Triethylammonium Dihydrogen Phosphate Research Articles

Catalytic One-pot Solvent Free Synthesis, Biological Activity, and Docking Study of New Series of 1, 3-thiazolidine-4-one Derivatives Derived from 2- (P-tolyl) Benzoxazol-5-amine.

In this study, a simple triethylammonium salt of phosphoric acid (triethylammonium dihydrogen phosphate) (4) in the liquid state was utilized as an inexpensive, efficient one-pot three components, solvent-free synthesis of thiazolidine-4-one derivatives, with good to excellent yields. Techniques such as FT-IR, 1H-NMR, 13C-NMR, 13C-NMR-DEPT-135, and MS. were used for the structural elucidation. The high biotic efficiency of the newly obtained compounds was confirmed by in vitro antimicrobial action against Gram-positive (S. Aureus), Gram-negative bacteria (P. Aeruginosa and E. Coli) and antifungal activity (C. Albicans) via microplate titer dilution technique. Finally, a molecular docking study was performed with a resolved crystal structure of S. Aureus D-alanine alanyl carrier protein ligase (PDB ID: 7VHV). This investigation aimed to synthesize a new series of thiazolidine-4-one derivatives combined with benzoxazole moiety. Ionic liquid assistance one-pot solvent-free synthesis method used to synthesize a new series of thiazolidine-4-one derivative 10(a-e). Structural identification of new synthesis and biological evaluation via techniques of (IR, 1H-NMR, 13C-NMR, 13C-NMR-DEPT-135, and MS). Ionic liquid is utilized as an inexpensive, efficient one-pot three-component solvent-free synthesis of thiazolidine-4-one derivatives with good to excellent yields. Most of the synthesized compounds showed high biological and anti-fungal activity, in line with the docking study against mentioned microorganism and crystal structure of PDB (ID: 7VHV), respectively.

Assessment of The Hygroscopic Behaviour of Proton-Conducting Ionic Liquids: Kinetics, Conductivity and Electrochemical Analysis

We report the synthesis of five proton-conducting ionic liquids (PCILs) by a neutralization reaction. The proton transfer from the corresponding Brønsted acid to the respective base was confirmed by FT-IR spectroscopy. The Karl-Fischer titration was used to measure the water contents of the PCILs exposed to air for different time intervals at a relative humidity of 36 ± 5% and 31 ± 5 °C. The rate of moisture uptake by the PCILs increased with the increase of their time of exposure to air and follows pseudo-first-order kinetics. The conductivity analysis reveals that the PCILs’ ionic conductivities further rise with increasing water contents and temperature. The conductivity data were fitted with the Arrhenius equation and activation energies (Ea) were deduced. The electrochemical analysis of the triethylammonium dihydrogen phosphate, TEADHP shows that the liquid has a wide (2.8 V) electrochemical window (EW) at the Pt electrode at 60 °C and 5% water. The EW becomes narrower as the temperature and water content of the TEADHP increase due to the increase in the rate of the water electrolysis. The data showed that during positive-going scans, Pt-oxides were formed due to the oxidation of water in the PCIL which plays an electrocatalytic role during formic acid oxidation in the medium.

On the Stability and Conformational Dynamics of Cytochrome c in Ammonium Ionic Liquids.

Owing to their potential applications in the extraction, purification, and preservation of biomolecules and biocatalysis, ionic liquids (ILs) have gained great attention in biotechnology. Although it is known that the structure and dynamics of proteins in ILs depend on the nature of both proteins and ILs, the biophysical mechanism governing the protein-IL interaction, which determines the stability of proteins or the activity of an enzyme in these nonconventional media, is yet to be understood clearly. Herein, we study the effect of two ammonium ILs, triethylammonium dihydrogen phosphate (TEAP) and tributylammonium dihydrogen phosphate (TBAP), on the stability and conformational dynamics of cytochrome c (Cyt c) in its native and unfolded states, employing primarily the single molecule-based fluorescence correlation spectroscopy (FCS) technique. The results show that the native structure of Cyt c is not significantly altered by TEAP, but the tertiary structure is perturbed to a great extent by TBAP, which comprises a longer alkyl chain. Fluctuations of the fluorescence intensity of Alexa488 dye-labeled Cyt c in FCS measurements reveal conformational dynamics (67 ± 10 μs) in the native state of Cyt c that is accelerated in the presence of both ILs but not affected when Cyt c is in its unfolded state. The present findings demonstrate how the stability of this protein can be modulated by using ammonium ILs of different alkyl chain lengths.

Sulfonate poly(ether ether ketone) incorporated with ammonium ionic liquids for proton exchange membrane fuel cell

Sulfonate poly(ether ether ketone) (SPEEK)/ammonium ionic liquids (AIL) composite membranes were fabricated using the solution casting method. AIL is a triethyl ammonium dihydrogen phosphate ([(CH3CH2)3NXH+] [H2PO4−], TEAP) or triethyl ammonium hydrogen sulfate ([(CH3CH2)3NH+] [HSO4−], TEAS). It was found that SPEEK/AIL composite membranes have glossy exteriors from SEM images. Compared to the SPEEK membrane, the thermal durability and proton conductivity of SPEEK/AIL composite membranes decreases due to the incorporation of the AIL which affects the original proton conduct chain and polymer structure. The proton conductivity of the SPEEK96-15S membrane and SPEEK75-35S membrane goes to 7.06 and 6.94 mS/cm respectively at 393 K. The performance of the proton exchange membrane fuel cell (PEMFC) with the SPEEK96-15S membrane and SPEEK75-35S membrane is better than that with the Nafion212 membrane when H2/O2 was humidified at 333 K.

Evaluating the transfer free energies of amino acids from water to ammonium-based ionic liquids at 298.15 K

The interactions between ionic liquids (ILs) and amino acids (AAs) can easily be quantified using the apparent transfer free energy (∆G′tr) values that can be used to interpret the stability of the proteins in the same solvent medium. In this study, ∆G′tr values of AAs such as phenylalanine (Phe), histidine (His), threonine (Thr), glutamine (Gln) and serine (Ser) from the water to ILs have been obtained from the solubility measurements, as a function of IL concentration at 298.15K under atmospheric pressure. The investigated ILs contain diethylammonium acetate (DEAA), diethylammonium hydrogen sulfate (DEAS), triethylammonium acetate (TEAA), triethylammonium hydrogen sulfate (TEAS), triethylammonium dihydrogen phosphate (TEAP), and trimethylammonium acetate (TMAA). The results reveal that the IL effect was specific and independent for each AA in the aqueous medium. Apparently, we observed a positive as well as negative ∆G′tr values for Phe, His, Glu, Thr, and Ser AAs in the ammonium-based ILs.

The Solubility and Stability of Amino Acids in Biocompatible Ionic Liquids

In recent years, ionic liquids (ILs) represent a new class of biocompatible co-solvents for biomolecules. In this work, we report the apparent transfer free energies (ΔG'tr) for six amino acids (AA) from water to aqueous solutions of six ammonium based ILs (diethylammonium acetate (DEAA), diethylammonium sulfate (DEAS), triethyl ammonium acetate (TEAA), triethylammonium sulfate (TEAS), triethylammonium dihydrogen phosphate (TEAP), and trimethylammonium acetate (TMAA)) through solubility measurements, as a function of IL concentration at 298.15 K under atmospheric pressure. Salting-out effect was found for AA in aqueous IL solutions with increasing IL concentrations. In addition, we observed positive values of ΔG'tr for AA from water to ILs, indicating that the interactions between ILs and AA are unfavorable. From the obtained results, we found that the selected ammonium based ILs act as stabilizers for the structure of AA.

Influence of Reactive Oxygen Species on the Enzyme Stability and Activity in the Presence of Ionic Liquids

In this paper, we have examined the effect of ammonium and imidazolium based ionic liquids (ILs) on the stability and activity of proteolytic enzyme α-chymotrypsin (CT) in the presence of cold atmospheric pressure plasma jet (APPJ). The present work aims to illustrate the state of art implementing the combined action of ILs and APPJ on the enzyme stability and activity. Our circular dichroism (CD), fluorescence and enzyme activity results of CT have revealed that buffer and all studied ILs {triethylammonium hydrogen sulphate (TEAS) from ammonium family and 1-butyl-3-methyl imidazolium chloride ([Bmim][Cl]), 1-methylimidazolium chloride ([Mim][Cl]) from imidazolium family} are notable to act as protective agents against the deleterious action of the APPJ, except triethylammonium dihydrogen phosphate (TEAP) ammonium IL. However, TEAP attenuates strongly the deleterious action of reactive oxygen species (ROS) created by APPJ on native structure of CT. Further, TEAP is able to retain the enzymatic activity after APPJ exposure which is absent in all the other systems.This study provides the first combined effect of APPJ and ILs on biomolecules that may generate many theoretical and experimental opportunities. Through this methodology, we can utilise both enzyme and plasma simultaneously without affecting the enzyme structure and activity on the material surface; which can prove to be applicable in various fields.

Effect of anion variation on the thermophysical properties of triethylammonium based protic ionic liquids with polar solvent

In this work, we explore the anion effect on the thermophysical properties of protic ionic liquids (PILs) such as triethylammonium acetate [Et3NH][CH3COO] (TEAA), triethylammonium dihydrogen phosphate [Et3NH][H2PO4] (TEAP) and triethylammonium hydrogen sulfate [Et3NH][HSO4] (TEAS) with polar solvent such as dimethylsulfoxide (DMSO). To understand the molecular interactions between DMSO with ILs, densities (ρ), ultrasonic sound velocities (u) and viscosities (η) have been measured over whole range of compositions and at three temperatures, 298.15, 303.15, and 308.15K under atmospheric pressure. A second order empirical polynomial and Arrhenius equations were used to correlate the ρ and η as function of temperature, respectively. Sound velocity mixing rules were used on experimental values. Further, the excess molar volume (VE), the deviation in isentropic compressibility (Δκs) and deviation in viscosity (Δη) were calculated using these properties. The obtained VE, Δκs and Δη values were correlated by using the Redlich–Kister polynomial equation.

Exploring the thermal stability of α-chymotrypsin in protic ionic liquids

Ammonium based ionic liquids (ILs) are biocompatible co-solvents that stabilize the native state of proteins. Experimentally, we have explored the stability of α-chymotrypsin (CT) in the presence of nine ILs, i.e., diethylammonium acetate (DEAA), diethylammonium hydrogen sulfate (DEAS), diethylammonium dihydrogen phosphate (DEAP), triethylammonium acetate (TEAA), triethylammonium hydrogen sulfate (TEAS), triethylammonium dihydrogen phosphate (TEAP), trimethylammonium acetate (TMAA), trimethylammonium hydrogen sulfate (TMAS), trimethylammonium dihydrogen phosphate (TMAP). Thermodynamic folding properties such as transition temperature (Tm), Gibbs free energy change of unfolding (ΔGU), enthalpy change (ΔH) and heat capacity change (ΔCp) of CT in ILs are obtained by fluorescence spectra analysis. Fluorescence and circular dichroism (CD) spectroscopy experiments were performed to probe CT stabilization and structural changes in the presence of ILs. Our experimental results suggest that the ILs act as stabilizers for the CT structure and the stability of CT depends on the structural arrangement of the ions of ILs. Our experimental results reveal that ILs (DEAA, DEAS and DEAP) having more hydrophobic ammonium cations [DEA+] are weak stabilizers for CT, while trimethyl ammonium cations [TMA+] ILs having small alkyl chain length such as TMAA, TMAS and TMAP are strong stabilizers and therefore more biocompatible for the native structure of CT.

Structural Basis for the Enhanced Stability of Protein Model Compounds and Peptide Backbone Unit in Ammonium Ionic Liquids

Protein folding/unfolding is a fascinating study in the presence of cosolvents, which protect/disrupt the native structure of protein, respectively. The structure and stability of proteins and their functional groups may be modulated by the addition of cosolvents. Ionic liquids (ILs) are finding a vast array of applications as novel cosolvents for a wide variety of biochemical processes that include protein folding. Here, the systematic and quantitative apparent transfer free energies (ΔG'(tr)) of protein model compounds from water to ILs through solubility measurements as a function of IL concentration at 25 °C have been exploited to quantify and interpret biomolecular interactions between model compounds of glycine peptides (GPs) with ammonium based ILs. The investigated aqueous systems consist of zwitterionic glycine peptides: glycine (Gly), diglycine (Gly(2)), triglycine (Gly(3)), tetraglycine (Gly(4)), and cyclic glycylglycine (c(GG)) in the presence of six ILs such as diethylammonium acetate (DEAA), diethylammonium hydrogen sulfate (DEAS), triethylammonium acetate (TEAA), triethylammonium hydrogen sulfate (TEAS), triethylammonium dihydrogen phosphate (TEAP), and trimethylammonium acetate (TMAA). We have observed positive values of ΔG'(tr) for GPs from water to ILs, indicating that interactions between ILs and GPs are unfavorable, which leads to stabilization of the structure of model protein compounds. Moreover, our experimental data ΔG'(tr) is used to obtain transfer free energies (Δg'(tr)) of the peptide backbone unit (or glycyl unit) (-CH(2)C═ONH-), which is the most numerous group in globular proteins, from water to IL solutions. To obtain the mechanism events of the ILs' role in enhancing the stability of the model compounds, we have further obtained m-values for GPs from solubility limits. These results explicitly elucidate that all alkyl ammonium ILs act as stabilizers for model compounds through the exclusion of ILs from model compounds of proteins and also reflect the effect of alkyl chain on the stability of protein model compounds.

Influence of biocompatible ammonium ionic liquids on the solubility of l-alanine and l-valine in water

Understanding the folding process of proteins or polypeptides in co-solvents is a fascinating and critical issue in biophysical chemistry. In recent years, ionic liquids (ILs) represent a versatility of the new class of co-solvents. To quantify the bimolecular interactions of amino acids (AA), such as l-alanine (Ala) and l-valine (Val) with biocompatible ILs, we report the apparent transfer free energies (ΔG′tr) for AA from water to aqueous solutions of six ammonium based ILs (diethylammonium acetate (DEAA), diethylammonium sulfate (DEAS), triethyl ammonium acetate (TEAA), triethylammonium sulfate (TEAS), triethylammonium dihydrogen phosphate (TEAP), and trimethylammonium acetate (TMAA)) through solubility measurements, as a function of IL concentration at 298.15K under atmospheric pressure. Salting-out effect was found for AA in aqueous IL solutions with increasing IL concentrations. In addition, we observed positive values of ΔG′tr for Ala and Val from water to ILs, indicating that the interactions between ILs and AA are unfavorable. From the solubility results, we envisage that the selected ammonium based-ILs provide stability to the structure of AA. Further, the stability of AA has been studied by means of the UV–vis spectroscopy.

Ammonium based ionic liquids act as compatible solvents for glycine peptides

In this article, we have reported the solubilities, apparent transfer free energies (ΔG′tr) and UV-visible absorption measurements of glycine peptides (GPs), such as glycine (Gly), diglycine (Gly2), and cyclic glycylglycine (c(GG)) in aqueous ionic liquids (ILs), bearing sulfate and phosphate anions with ammonium cation, at T=298.15K. Values of solubility were obtained from density (ρ) measurements of GPs in water and in aqueous ILs. The ammonium ILs such as diethylammonium hydrogen sulfate (DEAS) [(CH3CH2)2NH][HSO4], triethylammonium hydrogen sulfate (TEAS) [(CH3CH2)3NH][HSO4], and triethylammonium dihydrogen phosphate (TEAP) [(CH3CH2)3NH][H2PO4] have been used in the present study. We observed the positive values of ΔG′tr for Gly, Gly2, and c(GG) from water to ILs. These results reveal that the unfavourable interactions are dominated between ILs and the GPs. This indicates that the ammonium based ILs stabilize the GP structure. Further, we have used the ΔG′tr results to evaluate the transfer free energies (Δg′tr) contribution of the peptide backbone unit, also known as glycyl residue, (–CH2CONH–) as function of ILs concentration. Our results suggest that all the investigated ammonium ILs are compatible with GPs and act as stabilizers for GPs structure through exclusion of ILs from GPs’ surface. Furthermore, UV-vis spectrophotometer measurements are used as evidence for the stability of GPs in aqueous ILs at T=298.15K.

Influence of temperature on thermophysical properties of ammonium ionic liquids with N-methyl-2-pyrrolidone

To address the molecular interactions between ionic liquids (ILs) such as trimethylammonium acetate [(CH3)3NH][CH3COO] (TMAA), trimethylammonium hydrogen sulphate [(CH3)3NH][HSO4] (TMAS), trimethylammonium dihydrogen phosphate [(CH3)3NH][H2PO4] (TMAP) and triethylammonium dihydrogen phosphate [(CH3CH2)3NH][H2PO4] (TEAP) with N-methyl-2-pyrrolidone (NMP), density (ρ), ultrasonic sound velocity (u) and viscosity (η) measurements have been performed across the entire concentration range and the wide temperature range from 298.15 to 313.15K in steps of 5K under ambient pressure. Further, on the basis of the measured properties, excess volumes (VE), isentropic compressibility deviations (Δκs) and viscosity deviations (Δη) were obtained for all these systems under the same experimental conditions. The results are correlated by the Redlich–Kister type equation. The results are also analysed on anion dependent phenomena and temperature influence on measured and derived properties of ILs with NMP mixtures. A qualitative analysis of molecular interactions between ILs and NMP is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding.

Influence of protic ionic liquids on the structure and stability of succinylated Con A

We report the synthesis of a series of ionic liquids (ILs) from various ions having different kosmotropicity including dihydrogen phosphate (H2PO4−), hydrogen sulfate (HSO4−) and acetate (CH3COO−) as anions and chaotropic cation such as trialkylammonium cation. To characterize the biomolecular interactions of ILs with protein, we have explored the stability of succinylated Con A (S Con A) in the presence of these aqueous ILs, which are varied combinations of kosmotropic anion with chaotropic cation such as triethylammonium dihydrogen phosphate [(CH3CH2)3NH][H2PO4] (TEAP), trimethylammonium acetate [(CH3)3NH][CH3COO] (TMAA), trimethylammonium dihydrogen phosphate [(CH3)3NH][H2PO4] (TMAP) and trimethylammonium hydrogen sulfate [(CH3)3NH][HSO4] (TMAS). Circular dichroism (CD) and fluorescence experiments have been used to characterize the stability of S Con A by ILs. Our data distinctly demonstrate that the long alkyl chain IL TEAP is a strong stabilizer for S Con A. Further, our experimental results reveal that TEAP is an effective refolding enhancer for S Con A from a thermally denatured protein structure.

Ammonium ionic liquids as convenient co-solvents for the structure and stability of succinylated Con A

In this article, we present the synthesis of a series ionic liquids (ILs) having different kosmotropicity including dihydrogen phosphate (H2PO4-) and hydrogen sulphate (HSO4-) as anions and chaotropic cation such as alkylammonium. Here, we have investigated the biomolecular interactions and related associated structural changes of succinylated Con A (S Con A) with alkylammonium ILs by using several biophysical techniques including circular dichroism (CD) and fluorescence. The ILs studied in the present research includes diethylammonium dihydrogen phosphate [(CH3CH2)2NH+][H2PO4-] (DEAP), diethylammonium hydrogen sulphate [(CH3CH2)2NH+][HSO4-] (DEAS), triethylammonium dihydrogen phosphate [(CH3CH2)3NH+][H2PO4-] (TEAP) and triethylammonium hydrogen sulphate [(CH3CH2)3NH+][HSO4-] (TEAS). We observed that all ILs have a dominant contribution to the stabilization of the native structure of the S Con A. Our experimental results distinctly demonstrate that the long alkyl chain IL TEAP is a strong stabilizer and therefore more biocompatible for S Con A. Furthermore, the results reveal that phosphate anions of ILs are strong stabilizers and acted as effective refolding enhancers for thermally denatured protein structure, whereas the protein was not refolded in the sulphate anions of ILs. These findings suggest a new generation of protein stabilizers that can be applied to other protein folding studies and biological systems.

Synthesis of 1,8-dioxo-octahydroxanthenes and bis(indolyl)methanes catalyzed by [Et3NH][H2PO4] as a cheap and mild acidic ionic liquid

Triethyl ammonium dihydrogen phosphate was used as a cheap and mild acidic ionic liquid catalyst for synthesis of 1,8-dioxo-octahydroxanthenes and bis(indolyl)methanes. This methodology offers several advantages, such as good yields, short reaction times, simple procedure, and mild conditions.

Measurements and Molecular Interactions for N,N-Dimethylformamide with Ionic Liquid Mixed Solvents

To understand the molecular interactions between N,N-dimethylformamide (DMF) with two families of ionic liquids (ILs), we have measured thermophysical properties such as densities (rho) and ultrasonic sound velocities (u) over the whole composition range at 25 degrees C under atmospheric pressure. The excess molar volume (V(E)) and the deviation in isentropic compressibilities (DeltaK(s)) were predicted using these properties as a function of the concentration of IL. These results are fitted to the Redlich-Kister polynomials. The materials investigated in the present study included two families of ILs such as ammonium salts and imidazolium salts. Diethylammonium acetate ([Et(2)NH][CH(3)COO], DEAA), triethylammonium actetate ([Et(3)NH][CH(3)COO], TEAA), triethylammonium dihydrogen phosphate ([Et(3)NH][H(2)PO(4)], TEAP), and triethylammonium sulfate ([Et(3)NH][HSO(4)], TEAS) are ammonium salts and 1-benzyl-3-methylimidazolium chloride ([Bmim][Cl]) belongs to the imidazolium family. The intermolecular interactions and structural effects were analyzed on the basis of the measured and the derived properties. A qualitative analysis of the results is discussed in terms of the ion-dipole, ion-pair interactions, and hydrogen bonding between ILs and DMF molecules and their structural factors.

Application of triethylammonium salts as ionic liquid catalyst and medium for Fischer esterification

Triethylammonium sulfate, triethylammonium dihydrogen phosphate and triethylammonium tetrafluoroborate were applied as ionic liquid catalyst and medium for the esterification of carboxylic acids with primary alcohols. Esterification of aliphatic carboxylic acids in the presence of triethylammonium sulfate gave the corresponding esters in excellent yield. The ionic liquid and ester formed separate phases in the reaction facilitating separation of the product.