Abstract
Two metal-organic framework materials, MFM-130 and MFM-131 (MFM = Manchester Framework Material), have been synthesized using two oligoparaxylene (OPX) tetracarboxylate linkers containing four and five aromatic rings, respectively. Both fof-type non-interpenetrated networks contain Kagomé lattice layers comprising [Cu2(COO)4] paddlewheel units and isophthalates, which are pillared by the OPX linkers. Desolvated MFM-130, MFM-130a, shows permanent porosity (BET surface area of 2173 m(2)/g, pore volume of 1.0 cm(3)/g), high H2 storage capacity at 77 K (5.3 wt% at 20 bar and 2.2 wt% at 1 bar), and a higher CH4 adsorption uptake (163 cm(3)(STP)/cm(3) (35 bar and 298 K)) compared with its structural analogue, NOTT-103. MFM-130a also shows impressive selective adsorption of C2H2, C2H4, and C2H6 over CH4 at room temperature, indicating its potential for separation of C2 hydrocarbons from CH4. The single-crystal structure of MFM-131 confirms that the methyl substituents of the paraxylene units block the windows in the Kagomé lattice layer of the framework, effectively inhibiting network interpenetration in MFM-131. This situation is to be contrasted with that of the doubly interpenetrated oligophenylene analogue, NOTT-104. Calculation of the mechanical properties of these two MOFs confirms and explains the instability of MFM-131 upon desolvation in contrast to the behavior of MFM-130. The incorporation of paraxylene units, therefore, provides an efficient method for preventing network interpenetration as well as accessing new functional materials with modified and selective sorption properties for gas substrates.
Highlights
An advantage of porous metal−organic frameworks (MOFs) is that their design, structure, and properties can be varied by modification of the organic linkers, which can have different lengths, topologies, and geometries and can incorporate functional groups to enhance preferential binding of guest substrates via optimized pore shapes/diameters for molecular separation
We have developed a series of framework materials employing linear tetracarboxylate linkers and [Cu2(COO)4] paddlewheel units3 to generate fof-type networks
We have successfully synthesized in a novel and efficient manner two linear tetracarboxylate linkers containing paraxylene units and the respective [Cu2(COO)4]-based foftype networks MFM-130 and MFM-131. Both these frameworks are non-interpenetrating, despite the extra-long organic linkers used, and comprise Kagomé lattice layers pillared by the organic oligoparaxylene backbones
Summary
Nanoporous metal−organic frameworks (MOFs) constructed from metal cations or clusters bridged by polyfunctional organic linkers are an important class of hybrid materials which show great promise for gas storage and separation applications. An advantage of porous MOFs is that their design, structure, and properties can be varied by modification of the organic linkers, which can have different lengths, topologies, and geometries and can incorporate functional groups to enhance preferential binding of guest substrates via optimized pore shapes/diameters for molecular separation. We have developed a series of framework materials employing linear tetracarboxylate linkers and [Cu2(COO)4] paddlewheel units to generate fof-type networks. The assembly of isophthalate (benzene-3,5-dicarboxylate) units within tetracarboxylate linkers with [Cu2(COO)4] paddlewheels generates two-dimensional Kagomé lattices, which are pillared by the aromatic backbones of these linkers. The structural analogue NOTT-1043b constructed from a linear tetracarboxylate linker incorporates the same length of strut used in MFM-131, but without the methyl groups In this case, two identical fof-type lattices interpenetrate to form a doubly interpenetrated network in NOTT-104 (Figure 3c). Bar are 109 cm3/g (21.3 wt%) and 59 cm3/g (11.6 wt%) at 273 and 298 K, respectively These values are lower than those for other highly porous Cu(II)-based MOF materials such as NOTT-1226f (39.7 wt% at 273 K; 20.4 wt % at 298 K) and NOTT-12525 (40.0 wt% at 273 K; 18.2 wt% at 298 K), which is attributed to the smaller pore size and the absence of CO2-favorable organic functionalities in MFM-130a, they are higher than for most other frameworks without open metal sites such as ZIFs under the same conditions.. MFM-130a represents a rare example of a framework material showing simultaneously high C2 hydrocarbons adsorption capacities and high C2 hydrocarbons/CH4 selectivities at ambient temperature
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
