Glycolate Anions Research Articles

A small angle X-ray scattering study comparing protic ionic liquid solvent effects on the solution behaviors of hen egg white and human lysozyme

Proteins demand customized solvents for maintaining their stability. However, the specific impact of different ions on different proteins remains unclear. This study explores the effects of protic ionic liquid (PIL)-based solvents on two structurally similar proteins, namely hen egg white and human lysozyme. By employing size exclusion chromatography small-angle X-ray scattering (SEC-SAXS) and capillary SAXS, the effects of protein concentration (3 to 60 mg/mL), IL type (five PILs) and concentration (1, 10 and 20 mol% with water) and protein type on the aggregation behavior and radius of gyration (Rg) of the two lysozymes were studied. HEWL was mostly monomeric in buffer and solubilized beyond 20 mg/mL, while HL displayed slight aggregation in buffer but had increased aggregation at over 10 mg/mL. Further capillary SAXS data show that both proteins became more aggregated at concentrations exceeding 20 mg/mL and over 1 mol% PILs. The nitrate anion generally showed the “salting in” effect, while formate and glycolate anions induced the “salting out” effect on the two proteins. Overall, anion selection and protein solution behaviors at protein concentration of over 20 mg/mL and at 20 mol% ILs can be critical for maintaining the lysozyme stability.

Cytotoxicity of protic ionic liquids towards the HaCat cell line derived from human skin

In this work we have investigated the toxicity of 10 PILs, consisting of ethyl-, ethanol-, diethanol- and triethanolammonium cations paired with nitrate, formate, acetate and glycolate anions. Their toxicity was quantified by the EC50 values of each of these PILs towards HaCat cells, which are derived from human skin cells. Additional salts and solvents were used for comparison including DMSO, choline chloride, potassium nitrate, sodium acetate and ethanol to distinguish if the toxicity changes were due to ionicity, short chain amphiphilic behaviour, or specific ion effects. The toxicity followed the general trend of choline chloride < acetate containing PILs < DMSO < sodium acetate < ethanol < nitrate containing PILs or salt. Ethanolammonium acetate and ethylammonium acetate were identified as having the lowest toxicities of the PILs, being slightly more toxic than choline chloride or DMSO. Overall the toxicity was found to be highly dependent on the cation and anion combination, with the anion having a stronger affect. It was evident that the PILs can be tailored to vary their toxicities, and this is expected to be dependent on which cell lines are used.

FTIR Spectroscopic Study of the Secondary Structure of Globular Proteins in Aqueous Protic Ionic Liquids.

Protein misfolding is a detrimental effect which can lead to the inactivation of enzymes, aggregation, and the formation of insoluble protein fibrils called Amyloids. Consequently, it is important to understand the mechanism of protein folding, and under which conditions it can be avoided or mitigated. Ionic liquids (ILs) have previously been shown as capable of increasing or decreasing protein stability, depending on the specific IL, IL concentration and which protein. However, a greater range of IL-proteins need to be systematically explored to enable the development of structure-property relationships. In this work, the secondary structure of four proteins, lysozyme, trypsin, β-lactoglobulin and α-amylase, were studied in aqueous solutions of 10 protic ionic liquids (PILs) with 0–50 mol% PIL present. The PILs consisted of ethyl-, ethanol-, diethanol- and triethanolammonium cations paired with nitrate, formate, acetate or glycolate anions. The secondary structure was obtained using ATR-FTIR spectroscopy. It was found that lysozyme and trypsin retained its secondary structure, consistent with a native folded state, for many of the aqueous IL solutions which contained a formate or nitrate anion at the most dilute concentrations. In contrast, α-amylase and β-lactoglobulin generally had poor stability and solubility in the IL solutions. This may be due to the isoelectric point of α-amylase and β-lactoglobulin being closer to the pH of the solvents. All four proteins were insoluble in ethyl-, ethanol- and diethanolammonium acetate, though α-amylase and trypsin retained their secondary structure in up to 20 and 30 mol% of triethanolammonium acetate, respectively. It was evident that the protein stability varied substantially depending on the protein-IL combination, and the IL concentration in water. Overall, the findings indicated that some ions and some ILs were in general better for protein solubility and stability than others, such as acetate leading to poor solubility, and EAN and EAF generally leading to better protein stability than the other PILs. This study of four proteins in 10 aqueous PILs clearly showed that there are many complexities in their interactions and no clear general trend, despite the similarities between the PIL structures. This highlights the need for more and larger studies to enable the selection and optimization of PIL solvents used with biomolecules.

Catena-Poly[[[bis(glycolato-κ2 O,O′)copper(II)]-μ-4,4′-bipyridine-κ2 N:N′] ethane-1,2-diol monosolvate

In the title compound, {[Cu(C2H3O3)2(C10H8N2)]·C2H6O2} n , the CuII cation is six-coordinated in a slightly distorted octahedral manner by two N atoms from two different bridging 4,4′-bipyridine (4,4′-bipy) ligands and four O atoms from two individual glycolate anions. The 4,4′-bipy ligand bridges adjacent CuII centres, generating linear chains running parallel to the [1\overline10] direction. In the crystal structure, adjacent chains are further connected by classical O—H...O hydrogen bonds, resulting in a two-dimensional supermolecular network structure parallel to (100). The C atom of one of the ethane-1,2-diol solvent molecules is disordered over two sets of sites with occupancies of 0.51 (2) and 0.49 (2).

Low-temperature oxidation of methanal on nanostructured silver–amino anion exchanger catalysts

Nanostructured silver–amino anion exchanger composites have been synthesized as catalysts for the low-temperature oxidation of methanal with molecular oxygen in aqueous solution. The oxidative conversion of methanal reaches 80–100% at 298 K. The methanal oxidation reaction is size-dependent, and its rate increases with a decrease in the silver nanoparticle size. The fixed amino groups of anion-exchange matrix play the role of additional active sites for the adsorption of methanal in the form of methylene glycolate–anions, which facilitates the reaction.

Cellulose dissolution and regeneration using various imidazolium based protic ionic liquids

A new series of six protic ionic liquids (PILs) comprising substituted imidazolium cations paired with lactate or glycolate anions were synthesized for cellulose dissolution. All the six synthesized PILs were able to dissolve about 5wt% of cellulose. Especially, 1-ethyl imidazolium lactate showed highest dissolution power since 5wt% of cellulose solution was obtained within 20min at 80°C. The effects of dissolution temperature on cellulose dissolution time were also investigated. As the dissolution temperature increases, dissolution time reduces significantly. The regeneration of cellulose with higher yield was achieved by adding anti-solvent like deionized water to the cellulose solution. Both the initial and regenerated cellulose samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) analysis. The results showed that the crystalline structure of initial cellulose (cellulose I) gets converted to cellulose II. In addition, all regenerated cellulose possessed nanostructure and lower thermal decomposition temperature than the initial cellulose and had new vistas in the industrial applications.

Nanostructured Protic Ionic Liquids Retain Nanoscale Features in Aqueous Solution While Precursor Brønsted Acids and Bases Exhibit Different Behavior

Small- and wide-angle X-ray scattering (SWAXS) has been used to investigate the effect that water has on the nanoscale structure of protic ionic liquids (PILs) along with their precursor Brønsted acids and bases. The series of PILs consisted of primary, secondary, and tertiary alkylammonium cations in conjunction with formate, nitrate, or glycolate anions. Significant differences were observed for these systems. The nanoscale aggregates present in neat protic ionic liquids were shown to be stable in size on dilution to high concentrations of water, indicating that the water is localized in the ionic region and has little effect on the nonpolar domains. The Brønsted acid-water solutions did not display nanostructure at any water concentration. Primary amine Brønsted bases formed aggregates in water, which generally displayed characteristics of poorly structured microemulsions or a form of bicontinuous phase. Exceptions were butyl- and pentylamine with high water concentrations, for which the SWAXS patterns fitted well to the Teubner-Strey model for microemulsions. Brønsted base amines containing multiple alkyl chains or hydroxyl groups did not display nanostructure at any water concentration. IR spectroscopy was used to investigate the nature of water in the various solutions. For low PIL concentrations, the water was predominately present as bulk water for PIL molar fractions less than 0.4-0.5. At high PIL concentrations, in addition to the bulk water, there was a significant proportion of perturbed water, which is water influenced in some way by the cations and anions. The molecular state of the water in the studied amines was predominately present as bulk water, with smaller contributions from perturbed water than was seen in the PILs.

Intercalation of Ethylene Glycol into Yttrium Hydroxide Layered Materials

Intercalation of ethylene glycol into layered yttrium hydroxide containing nitrate counterions was accomplished by heating the reagents in a methanol solution of sodium methoxide under autogenous pressure at 413 K for 20 h. The resulting crystalline material had an expanded interlayer distance of 10.96 A, confirming the intercalation of an ethylene glycol derived species. Characterization of the material by FT-IR spectroscopy, thermogravimetric analysis, and the catalytic transesterification of tributyrin with methanol was consistent with direct bonding of ethylene glycolate anions (O(2)C(2)H(5)(-)) to the yttrium hydroxide layers, forming Y-O-C bonds. The layers of the material are proposed to be held together by H-bonding between the hydroxyls of grafted ethylene glycol molecules attached to adjacent layers. Glycerol can also be intercalated into yttrium hydroxide layered materials by a similar method.

Glycolate adsorption at gold and platinum electrodes: A theoretical and in situ spectroelectrochemical study

The adsorption of glycolate anions at sputtered gold thin-film electrodes was studied in perchloric acid solutions by cyclic voltammetry experiments combined with in situ Surface Enhanced Raman Scattering (SERS) and Surface Enhanced Infrared Reflection Absorption Spectroscopy under attenuated total reflection conditions (ATR-SEIRAS). Theoretical harmonic vibrational frequencies and band intensities obtained from B3LYP/LANL2DZ,6-31+G(d) calculations for glycolate species adsorbed on Au clusters with (1 1 1) orientation were used to interpret the experimental spectra. Vibrational data confirm the bidentate bonding of glycolate anions through the oxygen atoms of the carboxylate group, in a bridge configuration with the OCO plane perpendicular to the metal surface. The DFT calculations show no significant effect of the total charge of the metal cluster–adsorbate adduct on the vibrational frequencies of adsorbed glycolate species. The infrared experimental study is extended to platinum films electrochemically deposited onto sputtered gold thin-film electrodes showing the potential-dependent formation of adsorbed CO upon dissociative adsorption of glycolate anions. As in the case of gold, the reversible adsorption of glycolate anions takes place in a bidentate configuration as predicted by DFT calculations for glycolate adsorbed on Pt(1 1 1) clusters. At low glycolic acid concentration, the in situ ATR-SEIRA spectra evidence the formation of adsorbed oxalate as reaction intermediate.

Modification of polyol process for synthesis of highly platinum loaded platinum–carbon catalysts for fuel cells

A modified polyol process is developed to enhance the Pt loading during the preparation of carbon-supported platinum (Pt/C) catalysts. With the help of the zeta potential, the effect of pH on the electrostatic forces between the support and the Pt colloid is investigated. It is shown experimentally that the surface charge on the carbon support becomes more electropositive when the solution pH is changed from alkaline to acidic. This change does not, however, affect the electronegative surface charge of Pt colloids already attained and stabilized by glycolate anions. This new behaviour caused by the change in solution pH accounts for the enhanced yield of the process and does not affect the Pt particle size. All the experimental results reveal that this simple modification is a cost-effective method for the synthesis of highly Pt-loaded Pt/C catalysts for fuel cells.

Hydrothermal Synthesis of a Novel Uranium Oxalate/Glycolate via In-Situ Ligand Formation

A novel templated uranium oxalate/glycolate, (UO2)4(O)2(C2O4)(H2C2O3)2.2[(C8H20)N] (a = 7.9230(8) A, b = 13.3793(13) A, c = 17.4141(18) A, beta = 96.006(2) degrees , monoclinic, P21/n, Z = 2), has been synthesized under hydrothermal conditions via in-situ ligand synthesis. The oxalate and glycolate anions have been formed through the oxidation of 1,4-diazabicyclo[2.2.2]octane, which proceeds through intermediates such as piperazine and ethylene glycol. Reported herein is the synthesis of this compound, crystal structure, and mechanistic information regarding the oxidation pathway.

Synthesis, characterization and magnetic properties of disk-shaped particles of a cobalt alkoxide: Coii(C2H4O2)

A cobalt alkoxide, Co(OCH2CH2O), has been prepared from the reaction of cobalt acetate with ethanediol. This compound crystallizes as disk-shaped particles with diameter and thickness in the 0.4–1 µm and 100–250 nm ranges, respectively. Structural characterization (X-ray and electron diffraction) shows a layered arrangement with a brucite-like structure presenting a turbostratic disorder. The interlayer spacing and the Co⋯Co distance within the layer are c = 8.27 A and a = 3.09 A, respectively. UV-visible spectroscopy studies established that the Co(II) ions are located on octahedral sites. IR spectroscopy showed that the ethylene glycolate anions (OCH2CH2O)2− chelate the Co(II) cations. The magnetic properties of the compound were measured in the range of 2–300 K. Below 20 K, the compound exhibits 3D ferromagnetic order and the hysteresis loop shows a very high remanence-to-saturation ratio typical of a uniaxial magnetocrystalline anisotropy.

Physically interpenetrating networks in polyurethane ionomers/poly(vinyl alcohol) blends

AbstractThree series of blends of polyurethane ionomers (PUI) with poly(vinyl alcohol) (PVA) were prepared by mixing aqueous PUI emulsions with aqueous PVA solutions and then allowing them to dry. The characterization of the blends of various compositions was carried out using infrared spectroscopy, dynamic mechanical analysis, differential scanning calorimetry and tensile‐elongation testing. It was found that poly(ether‐urethane) cationomer (Cat‐Et)/PVA‐1 and poly(ether‐urethane) anionomer (An‐Et)/PVA‐2 blends exhibit a positive synergistic effect with respect to the tensile strength and that the amorphous phase of PVA is at least partially compatible with both the disordered hard domains and the soft domains of the ionomers. For the former blends, this behaviour is due to the formation of hydrogen bonding with the glycolate anions and ether groups, and for the latter blends to the formation of hydrogen bonds with the ether groups. For poly(ester‐urethane) cationomer (Cat‐Es)/PVA‐3 blends, there is no hydrogen bonding between these two components and no synergistic effect in the tensile strength after blending. Physically interpenetrating polymer networks (IPNs) are expected to occur in the former two blends, but not in the latter one.

Comparison between intramolecular proton transfers involving the carboxylate and alkoxide groups

We have studied the intramolecular proton transfer in the hydroxyacetate, hydrogenoxalate and glycolate anions by means of ab initio calculations. Due to the higher proton affinity of RO − as compared to R-COO −, there is only one minimum in the hydroxyacetate potential surface. Conversely, given that hydrogenoxalate and glycolate anions are symmetric systems, a transition state appears in both cases. The greater barrier in the hydrogenoxalate with respect to the glycolate anion can be attributed to the reorganisation energy of the substrate. The proton motion in the hydrogenoxalate molecule is clearly coupled to the motion of the other atoms.

A liquid-liquid distribution method for the study of complexation of cadmium in natural waters

Liquid-liquid distribution of cadmium between pyridine solution in benzene and aqueous phase containing iodide has been radiometrically investigated, in order to develop a simple method for the study of complexation of cadmium in aqueous solutions. The degree of complexation of cadmium can be determined from the decrease of the distribution ratio in the presence of complexing agents forming non-extractable complexes with this metal. The method was verified for the determination of the composition and stability constants of cadmium with acetate, tartrate, oxalate and glycolate anions and applied for the study of complexation of cadmium in natural waters.

ChemInform Abstract: CRYSTAL STRUCTURE OF TETRA(GLYCOLATO)URANIUM(IV) DIHYDRATE, A PHOTOREDUCTION PRODUCT OF URANYL IONS IN THE PRESENCE OF GLYCOLIC ACID

AbstractDer erste monomere Carboxylato‐Komplex von U(VI), Diaquo‐tetra‐(glycolato‐0,0′)‐uranium(IV), kristallisiert in der Raumgruppe P2, / a mit Z=2.

Crystal structure of tetra(glycolato)uranium(IV) dihydrate a photoreduction product of uranyl ions in the presence of glycolic acid

The crystal structure of the title compound has been determined as the first example of a monomeric carboxylatocomplex of UIV. The crystals are monoclinic, P21/a, with a= 6.555(6), b= 17.652(13), c= 8.008(2), β= 128.52(4), and Z= 2. The structure has been solved by the heavy-atom method and refined to R= 0.057 for 1 031 observed reflections. The uranium atoms are ten-co-ordinate, with bicapped square-antiprismatic geometry [U–O 2.38(2)–2.55(1)A], and the glycolate anions are planar, 1 : 4 co-ordinated.

Complexation of acetate, glycolate, lactate, malate and citrate anions with lanthanide(III) cations in aqueous solution as studied by NMR spectroscopy

Complexation of acetate, glycolate, lactate, malate and citrate anions with lanthanide(III) cations in aqueous solution as studied by NMR spectroscopy

ChemInform Abstract: COMPOSITION AND STABILITY OF COMPLEXES OF IRON(III) WITH GLYCOLATE ANIONS

Chemischer InformationsdienstVolume 5, Issue 30 Organoelement Compounds ChemInform Abstract: COMPOSITION AND STABILITY OF COMPLEXES OF IRON(III) WITH GLYCOLATE ANIONS SALOMEA KRZEWSKA, SALOMEA KRZEWSKASearch for more papers by this author SALOMEA KRZEWSKA, SALOMEA KRZEWSKASearch for more papers by this author First published: July 30, 1974 https://doi.org/10.1002/chin.197430355AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume5, Issue30July 30, 1974 RelatedInformation