49 research outputs found

    Advances Towards Synthetic Machines at the Molecular and Nanoscale Level

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    The fabrication of increasingly smaller machines to the nanometer scale can be achieved by either a “top-down” or “bottom-up” approach. While the former is reaching its limits of resolution, the latter is showing promise for the assembly of molecular components, in a comparable approach to natural systems, to produce functioning ensembles in a controlled and predetermined manner. In this review we focus on recent progress in molecular systems that act as molecular machine prototypes such as switches, motors, vehicles and logic operators

    Synthesizing Hypercrosslinked Polymers with Deep Eutectic Solvents to Enhance CO2/N2 Selectivity

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    Hypercrosslinked polymers (HCPs) are widely used in ion exchange, water purification, and gas separation. However, HCP synthesis typically requires hazardous halogenated solvents e.g., dichloroethane, dichloromethane and chloroform which are toxic to human health and environment. Herein we hypothesize that the use of halogenated solvents in HCP synthesis can be overcome with deep eutectic solvents (DES) comprising metal halides – FeCl3, ZnCl2 that can act as both the solvent hydrogen bond donor and catalyst forpolymer crosslinking via Friedel Crafts alkylation. We validated our hypothesis by synthesizing HCPs in DESs via internal and external crosslinking strategies. [ChCl][ZnCl2]2 and [ChCl][FeCl3]2 was more suitable for internal and external hypercrosslinking, respectively. The specific surface areas of HCPs synthesized in DES were 20 – 60 % lower than those from halogenated solvents, but their CO2/N2 selectivities were up to 453 % higher (CO2/N2 selectivity of poly-α,α’-dichloro-p-xylene synthesized in [ChCl][ZnCl2]2 via internal crosslinking reached a value of 105). This was attributed to the narrower pore size distributions of HCPs synthesized in DESs

    AIMs: a new strategy to control physical aging and gas transport in mixed-matrix membranes

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    The effect of controlling interactions between the components in a mixed-matrix membrane at the molecular level has been explored. A systematic series of soluble metal–organic polyhedra (MOPs) of varying external organic chain length were prepared and applied within polymer membranes to produce anti-aging intercalated membranes (AIMs). Use of a soluble porous additive allowed for intimate mixing between the polymer and the porous additive, eliminating the formation of non-selective gas transport voids at the interface, typically found in traditional mixed-matrix membranes. Moreover, the molecular interaction thus created provided a valuable tool for tailoring the physical aging rates of the membranes. Aging was slowed by a factor of three with the optimal tBu-MOP additive, and viscosity measurements revealed they held the strongest MOP–polymer interaction, confirming the utility of the AIMs approach. MOP loading was therefore able to be optimized for the maximum anti-aging effect by monitoring the relative change in viscosity. Absolute gas permeability scaled with the MOP external organic chain length, revealing solubility-driven diffusion.Melanie Kitchin, Jesse Teo, Kristina Konstas, Cher Hon Lau, Christopher J. Sumby, Aaron W. Thornton, Christian J. Doonan, and Matthew R. Hil

    Flow synthesis of hypercrosslinked polymers with additional microporosity that enhances CO2/N2 separation

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    Hypercrosslinked polymers (HCPs) are typically synthesised over 24 hour batch reactions, limiting productivity rates during scale-up production. Continuous flow synthesis can potentially overcome this limitation. However, the formation of insoluble HCP products, compounded by HCP expansion due to solvent adsorption during synthesis can clog flow reactors. Here, we overcome clogging issues through reactor design and optimisation of synthesis parameters. Using this reactor, we synthesised HCPs via internal, post-, and external crosslinking strategies underpinned by Friedel–Crafts alkylation over various synthesis parameters – residence time, substrate concentration, reagent ratio, and temperature. The space-time-yield (STY) values, a key parameter for productivity rates, of flow synthesis were 32–117 fold higher than those in batch reactions. HCPs produced via internal crosslinking in flow synthesis contained additional microporosity that enhanced CO2/N2 selectivity at 298 K by 850% when compared to HCPs produced in batch reactions. Outcomes from this work could enable high productivity scale-up production of HCPs for post-carbon capture

    Heterometallic CeIII–FeIII–salicylate networks : models for corrosion mitigation of steel surfaces by the ′Green′ inhibitor, Ce(salicylate)3

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    The syntheses and structures of the novel Ce&ndash;Fe bimetallic complexes [{Fe(sal)2(bpy)}2Ce(NO3)(H2O)3]&middot;EtOH and [{Fe(sal)2(bpy)}4Ce2(H2O)11][salH]2&middot;EtOH&middot;3H2O (salH2 = salicylic acid) suggest Fe3+&ndash;sal2&minus; units and Ce&ndash;OC(R)O&ndash;Fe bridging contribute to the formation of corrosion inhibitive layers on steel surfaces exposed to [Ce(salH)3(H2O)].<br /

    Application of lanthanoid catalysts for the synthesis of Michler's hydride

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    A series of lanthanoid (Ln(3+)) based Lewis acid catalysts were investigated as alternatives to other metal based catalysts for the formation of Michler's hydride, 4,4'-methylenebis(N,N-dimethylaniline) (1). The lanthanoid based Lewis acid catalysts were superior to previously published catalysts resulting in formation of 4,4'-methylenebis(N, N-dimethylaniline) (1) and N,N-dimethyl- 4-(4-(methylamino)benzyl) aniline (2). If paraformaldehyde was added to the reaction only 4,4'-methylenebis(N,N-dimethylaniline) (1) was formed

    Novel Mercury Phosphanylamides

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    The definitive version may be found at www.wiley.comMarcus L. Cole, Glen B. Deacon, Peter C. Junk, Kristina Konstas and Peter W. Roesk

    Performance evaluation of CuBTC composites for room temperature oxygen storage

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    Oxygen is commonly separated from air using cryogenic liquefaction.</p