A closer look into deep eutectic solvents: exploring intermolecular interactions using solvatochromic probes.

Deep eutectic solvents (DESs) constitute a new class of ionic solvents that has been developing at a fast pace in recent years. Since these solvents are commonly suggested as green alternatives to organic solvents, it is important to understand their physical properties. In particular, polarity plays an important role in solvation phenomena. In this work, the polarity of different families of DESs was studied through solvatochromic responses of UV-vis absorption probes. Kamlet-Taft α, ß, π* and ETN parameters were evaluated using different solvatochromic probes, as 2,6-dichloro-4-(2,4,6-triphenyl-N-pyridino)-phenolate (Reichardt's betaine dye 33), 4-nitroaniline, and N,N-diethyl-4-nitroaniline for several families of DESs based on cholinium chloride, dl-menthol and a quaternary ammonium salt ([N4444]Cl). In addition, a study to understand the difference in polarity properties between DESs and the corresponding ILs, namely ILs based on cholinium cation and carboxylic acids as anions ([Ch][Lev], [Ch][Gly] and [Ch][Mal]), was carried out. The chemical structure of the hydrogen bond acceptor (HBA) in a DES clearly controls the dipolarity/polarizability afforded by the DES. Moreover, Kamlet-Taft parameters do not vary much within the family, but they differ among families based on different HBA, either for DESs containing salts ([Ch]Cl or [N4444]Cl) or neutral compounds (dl-menthol). A substitution of the HBD was also found to play an important role in solvatochromic probe behaviour for all the studied systems.

Ionic liquids in pharmaceutical applications.

In the past several years, ionic liquids (ILs) have been at the cutting edge of the most promising science and technology. ILs not only have found applications in classical areas of knowledge but also are important candidates to solve classical problems within several societal challenges, such as clean and efficient energy, through the development of a broad swath of energy technologies, such as advanced batteries, dye-sensitized solar cells, double-layer capacitors, actuators, fuel cells, thermo-cells, and water splitting, essentially related to highly efficient carbon capture and storage technologies and resource efficiency to date. This review focuses on the application of IL methodologies to solve critical pharmaceutical problems, in particular, the low solubility and thus bioavailability of pharmaceutical compounds and the presence of polymorphs, which severely hamper the efficacy of important commercially available drugs. The development of strategies to use ILs as carriers of pharmaceutical active compounds is an extremely promising and wide avenue. Further, the synthesis of liquid salts through the discerning combination of cations and anions with several distinct pharmaceutical roles provides answers to some of today's pharmaceutical industrial challenges.

How does beta-cyclodextrin affect oxygen solubility in aqueous solutions of sodium perfluoroheptanoate?

The solubility of oxygen in aqueous solutions of sodium perfluoroheptanoate (NaPFHept) at different concentrations was measured at 310.15 K with an apparatus based on the saturation method. The effect of adding beta-cyclodextrin (betaCD) on the solubility of oxygen was also studied. Conductimetry measurements showed that the presence of betaCD in aqueous solutions of NaPFHept increases its critical micellar concentration (CMC). In the presence of betaCD (15 mM), the characteristic minimum of oxygen solubility observed at the CMC is shifted from 83 to 114 mM, and the curvature at the minimum is reduced to 64% of the value in the absence of betaCD. Chemical shift changes for the H5 protons of betaCD, recorded as functions of the initial concentration of NaPFHept, point to the formation of a relatively strong 1:1 inclusion in betaCD of the perfluoroheptanoate anion. Hence, it is suggest that the effect of adding betaCD on the solubility of oxygen cannot be accounted for only by the perfluoroheptanoate anion inclusion in betaCD, but has to be ascribed to the direct influence of this inclusion complex on disrupting the aggregation process reducing the increase of oxygen solubility after the CMC value.