Deep Eutectic Solvents formed by chiral components as chiral reaction media and studies of their structural properties

We present the realization, the use as reaction media/chiral organocatalysts/acid catalysts and the structural properties of novel chiral Deep Eutectic Solvents. These liquids are formed by mixtures of chiral HBD and HBA molecules that are common, relatively cheap and commercially available (the two enantiomers of camphorsulfonic acid as HBD) or easily one-step synthesized molecules from commercially available compounds ((S)- and (R)-N,N,N-trimethyl-(1-phenylethyl)ammonium methanesulfonate as HBA). These liquids proved to be highly-structured as showed by different yields and enantiomeric excesses observed in a probe reaction, suggesting these liquids to form diastereoisomerically different liquids by changing one of the two enantiomers. Their structural features were analyzed via 1H Pulsed Field gradient Spin Echo (PGSE) NMR, NMR titration, 1H NMR analyses of formation and differences in the chemical shifts of the peaks of the liquids. Density Functional Theory (DFT) optimization helped to define the structures of these liquids. The methanesulfonate counterion of HBA molecule showed to be relevant in order to obtain these highly-structured liquids as it interacts specifically with the HBD. These chiral Deep Eutectic Solvents revealed to be promising novel high-structured media for enantioselective reactions

Use of a Zwitterionic Surfactant to Improve the Biofunctional Properties of Wool Dyed with an Onion (Allium cepa L.) Skin Extract

To improve the loadability and antioxidant properties of wool impregnated with onion skin extract, the introduction of SB3-14 surfactant in the dyeing process was evaluated. A preliminary investigation on the surfactant–quercetin interaction indicated that the optimal conditions for dye solubility, stability, and surfactant affinity require double-distilled water (pH = 5.5) as a medium and SB3-14 in a concentration above the c.m.c. (2.5 × 10−3 M). The absorption profile of textiles showed the flavonoid absorption band (390 nm) and a bathochromic feature (510 nm), suggesting flavonoid aggregates. The higher absorbance for the sample dyed with SB3-14 indicated greater dye uptake, which was further confirmed by HPLC analysis. The Folin–Ciocalteu method was applied to evaluate the total phenol content (TPC) released from the treated wool, while the assays FRAP, DPPH, ABTS, and ORAC were applied to evaluate the corresponding total antioxidant activity (TAC). Higher TPCs (about 20%) and TACs (5–55%) were measured with SB3-14, highlighting textiles with improved biofunctional properties. Spectrophotometric analyses were also performed with an artificial sweat. The potential cytotoxic effect of SB3-14 in both monomeric and aggregated forms, cell viability, and induction of apoptosis were evaluated in RAW 264.7 cells. These analyses revealed that SB3-14 is safe at concentrations below the c.m.c

structure effects of amphiphilic and non amphiphilic quaternary ammonium salts on photodegradation of alizarin red s catalyzed by titanium dioxide

The role of surfactants such as single- and double-tailed tetraalkylammonium bromide and various non-amphiphilic tetraalkylammonium salts was investigated on the TiO2photocatalyzed degradation of Alizarin Red-S under UV light irradiation

Advances in the Development of Novel Green Liquids: Thymol/Water, Thymol/Urea and Thymol/Phenylacetic Acid as Innovative Hydrophobic Natural Deep Eutectic Solvents

Deep Eutectic Solvents (DESs) are increasing their relevance thanks to their ecologically favourable properties, their interesting structural features and their catalytic properties. In this paper we present three novel hydrophobic DESs mixtures prepared by mixing thymol with water, with urea and with phenylacetic acid. These natural DESs represent important advances in the development of green DESs liquids: Thymol/Water mixture is the first binary, water-based DES with hydrophobic properties; in Thymol/Urea DES, urea and its chelating properties were put in a water-separable phase; finally, Thymol/Phenylacetic acid DES is a mixture of two hydrogen-bond donor molecules showing hydrophobic and slightly acidic properties. The hydrogen bond properties within the different mixtures were investigated via DFT, while ab initio molecular dynamics results showed a substantial interaction between thymol and water in the Thymol/Water DES. Moreover, the investigated DESs show excellent extraction properties of heavy metal salts and phenols from aqueous phases

aquo-DESs: WATER-BASED BINARY NATURAL DEEP EUTECTIC SOLVENTS

Deep Eutectic Solvents (DESs) are a class of solvents that are increasing their relevance in the research activity thanks to their environmental-friendly features as well as to their structural characteristics and catalytic properties. Formed by no-solvent mixing of two substances, namely a hydrogen bond donor and a hydrogen bond acceptor, DESs are finding fruitful applications in many different topics as alternatives to common organic compounds. In this work the realization, the characterization and the solubility applications of a novel water- based class of DESs are proposed. These innovative liquids, called aquo-DESs, are binary mixtures of water with glycolic acid (GA) and with trimethylglycine (TMG): GA/H2O (1/4 molar ratio) and TMG/H2O (1/5 molar ratio). The DES identity of these mixtures was demonstrated by: shifts both in terms of the molar fraction and of the melting points in the experimental melting point curves from the theoretical ones; amounts of components over their reported maximum solubility in water; thermogravimetric profiles compared to the pure substances. The aquo-DESs were characterized in their viscosity and ionic conductivity in the temperature range 20-55 C, showing really low viscosity and low ionic conductivity, with a peculiar behavior of the ionic conductivity of GA/H2O DES. The solubilizing properties of aminoacids, phenols and carboxylic acids showed peculiar really high values whenever the solute can participate to the DES as DES component itself

Probing the Structural Features and the Micro-heterogeneity of Various Deep Eutectic Solvents and their Water Dilutions by the Photophysical Behaviour of Two Fluorophores

The structural features of a series of diverse Deep Eutectic Solvents (DESs) have been investigated and characterized by means of two fluorescent probes. The spectral and photophysical properties of the latter are strictly dependent on the experienced environment, so that they can provide insights into the polarity, viscosity, hydrogen-bond network, and micro-heterogeneity of the various DESs.In fact, the investigated DESs exhibit a variety of properties with regards to their hydrophilicity, acidity, and hydrogen-bond ability, and these details were deeply probed by the two fluorescent molecules. The effect of the addition of water, which is a key strategy for tuning the properties of these structured systems, was also tested. In particular, the excited state dynamics of the probes, measured by femtosecond-resolved transient absorption, proved instrumental in understanding the changes in the structural properties of the DESs, namely reduced viscosity and enhanced heterogeneity, as the water percentage increases. Differences between the various DESs in terms of both local microheterogeneity and bulk viscosity also emerged from the peculiar multi-exponential solvation dynamics undergone by the excited states of the probes.</div

Investigation of Base-free Copper-Catalysed Azide–Alkyne Click Cycloadditions (CuAAc) in Natural Deep Eutectic Solvents as Green and Catalytic Reaction Media

The click cycloaddition reaction of azides and alkynes affording 1,2,3-triazoles is a widely used and effective chemical transformation, applied to obtain relevant products in medicine, biology and materials science. In this work, a set of Natural Deep Eutectic Solvents (NADESs) as green and “active” reaction media, has been investigated in the copper-catalysed azide–alkyne cycloaddition reactions (CuAAc). The use of these innovative solvents has shown to improve the reaction effectiveness, giving excellent yields. NADESs proved to be “active” in these transformations for the absence of added bases in all the performed reactions and in several cases, for their reducing capabilities. The reactions outcomes were rationalized by DFT calculations which demonstrated the involvement of H-bonds between DESs and alkynes as well as a stabilization of copper catalytic intermediates. The green experimental conditions, namely the absence of a base, the low temperatures, the lowering of reagents and the possibility of recycling of the green solvents, outline the great potential of NADESs for CuAAc and in general, for green organic synthesis. </p

Physical absorption of CO2 in betaine/carboxylic acid-based Natural Deep Eutectic Solvents

The ability of somezwitterionic natural deep eutectic solvents (NADESs) based on N,N,N-trimethylglycine (TMG) and carboxylic acids (oxalic, glycolic and phenylacetic) to act as environmentally friendly solvents for CO2 capture has been investigated. The solubility of CO2 in the NADESs was measured gravimetrically at different temperatures in the range 298.15\u2013333.15 K, and at different pressures in the range 0.1\u20134 MPa. The effect of the adopted experimental conditions has been discussed. The highest uptake has been observed for phenylacetic acid/TMG DES at 313.15 K and 4 MPa (45.5 mg CO2/g DES). The efficiency of this NADES as CO2 sorbent when reused in subsequent capture cycles has been evaluated. This work might open new perspectives in developing the most appropriate combination of HBA and HBD components of the DESs and the most appropriate operative conditions for an environmentally friendly CO2 capture

Antioxidant Power on Dermal Cells by Textiles Dyed with an Onion (Allium cepa L.) Skin Extract

In this study, the phenol loading and antioxidant activity of wool yarn prepared with the aqueous extract of onion (Allium cepa L.) skin was enhanced by implementing the dyeing process with the use of alum as a mordant. Spectrophotometric and chromatographic methods were applied for the characterization of polyphenolic substances loaded on the wool yarn. The antioxidant/anti-inflammatory properties were evaluated by determining the level of intra- and extra-cellular reactive oxygen species (ROS) production in keratinocytes and dermal fibroblasts pre-treated with lipopolysaccharide put in contact with artificial sweat. An elevated dye uptake on wool was observed for the pre-mordanted sample, as demonstrated by high absorbance values in the UV-Visible spectral range. Chromatographic results showed that protocatechuic acid and its glucoside were the main phenolic acid released in artificial sweat by the wool yarns, while quercetin-4′-glucoside and its aglycone quercetin were more retained. The extract released from the textile immersed in artificial sweat showed a significant reducing effect on the intra-and extracellular ROS levels in the two cell lines considered. Cytofluorimetric analyses demonstrated that the selected mordant was safe at the concentration used in the dyeing procedure. Therefore, alum pre-mordanted textiles dyed with onion-skin extracts may represent an interesting tool against skin diseases