Mixed Solvent System Research Articles

Deciphering Co(III)‐Catalyzed Oxidative C−H/C−H Annulation Towards Maleimide‐Fused Imidazopyridine AEEgens†

A cobalt(III)‐catalyzed dual C(sp2)−H/C(sp2)−H activation of 2‐arylimidazopyridines and its annulation with N‐substituted maleimides leads to polycyclic aromatic heterocycles. This sustainable oxidative annulation uses earth‐abundant, less toxic, and cost‐effective cobalt(III) catalyst that complement expensive 2nd and 3rd‐row metals. This oxidative annulation features a broad substrate scope with very good functional group tolerance. These maleimide‐fused imidazopyridines display strong fluorescence in the region of 527− 536 nm with a Stokes shift of 83−87 nm and possess an excited state lifetime of 14.6−16.1 ns. Interestingly, such luminescent compounds show aggregation‐enhanced emission (AEE) behavior in the iPr‐OH/hexane mixed solvent system. Furthermore, field emission scanning microscopy (FESEM) reveals their spherical nano‐aggregates with an average diameter of ~216.8 nm. They can also be used as cellular‐imaging and picric acid‐sensing probes.

Toward nanosuspension preparation by modeling the solubility of levofloxacin and ofloxacin in ethanol + water solvent mixtures at different temperatures

The present study was conducted to assess the solubility of levofloxacin and ofloxacin in different mono- and mixed solvent systems at different temperatures to provide an experimental basis for the preparation of levofloxacin and ofloxacin nanosuspensions. To this end, the solubility of both compounds was evaluated using a solid–liquid equilibrium technique in DMSO, acetone, ethanol, NMP, and water monosolvents and ethanol–water mixed solvents at different volume fractions and temperatures. The modified versions of the van’t Hoff and Gibbs equations were recruited to calculate the thermodynamic properties of the solutions. The correlation between the solubility data of levofloxacin and ofloxacin and different mathematical models, including the Yalkowsky, Jouyban-Acree, and van’t Hoff models and their combinations was studied. According to the results, the highest and lowest solubility of levofloxacin and ofloxacin were attainable in 1 (pure ethanol monosolvent) and 0.1 v/v of ethanol fractions in ethanol/water mixed solvent. Moreover, the solubility of both compounds was superior at higher temperatures. Afterwards, the nanosuspensions were prepared using the solvent-antisolvent method. Different characterization techniques revealed the formation of the smallest particles with relatively irregular morphology in the 0.1 v/v volume fraction of ethanol in water. The XRD analysis exhibited the typical crystalline diffractions of levofloxacin and ofloxacin and the thermal transitions and stability of both compounds were investigated using DSC and TGA techniques. The results obtained in this study could be used to enhance the solubility and bioavailability of levofloxacin and ofloxacin during the drug formulation development and manufacturing processes.

Testing the prediction capability of trained models: sildenafil citrate solubility in propylene glycol and 1-propanol mixtures at different temperatures

ABSTRACT This study investigates the thermodynamic characteristics, equilibrium solubility, and solvation dynamics of sildenafil citrate within binary solvent systems composed of propylene glycol and 1-propanol. Utilizing both determination and computational approaches, the solubility patterns of sildenafil citrate were quantitatively assessed, revealing direct proportionality with increments in temperature and the concentration of propylene glycol. A comparative analysis using three distinct mathematical models to represent the solid–liquid phase equilibrium was conducted. Among these, the Jouyban-Acree-van’t Hoff model yielded the most comprehensive correlation by covering the effects of both temperature and solvent composition variations on the solubility, with a mean relative deviation (MRD%) of 6.4%, suggesting a robust alignment between the modelled and experimental solubility data. Previously trained models were tested to predict the solubility of the drug in mono- and mixed-solvents at various temperatures where accurate predictions were obtained with the MRD% of 19.1% (for mono-solvents), 8.1 and 14.4% (for mixed solvent systems).

Why Including Solvation is Paramount: First-Principles Calculations of Electrochemical CO2 Reduction to CO on a Cu Electrocatalyst.

Electrochemical reduction reaction of CO2 (eCO2RR) to produce valuable chemicals offers an attractive strategy to solve energy and environmental problems simultaneously. We have mapped out entire reaction pathways of eCO2RR to CO on Cu(100), including all intermediates and transition states using first-principles simulations. To accurately account for the solvent effect, the reaction was investigated with and without explicit water molecules, highlighting the limitations of the often (mis)used vacuum reaction pathway simplification. The results show that the reduction reaction was initiated under neutral pH conditions at an applied potential of -0.11 V (RHE, reversible hydrogen electrode) and all elementary reactions were thermodynamically favorable, while an applied potential of -1.24 V is required to ensure that all reactions exhibit spontaneous behavior. Detailed analysis revealed that solvation significantly influences the stability of the adsorbates and intermediates. Its inclusion notably alters the calculated reaction kinetics and energetic parameters by lowering the barrier energies and Gibbs free energies of all reactions. CO production proceeded mainly via the COOH* pathway (CO2-->trans-COOH*-->cis-COOH*-->CO*+OH*-->CO*-->CO). The use of water as a more sustainable and cost-effective solvent is compared to other options such as organic solvents, ionic liquids and mixed solvent systems, which are less sustainable and more expensive.

Measurement and correlation of solubility data for disulfiram in pure and binary solvents systems from 273.15 K to 318.15 K

The solubility of Disulfiram (DSF) was investigated in ten pure solvents and three binary solvent systems over a temperature range of 273.15 to 318.15 K using a static equilibrium technique. DSC and XRD were used to detect the melting point and stability of DSF in this study. The experimental results revealed a clear trend: DSF shows increased solubility with higher temperatures. Of all the solvents tested, dichloromethane exhibited the greatest solubility for DSF. The solubility of DSF in pure solvents can be arranged in the following sequence: dichloromethane > tetrahydrofuran > acetonitrile > ethyl acetate > n-Butanol > n-propanol > isobutanol > ethanol > methanol > isopropanol. Moreover, at constant temperature, the solubility of DSF increases as the proportion of the positive solvent in the mixed solvent system rises. Specifically, in the mixed solvent system, acetonitrile + isopropanol, DSF has the highest solubility when the mole fraction of the positive solvent approaches 0.8. Further investigation reveals that solvent polarity has a substantial influence on the dissolution process of DSF. Additionally, connections between solute and solvent molecules, and among solvent molecules were examined using the KAT–LSER model. Six thermodynamic models (Modified Apelblat model, Yaws model, λh model, CNIBS/R–K model, Jouyban–Acree model, and SUN model) were employed to fit the experimental data of DSF. The relative average deviation (RAD) and root-mean-square deviation (RMSD) were computed to evaluate the correlation of the results. The Yaws model and the CNIBS/R-K model demonstrate the most optimal fitting effect. This study provides fundamental data for the extraction, separation, refinement, crystallization, and prescription design of DSF. It offers significant guidance for the further expansion of industrial production, process improvement, and practical application.

Investigating Metastable Gelation Behavior of Coumarin‐Derived β‐Enaminone‐Boron Difluoride Complexes

AbstractGelation behavior was unearthed while investigating the photophysical properties of β‐enaminones and their difluoroboron complexes. To perform a systematic investigation, a library of β‐enaminone's difluoroboron complexes was prepared to examine their gelation behavior in organic solvents. Among the prepared compounds, the N‐butyl amine‐substituted β‐enamino diketone was found to exhibit metastable gelation properties in a mixed solvent system (methylene chloride and hexane). Our studies suggest that the presence of N‐butylamine moiety along with N,N‐dimethylamino substituent at difluoroboron enaminones is indispensable in imparting the metastable gelation behavior.

Solubility of letrozole in eight pure and five mixed solvents: Measurement, thermodynamic and molecular simulation analysis

In this work, the solubility of letrozole within eight single and five binary solvents was first systematically investigated at 283.15 K to 323.15 K via the gravimetric method. Subsequently, four thermodynamics formulas including modified Apelblat, λh, GSM and Jouyban-Acree were utilized to link the experimental outcomes of letrozole, all models achieved the good fitting performance and the ARD% was less than 2 %. The dissolvability of letrozole in chosen solvents exhibited a positive correlation with temperature, and co-solvency was observed in such mixed solvent systems as ethyl acetate + 1-propanol, and acetonitrile + 1-propanol. Furthermore, the sites of hydrogen bonding donor and acceptor of letrozole and solvents were analyzed through the molecular electrostatic potential surfaces (MEPs). Then solvent effect, solvation free energy and radial distribution function (RDF) analysis gained via molecular simulation were utilized to illuminate experimental phenomena, the outcomes manifested the polarity, cohesive energy density and other properties of solvents along with both solvent–solvent and solute–solvent interactions contributed differently to the dissolution processes. In the end, the apparent thermodynamic identities concerning letrozole within chosen solvent systems were computed under the van’t Hoff and Gibbs formulas, and outcomes showed that dissolution concerning letrozole was a procedure of endothermic and entropy mainly driven.

Effect of Methyl Red on the surface properties of DTAB in CH3OH–H2O

The purpose of this study is to investigate the effect of Methyl Red (MR) on the micellization and surface properties of a cationic surfactant, dodecyl trimethylammonium bromide (DTAB), in CH3OH–H2O mixed solvent systems at varying CH3OH parts by volumes (0.1, 0.2, 0.3, and 0.4) and temperatures (298.15 K, 308.15 K and 318.15 K). Surface tension and conductivity measurements were conducted to obtain the critical micelle concentration (CMC) and various surface properties such as premicellar slope (dγdlogC), maximum surface concentration (Γmax), minimum surface area occupied (πCMC), free energy of adsorption (ΔGadso), adsorption efficiency (pC20), packing parameter (P), and aggregation number (Nagg). The results indicate that the presence of MR significantly influences the behavior of DTAB in the mixed solvent system. In the absence of MR, the CMC increased with higher CH3OH content, while MR reduced the CMC, promoting micelle formation through dye-surfactant-ion-pair (DSIP) formation. Surface properties were enhanced in the presence of MR leading to higher surface pressure. Additionally, the free energy of adsorption (ΔGadso) became more negative with MR, indicating a more favorable adsorption process. Correlations of (dγdlogC), Γmax,γ0/γcmc, pC20, Nagg, CMC/C20 with the parts by volume of CH3OH at 298.15 K, 308.15 K, and 318.15 K are discussed with and without MR. The obtained results were used to examine the effect of MR on the surface properties of DTAB in the CH3OH–H2O medium. The change in properties can be explained in terms of the change in polarity of the medium and dye-surfactant ion pair (DSIP) formation.

Linking Solution Microstructure and Solvation Thermodynamics of Mixed-Solvent Systems: Formal Results, Critical Observations, and Modeling Pitfalls

Linking Solution Microstructure and Solvation Thermodynamics of Mixed-Solvent Systems: Formal Results, Critical Observations, and Modeling Pitfalls

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.

A mixed solvent system of amino crown ether and ionic liquids for a high-efficient extraction of cesium

Efficient extraction of Cs+ from aqueous solution was investigated by liquid–liquid extraction based on ionic liquids (ILs). In this study, Di(aminobenzo)-18-crown-6 (DAB18C6) was used as the extractant and three ILs (1-butyl-3-methylimidazolium hexafluorophosphate ([C4mim][PF6]), 1-hexyl-3-methylimidazolium hexafluorophosphate ([C6mim][PF6]), and 1-butyl-3-methylimidazolium bis-trifluoromethyl sulfonamide ([C4mim][NTf2])) were employed as co-extractants in the construction of a liquid–liquid extraction system for efficient and selective extraction of Cs+ from aqueous solutions. It was demonstrated that the DAB18C6-[C4mim][NTf2] mixed solvent system at 0.12 mol/L DAB18C6, a mass ratio of ILs/CHCl3 of 1:4 and a volumetric ratio of O/A of 1:1 exhibited a high % extraction of Cs+ up to 99.94 %, with a higher selectivity for Cs+ relative to coexisting ions such as K+ (βCs/K = 1216.7) and Rb+ (βCs/Rb = 139.03). The high selectivity of the extraction system for Cs+ was attributed to the lower hydration binding energy of Cs+ (−366.51 kJ/mol) and the stronger interaction between DAB18C6 and Cs+, g(r) = 12.7. Further, the hydrogen bonding interaction between the amino crown ether and ionic liquid increases the viscosity and surface tension of the extraction system, thus enhancing the stability of the system. Noteworthy, the most stable structure formed by DAB18C6-Cs+-[NTF2]− is attributed to cation exchange. In summary, this study demonstrates the great potential for efficient separation and extraction of cesium from aqueous solutions.

Unveiling the Factors Influencing Different Nucleation Pathways and Liquid-Liquid Phase Separation.

Exploring nucleation pathways has been a research hot spot in the fields of crystal engineering. In this work, vanillin as a model compound was utilized to explore the factors influencing different nucleation pathways with or without liquid-liquid phase separation (LLPS). A thermodynamic phase diagram of vanillin in the mixed solvent system of water and acetone from 10 to 55 °C was determined. It was found that the occurrence of LLPS might be related to different nucleation pathways. Under the guidance of a thermodynamic phase diagram, Raman spectroscopy and molecular simulation were applied to investigate the influencing factors of different nucleation paths. It was found that the degree of solvation is a key factor determining the nucleation path, and strong solvation could lead to LLPS. Additionally, the molecular self-assembly evolution during the crystallization process was further investigated by using small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). The findings indicate that larger clusters with a diffuse transition layer may lead to LLPS during the nucleation process.

Supramolecular J- and H-Aggregation of Naphthalimide-Conjugated Dipeptide in Mixed-Solvent Systems and its Application in Cell Imaging.

In this work, a core-substituted NMI-conjugated dipeptide (4MNLV) was extensively studied in mixed solvent systems to explore the polarity effect on the self-assembly pattern and their photophysical property. 4MNLV adopted J- or H- type aggregation pattern depending upon the polarity index of the solvent system chosen. The self-assembly process was achieved through the anti-solvent effect. UV-vis study suggested that if the stock solution of 4MNLV was diluted with a relatively more polar solvent (compared to the stock solvent), then the system acquired J- type of aggregation pattern by showing a red-shift in their absorption maxima (λmax). Conversely, when the stock was diluted by a relatively less polar solvent, H-type of aggregation was observed, where blue shift of λmax was noticed. The emission spectra and the lifetime of the self-assembled materials were also influenced by the chosen solvent system. The chirotopic behaviour of these self-assembled materials was studied through CD spectroscopy. Morphological study indicated the formation of helical nanofibrillar structures. The bright green fluorescence of these highly biocompatible naphthalimide-peptide conjugate was used for cell imaging application, indicating its futuristic scope.

Preferential Solvation of Cyclosporin in Aqueous Mixtures of Some Polymeric Cosolvents

Background: Cyclosporin is a cyclic peptide-drug used as immunosuppressant for the prophylaxisof transplant rejection whose physicochemical properties in mixed aqueous solvent systems isstill not well understood. The preferential solvation parameters of cyclosporin in aqueous binarymixtures of diethylene glycol monoethyl ether (DEGME), polyethylene glycol 200 (PEG 200) andpolyethylene glycol 400 (PEG 400) were computed. Methods: Reported mole fraction solubilities of cyclosporin in DEGME-aqueous mixtures,PEG 200-aqueous mixtures, and PEG 400-aqueous mixtures were processed by following theinverse Kirkwood-Buff integrals (IKBI) method as suggested by Marcus and Ben-Naim using somethermodynamic parameters reported in the literature for these aqueous-polymeric mixtures at298.15 K. Results: It is observed that cyclosporin is sensitive to preferential solvation effects in theseaqueous-polymeric binary solvent systems. The preferential solvation parameter by DEGME (δx1,3)is negative in water-rich mixtures but positive in mixtures of 0.12<x1<1.00. It is conjecturablethat hydrophobic hydration around the non-polar methyl and methylene groups of this drug thatcould be present in water-rich mixtures can significantly impact the drug solvation. Otherwise,in mixtures of 0.12<x1<1.00 in DEGME-aqueous mixtures, as well as in almost all the mixtureswith PEGs, the preferential solvation by polymeric cosolvents could be due to the acidic behaviorof cyclosporin in front of ether and hydroxyl oxygen atoms of these polymeric cosolvents. Conclusion: Cyclosporin is preferentially solvated by the polymeric solvents in almost all thestudied mixtures of these aqueous-polymeric binary solvent systems.

Thermodynamic properties of β-HMX in binary mixed solvent systems and its microscopic mechanisms

Octogen (HMX) is the most powerful military explosive in current use. However, the unclear thermodynamic molecular mechanisms severely limit the development of its production process. In this paper, the solubility of β-HMX in three binary mixed solvent systems (acetone + ethanol, acetone + dichloromethane, acetone + toluene) was measured via a dynamic method at temperature ranging from 283.15 to 313.15 K under atmospheric pressure. The experimental results reveal that the solubility of β-HMX in these binary mixed solvent systems is positively correlated with acetone molar fraction and temperature, and the solvent composition has a greater impact on its solubility compared with the temperature. Moreover, the solubility of β-HMX is further correlated with the Van’t Hoff equation, modified Apelblat equation, CNIBS/R-K model, Jouyban-Acree-Van’t Hoff model, Jouyban-Acree-Apelblat model and NRTL model, and the modified Apelblat equation can give better fitting result (ARD = 8.101 × 10−3, RMSD = 1.065 × 10−5). Finally, the microscopic mechanism of the thermodynamic properties of β-HMX in binary mixed solvents is revealed by investigating the types, intensity and interaction sites of interactions based on density functional theory (DFT) and molecular dynamic (MD) simulation. The results demonstrate that both acetone molecules and ethanol molecules can form certain intermolecular interactions with β-HMX molecules, which are the main driving force of solubilization. In contrast, solvent–solvent interactions have an antagonistic effect on the solubility of β-HMX in mixed solvents. This work can further be informative for researchers in the field of energetic material for the solubility evaluations and provide a reference for the industrial production and performance enhancement of HMX in the future.

Study on Fast Liquefaction and Characterization of Produced Polyurethane Foam Materials from Moso Bamboo.

Although bamboo is widely distributed in Japan, its applications are very limited due to its poor combustion efficiency for fuel. In recent years, the expansion of abandoned bamboo forests has become a social issue. In this research, the possibility of a liquefaction process with fast and efficient liquefaction conditions using moso bamboo as raw material was examined. Adding 20 wt% ethylene carbonates to the conventional polyethylene glycol/glycerol mixed solvent system, the liquefaction time was successfully shortened from 120 to 60 min. At the same time, the amount of sulfuric acid used as a catalyst was reduced from 3 wt% to 2 wt%. Furthermore, polyurethane foam was prepared from the liquefied product under these conditions, and its physical properties were evaluated. In addition, the filler effects of rice husk biochar and moso bamboo fine meals for the polyurethane foams were characterized by using scanning electron microscopy (SEM) and thermogravimetry and differential thermal analysis (TG-DTA), and the water absorption and physical density were measured. As a result, the water absorption rate of bamboo fine meal-added foam and the thermal stability of rice husk biochar-added foam were improved. These results suggested that moso bamboo meals were made more hydrophilic, and the carbon content of rice husk biochar was increased.

Unraveling the thermodynamic and clouding interactions of non-ionic micelles of polyethylene glycol tert-octylphenyl ether in water-ethanolamine mixtures: Effect of temperature and composition

The amines are potentially used as co-surfactants in an emulsion. The formation of mixed–micelle in the mixture of non-ionic surfactant polyethylene glycol tert-octyl phenyl ether (TX-114) in the water-ethanolamine mixed solvent system has been studied by the cloud point method at variable concentrations. In absence of any added compound, CP shows concentration-dependent variation. The values of CP in an aqueous medium are found to increase by enhancing their concentration range. The CP values of 1 % TX-114 solutions were found to either remain steady at lower concentrations and elevated at higher concentrations in the presence of secondary and tertiary ethanolamine. The CP decreases with an increasing number of ethanolic groups, while CP increases with alkyl branching. The ethanolamine's amines show CP variation by insinuating between the head part with proton rich amine groups at the micelle layer. The outcomes are examined within the light of a specific additive's capacity to evacuate water from the head gathering of the surfactant micelles. The stability of mixed micelle system has also been evaluated by foam ability and foam stability data.

28‐2: Distinguished Paper: Optimization of Ink Formulation and Ligand Engineering for QD‐LED Displays with Improved Performance

The efficiency and lifetime of inkjet‐printed QD‐LED displays are improved through the ligand exchange of Cd‐free QDs and optimal control of ink formulation. Dual ligands enhance colloidal stability and carrier transport properties. The introduction of appropriate additives in the mixed solvent system improves the inkjet processibility and the morphology of inkjet printed layers.

Measurement and correlation of solubility data for sodium picosulphate in selected pure solvents and mixed-solvent systems from 298.15 K to 328.15 K

An investigation was carried out to determine the solubility of the stimulant laxative drug Sodium Picosulphate (SP). A wide range of pure solvents were studied, including methanol, ethanol, 1-propanol, 1-butanol, dimethyl formamide, dimethyl sulfoxide, acetonitrile, 1,4-dioxane, acetic acid, and water. More to the point, the solubility of the compound was determined using mixed solvent systems; methanol + acetonitrile and water + acetonitrile. Experimental mole fraction solubility of SP was determined by the gravimetric method over a range of temperatures (298.15 K to 328.15 K) under atmospheric pressure (p=0.1MPa). According to experimental results, a temperature-dependent relationship exists between solubility and temperature. Further, we correlated the experimental mole fraction solubility data with theoretical models including Apelblat, Yaws, Van't Hoff, Modified Jouyban-Acree, CNIBS/R-K models. It appears that the results are well in agreement with the experimental results due to the small values of relative average deviation (RAD) and root mean square deviation (RMSD).The solubility data might be useful in the various areas such as modification, production, crystallization, and separation of SP.

Dual ligand exchange of Cd‐free quantum dots and optimal control of ink formulation for improving the performance of all‐inkjet‐printed quantum dot light‐emitting diodes

AbstractQuantum dot light‐emitting diodes (QD‐LEDs) have received significant attention as a next‐generation display technology aimed at large‐size panel production with lower manufacturing costs and excellent picture quality. Here, we demonstrated all‐inkjet‐printed 12.4‐in. full‐color QD‐LED display with the 182‐ppi resolution. The efficiency and lifetime of inkjet‐printed QD‐LEDs were improved through the ligand exchange of Cd‐free quantum dots (QDs), red and green InP and blue ZnSeTe QDs, and optimal control of ink formulation. Dual ligands enhanced colloidal stability and carrier transport properties. The introduction of appropriate additives in the mixed solvent system improved the inkjet processibility and the morphology of inkjet‐printed layers.