordination Polymers During Thermal and Chemical Exposure Revealed by Positron Annihilation , 2010, Advanced materials.

[28]  J. Marrot,et al.  VIII(OH)[O2C-C6H4-CO2].(HO2C-C6H4-CO2H)x(DMF)y(H2O)z(or MIL-68), a new vanadocarboxylate with a large pore hybrid topology: reticular synthesis with infinite inorganic building blocks? , 2004, Chemical communications.

[29]  Hong-Cai Zhou,et al.  Selective gas adsorption and separation in metal-organic frameworks. , 2009, Chemical Society reviews.

[30]  Jan Fransaer,et al.  Patterned Growth of Metal-Organic Framework Coatings by Electrochemical Synthesis , 2009 .

[31]  A. Matzger,et al.  Liquid phase separations by crystalline microporous coordination polymers , 2010 .

[32]  Mircea Dincă,et al.  Hydrogen storage in metal-organic frameworks. , 2009, Chemical Society reviews.

[33]  M. Mccoy.  A HEIGHTENED AGENDA: With regulatory threats growing, the AMERICAN CHEMISTRY COUNCIL steps up advocacy , 2010 .

[34]  Gérard Férey,et al.  Hybrid porous solids: past, present, future. , 2008, Chemical Society reviews.

[35]  Carlo Lamberti,et al.  The inconsistency in adsorption properties and powder XRD data of MOF-5 is rationalized by framework interpenetration and the presence of organic and inorganic species in the nanocavities. , 2007, Journal of the American Chemical Society.

[36]  A. Matzger,et al.  Gas and liquid phase adsorption in isostructural Cu3[biaryltricarboxylate]2 microporous coordination polymers. , 2011, Chemical communications.

[37]  R. J. Mitchell,et al.  Solid-state transformations of zinc 1,4-benzenedicarboxylates mediated by hydrogen-bond-forming molecules. , 2001, Chemistry.

[38]  John N. Sherwood,et al.  The temperature dependence of positron lifetimes in solid pivalic acid , 1981 .

[39]  A. Matzger,et al.  MOF@MOF: microporous core-shell architectures. , 2009, Chemical communications.

[40]  A. Matzger,et al.  A framework for predicting surface areas in microporous coordination polymers. , 2010, Langmuir : the ACS journal of surfaces and colloids.

[41]  Young Eun Cheon,et al.  A comparison of the H2 sorption capacities of isostructural metal-organic frameworks with and without accessible metal sites: [{Zn2(abtc)(dmf)2}3] and [{Cu2(abtc)(dmf)2}3] versus [{Cu2(abtc)}3]. , 2008, Angewandte Chemie.