Mixed Solvent System Research Articles

Solid-liquid equilibrium of forchlorfenuron in four binary solvents: Experiments, hansen solubility parameter and molecular simulation

In this research, the solubility of forchlorfenuron in 4 binary solvent systems {(methanol, ethanol, n-propanol and acetone) + water} was determined at certain experimental conditions (pressure of 101.3 kPa, temperature of 278.15 K-323.15 K) using laser dynamic monitoring method. Five thermodynamic models were applied to correlate and analyze the experimentally measured data. The modified Apelblat model has the lowest value of ARD (100ARD = 2.046 %) indicates that it fits best. The apparent thermodynamic properties during the dissolution process of forchlorfenuron in the four mixed solvent systems were explored using Van't Hoff equation. The effect of solvent properties on the dissolution was explored by calculating Hansen solubility parameters. For further understanding the solubility behavior on the molecular scale, molecular electrostatic potential analysis and Hirshfeld surface analysis were conducted to visualize the molecular surface charge distribution and predict the contact behavior between forchlorfenuron and solvent. Finally, the influence of intermolecular interactions between solute and solvent on solubility behavior was explored using radial distribution function analysis based on molecular dynamics simulations. And the results show the stronger intermolecular force corresponds to the larger solubility.

Probing pharmaceutically important amino acids L-isoleucine and L-tyrosine Solubilities: Unraveling the solvation thermodynamics in diverse mixed solvent systems

The study specifically investigates the solubilities of L-isoleucine and L-tyrosine in water-mixed solvent systems (DMF, DMSO, and ACN), exploring the behaviour of amino acids in complex environments. The experimental methods prioritize meticulous solvent purification to ensure reliable results. The work explores solubility data, uncovering temperature-dependent trends and intricate interactions influencing solubility in the chosen mixed solvent systems. The study emphasizes the impact of thermodynamic properties, solvent-solvent interactions, and amino acid structure on solubility patterns. The broader implications highlight the relevance of understanding amino acid behaviour in diverse solvent environments, offering potential applications in cosmetics and pharmaceutical industries. The distinct solubility patterns contribute valuable insights, enhancing on the understanding of the solution stability and interactions of L-isoleucine and L-tyrosine in different solvent systems. In conclusion, work suggests the enhanced utilization of L-isoleucine and L-tyrosine in various industries, driven by a profound understanding of their solubility in mixed solvent systems. The research expands our knowledge of amino acid behaviour, paving the way for advancements in industries relying on protein-based products and technologies.

The Emerging Role of Polyethylene Glycol-Water (PEG-H2O) as the Benign Mixed Solvent System in Organic Synthesis

Abstract: Polyethylene glycol (PEG) has become a popular solvent and green catalyst for a variety of chemical reactions. It is a stable and biodegradable polymeric catalyst used in organic synthesis because it may be recycled numerous times without significantly losing its catalytic activity. Recently, the use of PEG-H2O mixed solvent systems in organic synthesis has gained popularity. This article presents an overview of PEG-H2O solvent system-mediated organic reactions, with a main focus on the importance of the solvent system. The study also focuses on recent developments in the PEG-H2O solvent system-mediated synthesis of a number of heterocy-clic compounds. Important characteristics of these PEG-H2O solvent systems include high atom economies, gentle reaction conditions, faster reaction rates, readily isolated side products and high yields. Results from various reactions showed that the choice of proper ratio of PEG: H2O solvent system plays a key role in product yields.

A naphthalene based chemosensor for dual channel recognition of Al3+and relay recognition of Fe3+ in water-bearing system and bioimaging in zebrafish

A simple and rapidly responsive novel chemosensor SN (4-(((2-hydroxynaphthalen-1-yl)methylene)amino)-N-(pyrimidine-2-yl)benzenesulfonamide) was designed and synthesized using 2‑hydroxy‑1-naphthaldehyde as a fluorescent group and its structure was characterized by 1H NMR, 13C NMR and HRMS. Upon addition of only Al3+ in a mixed solvent system (DMSO/H2O, V/V = 9:1), significant changes in UV–visible and fluorescence spectra were observed. At the same time, the solution exhibited noticeable color changes (from yellow to colorless) and fluorescence responses (from no fluorescence to blue fluorescence). The fluorescence chemosensor SN demonstrated excellent selectivity and sensitivity towards Al3+ with detection limits (LOD) of 1.174 × 10−8 M. Therefore, the SN chemosensor enables rapid and efficient detection of trace amounts of Al3+ in both environmental and biological settings through colorimetric and dual-channel fluorescence responses. Furthermore, under the same conditions, the in-situ generated [SN + Al3+] system was used for relay detection of Fe3+ without the need for further optimization, purification, or separation steps. The experimental results showed that the addition of Fe3+ led to fluorescence quenching, eliminating interference from Al3+ during Fe3+ detection, and the detection limit was 1.85×10−8 M. In addition, the binding and sensing mechanism of chemosensor SN to Al3+ and [SN + Al3+] to Fe3+were described in detail by 1H NMR titration experiment, HRMS, density functional theory (DFT) calculation and time-dependent density functional theory (TD-DFT).

Operando Investigation of the Molecular Origins of Dipole Switching in P(VDF‐TrFE‐CFE) Terpolymer for Large Adiabatic Temperature Change

AbstractRelaxor ferroelectric polymers exhibiting a giant electrocaloric effect (ECE) can potentially be used to create next‐generation solid‐state coolers. Under an electric field, poly(vinylidene fluoride‐trifluoroethylene‐chlorofluoroethylene) terpolymer goes through a large dipolar entropy change producing a high adiabatic temperature change (ΔTECE). This work resolves the molecular origins of the large entropy change behind the electric field‐induced dipole switching. A Fourier transform infrared spectroscopy equipped with a high voltage source is used to operandoly observe the characteristic molecular vibrational modes. A short‐range trans (T) conformation of the CF2‐CH2 dyads interrupted by a gauche (G) conformation, e.g., TTTG in the terpolymer chain, undergoes a dynamic transformation that leads to a corresponding ΔTECE whenever an electric field is applied. The molecular dynamics simulation also proves that the energy barrier that the transformation from TTTGs into a long T sequence overcomes is smaller than that for all other conformations. A mixed solvent system is used to obtain T3G‐enriched terpolymer films exhibiting a 4.02 K ΔTECE at 60 MV m−1 and these films are employed to manufacture a 2‐layer‐cascaded cooling device that achieves a 6.7 K temperature lift, the highest reported value for a 2‐layer cascaded device made of fluoropolymers.

Fouling behavior of protein in mixed solvent systems: A combined experimental and simulation study

Membrane fouling in organic solvent environments remains poorly explored despite its significance in chemical and pharmaceutical industries. This study uses molecular dynamics (MD) simulations and experiments to explore lysozyme fouling in water, as well as four organic solvent environments, namely, 30 % v/v and 50 % v/v isopropyl alcohol (IPA), and 30 % v/v and 50 % v/v dimethyl sulfoxide (DMSO). Experimentally, flux declines were least with IPA and worst with DMSO. Biased simulations indicate the worst fouling in DMSO is tied to the most attractive lysozyme-membrane energy in the presence of DMSO. However, the relative attractive energies for IPA and water do not agree with the relative flux declines, indicating other factors are more influential when the interaction energies are similar. To understand the gentler flux decline for IPA despite the more attractive lysozyme-membrane energy, radial distribution functions (RDFs) were obtained from unbiased simulations. Analyses of the water and solvent films around both the membrane and the lysozyme molecule reveal that the denser water film around both entities induced by the presence of IPA serves as a barrier for fouling and thus leads to less flux decline. The results underscore the complexity of fouling in organic solvent systems, cautioning against direct use of the understanding based on aqueous systems.

Local composition-regular solution theory for analysis of pharmaceutical solubility in mixed-solvents

Local composition regular solution theory (LC-RST) model was developed by introducing non-equal i–j and j–i parameters into regular solution theory (RST) to account for specific molecular interactions. The LC-RST model was applied to the correlation of solubilities of active pharmaceutical ingredients (API) in hydrogen bond donor (HBD) – hydrogen bond acceptor (HBA) mixed-solvent systems. In the assessment of 32 API-mixed-solvent systems that contained 11 different APIs and 1947 data, it was determined that the LC-RST model had a logarithmic average relative deviation (ARDln) in solubility of 0.028, the Wilson model had an ARDln value of 0.24 and the purely predictive RST model had an ARDln value of 1.29. Partial molar excess enthalpies and entropies of the API in the mixed-solvents determined from the LC-RST model allowed estimation of API solubility regions where specific interactions occur between API and HBD-HBA complex molecules. In the correlation scheme, component numbers were designated as API molecule (1) – HBD molecule (2) - HBA molecule (3) and systems were grouped according to HBD molecule interactions with the API (pro-solvent, anti-solvent, synergistic with HBA molecule). Phenomenological parameter sensitivity analysis of the LC-RST model showed that dominant specific interactions tended to be 1–2 or 2–1 molecules for pro-solvent groupings, 2–3 or 2–3 molecules for anti-solvent groupings and all i–j and j-–i molecular pairs for synergistic HBD-HBA molecule groupings. Based on parameters determined from a given API-mixed-solvent system, the LC-RST model allows qualitative prediction of solubilities for other systems. The LC-RST model is simple to apply and it retains inherent predictive characteristics of regular solution theory.

The Effect of Solvents on the Crystal Morphology of Isosorbide Mononitrate and Its Molecular Mechanisms.

In this work, the modified attachment energy model was used to predict the crystal morphology of isosorbide mononitrate (ISMN) in the dichloromethane (CH2Cl2) solvent system and dichloromethane-n-hexane (CH2Cl2-C6H14) mixed solvent system. The solvent effect can significantly affect the crystal morphology, which can profoundly impact both the drug's physicochemical properties and the subsequent technological treatment process. In addition, the interactions between solvent molecules and crystal faces were investigated using molecular dynamics simulation, and radial distribution function (RDF) analysis was performed to determine the types of interactions. The structural parameter S was introduced to characterize the roughness of each crystal surface; the change in the CH2Cl2 diffusion coefficient before and after the addition of C6H14 was analyzed using mean square displacement (MSD). The calculation results of the modified attachment energy from the two solvent systems revealed that C6H14 could accelerate crystal growth, while the crystal morphology was not greatly affected, which is of some significance as a guide for the industrial crystallization process.

Aggregation-induced emission from optically active X-shaped molecules based on planar chiral [2.2]paracyclophane

An optically active π-stacked molecule was synthesized incorporating planar chiral [2.2]paracyclophane and o-carborane units to impart circularly polarized luminescence and aggregation-induced emission properties to the molecule. The molecule exhibited a strong emission from the aggregated state in a mixed solvent system (H2O/THF) and the solid state in the PMMA matrix. In the aggregated state, weak circularly polarized luminescence was observed owing to the random intermolecular orientation. On the other hand, the circularly polarized luminescence was clearly observed in the PMMA film containing 1 wt% molecule. Theoretical studies using time-dependent density functional theory reproduced the molecule’s circular dichroism and circularly polarized luminescence properties.

Exploring solubility and energetics: Dissolution of biologically important l-threonine in diverse aqueous organic mixtures across the temperature range of 288.15 K to 308.15 K

This research provides a thorough investigation into the solubility behavior and solution thermodynamics of l-threonine in significant organic solvent systems. The work was done on measuring the actual solubility and subsequently calculating overall transfer solvation free energetics (∆Genergetic0i) and transfer entropies (∆St0i) at a temperature of 298.15 K. These measurements were performed as l-threonine transitioned from water to different water-organic mixed solvents systems. The saturated solubilities of l-threonine were determined using the ‘gravimetric method’ at five equidistant temperatures namely 288.15 K, 293.15 K, 298.15 K, 303.15 K and 308.15 K. By analyzing the data on solubility, we further obtained the different energies involved in solvation related issues. In the case of single solvents, the nature of solubility of l-threonine was observed like: dimethylsulfoxide (DMSO) < acetonitrile (ACN) < N, N-dimethylformamide (DMF) < ethylene glycol (EG) < water (H2O), irrespective of the experimental conditions. Specifically, at 298.15 K, the solubilities of l-threonine in single solvents were found to be as follows: 0.8220 mol per kg of water, 0.3101 mol per kg of EG, 0.1337 mol per kg of DMF, 0.1107 mol per kg DMSO and 0.1188 mol per kg of ACN. This research critically examines the relationship between the experimental saturated solubility of l-threonine and the complex properties influencing its solvation energy in diverse aqueous organic solvent systems.

Limiting molar conductivity behaviour of ENR-50 electrolyte in mixed solvent system at ambient temperature

The present research investigates the behaviour of the limiting molar conductivity (Λo) of ENR-50/LiClO4 in a mixed solvent systemcomprising tetrahydrofuran (THF) and acetonitrile (ACN) at ambient temperature. The study uses the power law, to determine the Λovalue of ENR-50/LiClO4/THF:ACN at a specific reference salt concentration. The ENR-50/LiClO4 electrolyte system was prepared witha fixed THF:ACN ratio of 8:2, at different ENR-50 concentration of range between 0.001-0.003 g/cm3. The correlation values obtainedfor the three polymer concentrations ranged from 0.9959 to 0.9966. Regression analysis revealed that as the polymer concentrationincreases, the Λo decreases, indicating an inverse relationship which suggesting an enhanced ion dissociation due to an increase in total free-moving ions within the liquid polymer electrolyte system. The characterization of ENR-50/LiClO4/THF:ACN was verified through ATR-FTIR spectroscopy, confirming the ion dipole interaction between the C-O-C group of ENR-50 and Li ions.

Stable PbS colloidal quantum dot inks enable blade-coating infrared solar cells

Infrared solar cells are more effective than normal bandgap solar cells at reducing the spectral loss in the near-infrared region, thus also at broadening the absorption spectra and improving power conversion efficiency. PbS colloidal quantum dots (QDs) with tunable bandgap are ideal infrared photovoltaic materials. However, QD solar cell production suffers from small-area-based spin-coating fabrication methods and unstable QD ink. Herein, the QD ink stability mechanism was fully investigated according to Lewis acid–base theory and colloid stability theory. We further studied a mixed solvent system using dimethylformamide and butylamine, compatible with the scalable manufacture of method-blade coating. Based on the ink system, 100 cm2 of uniform and dense near-infrared PbS QDs (~ 0.96 eV) film was successfully prepared by blade coating. The average efficiencies of above absorber-based devices reached 11.14% under AM1.5G illumination, and the 800 nm-filtered efficiency achieved 4.28%. Both were the top values among blade coating method based devices. The newly developed ink showed excellent stability, and the device performance based on the ink stored for 7 h was similar to that of fresh ink. The matched solvent system for stable PbS QD ink represents a crucial step toward large area blade coating photoelectric devices.Graphical

Unusual long-term stability of enzymatic bioelectrocatalysis in organic solvents

Organic solvent tolerant enzymes are of tremendous importance for the pharmaceutical industry in search of high added-value chemicals. However, enzymes exhibit usually weak long-term activity and stability in various media. Here, we report a general strategy allowing stabilizing and keeping enzymes active in mixed-solvent systems upon immobilization on an electrode surface. It consists in the combination of an engineered solvent-tolerant enzyme, combined with fine-tuned osmium-based redox polymers where the concentration of osmium complex has been specifically tuned to minimize its deswelling, associated with the use of porous gold electrodes. This approach is validated with bilirubin oxidase as a model system. This copper enzyme is able to oxidize a wide range of substrates, combined with the reduction of O2 to water. While all other enzymatic systems irreversibly lose their activity and stability in the presence of 7.5 M methanol or below, this optimized enzymatic system stays functional in 12.5 M methanol with no loss in current density. It exhibits a half-life of more than 8 days, which is unprecedented in the literature. We show that this electrode can also operate in DMSO, dioxane, acetonitrile and acetone, thus opening up a very wide variety of applications in the field of bioelectrocatalysis and bioelectrosynthesis.

Effect of semicarbazide hydrochloride on the physicochemical properties of L-leucine and glycylglycine at varied temperatures and compositions

Density (ρ), sound speed (u) and viscosity (η) for an essential amino acid (L-leucine) and a peptide (diglycine) in water and (0.0496, 0.1002 and 0.1498) mol kg−1 mixed aqueous semicarbazide HCl solvent system at five distinct temperatures ranging (293.15 K – 313.15 K) and barometric pressure (101.3 kPa) have been acquired. Varied physicochemical properties like apparent molar parameters (Kϕ,s, Vϕ), hydration number (nH), partial molar parameters (K0ϕ,s, V0ϕ,), viscosity coefficients i.e. Jones Dole and Falkenhagen coefficients, transfer parameters (Vϕ,tro, Kϕ,s,tro, Btr) etc. have been enumerated from the empirically determined data. Moreover, the structure breaking (chaotropic) character of each examined protein subunit has been scrutinized through positive dBdT (temperature dependence of viscosity B-coefficient) values and negative (∂E0ϕ/∂T)p (Hepler’s constant) values. In addition, the cosphere overlap model has been used for a better understanding of assorted predominant molecular interactions in the examined solution mixtures.

A Zn-based Zig-Zag 1D chain type coordination polymer for removal of methylene blue dye from an aqueous solution

A 1D zig-zag zinc coordination chain, [Zn(piv)2]n (1) (where piv = pivalic acid) has been synthesized by a reaction of ZnCl2 with O-donor pivalic acid in the mixed solvent system (MeCN/MeOH) and structurally characterized via ultraviolet–visible spectroscopy (UV), Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, and X-ray crystallography. The crystal structure is a bridging chain of zinc metal connected via pivalic acids. The synthesized coordination polymer was explored for photochemistry to study photoluminescence and photocatalytic properties. The photocatalytic properties were investigated against methylene blue (MB) dye under UV light illumination. Under optimal reaction conditions (catalyst dosage = 10 mg, initial concentration of dye = 20 mg/L, pH = 9) the maximum photodegradation of methylene blue was found to be 72.56% in 120 min illumination time. The photocatalytic reaction showed pseudo-second-order kinetics with a rate constant of 0.012 L.mg−1.min−1. Furthermore, the recyclability test showed that compound 1 retained its photocatalytic potential even after five successive uses. The compound 1 could be a proficient and economical choice for the photocatalytic elimination of pollutants from wastewater.

Catalytic Conversion of Carbohydrates into 5-Hydroxymethylfurfural by Phosphotungstic Acid Encapsulated in MIL-101 (Cr, Sn) Catalyst in Deep Eutectic Solvents.

Herein, we report the synthesis of bimetal-organic frameworks (BMOFs) with both Brønsted and Lewis acidities, in which phosphotungstic acid (PTA) was encapsulated in BMOFs. It is efficient in converting starch to 5-hydroxymethyl-furfural (HMF) in deep eutectic solvents (DESs) such as choline chloride and formic acid. The highest yield of HMF (37.94%) was obtained using P0.5/BMOFs1.0 to catalyze starch in a mixed solvent system comprising DESs and ethyl acetate (EAC) (v/v; 2:3) at 180 °C and a reaction time of 10 min. Employing a DES as a cocatalyst and solvent reduced the use of organic solvents. The catalyst showed adequate reusability, and the HMF yield only decreased by 2.88% after six cycles of reuse compared with that of the initial catalyst. This study demonstrates the application potential of BMOFs in the conversion of biomass to useful molecules with commercial and/or research value.

Recycling of lithium and fluoride from LiF wastewater from LiF synthesis industry by solvent extraction

The LiF synthesis industry produces a large amount of wastewater that contains ∼0.36 g/L lithium and ∼1.10 g/L fluorine. The traditional treatment solidified fluoride by excessive CaO, resulting in waste of lithium resources and generation of CaF2-CaO solid waste. To recover the Li and F from the LiF wastewater, a two-section solvent extraction process using acidic solvent and mixed solvent as organic solvent was designed and the extraction mechanism were systematically investigated. The result showed that Li extraction was extracted by a cation exchange mechanism with D2EHPA (di-2-ethyl hexyl phosphoric acid), 99.72% Li recovery and battery-grade LiCl solution (3.40 g/L) were achieved by mixed the LiF aqueous with the saponified D2EHPA at 25 ℃ for 6 mins with 4.60 equilibrium pH. After then, F was recovered by mixed neutral solvent system, which coordination binding with HF molecule. The ultimately residue contains ∼1 mg/L Li and < 6 mg/L F. Besides, high-purity LiF products (LiF>99.95%) was generated by stripping with LiOH, F recovery is 99.45%. 2-stage extraction process realizes lithium and fluoride recovery with short process, no pollution and great prospect of industrialization.

Thermodynamic analysis and molecular dynamic simulation of solid–liquid equilibrium behavior of antipsychotic drug aripiprazole (Form III) in three binary solvent mixtures

Aripiprazole (APZ), an effective second-generation antipsychotic drug indicated for the treatment of schizophrenia, was chosen to investigate its solubility in three binary solvent mixtures at the temperature range of 278.15–318.15 K. Due to clinical usage Form III is metastable, and the solubility was studied via the synthetic method. It was found that in the butanone + acetone and butanone + ethyl acetate mixed solvent systems, the solubility values of APZ Form III increased with the increase of the proportion of butanone solvent, and the maximum mole fraction solubility at each selected temperature point ranges from 0.001924 to 0.009015. However, in the mixed solvent system of butanone and n-propanol, the solubility of APZ Form III reaches its maximum when the molar fraction of butanone is 0.6 with the maximum mole fraction solubility at each selected temperature point ranging from 0.003126 to 0.012721. The modified Apelblat model, λh model, Van’t Hoff model, and NRTL model were used to correlate the experimental solubility data of APZ Form III, and the results showed that these models are suitable. In addition, according to the result of mixing thermodynamic functions, the negative values of ΔmixG and ΔmixH in all binary solvent mixtures are negative, indicating that the dissolution process of APZ Form III in the binary solvent mixtures is spontaneous and entropy-driven. Furthermore, the molecular dynamic simulations were used to illustrate and understand the dissolution behavior of APZ Form III in selected solvents from a molecular perspective.

Bis-cyanostilbene based fluorescent materials: A rational design of AIE active probe for hypochlorite sensing

In the present investigation cyanostilbene based molecular probes, PCS and PCO, bearing N,N-dimethylthiocarbamate and N,N-dimethylcarbamoyal groups, respectively, have been synthesised. These probes exhibit AIEE activity in their aggregated state in the mixed solvent system of THF: H2O by way of turning on their emission, which has also been observed in powder, neat thin films and hybrid polymer films. While the probe PCO is silent to ClO−, PCS exhibits a significant response towards ClO− rationalised on the basis of HOCl specific oxidation of thiocarbamate, which is also extended to detect ClO− in water samples. Additionally, applicability of the test strips of PCS for rapid on-site detection of ClO− has been demonstrated. The experimental results are supplemented by the theoretical calculations wherever possible.

All green sulfolane-based solvent enhanced electrical conductivity and rigidity of perovskite crystalline layer

Industrial commercialization of perovskite solar cells not only depends on sufficient device performance, but also requires complete elimination of hazardous solvents in the fabrication process to enable sustainable development of the technology. This work reports a new solvent system based on sulfolane, gamma-butyrolactone (GBL), and acetic acid (AcOH) as a significantly greener alternative to common but more hazardous solvents. Interestingly, this solvent system not only resulted in densely-packed perovskite layer of bigger crystal size and better crystallinity, the grain boundaries were found to be more rigid and highly conductive to electrical current. The physical changes at the grain boundaries were due to the sulfolane-infused crystal interfaces, which were expected to facilitate better charge transfer and provide stronger barrier to moisture within the perovskite layer, yielding higher current density and longer performance of the device as a result. In fact, by using a mixed solvent system consisting of sulfolane, GBL, and AcOH in the volume ratio of 70.0:27.5:2.5, the device stability was better and the photovoltaic performance was statistically comparable with those prepared using DMSO-based solvent. Our report reflects unprecedented findings of enhanced electrical conductivity and rigidity of the perovskite layer simply by using an appropriate choice of the all-green solvent.