The mutual solubility of carbon dioxide and alcohols over a wide range of temperature and pressure provides a useful and tunable medium for reactions and separations. For many years, researchers have used alcohols as cosolvents in supercritical CO2, and recently CO2-swollen alcohols have been used for antisolvent crystallization and as mobile phases for chromatography. However, little consideration has been given to chemical interaction between the alcohols and CO2. We have confirmed that such an interaction does exist and can create an acidic environment. By isolating reaction products we have demonstrated that alcohol−CO2 complexes react similarly to carboxylic acids with diazodiphenylmethane, a compound typically used to evaluate acid strengths. Our evidence indicates that the behavior of CO2−alcohol systems is comparable to that of CO2−water systems, where carbonic acid is formed.

This work details the development of a cotton fabric functionalized with UiO-66-NH2 metal–organic framework (MOF). The materials were made by seeding the growth of the MOF on the cotton by first bonding zirconium (Zr) to the surface of the fabric utilizing cyanuric chloride modified with a thiol. After seeding the fabrics with Zr, UiO-66-NH2 was grown on the fabric using a hydrothermal method. Several different routes of attaching Zr to cyanuric chloride were examined. Scanning electron microscopy (SEM) and powder X-ray diffraction (PXRD) data are consistent with UiO-66-NH2, and the fabrics have surface areas between 45 and 125 m2/g depending on the synthetic conditions used to produce the materials. The functionalized cotton reacts with dimethyl 4-nitrophenyl phosphate (DMNP), a chemical nerve agent simulant, as monitored by UV–vis spectroscopy. The results illustrate that MOF–fiber composites can be created using natural fibers, and the resulting composites provide similar chemical warfare agent (CWA) simulant reactivity as observed on composites of MOFs and synthetic polymers..

Dedicated to Professor Thomas P. MurrayProposed by Singer and Nicolson in 1972, [1] the fluid-mosaic model holds that the phospholipid bilayer is a dynamic twodimensional solvent milieu. Its proper function is closely tied to its "fluidity", and that is often quantified by reference to the melting point, T m (increased fluidity corresponds to a lower T m value). The fluid-mosaic model is highly evocative of the emerging picture of nanoscale structuring in ionic liquids (ILs), [2,3] and just as the function of phospholipid bilayers is tied to the T m value, so too is the utility of ILs. Whereas the former often have low T m values despite being composed of charged species with long aliphatic appendages, the fluidity of ILs generally decreases when progressively longer aliphatic appendages are used. [4] It is a challenge to design imidazolium ILs (the most common IL class) that incorporate progressively more lipophilic structural elements while keeping their melting points below room temperature (Figure 1). [4][5][6][7][8][9] Indeed, the T m values of these ILs begin to rise dramatically once an appended Nalkyl group exceeds seven carbon atoms in length. Herein we report that by using an approach modeled on homeoviscous adaptation (HVA), [10] ILs with very long alkyl appendages and very low T m values can be prepared. This discovery may have significant implications for IL use in enzymatic catalysis, lubricants, heat-transfer fluids, and gas storage and separation, among other applications.Widely accepted as a mechanism by which the melting temperature of cell membranes is modulated, HVA is the incorporation into cell membranes of phospholipids with "kinked" tail structures.[10] It is argued that the packing efficiency of the collective membrane hydrophobic components is diminished by the presence of these phospholipids and that increased fluidity results. A comparison of the T m value of distearoylphosphatidylcholine with that of dioleylphosphatidylcholine provides a dramatic example of how much impact this seemingly trivial difference can have. The former, with its linear, saturated C 18 tails has a T m value of 58 8C; the latter, with its "kinked" C 18 tails (each of which incorporates a cis-alkenyl group), has a T m value of À22 8C. This effect is also at the heart of the T m difference between the solid triacyl glycerols called fats, and those that are liquid at room temperature known as oils. In both instances, the effect is probably entropic in nature, as in the case of anthracene ("linear", T m = 217 8C) and phenanthrene ("kinked", T m = 99 8C).[11] Accordingly, we hypothesized that ILs with long, unsaturated, aliphatic tail structures would, like the corresponding phospholipids, have significantly lower T m values than their counterparts with saturated appendages.To test the validity of our hypothesis by measuring their T m values, we prepared a series of lipid-inspired ILs in a threestep process from high-purity (99 + %) fatty-alcohol mesylates, 1-methylimidazole, NaI, and NaTf 2 N.[12] Each of the ILs ...

This work examines six task-specific ionic liquids (TSILs), comprised of the taurinate anion paired with five tetraalkylammonium cations (where alkyl = methyl, ethyl, propyl, butyl, and hexyl) and a tetrabutylphosphonium cation, impregnated in ordered mesoporous silica, SBA-15. The composites showed significantly increased CO 2 uptakes relative to the parent SBA-15 materials. The surface area of these materials varies from approximately 5 to 1000 m 2 /g depending on the amount of IL loaded into the silica pores. The presence of n-hexyl side chains on the TSIL significantly reduces water loading, indicating that judicious IL selection may provide a means of controlling water uptake. After exposure to water vapor, three of the six cation-taurinate composites displayed an increase in CO 2 capacity. X-ray diffraction data of the composite of tetramethylammonium taurinate and SBA-15 shows that the ionic liquid is crystalline inside the pores of the silica. Isotherms are measured at several different temperatures and the results show that storage at ambient humidity significantly impacts the capacity of these materials. By comparison, the TSILs supported on an amorphous porous support, BPL activated carbon, showed no increase in CO 2 adsorption capacity. The results provide physical insight into the synthesis, structure, porosity, and sorption capacity of composites of adsorbents and ionic liquids that need to be considered prior to application.

Fluorous biphasic chemistry enables the recovery of homogeneous catalysts but presents engineering challenges because of issues concerning phase contacting and solvent loss. The addition of gaseous CO2 to fluorous−organic biphasic systems results in a single homogeneous liquid phase at temperatures well below the upper critical solution temperature of the binary liquid mixture. This phenomenon is due to the high solubility of CO2 in both organic liquids and fluorocarbons, and it facilitates reactions and can also reduce fluorous solvent losses. We demonstrate two homogeneously catalyzed reactions, a hydrogenation and an epoxidation, which result in an enhancement in the turnover frequency of 70% and 50%, respectively, for the CO2-merged phase relative to the fluorous biphasic system. This creates new opportunities for the use of fluorous-sequestered catalysts.