Pure Solvents Research Articles

Energy relaxation of N2O in gaseous, supercritical, and liquid xenon and SF6.

Rotational and vibrational energy relaxation (RER and VER) of N2O embedded in xenon and SF6 environments ranging from the gas phase to the liquid, including the supercritical regime, is studied at a molecular level. Calibrated intermolecular interactions from high-level electronic structure calculations, validated against experiments for the pure solvents, were used to carry out classical molecular dynamics simulations corresponding to experimental state points for near-critical isotherms. The computed RER rates in low-density solvents of krotXe=(3.67±0.25)×1010 s-1 M-1 and krotSF6=(1.25±0.12)×1011 s-1 M-1 compare well with the rates determined by the analysis of two-dimensional infrared experiments. Simulations find that an isolated binary collision description is successful up to solvent concentrations of ∼4 M. For higher densities, including the supercritical regime, the simulations do not correctly describe RER, probably due to the neglect of solvent-solute coupling in the analysis of the rotational motion. For VER, the near-quantitative agreement between simulations and pump-probe experiments captures the solvent density-dependent trends.

Outer Helmholtz plane adsorption regulation to achieve low-concentration of pure propylene carbonate solvent electrolytes compatible with graphite anode

The low melting point and high polarity of propylene carbonate (PC) make it an ideal solvent for electrolytes of lithium-ion batteries (LIBs), but the incompatibility with graphite anode hinders the application. In the present study, a new method is developed to solve this problem from a new viewpoint. Introduction of saturated LiNO3 (0.14 mol L‒1) into pure PC electrolyte containing lithium salt with normal concentration (1.38 mol L‒1) leads to a perfect compatibility with graphite anode. Li/Graphite cell using this pure PC electrolyte shows a reversible capacity of 350.0 mAh g‒1 and a 200-cycle capacity retention of 96.3 %. Further mechanism study and theoretical computation indicate that the NO3‒ anions are adsorbed to outer Helmholtz plane of the electric double layer at the graphite anode interface. This changes the Li+ solvation structure in the electric double layer, facilitating the Li+ desolvation process hence resulting in high compatibility with the graphite anode. The most prominent advantage of the present strategy is that, because of the adsorption of NO3‒ anions to the outer Helmholtz plane, the compatibility with graphite anode could be improved by introduction of tiny amount of Li salt without large change of the bulk phase properties of the electrolyte. This work provides a new understanding of the compatibility from the viewpoint of outer Helmholtz plane, which might deliver new insights for the optimization of electrolytes for LIBs.

Solubility of Perindopril l-Arginine in 10 Pure Solvents and 3 Binary Solvents from 278.15 to 323.15 K

Solubility of Perindopril <scp>l</scp>-Arginine in 10 Pure Solvents and 3 Binary Solvents from 278.15 to 323.15 K

Nonradiative Deactivation of the Fluorescent Ag16-DNA and Ag10-DNA Emitters: The Role of Water.

The luminescent quantum yield of silver-cluster emitters stabilized by short oligonucleotides (AgN-DNA) may be efficiently tuned by replacing nucleobases in their stabilization DNA matrices with analogues. In the present study, we proposed a valuable and straightforward theoretical methodology for assessing the photophysical behaviors emerging in AgN-DNA emitters after excitation. Using green Ag10-DNA and near-IR Ag16-DNA emitters we demonstrate how point guanine/inosine replacement could affect the photophysical rate constants of radiative/nonradiative processes. The main deactivation channel of the fluorescence of Ag16-DNA is intersystem crossing, which is in line with experimental data, whereas for Ag10-DNA the calculations overestimate the intersystem crossing rate possibly due to pure solvent contributions.

Solvation dynamics of furazolidone in pure organic solvents and aqueous EDTA disodium salt mixtures: molecular interactions and thermodynamic insights

Solvation dynamics of furazolidone in pure organic solvents and aqueous EDTA disodium salt mixtures: molecular interactions and thermodynamic insights

Preparation of ethylcellulose/technical alkaline lignin composite films using 1,4-Dioxane/water as solvents

The poor solvent power of pure solvent systems to lignin certainly induced the inhomogeneous dispersion of lignin in the composite materials. Here, a 1,4-Dioxane/water binary system is used as the solvent to prepare technical alkaline lignin/ethylcellulose composite films. The tensile strength and elongation at break of optimal sample EC1-AL0.2-GDE0.2 reached 26.8 MPa and 21.4 %, respectively. Also, the wettability, thermal stability, and corrosion resistance were adjusted by the technical alkaline lignin.

Estimation of Electric Dipole Moment by Solvatochromism, Computational Method, and Study of the Effect of Solvents by Preferential Solvation of 6 - Methoxy-4-(4-Nitro-Phenoxy Methyl)-Chromen-2-One (6mnpm).

At room temperature, the absorption and fluorescence properties of coumarin 6-Methoxy-4-(4-nitro-phenoxy methyl)-chromen-2-one (6MNPM) are investigated in pure organic solvents and a combination of acetonitrile (ACN) and tetrahydrofuran (THF). The pure solvents' influence on spectral characteristics is examined by applying theories such as Kamlet and Catalan's multiple linear regression techniques, Reichardt's microscopic solvent polarity parameter, and the Lippert-Mataga polarity function. The significant role of solute-solvent interactions in pure solvents, particularly dielectric interaction and hydrogen bonding. However, hydrogen bonding interactions dominate the contribution of dielectric interactions. The electric dipole moments of both the ground as well as excited states had been calculated using the Solvatochromic method. The value of the excited state electric dipole moment and the redshifts of the emission spectra show that the emitting singlet state has an intramolecular charge transfer (ICT) character. From Catalan's linear regression, we found that di-polarity has a much smaller influence than polarizability. By solvation study, we conclude that Tetrahydrofuran solvent is preferred over Acetonitrile.

Alkali metal cation adsorption–induced surface polarization in polymeric carbon nitride for enhanced photocatalytic hydrogen peroxide production

Photocatalytic hydrogen peroxide (H2O2) generation on the catalyst surface from oxygen is an electron-demanding process, making the construction of an electron-rich surface highly advantageous. In this study, a localized electric field was observed on the surface of polymeric carbon nitride (g-C3N4) when alkali metal cations were adsorbed onto it. These fields effectively inhibited surface carrier recombination and extended their lifespan, thereby enhancing H2O2 production. As a result, g-C3N4 achieved a superior H2O2 yield of 2.25 mM after 1 h in a 0.25 M K+ solution, which was 2.06 times greater than that (1.09 mM) achieved in a pure solvent. Notably, the increase in photocatalytic efficiency showed a remarkable dependence on ion species. At low concentrations, H2O2 generation efficiency was in the order of Li+ < Na+ < K+ < Rb+ < Cs+. However, after optimizing the ion concentration, the highest H2O2 production was achieved in a solution containing K+ instead of Cs+. Molecular dynamics simulations and temperature-dependent photocatalysis experiments revealed that the synergistic interaction between adsorption energy and adsorption distance was crucial in governing the extent to which alkali metal cation adsorption enhanced g-C3N4 photocatalytic H2O2 production. This study provides theoretical insights for the design of materials for electron-demanding photocatalysis and aids in understanding variations in photocatalytic behavior in natural waters.

Solubility, molecular simulation, and dissolution thermodynamic of L-asparagine monohydrate in twelve pure solvents

In this paper, the solubility of L-asparagine monohydrate (LAM) in methanol, ethanol, water, n-propanol, n-butanol, i-propanol, i-butanol, acetonitrile, methyl acetate, ethyl acetate, butyl acetate, and propyl acetate, were measured using gravimetric method. Under standard pressure, a total of ten temperatures from 278.15 to 323.15 K every 5 K, were considered in this work. The experimental results showed that the solubility of LAM in single solvent increased with rising of temperature. The decreasing trend of solubility in alcoholic solvents was found to be methanol > ethanol > n-propanol > i-butanol > n-butanol > i-propanol, and water > methyl acetate > propyl acetate > butyl acetate > ethyl acetate > acetonitrile in non-alcoholic solvents. The maximum molar solubility of LAM was found in water (x1 = 0.009144, T = 323.15 K), and the minimum value was obtained in acetonitrile (x1 = 0.000001569, T = 278.15 K). Five thermodynamic models including Yaws model, the modified Apelblat equation, Wilson model, NRTL model, and UNIQUAC equation, were chosen to describe the solubility results, among which the UNIQUAC equation presented satisfactory correlations of solubility data by the analysis of relative regression deviations (ARD). The electrostatic potential surface of LAM and solvents were calculated and presented to investigate the intermolecular forces, as well as a density functional theory (DFT) calculation of molecular binding energies. The Hansen solubility parameters (HSPs) analysis was applied to investigate the similarity between solvents and LAM for further understanding of dissolution behaviors. It has been demonstrated that a combination of solvent polarities, molecular interactions, HSPs is contributed to the solubility of LAM in different solvents. Finally, the Gibbs energy, enthalpy and entropy of dissolution were determined, indicating that the dissolution of LAM is endothermic and entropy driven. The experimental solubility obtained is essential for further design, operation and optimization of LAM crystallization processes.

Screening of the biphenyl polyamides nanofilms appropriate for molecular separation in organic solution feed

Developing polymeric separation membranes that combine excellent solvent stability, high permeability, and customizable molecular weight interception remains a challenge. Herein, thin-film composite (TFC) polyamide (PA) membranes with poly(ether ether ketone) (PEEK) support and biphenyl-centered polyamides active layer were fabricated through interfacial polymerization technique for the first time. Enhanced solvent stability was exhibited by the fabricated membranes due to the intrinsic resistance to organic solvents possessed by PEEK and biphenyl polyamides. The separation performance of the obtained membranes was systematically studied by relating to the properties of PA nanofilms in terms of nano-mechanical strength, morphologies, and microporosity. The organic solvent nanofiltration (OSN) performance of the resultant membranes in terms of permeability and molecular weight cut-off (MWCO) could be regulated. The optimized membrane exhibited a pure solvent permeability as high as 21.6 L m−2 h−1 bar−1 for acetonitrile and 14.0 L m−2 h−1 bar−1 for methanol. It also showed excellent long-term durability with almost unchanged permeability as well as solute retention remained above 97.8 % after a cumulative OSN operation of N, N-Dimethylformamide (DMF) based feed for 240 h. In particular, OSN membrane with targeted MWCOs covering the range of 170–370 g·mol−1 could be fabricated by selecting appropriate biphenyl acyl chlorides as building blocks. This approach offers a scalable and versatile platform for the development of solvent-stable, highly permeable, and customizable MWCO membranes for process-oriented OSN.

Solvatochromism, preferential solvation and excited state dipole moments of flufenamic acid in different solvent polarities

The influence of pure solvent and binary solvent mixtures on the optical properties of non-steroidal anti-inflammatory drug (NSAID) molecule, specifically flufenamic acid (FLA), has been studied using absorption and fluorescence spectroscopic techniques. A bathochromic shift is observed in the emission wavelength of FLA with an increase in the solvent polarity of pure solvents, attributed to the highest stability of the excited state. The spectral properties are correlated with Lippert–Mataga, solvent polarity parameter, Kamlet, and Catalan solvent polarity parameters, suggesting that both general and specific solvent effects influence the spectral properties, with general solvent effects dominating over specific solvent effects. Preferential solvation studies have been carried out in tetrahydrofuran (THF) and water solvent mixture, revealing variations in the preference for solvation of FLA as a function of the mole fraction of water. Solvatochromic data are utilized to estimate the excited state dipole moment in pure solvents using different solvatochromic methods, revealing that the excited state dipole moment of FLA is higher than its ground state counterpart. The increase in dipole moment in the excited state compared to the ground state is explained based on intramolecular charge transfer (ICT), with elaboration and discussion on the possible resonance structure corresponding to ICT, inferring the more polar nature of the excited state compared to the ground state. The effect of solute polarizability on the excited state dipole moment and change in dipole moment is also discussed.

Partial molar and microstructural properties of binary propane + o-toluidine system near the critical point of pure solvent based on the VLE measurements and modeling with CP-PC-SAFT and mg-SAFT equation of states

The isothermal VLE properties (PTxy relationship) of a binary supercritical (SC) C3H8 + o-toluidine mixture was measured by means of static-analytic method with fluid phase sampling at equilibrium conditions. The measurements were made at three temperatures of (393.15, 433.15, and 473.15) K and pressures up to 10.41 MPa. An experimental VLE apparatus, a high-temperature and high-pressure optical cell, has been used to measure the phase equilibrium properties (PTxy) of the binary SC C3H8 + o-toluidine mixture. The combined expanded absolute and relative uncertainties of the temperature, pressure, and the phase concentration measurements at 0.95 confidence level with a coverage factor of k = 2 is estimated at 0.15 K, 0.5 %, 4.2 % (for x) and 4.8 % (for y), respectively. The critical curve data, TC−x,PC-x, and PC− TC projections, have been derived based on the measured VLE data. The measured VLE and the derived critical curve data were used to estimate the theoretically important and physical meaning of Krichevskii parameter, ∂P∂xTCVC∞. Thermodynamic (partial molar properties, V¯2∞,H¯2∞,C¯P2∞, and distribution equilibrium constant KD), and microstructural (cluster’s size, Nexc∞) properties of infinite-dilute C3H8 + o-toluidine mixture near the critical point of pure solvent (C3H8) were calculated based on the derived Krichevskii parameter and pure solvent (SC C3H8) properties. CP-PC-SAFT and mg-SAFT equation of state (EoS), with zero interaction parameter, k12 = 0, for both models (pure prediction models, no adjustable parameters) were successfully applied to the present PTxy phase equilibria for the SC C3H8 + o-toluidine mixture. The present measured VLE data for C3H8 + o-toluidine system along with the reported pure compound properties of pure propane and o-toluidine have been used to examine the predictive capabilities of the theoretically based CP-PC-SAFT and mg-SAFT models of EoS. It was demonstrated that mg-SAFT is superior in predicting VLE of the C3H8 + o-toluidine system with k12 = 0.

Study of the Optical and Acoustic Parameters and Surface Tensions of 3,4,4′-Trichlorodiphenylurea in Binary Mixtures with Different Organic Solvents between (293.15 and 323.15) K

In the present investigations, the density, refractive index and speed of sound for pure organic solvents and binary liquid mixtures of 3,4,4′-Trichlorodiphenylurea between (293.15 and 323.15) K temperatures have been measured up to the solubility limit. From these experimental results, the acoustic impedance, the isentropic compressibility coefficient, the space-filling factor, the specific refraction, the relaxation strength, the intermolecular free length, the surface tension, the solubility and the solvation number of triclocarban in six organic solvents, namely ethyl alcohol, n-Propyl alcohol, n-Butyl alcohol, Tetrahydrofuran, N,N-Dimethylformamide and N,N-Dimethylacetamide have been computed. The studied acoustic and optical parameters and surface tension behavior versus temperature in pure solvents and binary mixtures were useful in understanding the nature and the extent of interaction between the solute and solvent molecules. The results also show the presence of higher degree of interaction between triclocarban and nitrogen-containing solvents in comparison with other solvents. The distribution of triclocarban in water/organic solvent mixtures is frequently encountered in wastewater treatment plants.

Thermo-kinetic synergy in separating dimethyl carbonate/methanol/water mixtures using ionic liquids-based mixed solvents

The low selectivity of traditional organic solvents and the limited mass transfer efficiency caused by the high viscosity of ionic liquids (ILs) pose challenges in separating of dimethyl carbonate (DMC)/methanol/water mixtures. Therefore, a novel mixed solvent is proposed with a mass ratio of methyl salicylate to 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide of 6:4. The synergistic effects of thermodynamic, kinetic, and economic performance using the mixed solvent are investigated. Comparisons of overall efficiency and total annual cost (TAC) for four process configurations using direct and indirect extractive distillation sequences to produce industrial and battery-grade DMC products are conducted. The results indicate that direct extractive distillation outperforms the indirect sequence, reducing TAC by 6.1–14.3 % for producing industrial-grade DMC and 6.6–15.8 % for battery-grade DMC. Additionally, using mixed solvents in direct extractive distillation is more effective than using pure solvents, enhancing mass transfer coefficients by 2.8–20.9 % for industrial-grade DMC and 1.8–17.8 % for battery-grade DMC. This approach also reduces TAC by 3.2–3.6 % for industrial-grade DMC and 4.7–5.7 % for battery-grade DMC.

Determination of the dissolution behavior of 3,4-bis (3-nitrofuran-4-yl) furazan in different solvents using solubility parameters and interaction energy aided analysis

The atmospheric pressure solubility of 3,4-Bis(3-nitrofurazan-4-yl)furoxan(DNTF) in 9 pure solvents (n-propanol, isopropanol, propionic acid, formic acid, carbon tetrachloride, o-xylene, chlorobenzene, anisole, and 1,2-dichloroethane) was studied using dynamic laser monitoring method. Using various equations, including the modified Apelblat equation, Van’t Hoff equation, Yaws model, NRTL model, and Wilson model to establish the relationship between solubility data. The modified Apelblat equation was used to effectively correlate the solubility data, demonstrating a strong correlation between the equation and experimental data. Meanwhile, Hansen solubility parameters analysis and density functional theory calculation of interaction energy were also used to investigate the mechanism of the solubility behavior of DNTF in different solvents. In addition, apparent thermodynamic parameters such as standard dissolution enthalpy, standard dissolution entropy, and standard Gibbs free energy of DNTF in these solvents were calculated. These findings provide valuable insights for future research on DNTF crystallization.

Experimental and computational insight in molecular interactions of imidazolium based deep eutectic solvent with selected alcohols (C1 and C2)

The experimental thermophysical properties (densities (ρ), speed of sound (u) and refractive (nD) indices) of binary mixtures containing 1:3 mol ratio of [1-butyl-3-dimethylimidazolium chloride to ethylene glycol] [BMIM]Cl: EG], deep eutectic solvent (DES), with selected alcohols (methanol and ethanol) were measured. The measurements of the binary mixtures and the pure solvents were conducted at temperatures ranging from (293.15 to 313.15) K in the interval of 5 K and at ambient pressure using an Anton Paar densitometer. Thermodynamic properties such as excess molar volumes (VmE), intermolecular free length (Lf), isentropic compressibilities (ks), deviation in isentropic compressibilities (Δks) and deviation in refractive indices (ΔnD) were computed from the measured data of physical properties. These excess thermodynamic properties are utilized to investigate the intermolecular interactions occurring between imidazolium DES and methanol or ethanol. Geometry optimization calculations were undertaken using Density Functional Theory (DFT) to model the structure of DES with a 1:1 mol ratio employing the B3LYP-D3 functional and a basis set of 6–31G++**. The DFT results revealed that the interaction energies within the DES in the presence of solvent favoured the formation of the complex. Furthermore, interrogation of the optimized structures at molecular level showed that the interactions were mediated by the electrostatic ionic bonding with the co-solvent playing a significant role in solubility. The excess molar volumes of binary mixtures were correlated using the Lorentz-Lorenz equation, and the densities and refractive indices were predicted using the Lorentz-Lorenz equation. The interaction energies and electrostatic interactions between the different solvents were predicted using quantum mechanics. The experimental data was found to be in good agreement with the theoretical data for the measured properties as well as the computational predictions of the stability of the systems.

Clusters of solvated ferrous ion in water–ammonia mixture: Structures and noncovalent interactions

The behavior of metal ions is commonly studied in pure solvent although, in our daily life, these metals are involved in mixtures of solvents. In the present study, we investigated structures, relative stabilities and temperature dependance of solvated ferrous ion in water–ammonia mixture solvent at 0K and at various temperatures ranging from 25K to 400K. All the calculations are performed at the MN15 level of theory associated with the aug-cc-pVDZ basis set. For deep understanding of binding patterns in solvated ferrous ion in water–ammonia mixture solvent, noncovalent interactions are presented based on the QTAIM analysis using AIMAll. Our results prove that the ferrous ion is more stable when it is solvated by ammonia instead of water. In addition, hydrogen bonds are weakened by the presence of ammonia molecules. The temperature dependence of the different obtained geometries indicates that from s=6 (s is the sum of water and ammonia molecules around the ferrous ion), when the number of water molecules is almost equal to that of ammonia, the structures with coordination number 5 are dominant. However, the coordination number is six when there are a maximum water molecules (rich water solution) or maximum ammonia molecules (rich ammonia solution) around the ferrous ion (for s≥6). The QTAIM analysis shows that there are two coordination bondings and four hydrogen bondings. Furthermore, it is found that the Fe2+⋯N coordination bondings are stronger than the Fe2+⋯O confirming that the ferrous ion prefers to be solvated by ammonia instead of water.

Hydrogen-rich solvent method enhances the extraction of phenolics, pigments, reducing sugars, organic acids, and vitamin C from cowslip (Primula veris L.) flower

Cowslip (Primula veris L.) is an anioxidant-rich plant used for many food and medicinal purposes. In this study, the effect of incorporating hydrogen (H2) into water (HRW), ethanol (HRE), and methanol (HRM) on the extraction of flavonoids (TFC), phenolics (TPC), and antioxidants (metal chelation, FRAP, DPPH, and ABTS) as well as color (L*, a*, b*, C*, H°), chlorophyll (a, b), lycopene, and β-carotene of wild cowslip flowers was evaluated. The results were submitted to Principal Component Analysis and correlation. Phenolic compounds, organic acids, vitamin C, and sugar content of the extract were analyzed using high-performance reverse phase liquid chromatography (HPLC-DAD/RID). The highest TPC, TFC, and antioxidant activity (metal chelation, FRAP, DPPH, and ABTS) were shown for HRM samples, followed by HRE samples, while the lowest were found for pure solvents. Incorporating H2 into all solvents significantly increased TPC, TFC, metal chelation, DPPH, and ABTS scavenging activity, as well as b*, C*, H°, chlorophyll, lycopene, and β-carotene values. The levels of some phenolics (catechin, epicatechin, rutin, and quercetin), organic acids (tartaric acid and succinic acid), reducing sugars (maltose, glucose, and fructose), and ascorbic acid increased by 10–90 % when an H2-rich solvent was used instead of the pure solvent. This is the first report showing the enhanced extraction of organic acids, pigments, and ascorbic acid by hydrogen-rich solvent. The main benefits of the HRS method are its sustainability and high efficiency in extracting bioactive compounds from medicinal plants.

Monomer Trapping Synthesis Toward Dynamic Nanoconfinement Self-healing Eutectogels for Strain Sensing.

The rapid advancement in attractive platforms such as biomedicine and human-machine interaction has generated urgent demands for intelligent materials with high strength, flexibility, and self-healing capabilities. However, existing self-healing ability materials are challenged by a trade-off between high strength, low elastic modulus, and healing ability due to the inherent low strength of noncovalent bonding. Here, drawing inspiration from human fibroblasts, a monomer trapping synthesis strategy is presented based on the dissociation and reconfiguration in amphiphilic ionic restrictors (7000-times volume monomer trapping) to develop a eutectogel. Benefiting from the nanoconfinement and dynamic interfacial interactions, the molecular chain backbone of the formed confined domains is mechanically reinforced while preserving soft movement capabilities. The resulting eutectogels demonstrate superior mechanical properties (1799% and 2753% higher tensile strength and toughness than pure polymerized deep eutectic solvent), excellent self-healing efficiency (>90%), low tangential modulus (0.367MPa during the working stage), and the ability to sensitively monitor human activities. This strategy is poised to offer a new perspective for developing high strength, low modulus, and self-healing wearable electronics tailored to human body motion.

Investigation of the solubility behavior of emodin and aloe-emodin in water + ethanol mixtures at various temperatures ranging from 283.15 K to 323.15 K

A thermostated reactor and UV–visible spectrophotometer analysis were used to determine the solubility of emodin and aloe-emodin, two naturally occurring compounds with pharmacological activity. At a pressure of 0.1 MPa under atmospheric conditions, and temperatures from 283.15 to 323.15 K with intervals of 5 K, the solubility in different water–ethanol combinations was the primary focus of the investigation. Under constant solvent composition, a positive correlation was observed between the solubility of emodin/ or aleo-emodin and the experimental temperature in all examined mixed solvent systems. To better understand the relationships between solutes and solvents and the interactions between several solvents, the KAT-LSER model was used to conduct multiple linear regression analysis on systems containing either pure solvents or a combination of solvents. In addition, several thermodynamic models were used to establish a connection with the empirical solubility data. These models included the Jouyban-Acree, Apelblat-Jouyban-Acree, van’t Hoff-Jouyban-Acree, and Ma models. The correlation findings demonstrate that all four thermodynamic models accurately predicted emodin and aleo-solubility emodin’s behavior under different solvent and temperature settings. Furthermore, the thermodynamic characteristics of emodin solubility in binary solvent combinations were determined using the van’t Hoff model. According to the findings, two compounds were found to undergo endothermic and non-spontaneous dissolution.