Browsing by Author "Telfer SG"

Now showing 1 - 7 of 7
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    Gas adsorption in the topologically disordered Fe-BTC framework
    (Royal Society of Chemistry, 2021-11-19) Sapnik AF; Ashling CW; Macreadie LK; Lee SJ; Johnson T; Telfer SG; Bennett TD
    Disordered metal-organic frameworks are emerging as an attractive class of functional materials, however their applications in gas storage and separation have yet to be fully explored. Here, we investigate gas adsorption in the topologically disordered Fe-BTC framework and its crystalline counterpart, MIL-100. Despite their similar chemistry and local structure, they exhibit very different sorption behaviour towards a range gases. Virial analysis reveals that Fe-BTC has enhanced interaction strength with guest molecules compared to MIL-100. Most notably, we observe striking discrimination between the adsorption of C3H6 and C3H8 in Fe-BTC, with over a twofold increase in the amount of C3H6 being adsorbed than C3H8. Thermodynamic selectivity towards a range of industrially relevant binary mixtures is probed using ideal adsorbed solution theory. Together, this suggests the disordered material may possess powerful separation capabilities that are rare even amongst crystalline frameworks.
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    Guest size limitation in metal-organic framework crystal-glass composites
    (Royal Society of Chemistry, 2021-03-01) Ashling CW; Macreadie LK; Southern TJF; Zhang Y; McHugh LN; Evans RC; Kaskel S; Telfer SG; Bennett TD
    Metal-organic framework crystal-glass composites (MOF CGCs) have previously been formed by embedding crystalline MIL-53(Al) within a ZIF-62 glass (agZIF-62) matrix. Here we highlight thermal stability considerations in the formation of MOF CGCs, and subsequently report the synthesis of two novel MOF CGCs, by incorporating MIL-118 and UL-MOF-1 withinagZIF-62. These new materials, alongside the prototypical MOF CGC, formed using MIL-53(Al), were studied using scanning electron microscopy, powder X-ray diffraction, and gas sorption techniques. The gas uptake in composites formed from MIL-118C and UL-MOF-1 is largely dominated by theagZIF-62 matrix, suggesting that to improve the porosity of the MOF CGC, the matrix porosity must be improved, or a percolation threshold must be overcome.
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    In Situ Investigation of Multicomponent MOF Crystallization during Rapid Continuous Flow Synthesis
    (American Chemical Society, 2021-11-17) He B; Macreadie LK; Gardiner J; Telfer SG; Hill MR
    Access to the potential applications of metal-organic frameworks (MOFs) depends on rapid fabrication. While there have been advances in the large-scale production of single-component MOFs, rapid synthesis of multicomponent MOFs presents greater challenges. Multicomponent systems subjected to rapid synthesis conditions have the opportunity to form separate kinetic phases that are each built up using just one linker. We sought to investigate whether continuous flow chemistry could be adapted to the rapid formation of multicomponent MOFs, exploring the UMCM-1 and MUF-77 series. Surprisingly, phase pure, highly crystalline multicomponent materials emerge under these conditions. To explore this, in situ WAXS was undertaken to gain an understanding of the formation mechanisms at play during flow synthesis. Key differences were found between the ternary UMCM-1 and the quaternary MUF-7, and key details about how the MOFs form were then uncovered. Counterintuitively, despite consisting of just two ligands UMCM-1 proceeds via MOF-5, whereas MUF-7 consists of three ligands but is generated directly from the reaction mixture. By taking advantage of the scalable high-quality materials produced, C6 separations were achieved in breakthrough settings.
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    Photoinduced Electron Transfer in Multicomponent Truxene-Quinoxaline Metal-Organic Frameworks
    (American Chemical Society, 2022-09-27) Cornelio J; Lee SJ; Zhou T-Y; Alkaş A; Thangavel K; Pöppl A; Telfer SG
    Metal-organic frameworks (MOFs) can respond to light in a number of interesting ways. Photochromism is observed when a structural change to the framework is induced by the absorption of light, which results in a color change. In this work, we show that introducing quinoxaline ligands to MUF-7 and MUF-77 (MUF = Massey University Framework) produces photochromic MOFs that change color from yellow to red upon the absorption of 405 nm light. This photochromism is observed only when the quinoxaline units are incorporated into the framework and not for the standalone ligands in the solid state. Electron paramagnetic resonance (EPR) spectroscopy shows that organic radicals form upon irradiation of the MOFs. The EPR signal intensities and longevity depend on the precise structural details of the ligand and framework. The photogenerated radicals are stable for long periods in the dark but can be switched back to the diamagnetic state by exposure to visible light. Single-crystal X-ray diffraction analysis reveals bond length changes upon irradiation that are consistent with electron transfer. The multicomponent nature of these frameworks allows the photochromism to emerge by allowing through-space electron transfer, precisely positioning the framework building blocks, and tolerating functional group modifications to the ligands.
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    Selective capture of carbon dioxide from hydrocarbons using a metal-organic framework
    (Springer Nature Limited, 2021-01-08) Qazvini OT; Babarao R; Telfer SG
    Efficient and sustainable methods for carbon dioxide capture are highly sought after. Mature technologies involve chemical reactions that absorb CO2, but they have many drawbacks. Energy-efficient alternatives may be realised by porous physisorbents with void spaces that are complementary in size and electrostatic potential to molecular CO2. Here, we present a robust, recyclable and inexpensive adsorbent termed MUF-16. This metal-organic framework captures CO2 with a high affinity in its one-dimensional channels, as determined by adsorption isotherms, X-ray crystallography and density-functional theory calculations. Its low affinity for other competing gases delivers high selectivity for the adsorption of CO2 over methane, acetylene, ethylene, ethane, propylene and propane. For equimolar mixtures of CO2/CH4 and CO2/C2H2, the selectivity is 6690 and 510, respectively. Breakthrough gas separations under dynamic conditions benefit from short time lags in the elution of the weakly-adsorbed component to deliver high-purity hydrocarbon products, including pure methane and acetylene.
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    Synergistic Effect of Redox Dual PdO x/MnOx Cocatalysts on the Enhanced H2 Production Potential of a SnS/α-Fe2O3 Heterojunction via Ethanol Photoreforming.
    (American Chemical Society, 2022-11-22) Etemadi H; Soltani T; Yoshida H; Zhang Y; Telfer SG; Buchanan JK; Plieger PG
    In the quest for optimal H2 evolution (HE) through ethanol photoreforming, a dual cocatalyst-modified heterocatalyst strategy is utilized. Tin(II) sulfide (SnS) was hybridized with α-Fe2O3 to form the heterocatalyst FeOSnS with a p-n heterojunction structure as confirmed by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), UV-vis diffusive reflectance spectroscopy (UV-vis DRS), and Brunauer-Emmett-Teller (BET) techniques. PdOx and PdOx /MnOx cocatalysts were loaded onto the FeOSnS heterocatalyst through the impregnation method, as verified by high-resolution transform electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and elemental mapping. Photocatalytic ethanol photoreforming resulted in the production of H2 as the main product with a selectivity of 99% and some trace amounts of CH4. The FeOSnS2-PdOx 2%/MnOx 1% photocatalyst achieved the highest HE rate of 1654 μmol/g, attributed to the synergistic redox contribution of the PdOx and MnOx species.
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    Tuning the Stereoselectivity of an Intramolecular Aldol Reaction by Precisely Modifying a Metal-Organic Framework Catalyst
    (Wiley-VCH GmbH, 2022-06-15) Cornelio J; Telfer SG
    We report the catalysis of an enantioselective, intramolecular aldol reaction accelerated by an organocatalyst embedded in a series of multicomponent metal-organic frameworks. By precisely programming the pore microenvironment around the site of catalysis, we show how important features of an intramolecular aldol reaction can be tuned, such as the substrate consumption, enantioselectivity, and degree of dehydration of the products. This tunability arises from non-covalent interactions between the reaction participants and modulator groups that occupy positions in the framework remote from the catalytic site. Further, the catalytic moiety can be switched form one framework linker to another. Deliberately building up microenvironments that can influence the outcome of reaction processes in this way is not possible in conventional homogenous catalysts but is reminiscent of enzymes.