Study Of Solvent Effects Research Articles

Solubility Determination of c-Met Inhibitor in Solvent Mixtures and Mathematical Modeling to Develop Nanosuspension Formulation.

The solubility and dissolution thermodynamics of new c-Met inhibitor, ABN401, were determined in eleven solvents and Transcutol® HP–water mixture (TWM) from 298.15 to 318.15 K. The experimental solubilities were validated using five mathematical models, namely modified Apelblat, van’t Hoff, Buchowski–Ksiazaczak λh, Yalkowsky, and Jouyban–Acree van’t Hoff models. The experimental results were correlated and utilized further to investigate the feasibility of nanosuspension formation using liquid anti-solvent precipitation. Thermodynamic solubility of ABN401 increased significantly with the increase in temperature and maximum solubility was obtained with Transcutol® HP while low solubility in was obtained water. An activity coefficient study indicated that high molecular interaction was observed in ABN401–Transcutol® HP (THP). The solubility increased proportionately as the mole fraction of Transcutol® HP increased in TWM, which was also supported by a solvent effect study. The result suggested endothermic and entropy-driven dissolution. Based on the solubility, nanosuspension was designed with Transcutol® HP as solvent, and water as anti-solvent. The mean particle size of nanosuspension decreased to 43.05 nm when the mole fraction of ABN401 in THP, and mole fraction of ABN401 in TWM mixture were decreased to 0.04 and 0.1. The ultrasonicated nanosuspension appeared to give comparatively higher dissolution than micronized nanosuspension and provide a candidate formulation for in vivo purposes.

Temperature and Solvent Effects on H2 Splitting and Hydricity: Ramifications on CO2 Hydrogenation by a Rhenium Pincer Catalyst.

The catalytic hydrogenation of carbon dioxide holds immense promise for applications in sustainable fuel synthesis and hydrogen storage. Mechanistic studies that connect thermodynamic parameters with the kinetics of catalysis can provide new understanding and guide predictive design of improved catalysts. Reported here are thermochemical and kinetic analyses of a new pincer-ligated rhenium complex (tBuPOCOP)Re(CO)2 (tBuPOCOP = 2,6-bis(di-tert-butylphosphinito)phenyl) that catalyzes CO2 hydrogenation to formate with faster rates at lower temperatures. Because the catalyst follows the prototypical "outer sphere" hydrogenation mechanism, comprehensive studies of temperature and solvent effects on the H2 splitting and hydride transfer steps are expected to be relevant to many other catalysts. Strikingly large entropy associated with cleavage of H2 results in a strong temperature dependence on the concentration of [(tBuPOCOP)Re(CO)2H]- present during catalysis, which is further impacted by changing the solvent from toluene to tetrahydrofuran to acetonitrile. New methods for determining the hydricity of metal hydrides and formate at temperatures other than 298 K are developed, providing insight into how temperature can influence the favorability of hydride transfer during catalysis. These thermochemical insights guided the selection of conditions for CO2 hydrogenation to formate with high activity (up to 364 h-1 at 1 atm or 3330 h-1 at 20 atm of 1:1 H2:CO2). In cases where hydride transfer is the highest individual kinetic barrier, entropic contributions to outer sphere H2 splitting lead to a unique temperature dependence: catalytic activity increases as temperature decreases in tetrahydrofuran (200-fold increase upon cooling from 50 to 0 °C) and toluene (4-fold increase upon cooling from 100 to 50 °C). Ramifications on catalyst structure-function relationships are discussed, including comparisons between "outer sphere" mechanisms and "metal-ligand cooperation" mechanisms.

A spectroscopic study of solvent effects on the formation of Cu(ii)-chloride complexes in aqueous solution.

A combination of electronic (UV-vis) and X-ray absorption (EXAFS, XANES) spectroscopies has been used to investigate the formation of copper(ii)/chloride complexes in concentrated aqueous solutions. It is established that lowering the water activity by the addition of Mg(ClO4)2 at a constant Cl-/Cu(ii) ratio results in the replacement of water molecules by Cl- ions in the primary coordination shell of Cu(ii). This behavior closely parallels the effect of increasing the Cl-/Cu(ii) ratio and demonstrates that full understanding of the stoichiometry and structures of the complexes formed in concentrated metal-ion chloride solutions requires explicit consideration of the role of the solvent.

A reaction density functional theory study of solvent effect in the nucleophilic addition reactions in aqueous solution

Whereas the proper choice of reaction solvent constitutes the cornerstone of the green solvent concept, solvent effects on chemical reactions are not mechanistically well understood due to the lack of feasible molecular models. Herein, by taking the case study of nucleophilic addition reaction in aqueous solution, we extend the proposed multiscale reaction density functional theory (RxDFT) method to investigate the intrinsic free energy profile and total free energy profile, and study the solvent effect on the activation and reaction free energy for the nucleophilic addition reactions of hydroxide anion with methanal and carbon dioxide in aqueous solution. The predictions of the free energy profile in aqueous solution for these two nucleophilic addition reactions from RxDFT have a satisfactory agreement with the results from the RISM and MD-FEP simulation. Meanwhile, the solvent effect is successfully addressed by examining the difference of the free energy profile between the gas phase and aqueous phase. In addition, we investigate the solvent effect on the reactions occurred near solid–liquid interfaces. It is shown that the activation free energy is significantly depressed when reaction takes place in the region within 10 Å distance to the substrate surface owing to the decrease of hydration free energy at the solid–liquid interface.

A reaction density functional theory study of solvent effects on keto-enol tautomerism and isomerization in pyruvic acid

It is important to study the solvent effect on keto-enol tautomerism that has applications in many areas of chemical engineering. In this work, we use a multiscale reaction density functional theory (RxDFT) to study the keto-enol tautomerism and isomerization of pyruvic acid. The results show that both effects of solvation and water assistance could reduce the reaction barriers. The water molecule participates the reaction as a catalyst to accept/give the protons with forming a hexagonal ring in the transition state. As a result of this temporary and intermediate hexagonal ring, the solute configuration undergoes a small variation during the reaction, giving a diminished contribution to the intrinsic reaction free energy. The solvent distribution shows a local ordering behavior near the solute that also reduces the contribution of solvation effect to the reaction barrier. Water assistance plays a major role in both pre-reaction and post-reaction process. In terms of the driving force for the reaction, the effects of both solvation and water assistance are important. • The solvent effect is studied by the proposed reaction density functional theory. • Both effects of solvation and water assistance could reduce the reaction barriers. • The solvent distribution shows a local ordering behavior near the solute.

Equilibrium solubility, preferential solvation and solvent effect study of clotrimazole in several aqueous co-solvent solutions

The equilibrium solubility of clotrimazole in co-solvent mixtures of n-propanol/isopropanol/acetonitrile/1,4-dioxane + water was attained by the saturation shake-flask technique at temperatures between 278.15 K and 323.15 K under ambient pressure of 101.2 kPa. The solubility of clotrimazole in mole fraction scale increased with increasing temperature and mass fractions of n-propanol/isopropanol/acetonitrile/1,4-dioxane. The maximum value was recorded in the neat co-solvent for each mixture studied. The Jouyban-Acree model and van’t Hoff-Jouyban-Acree model were applied to mathematically describe the dependence of clotrimazole solubility upon the co-solvent content and temperature, obtaining the values of relative average deviations and root-mean-square deviations no more than 8.02 × 10−2 and 8.17 × 10−4, individually. KAT-LSER model was implemented to quantitatively acquire evidence about solvent effect upon the variation of clotrimazole solubility magnitudes. The variation in clotrimazole solubility mainly depended upon the Hildebrand solubility parameter and dipolarity-polarizability of solutions in the four aqueous systems studied. Quantitative investigation was carried out for the local mole fractions of n-propanol/isopropanol/acetonitrile/1,4-dioxane and water around solute clotrimazole by using the Inverse Kirkwood–Buff integrals way utilized to the solubility data determined. Clotrimazole was preferentially solvated by n-propanol/isopropanol/acetonitrile/1,4-dioxane for these aqueous co-solvent mixtures in intermediate and n-propanol/isopropanol/acetonitrile/1,4-dioxane-rich proportions.

Study of solvent effect on the stability of isothiocyanate iberin, a breakdown product of glucoiberin

Iberin (IBR) is an isothiocyanate (ITC) with chemopreventive properties on different types of cancer. The need of quantifying IBR either in natural products or in food supplements makes the availability of suitable and stable analytical standards necessary. The choice of proper solvents for ITCs storage and experiment setup is a critical point due to ITCs reactivity. As IBR reference standard is sometimes supplied in ethanol, methanol is also frequently utilised as a solvent in ITCs analysis. A study on IBR stability in the most common solvents used in liquid chromatography and at different pH is presented.A fast UHPLC-PDA-ESI/MS analysis was used to separate IBR from degradation products, to monitor IBR stability at three temperatures and at different pH. The fastest degradation was observed in methanol/water mixture. IBR degraded always faster in methanol than in ethanol. At 20 °C, the degradation in ethanol and in water was comparable. At 30 °C and 40 °C the degradation in water was faster than either in ethanol or methanol. Ethyl thiocarbamate, methyl thiocarbamate and disubstituted thiourea degradation products, in ethanol, methanol and water respectively, were tentatively assigned. IBR was stable in acetonitrile and at acidic pH but it was unstable at alkaline pH.

Quantum study of solvent effect with POPC phospholipid bilayers in a cell membrane and its impact on active and targeted drug delivery

In this study, since the system was relatively large, the modified methods of molecular mechanics and quantum mechanics were used to obtain changes in the thickness of the membrane phospholipids by different solvents. Thus, according to the theory of fluidity Mosaic, the changes that were made due to various solutions and, consequently, the constant change of solution dielectric effect on the thickness of the phospholipid membrane. By comparing these changes, it was found that changes in the width of the inner layers in the vicinity of different solvents, with the shift from this effect, are consistent with the total width of the phospholipid membrane. It seems to be the determining factor in changing the width of the diaphragm against different solvents of the phospholipid inner layer. Accordingly, the depth of membrane thinning was calculated for each solvent in comparison with the water solution, which was reduced by decreasing the solvent dielectric constant, thinning of the solution and the phospholipid membrane, respectively. Thermodynamic functions for the usual solution were calculated using frequency studies and thermodynamic relations. These functions indicate that the system is stable in terms of thermodynamics and stabilizes the desired solution without distorting structural integrity. Hence, these structures can be used as agents for the delivery, exchange, and absorption of materials. The membrane structures studied in this study are used in the mechanism, and drug delivery interactions in the body and the pharmaceutical industry as a channel for the delivery and exchange, and these results can be used in the discussion of intelligent redeploy of drugs and Nano drug. So, paying attention to the operating environment and the thinning factor and the thickness of the membrane increase the reactivity, improve the solubility and delivery of drugs, reduce the dose of the medicine and increase its effectiveness.

A Method for the Preparation of β-Amino-α,β-unsaturated Carbonyl Compounds: Study of Solvent Effect and Mechanism.

An efficient method for the preparation of β-amino-α,β-unsaturated carbonyl compounds is demonstrated. Bench-stable sodium 3-oxo-enolates were prepared from carbonyl compounds, and reacted with amines in the presence of an acid and a desiccant. DFT studies revealed contrasting mechanisms toward the reactivity of aliphatic amines in protic solvents and aromatic amines in aprotic solvents. While the former proceeds through the formation of an imine, the latter passes through the Michael addition-elimination mechanism.

A Computational Study of Solvent and Electric Field Effects on Propylene Oxide Ring‐Opening Reaction

AbstractEthylene glycol (EG) is an important chemical and is widely used in the chemical industry. Hydration of ethylene oxide is a common way to produce EG. We performed density function calculations of propylene oxide (PO) ring‐opening reaction under basic, neutral and acidic conditions. We examined the influence of the solvent and electric field (EF) on the geometry, kinetics and thermodynamics of the ring‐opening. The solvent effect increases/decreases the ring‐opening barriers in the basic/neutral systems and EF exhibits significant influence on barriers and reaction heats in basic condition. All the energetic variation due to solvent and EF can be rationalized with the dipole moments of reactants, transition states, and products.

Theoretical study of solvent effects on the hyperpolarizabilities of two chalcone derivatives

The use of organic as nonlinear optical materials has been intensively explored in the recent years due to the ease of manipulation of the molecular structure and the synthetic flexibility regarding the change of substituent groups. In the present work, the linear and nonlinear properties of two chalcones derivatives (E)-1-(4-methylphenyl)-3-phenylprop-2-en-1-one (4MP3P) and (E)-1-(4-Nitrophenyl)-3-phenylprop-2-en-1-one (4NP3P), that differ by the substituent position at the phenyl ring, were studied in the presence of protic and aprotic solvents simulated by the Polarizable Continuum Model (PCM) at DFT/B3LYP/6-311+G(d) level. The static and dynamic (1064 nm) molecular parameters as the dipole moment, linear polarizability, first and second hyperpolarizabilities were studied as function of the solvent dielectric constant value. The geometrical behavior as the chemical bond angles, torsion angles, and partial charges distribution of the compounds were studied, including calculations of gap energies in various solvents. The obtained results revealed that the substituent change of CH3 (4MP3P) to NO2 (4NP3P) benefits the nonlinear optical properties of the compounds in the presence of the solvent media, the absolute values of the parallel first hyperpolarizability were the ones that present the greater variation.

Study of solvent effect on structural and photoconductive behavior of ternary chalcogenides InBiS3-In2S3-Bi2S3 composite thin films deposited via AACVD

Abstract In the present work ternary composite InBiS3-In2S3-Bi2S3 (IBS) thin films are developed using a homogeneous mixture of precursors [Bi(S2CN(C2H5)2)3]2 (1) and [In(S2CNCy2)3]‧2py (2), separately in toluene and chloroform solutions at 500°C under an inert atmosphere of argon gas via aerosol assisted chemical vapor deposition (AACVD) technique. The phase purity, chemical composition and morphological study of both the films deposited from toluene and chloroform solutions are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and Field emission scanning electron microscopy (FESEM). The surface morphology showed rod like structure of the films developed from toluene while the films grown from chloroform solution give flake like shapes. The UV-visible spectroscopy explicated that the thin films developed from toluene and chloroform solutions show wide range absorption in whole visible region. Linear Scan voltammetry results show that both the films give negligible dark current, however, the films fabricated from toluene solution give a sharp steep curve with maximum photocurrent density of 2.3 mA‧cm-2 at 0.75 V vs Ag/AgCl/3M KCl using 0.05 M sodium sulphide solution under AM 1.5 G illumination (100 mW‧cm-2), while the film grown from chloroform generates a photocurrent density of 2.1 mA‧cm-2 under similar conditions. The LSV outcomes are further supported by electrochemical impedance spectroscopy (EIS) that gives charge transfer resistance (Rct) value of 8,571 Ω for the films developed from toluene as compared to films fabricated from chloroform with Rct value of 12,476 Ω.

Study of solvent effect on the synthesis of magnetic molecularly imprinted polymers based on ultrasound probe: Application for sulfonamide detection.

In this work, a comparative study of the effect of various solvents on the synthesis of magnetic molecularly imprinted polymers (MMIPs) based on the use of high-power ultrasound probe is reported for the first time. Dimethylsulfoxide (DMSO), dimethylformamide (DMF), ethanol, acetonitrile and acetone were studied as solvents for the synthesis of MMIPs. Several crucial experimental conditions such as the time of synthesis and the applied amplitude were investigated. DMSO, DMF and ethanol were successfully used for ultrasound-assisted synthesis of MMIPs. However, for the polymerization performed using acetonitrile and acetone, no significant conversion to product was observed. Under optimal conditions for each solvent tested, the synthesized MMIPs were characterized using several techniques such as Scanning/Transmission Electron Microscopy (SEM and STEM modes), X-Ray Diffraction, Fourier Transform Infra-Red Spectroscopy, Thermal Gravimetric Analysis and Vibrating Sample Magnetometer system. The study of adsorption time of MMIPs showed that fast adsorption occurred due to the presence of specific imprinted sites on the surface. Moreover, isotherm study showed that the experimental equilibrium data fitted well with Freundlich model. The results of selectivity study indicated that MMIPs could selectively recognize the target molecule. Due to its high adsorption properties and easiness of preparation, MMIP-DMSO was used successfully as adsorbent material in solid-phase extraction coupled to a colorimetric method for sulfamethoxazole (SMX). After optimizing analytical conditions, a calibration plot was performed in the concentration range from 0.2 to 5 µg·mL-1 with limits of detection and quantitation of 0.06 and 0.2 µg·mL-1, respectively. The developed procedure was applied successfully for SMX determination in spiked tap and mineral waters showing satisfactory recoveries. Besides, reusability study demonstrated that MMIP could be reused at least 8 times keeping good binding capacity.

Quantifying solvent effects through QSPR: A new look over different model equations

The heterolysis reactions of 3 tertiary alkyl halides (2-chloro-2-methylpropane, 2-bromo-2-methylpropane and 3-bromo-3-ethylpentane) in a set of 21 protic and aprotic solvents, representative of various classes of solvents, were used to study solvent effects upon reactivity, at 298.15 K. Quantitative Structure-Property Relationships established through the use of multiple linear regressions, namely a model equation based on the solvatochromic parameters π*, α and β (the KAT equation), was shown to provide robust and predictive quantifications of the main solute-solvent interactions which prevail in the studied reaction processes. Changes in the departing halogen and in the size of the carbonated skeleton induce well quantified sensitivities to each solvent descriptor depending on the type of interaction being modeled. Other model equations were tested, and results evidenced some weaknesses related to inadequate solvent description ability or ill-conceived scales' use.

Synthesis, photophysical, DFT and solvent effect studies on biologically active benzofuran derivative: (5-methyl-benzofuran-3-yl)-acetic acid hydrazide

Abstract The synthesis, photophysical, DFT and solvent effect studies on novel benzofuran derivative namely, (5-methyl-benzofuran-3-yl)-acetic acid hydrazide [5MLBH] are reported. The probe is characterized by 1H NMR, 13C NMR, IR and mass spectral methods. Absorption and fluorescence maxima of 5MLBH are determined for different solvents of varying polarity and solvatochromic behavior and dipole moments are investigated. Results indicate that, excited state dipole moment (μe) values are higher than ground state dipole moment (μg) values and suggest that, probe molecule 5MLBH is more polar in excited state than ground state. Energy band gap is determined from HOMO-LUMO and absorption threshold wavelengths. Using HOMO-LUMO energies, chemical hardness of probe molecule is estimated. From DFT molecular electrostatic potential (MESP) plots, electrophilic site and nucleophilic site were identified. Using Catalan parameters, solute-solvent interactions were analyzed. Preliminary investigations suggest, probe 5MLBH may be considered as potential candidate for luminescence materials, fluorescent probes and for designing non-linear optical materials in future.

Study of Solvent Effects on the Uv/Visible Spectra of A Newly Synthesized Azo-Dye5-(8-Quinaldinolazo)-Para Phenyl Acetic Acid

The solvent effect can be determined by Solvent polarity scale ,solvatochromic parameter which has different position of UV-Visibile absorption band in the range between 300 nm to 600 nm. The spectral characteristics of this azo dyes( QAPA) in different solvents at room temperature was analyzed which is the aim of studying the effect of solvents on the absorption spectra of this dyes in organic solvent of different characters. The solvatochromic behaviors of (QAPA) dye and solvent ? solute interactions can be analyzed by means of linear( solvation). The absorption spectra was( QAPA) dyes found to be two main bands at which 435nm which saw that Transition ?-?* of the - N=N- group show a hypsochromic shift and550nm with n-?* transition This band is found to be highly dependent on solvent polarity and it shows a bathochromic shift with increasing solvent polarity, which may be indicated in azo- enaminetautomers. So, the absorption at longer wavelengths may be assigned to the hydrazone tautomer or common anion form. Absorption maxima of dyes are dependent on solvent polarity. Solvation of dye molecules probably occurs via dipole-dipole interactions in non-hydrogen-bond donating solvents, In hydrogen-bond donating solvents the phenomenon is more hydrogen bonding in nature.

Theoretical Study of Solvent Effect on the Kinetics and Thermochemistry of the Reaction of a (NHC)Cu(boryl) Complex with Ethylene

In this investigation, we describe solvent effect on the ethylene insertion into Cu–B bond in a (NHC)Cu(boryl) complex using MPW1PW91 quantum chemical methods. Solvent effects were explored by using the self-consistent reaction field (SCRF) method based on polarizable continuum model (PCM) in cyclopentanol, acetone, methanol, nitromethane, and dimethylsulfoxide. The progress of the reaction was quantitatively studied using the bond orders of the C–C bond of ethylene, and the percentages of bond cleavage (BCCC) of C–C bond at the transition state were described. The linear correlations between barrier energy, bond distances variations and thermodynamic parameters with dielectric constants of solvents were investigated. Rate constant of the title reaction over the temperature range of 200–1200 K was calculated in gas phase.

Study of solvent effect on thermodynamic stability and electron efficiency of MZ-341 dye

Photo physical and thermodynamic properties of D-π-A organic dye, MZ-341(4-[4-(diphenylamino)phenyl]-7-oxo-7Hbenzimidazo[2,1-a]benzo[de]isoquinoline-11-carboxylic acid), have been investigated for ground and excited states, in order to indicate the different effects of solvent on it as an organic sensitizer in Dye-sensitized Solar Cells (DSSCs). Calculations were performed with Density functional theory approach (DFT) and Time-dependent Density functional theory (TD-DFT) in three different solvents, including water, acetonitrile and carbon tetrachloride. In this work solvation free energy, electron transfer during excitation, Q factor, dipole moment, electronic absorption spectra, recombination (ability of charge injection), life time of excited states, intramolecular bond lengths, light harvesting energy (LHE) by dye and exciton binding energy (EBE) were investigated for ground and excited states. The analysis indicates that amount of intramolecular charge transfer is less in more polar solvents than other solvents. Due to the change in charge distribution during excitation, changes in the value and orientation of the dipole moment and Q factor are generated so it is recognized in more polar solvents; dipole moment and Q factor are higher. Our results showed that solvent also have effect on solvation free energy parameter (ΔG solvation) and consequently the stability of dye so it has been investigated that acetonitrile is the best solvent for use with MZ-341 dye due to the electron and thermodynamic properties.

Theoretical Studies of Solvent Effect on the Structure, Вonding, and Spectroscopic Рroperties (IR, NMR) in the cis-[Pt(PH3)2(NCS)2] and [Pt(PH3)2(SCN)2] Linkage Isomers

The present investigation explores the stability of linkage isomers of cis-[Pt(PH3)2(NCS)2] and [Pt(PH3)2(SCN)2] by the use of MPW1PW91 quantum method. The polarity of solvent effect on dipole moment, structural parameters, and electronic properties, spectroscopic properties (IR and NMR) was studied. The selected vibrations of IR-active in different solvents were obtained and correlated with Kirkwood–Bauer–Magat equation (KBM). The d-orbitals energies of platinum were calculated by NBO analysis. It was seen good correlation were obtained between 195Pt chemical shifts and the spectral parameters obtained from the energies of electronic transitions between Pt d-orbitals in the cis-[Pt(PH3)2(NCS)2] complex. Also, 1J(Pt–N) values were correlated with Pt–N distances.

A remarkable solvent effect on reductive amination of ketones

We report the first systematic study of solvent effect on reductive amination of ketones with ammonia and dihydrogen (H2) over Ru/C, Rh/C, Pd/C and Pt/C catalysts. Protic (water, methanol, ethanol and isopropanol), aprotic polar (dioxane and tetrahydrofuran) and aprotic apolar (cyclohexane and toluene) solvents were investigated. Reaction kinetic model was built to reveal solvent-dependent reaction pathway and solvent-related rate constant for individual steps. Primary amine is produced via two distinct routes, i.e., hydrogenation of imine and hydrogenolysis of Schiff base adduct. These two routes co-exist in organic solvents, while the preference of which route to take heavily depends on the nature of the solvent. In contrast, the formation of imine and Schiff base are not favored in water, resulting in high selectivity towards alcohol. Methanol is identified as the best solvent for reductive amination of ketones, attributed to the highest rates for imine and Schiff base formation compared to other solvents, as well as high hydrogenation activity.