Unlike Molecules Research Articles

Excess acoustic and volumetric properties of polyethylene glycol 200 + methyl/ethyl methacrylate binary mixtures at different temperatures: An experimental and theoretical study

The excess and partial molar properties of binary liquid mixtures can be used to unveil the prevailing intermolecular interactions. The densities, ρ and speeds of sound, u for pure polyethylene glycol 200 (PEG 200), methyl methacrylate, ethyl methacrylate and their binaries (PEG 200 + methyl/ethyl methacrylate) have been measured over the entire composition range in the temperature range (293.15 to 323.15) K at 5 K intervals and at pressure, p = 100 kPa. The excess molar volume, excess isentropic compressibility, excess speed of sound, excess intermolecular free length, excess molar isentropic compressibility and excess acoustic impedance were evaluated using the experimental data. The partial and excess partial molar volumes/compressibilities of the components at each mole fraction and at infinite dilution have also been calculated. The results have been interpreted on the basis of prevailing intermolecular interactions as well as structural effects between like and unlike molecules. The results indicate the effect of the size of alkyl group on excess functions and interactions in these systems and the PEG-methacrylate interactions follow the order: methyl methacrylate > ethyl methacrylate. Scaled particle theory has also been used for the theoretical estimation of the speeds of sound and compared with experimental values. FT-IR spectra of pure PEG 200, methyl methacrylate, ethyl methacrylate and equimolar PEG 200 + methyl methacrylate/ethyl methacrylate mixtures were also recorded and analysed for better understanding of prevailing intermolecular interaction.

ULTRASONIC STUDY OF BINARY MIXTURES OF DHMOH AND ACETONE AT 288.15-313.15 K

The density (ρ), viscosity (η), and ultrasonic velocity (u) have been measured in the binary solutions of Dihydromyrcenol (DHMOH) with acetone at different temperatures: 288.15−313.15 K to understand the molecular interaction between these solutions. From the measured values, various acoustical parameters such as adiabatic compressibility (), acoustic impedance (Z), molecular free length (Lf), molar volume (Vm), free volume (Vf), Relative association (RA), internal pressure (i), and molar sound velocity (Um) were determined and correlated with concentration at different temperatures. The observed behaviour of these parameters concerning different compositions is discussed in terms of their molecular interactions between the unlike molecules of the binary solutions. The variations in measured and calculated values with concentration and temperature confirmed the presence of molecular interaction in the mixtures and were further confirmed by relative association.

Solubility enhancement of Cefpodoxime acid by aqueous solution of paracetamol through acoustical, polarizable continuum model and antimicrobial activity studies

The pharmacological response of an antibiotic depends on the optimum concentration of homogenous solution of the drug and deviation from this may result in major problems with generic and formulation developments of new chemical entities (NCE’s). Further, the introduction of additional new drugs with greater pharmacokinetic activity is limited because of their poor aqueous solubility. In the present work, an attempt has been made to explore the enhancement of solubility and hence the bioavailability or antimicrobial activity of a pharmaceutically significant drug Cefpodoxime acid (CA), a metabolite of third generation cephalosporin antibiotic cefpodoxime proxetil (CP), by the addition of aqueous paracetamol (PA) solution. Ultrasonic investigation has been carried out on the aqueous solutions of PA containing different concentration of CA at ambient and physiological temperatures and at pressure 101.3 kPa. The measured values of ultrasonic velocity, density and dynamic viscosity and the computed acoustical parameters at 303.15 K, 310.15 K and 313.15 K reveal significant intermolecular interactions between unlike drug molecules. The polarizable continuum model (PCM) study for the two drugs in four different solvents is applied in the calculation of free energy of solution (ΔGsol) which provide valid information regarding the mutual solubility of the two drugs and possible enhancement of bioavailability of CA in presence of PA. Antimicrobial activity of CA in the presence of PA in aqueous medium confirms the improvisation of solubility of CA drug. The data obtained through antimicrobial activity studies support the increased pharmacokinetic activity of CA in the presence of PA in aqueous environment.

Application of ERAS-model and PFP theory on excess and deviation properties for binary systems of ionic liquid + amine derivatives

Thermodynamics of mixtures includes ionic liquid 2-hydroxyethylammonium propionate [2-HEAPr] + 1-propanol, 3-amino-1-propanol [AP], 1-amino-2-propanol [MIPA], and monoethanolamine [MEA] were studied. Density ρ, speed of sound u, and refractive index nD of pure and mixtures were measured at T = (298.15, 308.15, 318.15) K. Excess molar volume VmE, excess partial molar volume Vm,iE, excess thermal expansion coefficient αE, isothermal coefficient of excess molar enthalpy (∂Hm∂P)T,x, deviations in isentropic compressibility Δ ks, and refractive index Δ nD were calculated and data correlated with Redlich-Kister polynomial relation. The Prigogine-Flory-Patterson (PFP) and Extended Real Associated Solution (ERAS) models were applied to analyze intramolecular and intermolecular interactions between like and unlike molecules. The accuracy of theoretical models were found to be in agreement with empirical results. Finally, the study confirmed the structures of the ILs using FT-IR and HNMR analysis.

Experimental analysis of volumetric, acoustic, viscometric and optical properties of water with 1-amino-2-propanol, 1,2-diaminopropane and 1,3-diaminopropane at T=298.15 -318.15 K: Molecular Modelling by Graph, PFP and IR spectroscopy investigations

BackgroundLiquid mixtures are used as a solvent in most of the natural systems and chemical processes. Therefore, the physicochemical properties of liquid mixtures at different compositions and at different temperatures have a significant role in the optimization of chemical processes. The present report involves the analysis of the thermophysical properties of water (1) and amines (2). MethodsDensity, ρ, dynamic viscosity, η, refractive index, nD, and speed of sound, u, data were measured for binary mixtures of water (1) and amines (1A2P (1-amino-2-propanol), 1,2-DAP (1,2-diaminopropane) and 1,3-DAP (1,3-diaminopropane) (2) at five different temperatures (T = 298.15 to 318.15 K) and at 0.1 MPa pressure. Based on experimental data, the excess molar volume, VmE, deviation in dynamic viscosity, Δη, excess Gibbs free energy of activation, G*E, deviation in refractive index, ΔnD, excess ultrasonic speed, uE, excess isentropic compressibility, KsE, deviation in free volume, ΔVf, excess available volume, VaE, and excess intermolecular free length, LfE, were calculated and these evaluated properties were fitted to Redlich-Kister polynomial (R.K.). The VmE data was analyzed by Prigogine-Flory-Patterson (PFP) theory. The dynamic viscosity, η, values were studied by different correlations. The VmE and Δη data were also analyzed by Graph theoretical approach (GTA). Raman and FT-IR spectroscopic studies give important information about the intermolecular interactions present between unlike molecules water (1) and amines (2) which is also recognized by GTA. Significant findingsThe value of VmE and KsE values were found negative over the whole composition range, and it follow the sequence as: 1,2-DAP > 1,3-DAP > 1A2P with water at equimolar composition. GTA and PFP well supported the VmE data. GTA studies help in investigating the specific intermolecular interactions between unlike components. Further, Graph theory studies predicted OH—–NH interaction is dominant interaction among all interactions which were also supported by Raman and FTIR spectroscopic studies.

PC-SAFT model and experimental explicating interaction of binary and ternary systems of 2-ethoxyethanol, methylcyclohexane and N-methylcyclohexylamine

In this project upon measurements of density ρ, speed of sound u, and refractive index nD, the excess molar volumes VmE, deviations in isentropic compressibility ΔKs, and in refractive index ΔnD, were calculated for the whole range of composition and temperatures of T = (298.15–308.15–318.15)K for binary and ternary systems of 2-ethoxyethanol, methylcyclohexane, and N-methylcyclohexylamine. Results correlated with the Redlich-Kister and Cibulka equations. The Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equation of state was used to predict density and there was a good agreement between calculated and experimental density. Intermolecular interactions between like and unlike molecules were discussed for the systems. It seems that study provides useful insights into the properties and behavior of these mixtures, which could have potential applications in various fields such as chemistry and materials science.

Study of non-ideality behavior in p-methyl acetophenone and 2-alkanol mixtures

In the current study, the density and viscosity of four binary fluids of p-methyl acetophenone with 2-propanol up to 2-hexanol systems at various temperatures (293.15 K, 303.15 K, 313.15 K, and 323.15 K) have been reported. Excess molar volume (VmE) and viscosity deviation (Δη) for the mixtures above were calculated. Negative values of VmE for all solutions were obtained. Also, values of viscosity deviations were negative for p-methyl acetophenone + 2-alkanol at all temperatures. Findings revealed that in the mixtures containing shorter alcohols, molecular interactions are stronger, and intermolecular forces reduce with the alcohol chain. Dipole-dipole interactions, the formation of hydrogen bonds between unlike molecules, and steric hindrances are the main intermolecular forces in the mixtures. Moreover, the PC-SAFT model was used to correlate the binary densities at different temperatures. Scientific papers have not yet reported the density and viscosity values of the mentioned fluids.

Density, Speed of Sound, and Viscosity of Binary Liquid Mixtures of 1-Butoxy-2-propanol with Diisopropylamine, Di-n-butylamine, and Tri-n-butylamine at 298.15, 303.15, and 308.15 K

In the present paper, binary mixtures of 1-butoxy-2-propanol with diisopropylamine, di-n-butylamine, and tri-n-butylamine were studied. To achieve that goal, the density (ρ), speed of sound (u), and viscosity (η) of the binary mixtures were measured over the entire composition range and temperature range from 298.15 to 308.15 K. With the help of experimentally measured data, various excess and deviation thermodynamic parameters were calculated and discussed in terms of intermolecular interactions among studied mixtures. Strong interactions among unlike molecules were confirmed by calculated parameters. Excess and deviation parameters were correlated with composition using the Redlich–Kister equation. Various semi-empirical relations for viscosity were also tested for the binary liquid mixtures.

Thermodynamic properties, viscosity modelling and FTIR studies of binary liquid mixtures of 2-isopropoxy ethanol with amines at different temperatures

Thermodynamic and spectral analysis for binary liquid mixtures of 2-isoporopxy ethanol with diisopropylamine, di-n-butylamine and tri-n-butylamine has been carried out in the present discussion. For this purpose, measurements of density, speed of sound and viscosity for binary mixtures were carried out over the entire composition range and at temperatures (298.15, 303.15 and 308.15) K. Various excess and deviation parameters were evaluated using the measured properties. Behaviour of calculated parameters was found quite sensitive towards the intermolecular interactions. Change in behaviour of these parameters with composition and temperature has been discussed in terms of intermolecular interactions due to physical and chemical effects among unlike molecules. Excess parameters were correlated with composition using Redlich-Kister polynomial. Existing theories and semi-empirical relations for viscosity were tested. Spectroscopic methods were also utilized to support the results obtained from above calculated parameters qualitatively.

Volumetric and Spectroscopic Studies of 1-ethyl-3-methylimidazolium Ethylsulfate/Propane-1-ol Binary Mixtures at Different Temperatures

Binary mixtures of an ionic liquid, 1-ethyl-3-methylimidazolium ethyl sulfate ([C2mim]C2H5SO4) with propane-1-ol were prepared over an entire composition range and density, dynamic viscosity, and refractive index at T = 293.15 to T = 333.15 K at atmospheric pressure were measured. The excess properties for the binary systems were determined and successfully fitted to a polynomial equation of the Redlich–Kister type. The variation of excess thermodynamic parameters predicted stronger intermolecular interactions and effective packing in the binary system compared to components. Thermodynamic activation parameters were also calculated from the Eyring equation, which varied with the concentration of [C2mim]C2H5SO4. The variation of these parameters also suggested the presence of strong heteromolecular interactions. The near-infrared (NIR) spectroscopic measurements were conducted in the temperature range from 293.15 K to 333.15 K and spectral variations were analyzed. The NIR data were further evaluated using principal component analysis (PCA) and two-dimensional (2D) correlation spectroscopy. The predicted molecular-level interactions mainly come from different types of HBs formed between unlike molecules in the binary system. The binary mixture may open up a plethora of possible uses due to its novel, distinctive molecular-level interactions, and favorable thermodynamic properties.

New Prediction Model of Surface and Interfacial Energies Based on COSMO-UCE.

The nature and strength of intermolecular and surface forces are the key factors that influence the solvation, adhesion and wetting phenomena. The universal cohesive energy prediction equation based on conductor-like screening model (COSMO-UCE) was extended from like molecules (pure liquids) to unlike molecules (dissimilar liquids). A new molecular-thermodynamic model of interfacial tension (IFT) for liquid-liquid and solid-liquid systems was developed in this work, which can predict the surface free energy of solid materials and interfacial energy directly through cohesive energy calculations based on COSMO-UCE. The applications of this model in prediction of IFT for water-organic, solid (n-hexatriacontane, polytetrafluoroethylene (PTFE) and octadecyl-amine monolayer)-liquid systems have been verified extensively with successful results; which indicates that this is a straightforward and reliable model of surface and interfacial energies through predicting intermolecular interactions based on merely molecular structure (profiles of surface segment charge density), the dimensionless wetting coefficient RA/C can characterize the wetting behavior (poor adhesive (non-wetting), wetting, spreading) of liquids on the surface of solid materials very well.

Thermodynamics of liquid and fluid mixtures from the kinetic Monte Carlo viewpoint.

In this study a binary mixture is modelled in a uniform simulation cell at various temperatures using an extended version of the grand canonical kinetic Monte Carlo (GC-kMC) method. The main goal of this study is to consider the thermodynamic properties of binary liquids, gases, and gas-liquid mixtures from a more general point of view than that applied to the particular case of vapour-liquid equilibrium when the pressure and partial chemical potentials in coexisting phases are the same. Particular attention is paid to thermodynamic functions such as chemical potentials, Gibbs free energy and entropy. For the pair potential of unlike molecules a more universal scheme is proposed in comparison with the Lorentz-Berthelot combining rule. The approach is tested on an Ar-Kr mixture in a wide range of temperatures. In all cases, the obtained values of chemical potentials, pressure and internal energy for the entire set of component densities and temperature fully satisfy the Gibbs-Duhem equation with a high degree of accuracy. For the case of vapour-liquid equilibrium, the developed approach made it possible to reproduce the experimental pressure-composition diagrams with the highest accuracy ever achieved in the literature. Despite the fact that the Ar-Kr mixture, according to Raoult's law, is close to an ideal system, it was found that the partial pressures in the liquid phase or in a dense supercritical gas mixture are non-linear functions of the composition, and the partial pressure of the heavier component (Kr) can even be negative.

Role of Nanoparticles in Acoustical and Dielectric Measurements using Binary Non-Polar Fluid

In this work, the experimental values of dielectric constant and acoustical parameters for binary mixture (benzene + diethylamine) and hybrid CuO nanofluid (CuO + diethylamine + benzene) were studied for various molar fraction from 0.01 to 0.06 M with different temperatures ranging from 298 to 318 K. Molecular interaction depends on the concentration, inclusion of CuO nanoparticles and temperature. FTIR analyses also revealed that despite the rise in temperature, no bond breakdown between the molecules is found. The results demonstrate that the weak interaction due to van der Waals forces exist between the unlike molecules due to dipole-induced dipole interactions.

The study of intermolecular interactions in [Bmim][PF6] + 1-octyl-2-pyrrolidone binary mixtures from volumetric, acoustic, optical and spectroscopic measurements

Under 101.3 kPa pressure, the densities, speeds of sound, and refractive indices of [Bmim][PF6] + 1-octyl-2-pyrrolidone mixtures were determined experimentally over the whole composition range and at 303.15 to 323.15 K. The excess molar volumes (VmE), excess values of partial molar volumes (V¯mE), partial molar volumes at infinite dilution (V¯mE,∞), excess values of isentropic compressibility (KsE), speeds of sound (uE) and isobaric thermal expansion coefficient (αPE) have been calculated using these experimental data. The Redlich–Kister polynomial equation has been adequately fitted to the computed data. Intermolecular interactions between like and unlike molecules have been interpreted using the experimental and computed data. The Prigogine–Flory–Patterson theory of excess molar volume and IR spectroscopic studies supported the conclusions drawn from volumetric and acoustic properties.

Experimental and theoretical investigation of thermodynamic properties and hydrogen bonding strength of binary mixtures: Insights from FTIR and DFT calculation

• Volumetric, acoustic and derived properties were reported for seven binary systems. • Influence of geometrical and hydrogen bonding on studied properties were reported. • FTIR analysis was carried out to confirm the hydrogen bond formation. • DFT calculations were performed, the resultant data is good agreement with experimental data. Present study reveals that experimental measurements of density ( ρ ), sound speed ( u ) of binary mixtures of o -toluidine with 1-propanol, 1-butanol, 1-pentanol, 1-hexanol, 1-heptanol, 1-octanol and 1-nonanol were measured at T =298.15 K and P =0.1 MPa. The ρ and u data was intern used to calculate the various thermodynamic properties. The attained results were used to understand the nature of interaction between like and unlike molecules in terms of hydrogen bonding, dipole-dipole interactions and packing efficiency. The derived excess properties were fitted into polynomial equations. The resultant V E magnitude gradually changes from negative sign to positive sign through the formation of ‘S’ type curve. The formation of hydrogen bonding and strength between the component molecules were confirmed by FTIR spectroscopy and DFT computational study, respectively. The results of the experimental and derived thermodynamic properties are good agreement with DFT theoretical model. Relation between the excess volumes of o-toluidine with chain length of 1-alkanoles: A graphical representation at 298.15 K.

Volumetric, Optical, and Spectroscopic Study of Molecular Interactions for Binary Liquid Mixtures of Gamma-Valerolactone with 2-Alkoxyethanols

Physical parameters such as densities, ρ, and refractive indices, nD, of pure gamma-valerolactone/2-alkoxyethanols and their binaries have been determined over the whole composition range at different temperatures (298.15, 303.15, 308.15, and 313.15 K) and pressure = 0.1 MPa. From the experimental results, excess properties such as excess molar volumes, VmE, deviations in refractive indices, ΔϕnD, and deviations in molar refractions, ΔϕRM, have been calculated. The predicted data were fitted to the Redlich–Kister-type polynomial equation to derive the binary interaction parameters and recognize standard deviations between experimental and calculated values of the liquid solutions. Furthermore, the partial molar volumes, V¯m,1, V¯m,2, and excess partial molar volumes, V¯m,1E, V¯m,2E, were also computed. The Prigogine–Flory–Patterson theory and Graph theory were employed to correlate experimental VmE values. The departure of real mixtures from ideal behavior was interpreted in terms of strength and nature of molecular interactions. Furthermore, Fourier-transform infrared spectroscopy studies of the investigated solution along with pure components were also reported to obtain a better insight into intermolecular interactions between unlike molecules. In our study, positive values of VmE and negative values of ΔϕnD were observed, which suggests weak dispersion forces between dissimilar molecules.

Scrutiny of physico‐chemical properties of extractant‐diluent phase: Keystone of extraction systems

AbstractSolvent extraction is one of the hydro metallurgical techniques adopted due to its ease for efficient separation of metal ions. The separation and extraction of metals are enabled using privileged metal distribution between the aqueous and organic phase. Commercially available solvent extractants and recently the designer solvents like ionic liquids have gained adequate attention in the area of separation science for the retrieval of different metal ions. Diluents play an important role by ensuring the improved hydrodynamics of the extraction system. The physico‐chemical characteristics of the organic phase solution need to be scrutinized thoroughly in order to optimize the extraction conditions. Investigation on the interaction between extractant and diluent at molecular level is vital for the assessment of extraction efficiency. Density, viscosity, dielectric constant, refractive index, conductivity, and acoustic properties provide evidence on the molecular organizations between these unlike molecules. The aim of this review is to project on the importance of physical, chemical, and thermodynamic properties for fabricating an efficient combination of extractants‐diluents to achieve maximum extraction output.

Dynamics of type V menthol-thymol deep eutectic solvents: Do they reveal non-ideality?

We have established a comprehensive study of the molecular dynamics of the menthol-thymol mixture, the prototype of the new class of type V deep eutectic solvents. Dielectric spectroscopy and differential scanning calorimetry were combined to assess the dipolar relaxation and glassy dynamics over an extended range of timescales (10-6 – 102 s) and for eleven different compositions including the two pure constituents. Positive deviations from ideal mixing approximation were demonstrated for both the solvent dielectric strength and the glass transition. They support the idea that preferential H-bond interactions between unlike molecules induce structural rearrangements in the DES mixtures. Excellent glassforming capability of the DES mixtures was demonstrated for a broad range of compositions (xThymol = 0.4–0.7). In this case, the dipolar dynamics could be assessed from the normal liquid to the deeply supercooled state. Many salient parameters of the relaxation functions, including fragility, non-Debye character and rotation-translation decoupling point to the development of dynamic heterogeneities.

Electrostatic polyelectrolyte complexes: thermodynamic assembly properties

Polysaccharides are common ingredients in medical, technological and industrial products. In many formulations, the oppositely charged polysaccharides (two major biopolymers) are used simultaneously. Understanding their interactions can help control physical properties and stability of formulating. The excess conductivity, σE, and excess energy of activation (ΔΕσ)Ε of electrical conductivity have been investigated by using electrical conductivities measurements for solution of Sodium carboxymethylcellulose (CMC) + solution of chitosan (CH) mixtures over the entire range of volumes fractions X1 of CMC for three different temperatures. This system exhibited a very large negative value of σE and very large positive values (ΔΕσ)Ε due to increased hydrogen bonding interactions and correlation length between unlike molecules in the two critical regions, and very large differences between the pure components. The activations parameters ΔΗσ and ΔSσ have been also calculated, and show that the two critical regions have an important effect on the electrical conductivity properties. In this study, (ΔHσ)ϕ1, (ΔHσ)c ϕ1, (ΔHσ)ϕ2, (ΔHσ)c ϕ2, Xϕ1, Xϕ1, XC ϕ1 and XC ϕ2 were identified.

Thermodynamic Excess Properties of Binary Mixtures of Acetyl acetone and Ethyl Acetate

The density (ρ), viscosity (η), surface tension (σ), and refractive index (R) of binary mixtures of acetylacetone (acac) with ethyl acetate (Etac) were determined at atmospheric pressure over the entire composition range of mixtures. The values of mixtures and pure liquids have been used to calculate the excess volume (VE), deviation in viscosity (Δη), and deviation in surface tension. The computed results were fitted to the Redlich–Kister polynomial equation. The excess molar volume (VE) for the binary system investigated exhibits a positive deviation at 298.15 K, and the positive deviation at 303.15 K becomes too negative as the mole fraction Xacac increases. The deviation in viscosity (Δη) and deviation in surface tension (Δσ) show negative values from the ideality at 303.15 The negative magnitude suggests the presence of strong intermolecular interactions between unlike molecules in the binary mixtures.