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Ionicliquids (ILs) are ionic compounds that are liquid at roomtemperature. We studied the spontaneous mixing behavior between twoILs, ethylammonium nitrate (EAN) and 1-butyl-3-methylimidazolium hexafluorophosphate([BMIM][PF6]), and observed notable phenomena. Experimentalstudies showed that the interface between the two ILs was unusuallylong-lived, despite the ILs being miscible with one another. Moleculardynamics (MD) simulations supported these findings and provided insightinto the micromixing behavior of the ILs. We found that not only didthe ions experience slow diffusion as they mix but also exhibitedsignificant ordering into distinct regions. We suspect that this orderingdisrupted concentration gradients in the direction normal to the interface,thus hindering diffusion in this direction and allowing the macroscopicinterface to remain for long periods of time. Intermolecular interactionsresponsible for this behavior included the O–NH interactionbetween the EAN ions and the carbon chain–carbon chain interactionsbetween the [BMIM]+cations, which associate more stronglyin the mixed state than in the pure IL state. [ABSTRACT FROM AUTHOR]

Recently, a number of publications have suggested thationic liquids(ILs) can absorb solid particles. This development may have implicationsin fields likeoil sand processing, oil spill beach cleanup, and water treatment.In this Article, we provide a computational investigation of thisphenomenon via molecular dynamics simulations. Two particle surfacechemistries were investigated: (1) hydrocarbon-saturated and (2) silanol-saturated,representing hydrophobic and hydrophilic particles, respectively.Employing 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]) as a model IL, these nanoparticles were allowed to equilibrateat the IL/water and IL/hexane interfaces to observe the interfacialself-assembled structures. At the IL/water interface, the hydrocarbon-basednanoparticles were nearly completely absorbed by the IL, while thesilica nanoparticles maintained equal volume in both phases. At theIL/hexane interface, the hydrocarbon nanoparticles maintained minimalinteractions with the IL, whereas the silica nanoparticles were nearlycompletely absorbed by it. Studies of these two types of nanoparticlesimmersed in the bulk IL indicate that the surface chemistry has agreat effect on the corresponding IL liquid structure. These effectsinclude layering of the ions, hydrogen bonding, and irreversible absorptionof some ions to the silica nanoparticle surface. We quantify theseeffects with respect to each nanoparticle. The results suggest thatILs likely exhibit this absorption capability because they can formsolvation layers with reduced dynamics around the nanoparticles. [ABSTRACT FROM AUTHOR]

Muconic acid is a promising platform biochemical and precursor to adipic acid, which can be used to synthesize various plastics and polymers. In this study, the systematic construction and comparative evaluation of a modular network of non-natural pathways for muconic acid biosynthesis was investigated in Escherichia coli, including via three distinct and novel pathways proceeding via phenol as a common intermediate. However, poor recombinant activity and high promiscuity of phenol hydroxylase ultimately limited "phenol-dependent" muconic acid production. A fourth pathway proceeding via p-hydroxybenzoate, protocatechuate, and catechol was accordingly developed, though with muconic acid titers by this route reaching just 819 mg/L, its performance lagged behind that of the established, "3-dehydroshikimiate-derived" route. Finally, these two most promising pathways were coexpressed in parallel to create a synthetic "metabolic funnel" that, by enabling maximal net precursor assimilation and flux while preserving native chorismate biosynthesis, nearly doubled muconic acid production to up to >3.1 g/L at a glucose yield of 158 mg/g while introducing only a single auxotrophy. This generalizable, "funneling" strategy is expected to have broad applications in metabolic engineering for further enhancing production of muconic acid, as well as other important bioproducts of interest.