A novel bismuth-based metal-organic framework for high volumetric methane and carbon dioxide adsorption

Solvothermal reaction of H4L (L = biphenyl-3,3’,5,5’-tetracarboxylate) and Bi(NO3)3·(H2O)5 in a mixture of DMF/MeCN/H2O in the presence of piperazine and nitric acid at 100 oC for 10 h affords the solvated metal-organic polymer [Bi2(L)1.5(H2O)2]·(DMF)3.5·(H2O)3 (NOTT-220-solv). A single crystal X-ray structure determination confirms that it crystallises in space group P2/c and has a neutral and non-interpenetrated structure comprising binuclear {Bi2} centres bridged by tetracarboxylate ligands. NOTT-220-solv shows a 3,6-connected network having a new framework topology with a {4·62}2{42·65·88}{62·8} point symbol. The desolvated material NOTT-220a shows exceptionally high adsorption uptakes for CH4 and CO2 on a volumetric basis at moderate pressures and temperatures with a CO2 uptake of 553 gL-1 (20 bar, 293 K) with a saturation uptake of 688 gL-1 (1 bar, 195 K). The corresponding CH4 uptake of 165 V(STP)/V (20 bar, 293 K) and 189 V(STP/V) (35 bar, 293 K) is within the top three MOF materials under the same conditions, surpassed only by PCN-14 and Ni-MOF-74 (230 and 190 V(STP)/V 35 Bar, 298 K). The maximum CH4 uptake for NOTT-220a was recorded at 20 bar and 195 K to be 287 V(STP)/V, while H2 uptake of NOTT-220a at 20 bar, 77 K is 42 gL-1. These gas uptakes have been modelled by Grand Canonical Monte Carlo (GCMC) and Density Functional Theory (DFT) calculations, which confirm the experimental data and give insights into the nature of the binding sites of CH4 and CO2 in this porous hybrid material

Rational syntheses of helical π-conjugated oligopyrrins with a bipyrrole linkage: geometry control of bis-copper(II) coordination

Rational syntheses of long-chain helical π-conjugated oligopyrrins and their bis-copper complexes afford systematically modulated optical and magnetic properties.</p

Unravelling exceptional acetylene and carbon dioxide adsorption within a tetra-amide functionalized metal-organic framework

Understanding the mechanism of gas-sorbent interactions is of fundamental importance for the design of improved gas storage materials. Here we report the binding domains of carbon dioxide and acetylene in a tetra-amide functionalized metal-organic framework, MFM-188, at crystallographic resolution. Although exhibiting moderate porosity, desolvated MFM-188a exhibits exceptionally high carbon dioxide and acetylene adsorption uptakes with the latter (232 cm3 g−1 at 295 K and 1 bar) being the highest value observed for porous solids under these conditions to the best of our knowledge. Neutron diffraction and inelastic neutron scattering studies enable the direct observation of the role of amide groups in substrate binding, representing an example of probing gas-amide binding interactions by such experiments. This study reveals that the combination of polyamide groups, open metal sites, appropriate pore geometry and cooperative binding between guest molecules is responsible for the high uptakes of acetylene and carbon dioxide in MFM-188a

Amides do not always work: observation of guest binding in an amide-functionalised porous host

An amide-functionalised metal organic frame-work (MOF) material, MFM-136, shows a high CO2 uptake of 12.6 mmol g-1 at 20 bar and 298 K. MFM-136 is the first example of acylamide pyrimidyl isophthalate MOF without open metal sites, and thus provides a unique platform to study guest bind-ing, particularly the role of free amides. Neutron diffraction reveals that, surprisingly, there is no direct binding between the adsorbed CO2/CH4 molecules and the pendant amide group in the pore. This observation has been confirmed un-ambiguously by inelastic neutron spectroscopy. This suggests that introduction of functional groups solely may not neces-sarily induce specific guest-host binding in porous materials, but it is a combination of pore size, geometry, and functional group that leads to enhanced gas adsorption properties

Observation of Binding and Rotation of Methane and Hydrogen within a Functional Metal-Organic Framework

The key requirement for a portable store of natural gas is to maximize the amount of gas within the smallest possible space. The packing of methane (CH₄) in a given storage medium at the highest possible density is, therefore, a highly desirable but challenging target. We report a microporous hydroxyl-decorated material, MFM-300­(In) (MFM = Manchester Framework Material, replacing the NOTT designation), which displays a high volumetric uptake of 202 v/v at 298 K and 35 bar for CH₄ and 488 v/v at 77 K and 20 bar for H₂. Direct observation and quantification of the location, binding, and rotational modes of adsorbed CH₄ and H₂ molecules within this host have been achieved, using neutron diffraction and inelastic neutron scattering experiments, coupled with density functional theory (DFT) modeling. These complementary techniques reveal a very efficient packing of H₂ and CH₄ molecules within MFM-300­(In), reminiscent of the condensed gas in pure component crystalline solids. We also report here, for the first time, the experimental observation of a direct binding interaction between adsorbed CH₄ molecules and the hydroxyl groups within the pore of a material. This is different from the arrangement found in CH₄/water clathrates, the CH₄ store of nature

Selective adsorption of sulfur dioxide in a robust metal-organic framework material

Selective adsorption of SO2 is realized in a porous metal–organic framework material, and in-depth structural and spectroscopic investigations using X-rays, infrared, and neutrons define the underlying interactions that cause SO2 to bind more strongly than CO2 and N2

First Observation of the Doubly Charmed Baryon Xi_cc^+

We observe a signal for the doubly charmed baryon Xi_cc^+ in the charged decay mode Xi_cc^+ --> Lambda_c^+ K- pi+ in data from SELEX, the charm hadro-production experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1 +/- 0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is (3519 +/- 1) MeV/c^2. The Gaussian mass width of this state is 3MeV/c^2, consistent with resolution; its lifetime is less than 33fsec at 90% confidence.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

Enhancement of CO2 Adsorption and Catalytic Properties by Fe-Doping of [Ga-2(OH)(2)(L)] (H4L = Biphenyl-3,3 ',5,5 '-tetracarboxylic Acid), MFM-300(Ga-2)

Metal-organic frameworks (MOFs) are usually synthesized using a single type of metal ion, and MOFs containing mixtures of different metal ions are of great interest and represent a methodology to enhance and tune materials properties. We report the synthesis of [Ga-2(OH)(2)(L)] (H4L = biphenyl-3,3',5,5'-tetracarboxylic acid), designated as MFM-300(Ga-2), (MFM = Manchester Framework Material replacing NOTT designation), by solvothermal reaction of Ga(NO3)(3) and H4L in a mixture of DMF, THF, and water containing HCl for 3 days. MFM-300(Ga-2) crystallizes in the tetragonal space group I4(1)22, a = b = 15.0174(7) angstrom and c = 11.9111(11) angstrom and is isostructural with the Al(III) analogue MFM-300(Al-2) with pores decorated with -OH groups bridging Ga(III) centers. The isostructural Fe-doped material [Ga1.87Fe0.13(OH)(2)(L)], MFM-300(Ga1.87Fe0.13), can be prepared under similar conditions to MFM-300(Ga-2) via reaction of a homogeneous mixture of Fe(NO3)(3) and Ga(NO3)(3) with biphenyl-3,3',5,5'-tetracarboxylic acid. An Fe(III)-based material [Fe3O1.5(OH)(HL)(L)(0.5)(H2O)(3.5)], MFM-310(Fe), was synthesized with Fe(NO3)(3) and the same ligand via hydrothermal methods. [MFM-310(Fe)] crystallizes in the orthorhombic space group Pmn2(1) with a = 10.560(4) angstrom, b = 19.451(8) angstrom, and c = 11.773(5) angstrom and incorporates mu(3)-oxo-centered trinuclear iron cluster nodes connected by ligands to give a 3D nonporous framework that has a different structure to the MFM-300 series. Thus, Fe-doping can be used to monitor the effects of the heteroatom center within a parent Ga(III) framework without the requirement of synthesizing the isostructural Fe(III) analogue [Fe-2(OH)(2)(L)], MFM-300(Fe-2), which we have thus far been unable to prepare. Fe-doping of MFM-300(Ga-2) affords positive effects on gas adsorption capacities, particularly for CO2 adsorption, whereby MFM-300(Ga1.87Fe0.13) shows a 49% enhancement of CO2 adsorption capacity in comparison to the homometallic parent material. We thus report herein the highest CO2 uptake (2.86 mmol g(-1) at 273 K at 1 bar) for a Ga-based MOF. The single-crystal X-ray structures of MFM-300(Ga-2)-solv, MFM-300(Ga-2), MFM-300(Ga-2)center dot 2.35CO(2), MFM-300(Ga1.87Fe0.13)-solv, MFM-300(Ga1.87Fe0.13), and MFM-300(Ga1.87Fe0.13)center dot 2.0CO(2) have been determined. Most notably, in situ single-crystal diffraction studies of gas-loaded materials have revealed that Fe-doping has a significant impact on the molecular details for CO2 binding in the pore, with the bridging M-OH hydroxyl groups being preferred binding sites for CO2 within these framework materials. In situ synchrotron IR spectroscopic measurements on CO2 binding with respect to the -OH groups in the pore are consistent with the above structural analyses. In addition, we found that, compared to MFM-300(Ga-2), Fe-doped MFM-300(Ga1.87Fe0.13) shows improved catalytic properties for the ring-opening reaction of styrene oxide, but similar activity for the room-temperature acetylation of benzaldehyde by methanol. The role of Fe-doping in these systems is discussed as a mechanism for enhancing porosity and the structural integrity of the parent material.We thank the Universities of Nottingham and Manchester for support. M.S. acknowledges receipt of an ERC Advanced Grant and EPSRC Programme Grant. We also thank EPSRC for funding of X-ray equipment. We acknowledge the use of instrumentation within the Nottingham Nanotechnology and Nanoscience Centre, and thank Dr. Christopher Parmenter for assistance. We thank Conacyt, Mexico, for funding to C.P.K. We are especially grateful to Diamond Light Source for access to Beamlines Ill (EE8943), 119 (MT7548, MT8448, MT8937), and B22 (SM11279).Krap, CP.; Newby, R.; Dhakshinamoorthy, A.; García Gómez, H.; Cebula, I.; Easun, TL.; Savage, M.... (2016). Enhancement of CO2 Adsorption and Catalytic Properties by Fe-Doping of [Ga-2(OH)(2)(L)] (H4L = Biphenyl-3,3 ',5,5 '-tetracarboxylic Acid), MFM-300(Ga-2). Inorganic Chemistry. 55(3):1076-1088. doi:10.1021/acs.inorgchem.5b02108S1076108855