Water Binary Solvent Research Articles

Effect of polymorphism on thermodynamic properties of cefamandole nafate

For solid state active pharmaceutical ingredient (API), it might be able to exist in different crystal structures, which is well known as polymorphism. Different polymorphs of the same pharmaceutical might exhibit different physicochemical properties. In this work, the effect of polymorphism on thermodynamic properties of cefamandole nafate was investigated in detail. Two new polymorphic forms of cefamandole nafate were successfully prepared and characterized by powder X-ray diffraction (PXRD) and differential scanning calorimetry (DSC). It was found that form IV has higher melting temperature than form V. By using dynamic method, the solid–liquid equilibrium of cefamandole nafate form IV and form V were experimentally determined and compared in (ethanol + water) binary solvent mixtures over the temperature ranges of (278.15–308.15) K. The effects of solvent and temperature on the solubility of these two forms were discussed. It was found that the solubility data of cefamandole nafate form V are higher than those of form IV. The experimental solubility data were correlated by the modified Apelblat equation, the CNIBS/R–K equation and the Jouyban–Acree model, respectively. Furthermore, the dissolution thermodynamic properties, including the enthalpy, entropy and Gibbs free energy change, were also calculated. Combining the results of DSC analysis, the solubility and the thermodynamic properties, it can be concluded that the thermodynamic properties of the two forms are apparently different.

Thermodynamic studies on metal complexes of Pb2+, Zn2+, Sr2+ and Mg2+ with 2-amino pyrimidine in water and water-acetonitrile binary solvent systems at 298.15 K, 308.15 K and 318.15 K by conductometric method

Thermodynamic studies on metal complexes of Pb2+, Zn2+, Sr2+ and Mg2+ with 2-amino pyrimidine in water and water-acetonitrile binary solvent systems at 298.15 K, 308.15 K and 318.15 K by conductometric method

The electrospinning behavior of poly(vinyl alcohol) in DMSO–water binary solvent mixtures

The fiber diameters obtained from PVA–DMSO–water ternary system are the result of the interplay between the solvent–solvent and solvent–polymer interactions.

Determination and correlation of solubility and solution thermodynamics of oxiracetam in three (alcohol + water) binary solvents

In this paper, we proposed a static analysis method to experimentally determine the (solid+liquid) equilibrium of racemic oxiracetam in (methanol+water), (ethanol+water) and (isopropanol+water) binary solvents with alcohol mole fraction ranging from 0.30 to 0.90 at atmosphere pressure (p=0.1MPa). For the experiments, the temperatures range from (283.15 to 308.15)K. The results showed that the solubility of oxiracetam increased with the increasing temperature, while decreased with the increasing organic solvent fraction in all three tested binary solvent systems. The modified Apelblat model, the CNIBS/Redlich–Kister model, the combined version of Jouyban–Acree model and the NRTL model were employed to correlate the measured solubility values, respectively. Additionally, some of the thermodynamic properties which can help to evaluate its dissolution behavior were obtained based on the NRTL model.

Polypyrrole–vinyl aniline modified cyclohexanone formaldehyde resin copolymers: a comparative study of the resin preparation

ABSTRACTIn this study, the synthesis of polypyrrole‐b‐vinyl aniline modified cyclohexanone formaldehyde resin (PPy‐b‐CFVAnR) block copolymers by a combination of condensation polymerization and chemical oxidative polymerization processes was examined. First, a cyclohexanone formaldehyde resin containing vinyl aniline units [4‐ vinyl aniline modified cyclşohexanone formaldehyde resin (CFVAnR)] was prepared by a direct condensation reaction of 4‐vinyl aniline and cyclohexanone with formaldehyde in an in situ modification reaction. CFVAnR and pyrrole (Py) were then used with a conventional method of in situ chemical oxidative polymerization. The reactions were carried out with heat‐activated potassium persulfate salt in the presence of p‐toluene sulfonic acid in a dimethyl sulfoxide–water binary solvent system; this led to the formation of desired block copolymers. The effects of the oxidant–monomer molar ratio, dopant existence, addition order of the reactants, and reaction temperature on the yield, conductivity, and morphology of the resulting products were investigated. PPy‐b‐CFVAnR copolymers prepared with a resin‐to‐Py molar ratio of 1:40 showed conductivity in the range 3.7 × 10−1 to 3.8 × 10−2 S/cm. Oxidant‐to‐Py molar ratios of 0.5 and 1.0 were proposed to be the optimum stoichiometries for higher conductivity and yield, respectively, of the copolymer. The morphology of the copolymer (PPy‐b‐CFVAnR) was investigated with environmental scanning electron microscopy analyses. The results indicate that the surface of the copolymer was composed of well‐distributed nanospheres with average particle diameters of 60–85 nm. Also, the synthesized PPy‐b‐CFVAnR had a higher thermal stability than the pure CFVAnR. The chemical composition and structure of the PPy‐b‐CFVAnR copolymers were characterized by Fourier transform infrared spectroscopy and measurement. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 132, 42841.

A Study of the Solvation Structure of L-Leucine in Alcohol-Water Binary Solvents through Molecular Dynamics Simulations and FTIR and NMR Spectroscopy.

The solvation structures of l-leucine (Leu) in aliphatic-alcohol-water and fluorinated-alcohol-water solvents are elucidated for various alcohol contents by using molecular dynamics (MD) simulations and IR, and (1) H and (13) C NMR spectroscopy. The aliphatic alcohols included methanol, ethanol, and 2-propanol, whereas the fluorinated alcohols were 2,2,2-trifluoroethanol and 1,1,1,3,3,3-hexafluoro-2-propanol. The MD results show that the hydrophobic alkyl moiety of Leu is surrounded by the alkyl or fluoroalkyl groups of the alcohol molecules. In particular, TFE and HFIP significantly solvate the alkyl group of Leu. IR spectra reveal that the Leu C-H stretching vibration blueshifts in fluorinated alcohol solutions with increasing alcohol content, whereas the vibration redshifts in aliphatic alcohol solutions. When the C-H stretching vibration blueshifts in the fluorinated alcohol solutions, the hydrogen and carbon atoms of the Leu alkyl group are magnetically shielded. Consequently, TFE and HFIP molecules may solvate the Leu alkyl group through the blue-shifting hydrogen bonds.

Electrochemical preparation of a molecularly imprinted polypyrrole modified pencil graphite electrode for the determination of phenothiazine in model and real biological samples

A sensitive electrochemical sensor for determination of phenothiazine (PTZ) was introduced based on molecularly imprinted polymer (MIP) film. A computational study was performed to evaluate the template–monomer geometry and interaction energy in the prepolymerization mixture. The electrode was prepared during electropolymerization of pyrrole (Py) on a pencil graphite electrode (PGE) by cyclic voltammetry (CV) technique. The quantitative measurements were performed using differential pulse voltammetry (DPV) in Britton–Robinson (BR) buffer solutions using 60% (v/v) acetonitrile–water (ACN/H2O) binary solvent. The effect of important parameters like pH, monomer concentration, number of cycles, etc on the efficiency of MIP electrode was optimized and the calibration curve was plotted at optimal conditions. Two dynamic linear ranges of 1–300µmolL−1 and 0.5–10mmolL−1 were observed. The detection limit (based on S/N=3) of PTZ was obtained 3×10−7molL−1. The MIP/PGE has been successfully applied as a selective sensor for fast and accurate determination of PTZ in some model and real biological samples.

Measurement, correlation of the solubility and solution thermodynamics of 2-cyanoguanidine in (methanol + water) binary solvent systems from T = (283.15 to 343.15) K

The solubility of 2-cyanoguanidine in binary solvent mixtures (water+methanol) were experimentally measured from T=(283.15 to 343.15)K by the static method. The mass fraction of methanol wt is 0.100, 0.200, 0.300, 0.400, 0.500, and 0.600. The experimental results show that values obtained increased with temperature increasing from (283.15 to 343.15)K. Good agreement was found between the experiments and calculations by the modified Apelblat equation, fifth-order polynomial equation and semi-empirical Buchowski–Ksiazczak λh equation. Our experiment values were proven to give best agreement with the modified Apelblat equation. The dissolution enthalpy ΔdisH (24119.2 to 38593.9J·mol−1), the dissolution entropy ΔdisS (48.4083 to 90.7083J·mol−1·K−1) and the molar Gibbs free energy ΔdisG (7507.9 to 12909.8J·mol−1) were calculated on the basis of the modified Apelblat equation analysis. The solubility and dissolution properties of 2-cyanoguanidine in (water+methanol) binary solvent mixtures obtained in this paper will provide essential support for 2-cyanoguanidine industrial design and further theoretical studies.

Preferential Solvation of Ketoprofen in Some Co-solvent Binary Mixtures

The preferential solvation parameters of ketoprofen (KTP) in ethanol (EtOH) + water and propylene glycol (PG) + water binary solvent mixtures were obtained from their thermodynamic properties by means of the inverse Kirkwood–Buff integrals (IKBI) and quasi-lattice quasi-chemical methods. According to the IKBI method, it is found that KTP is very sensitive to specific solvation effects, so the preferential solvation parameter by co-solvents, δx 1,3, is negative in the water-rich mixtures of both binary systems but positive in the other compositions at temperatures of 293.15, 303.15 and 313.15 K. From this it can be assumed that, in water-rich mixtures, hydrophobic hydration around the aromatic rings and the methyl group, present in the drug, plays a relevant role in the solvation. The bigger amount of drug solvation by the co-solvent in mixtures of similar solvent proportions and in co-solvent-rich mixtures could be due mainly to polarity effects. Moreover, in these mixtures the solute will be acting as a Lewis acid with the co-solvent molecules, because they are more basic than water.

Solubilities of 1,1′-[1,2-Ethanediylbis(oxy-1,2-ethanediyl)]bis-[3-methyl-1H-imidazolium-1-yl] Dihexafluorophosphate in Water, Methanol, Ethanol, Dimethylformamide, Dimethyl Sulfoxide, and (Acetone + Water) Binary Solvent Mixtures

The chemical structure of a new gemini dicationic imidazolium ionic liquid, 1,1′-[1,2-ethanediylbis(oxy-1,2-ethanediyl)]bis-[3-methyl-1H-imidazolium-1-yl] dihexafluorophosphate ([C6O2(mim)2][PF6]2), was established by 1HNMR. The thermal stability of [C6O2(mim)2][PF6]2 was studied with differential scanning calorimetry and thermogravimetric analyses. With the use of the analytical stirred-flask method at atmospheric pressure, the solubilities of [C6O2(mim)2][PF6]2 in water, methanol, ethanol, dimethylformamide, dimethyl sulfoxide, and (acetone + water) binary solvent mixtures were measured from (283.00 to 323.00) K. The experimental data was correlated with the modified Apelblat equation.

Probe Dependent Solvation Dynamics Study in a Microscopically Immiscible Dimethyl Sulfoxide-Glycerol Binary Solvent.

Excited state dipole solvation of three coumarin dyes with different hydrophobicities was studied in DMSO-glycerol binary solvent. The solvation times obtained from the three dyes are remarkably different. The highly hydrophilic dye coumarin 343 (C343) exhibits the slowest solvation time (>12 ns) among all the dyes we used. This is in contrast to the most hydrophobic dye coumarin 153 (C153), where the solvated state is reached just within ∼104 ps. However, the moderately hydrophobic dye coumarin 480 (C480) demonstrates an intermediate (∼396 ps) solvation time. Unprecedented slowdown of solvation time of C343 is probably due to the slow diffusion of solvent molecules in the glycerol-rich first solvation shell followed by hydrogen bond rearrangements around the solute dipole. On the other hand, fast solvation of hydrophobic dye C153 is most likely caused by the fast reorganization dynamics of hydrophobic -CH3 groups of DMSO or the carbon backbone of the glycerol molecule around the solute dipole. Interestingly, a remarkable probe dependency in solvation dynamics was not observed in the case of DMSO-water binary solvent or in a neat solvent isopropanol. Probe dependent solvation in a DMSO-glycerol mixture is attributed to the microscopic phase segregation and different locations of coumarin dyes within this binary solvent.

Thermodynamic studies on metal complexes of Co2+, Ni2+, Cu2+ and Cd2+ with 8-hydroxy 5-quinolinesulfonic acid in water, methanol and water-methanol binary solvent systems at 303.15 K, 313.15 K and 323.15 K by conductometric method

Thermodynamic studies on metal complexes of Co2+, Ni2+, Cu2+ and Cd2+ with 8-hydroxy 5-quinolinesulfonic acid in water, methanol and water-methanol binary solvent systems at 303.15 K, 313.15 K and 323.15 K by conductometric method

Thermodynamic studies on metal complexes of Co2+, Ni2+, Cu2+ and Cd2+ with 8-hydroxy 5-quinolinesulfonic acid in water, methanol and water-methanol binary solvent systems at 303.15 K, 313.15 K and 323.15 K by conductometric method

Thermodynamic studies on metal complexes of Co2+, Ni2+, Cu2+ and Cd2+ with 8-hydroxy 5-quinolinesulfonic acid in water, methanol and water-methanol binary solvent systems at 303.15 K, 313.15 K and 323.15 K by conductometric method

Characterization and Structure Analysis of Cefodizime Sodium Solvates Crystallized from Water and Ethanol Binary Solvent Mixtures

Only a few studies of heterosolvate are reported in the literature. In this article, heterosolvates of cefodizime sodium were prepared in water/ethanol binary solvent mixtures and characterized. Through thermal analysis and composition determination, we deduced that both water and ethanol molecules participated in the forming of crystal lattice. The general chemical name of heterosolvates may be defined as cefodizime sesquihydrate sesquiethanolate. Then, the studies on infrared ATR and Raman spectroscopy provided a strong evidence of intermolecular hydrogen bonds. Further, the crystal structure of solvates was analyzed by the powder X-ray diffraction data. The results indicated that the structure differences between solvate and raw material were mainly caused by the solvent effect, leading to forming solvation through intermolecular hydrogen bonding.

Continuous preparation of zein colloidal particles by Flash NanoPrecipitation (FNP)

This study utilized a facile and continuous technique termed Flash NanoPrecipitation (FNP) to produce zein colloidal particles (ZP) without or with sodium caseinate (NaCas) as the stabilizer. The colloidal particle preparations were performed through a self-made Confined Impinge Jet (CIJ) mixer, and compared with traditional antisolvent processes. The influences of FNP processing parameters on the size of zein colloid particles, including flow rates, outlet configurations, solute concentrations and ethanol concentrations, were extensively discussed. The influences of viscous properties, buffering capacity and self-assembly of zein or NaCas on particle size and size distributions were also discussed. Particle sizes of ZP produced by the FNP technique are below 350nm, even at high zein concentrations (2.5–7.5% w/v). Solvent systems with different ethanol concentrations yielded zein colloid particles with similar size, showing an attractive feature for industrial applications and encapsulating actives with different solubility in ethanol–water binary solvent. This study opens a promising pathway for continuously producing ZP via the FNP procedure.

Solubility of glycine in binary system of ethanol + water solvent mixtures: Experimental data and thermodynamic modeling

The solubility of glycine in different compositions of ethanol–water binary solvent mixtures was measured over the temperature range of (278.15–328.15) K at intervals of 5.00K by employing an analytical stirred-flask method. The solubility data were fitted using the modified Apelblat equation and the combined nearly ideal binary solvent/Redlich–Kister (CNIBS/R–K) equation, respectively. The modified Apelblat equation was found to regress the solubility data much better than the other two equations. The Van’t Hoff equation was used to calculate the apparent molar enthalpy and the apparent molar entropy of solution in the binary mixture solvent system, the dissolving process was endothermic and entropy-driving. The experiment results and correlation models could be used as essential data in the purification of glycine.

Thermosolvatochromism of Nitrospiropyran and Merocyanine Free and Bound to Cyclodextrin

The thermosolvatochromism of nitrospiropyran free and bound to cyclodextrin was studied in dimethylsulfoxide (DMSO)-water binary solvent systems. Spiropyran was interconverted to merocyanine by heating the sample to 55 °C. The merocyanine (MC) was converted back to spiropyran (SP) either by cooling the sample to room temperature or irradiating the sample with a visible light emitting diode. Steady state absorption spectra of SP and MC samples in the free state and bound to cyclodextrin were obtained in several DMSO-water binary solutions. Emission spectra of MC both free and cyclodextrin-bound were also acquired. Blue-shifted absorption and emission spectra of the studied molecules with increasing solvent polarity suggest that the dipole moments of free and bound merocyanines are higher in the ground state compared to the excited state. Merocyanine dipole moments in the ground and excited states were determined using thermosolvatochromism measurements and the Lippert-Mataga, Bakhshiev, and Kawski-Chamma-Viallet polarity functions. A large change in the dipole moment (ca. 16 D) of the merocyanine in aqueous DMSO was obtained upon electronic excitation, S(1) ← S(0). Analysis of the merocyanine Stokes' shifts as a function of solvent polarity indicates that both general solvent effects and specific solvent effects are present in all systems studied. These findings reveal that merocyanine could be utilized as a polarity sensor for DMSO-water binary solutions.

Effects of intramolecular hydrogen bonding and solvent composition on acidity of some dihydroxy-thioxanthone derivatives in methanol–water binary solvents

► The acidity constant of some new dihydroxy thioxanthone derivatives was determined. ► The effect of inter and intra hydrogen bonding on acidity constants were explained. ► The effect of solvent composition (methanol–water) was also investigated. ► 1,3-Dihydroxy derivative unexpectably showed one ionization step. ► The findings of this article are of especial importance for analytical applications. The acidity constant of four recently synthesized dihydroxy-thioxanthone derivatives (i.e., 1,4-dihydroxy; A1, 3-methyl-1,4-dihydroxy; A2, 2,3-dihydroxy; A3 and 1,3-dihydroxy; A4) in methanol–water binary mixed solvents were determined by multivariate analysis of spectrophotometric-pH-metric data. The solutes A1, A2 and A3 exhibited two ionization steps whereas one ionization step was observed for A4, attributed to the strong intramolecular hydrogen-bonding formed between the hydrogen of 1-hydroxy and its neighbor carbonyl group. The effects of molecular structure on the acid–base behavior of solutes were discussed mainly based on intra and intermolecular hydrogen bonding. The effects of solvent composition on the acidity constant were explained through linear solvation free energy relationship (LSFER) study. It was found that each ionization step of each solute can be modeled by different reduced models of Kamlet–Taft, proposing that they behave differently. Finally, the effect of solvent composition on the calculated pure absorption spectra of the different acid–base species was investigated.

Aggregation of imidazolium based ionic liquids in binary methanol–water solvents: A linear solvation free energy relationship study

Aggregation behavior of an imidazolium based ionic liquid (IL), namely 1-dodecyl-3-methylimidazolium chloride [C 12mim][Cl] and a surfactant with the same aliphatic chain, dodecyl trimethylammonium chloride (DTAC), are studied and compared in different mole fractions of methanol–water binary solvents using conductometry. From the conductivity data, micellar parameters including critical micelle concentration (CMC), degree of counter ion dissociation (α) and Gibbs free energy of micellization (ΔG°mic) for both species were calculated as a function of methanol mole fraction. It was found that similar to the surfactant DTAC, the ionic liquid [C 12mim][Cl] forms micellar aggregation in pure water and methanol as well as in their binary mixtures. The CMC values for both compounds were increased up to a methanol mole fraction of 0.5 and then decreased at higher mole fractions. This was attributed to the preferential solvation and formation of methanol–water cluster in binary mixed solvents. The changes in CMC of [C 12mim][Cl] and DTAC as a function of methanol mole fraction were also described by changing in solvatochromic properties of solvents through linear solvation free energy relationship (LSFER) study. A linear relationship between log (CMC) and two solvatochromic Kamlet-Taff parameters including polarity/polarizability (π*) and hydrogen-bond basicity (β) was observed.

Determination of nicotine in tobacco with second-order spectra data of charge-transfer complex in ethanol–water binary solvents processed by parallel factor analysis

A new spectrophotometric method for the determination of nicotine in mixtures without pre-separation has been proposed. Nicotine could react with 2,4-dinitrophenol through a charge-transfer reaction to form a colored complex. The second-order data from the visible absorption spectra of the complex in a series of ethanol–water binary solvents with various water volume fractions could be expressed as the combination of two bilinear data matrices. With the bilinear model, the second-order spectra data of mixtures containing nicotine and other interferents could be analysed by using second-order calibration algorithms, and the determination of nicotine in the mixtures could be achieved. The algorithm used here was parallel factor analysis. The method has been successfully used to determine nicotine in tobacco samples with satisfactory results.