Strong Solute-solvent Interactions Research Articles

The salinity management of saline soil by ultrasonic characterization of Arginine with saline salt

The ultrasonic and thermodynamic study of liquids is important probe to understand intermolecular behavior of liquid system. Nowadays, soil salinity is serious issue in agriculture sector. Salinity affects the productivity and sustainability of agriculture. We have to think on soil salinity due to high population density, multidimensional climate and globalization. Production of food mainly green vegetables is vital. Amino acid improves mineral uptake and growth of plants. The main aspect of present study is to counteract the soil salinity problem. Arginine plays vital role in physiological processes of plants and effective under the stress condition. L-Arg is a precursor to polyamines. Raising arginine concentrations greatly improved bean development, enhanced fresh and dry mass growth, and raised growth parameters. L-Arg had a far greater impact on the crop. L-Arg had a very positive impact on plant. L-Arginine supplementation is advantageous for maize plant growth and development, particularly under the stressful condition. The effect of arginine on saline salt (NaCl) over the four different temperatures shows strong solute–solvent interaction between molecules. The molecular interaction is stronger at higher concentrations of saline salts. Therefore arginine is effective under the salt stress condition.

Physico-chemical and biological studies of some Copper(I) complexes in binary mixtures of polar solvents at variable temperature

Physico-chemical parameters like, conductance, viscosity, volumetric, thermo acoustic, thermodynamics of viscous flow, were thoroughly evaluated from the experimentally obtained data of specific conductance, viscosity, density, and ultrasonic velocity. These parameters were evaluated for Copper(I) nitrate complexes in binary mixtures of polar solvents, Dimethylsulfoxide (DMSO), Pyridine (Py), and Nitromethane (NM) at variable temperatures (298 K-318 K) and at 1 atmospheric pressure. Ionic B values were evaluated using Jones-Dole equation to determine the extent of molecular interactions. From the measured viscosity, using Erying's transition state theory, the thermodynamic parameters of viscous flow such as Gibb's energy of activation (ΔG)*, enthalpy of activation (ΔH)*, and entropy of activation (ΔS)* were also evaluated. The thermodynamic function showed the values of ΔH* as positive for all electrolytes and ΔS* as negative. From the conductance data, the Energy of Activation (Ea) and ionic walden product (λoη) were evaluated and tabulated. Further, in order to discover more about the solute–solvent interactions, limiting apparent molar volume (ɸ˚v), Masson’s coefficient (Sv), partial molar expansibilities (ɸ˚E) and Hepler’s constant were also calculated from density and velocity data at variable temperatures. Limiting apparent molar volume ɸ˚v values for both binary mixtures were positive, indicating strong solute–solvent interactions. Thermo acoustical parameters like internal pressure (πi), Rao’s constant (Rm) and Wada’s constant (W) were also evaluated. The results from all the studies showed the possible solvation in DMSO + Py solvent mixture as compared to DMSO + NM system. Further, the copper(I) nitrate complexes with bioactive ligands were tested against Gram positive strains (S mutans MTCC 497 and S aureus MTCC 7443), Gram negative strains (S enteric MTCC 164 and P aeruginosa MTCC 4673) and fungus (A parasiticus NCIM 696, Candida albicans MTCC 183 and A niger NCIM 501). The zone of inhibition was also measured for the complexes. All the complexes with potential bioactive ligand containing Nitrogen and Sulphur atom bonded to central copper atom showed antibacterial and antifungal activity.

Volumetric and Ultrasonic Studies of PEG200, PEG400, and Ethanol–Chlorhexidine Solutions at Various Temperatures

The density and sound velocity values for polyethylene glycols (PEGs) with molecular weights 200 and 400 in ethanol–chlorhexidine solutions were investigated at different temperatures, 288.15 to 318.15 K, and concentrations of 0.001, 0.003, and 0.005 mol·kg–1. The apparent molar properties and partial molar properties of ethanol–chlorhexidine solutions containing PEGs (200/400) were obtained using this experimental data. The thermodynamic parameters, such as apparent molar volume, (Vϕ), and limiting partial molar volume, (Vϕ0), are determined using density values obtained experimentally, whereas acoustic properties, such as apparent molar isentropic compression, (Kϕ, s), and limiting partial molar isentropic compression, (Kϕ, s0), are calculated using sound velocity values. These thermodynamic apparent and partial molar properties imply the occurrence of strong solute–solvent interactions. The temperature-dependent partial molar volume and partial molar expansibilities (Eϕ0) were also calculated. The presence of strong solute–solvent interactions has been discovered in the liquid mixtures.

Thermodynamic characterization of interactions between environmental contaminants and room temperature ionic liquids using static headspace gas chromatography with vacuum ultraviolet detection

Understanding the thermodynamic interactions between an analyte and the sample phase is of paramount importance when choosing a co-solvent in headspace analysis. A sample phase – gas phase equilibrium partition coefficient (Kp) is used fundamentally to describe the distribution of the analyte between the two phases. Kp determinations by headspace gas chromatography (HS-GC) were acquired by two methods: vapor phase calibration (VPC) and phase ratio variation (PRV). Here, we demonstrated a pressurized – loop headspace system in conjunction with gas chromatography vacuum ultraviolet detection (HS-GC-VUV) to directly calculate the concentration of analytes in the gas phase from room temperature ionic liquids (RTILs) sample phases, using pseudo-absolute quantification (PAQ). PAQ, an attribute of VUV detection, allowed for quick determination of Kp and other thermodynamic properties, such as enthalpy (ΔH) and entropy (ΔS) of the system through the use of van't Hoff plots in the temperature range of 70–110 °C. The Kp determinations by PAQ were comparable to those obtained using the VPC method with percent difference ranging from ≤ 1–33%. Kp determinations were made for analytes (cyclohexane, benzene, octane, toluene, chlorobenzene, ethylbenzene, m-,p-, and o-xylene) at the varying temperatures (70–110 °C) using different RTILs (1-ethyl-3-methylimidazolium ethylsulfate ([EMIM][ESO4]), 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and tris(2-hydroxyethyl)methylammonium methylsulfate ([MTEOA][MeOSO3])) and (1-ethyl-3-methylimidazolium bis(trisfluoromethanesulfonyl)imide ([EMIM] [NTF2])). The results from the van't Hoff analysis revealed that [EMIM] cation-based RTILs exhibit strong solute-solvent interactions with analytes that have π- electrons.

Rapid vibrational relaxation dynamics and strong Solute-Solvent interactions of the nitrite anion

In this work, we have used steady-state and ultrafast vibrational spectroscopy to measure the absorption band centers and widths, as well as vibrational energy relaxation (VER) lifetimes for the antisymmetric ν3 stretching band of the nitrite (NO2–) anion in H2O, D2O, and DMSO. The nitrite IR absorption bands are very broad and the excited state has an extremely short VER lifetime in all three solvents, suggesting that NO2– interacts quite strongly with all of them. We also measured and analyzed reflection spectra for NaNO2 pressed pellets and determined that the damping is fast in the reststrahlen band.

Multiple Facets of Modeling Electronic Absorption Spectra of Systems in Solution.

In this Perspective, we outline the essential physicochemical aspects that need to be considered when building a reliable approach to describe absorption properties of solvated systems. In particular, we focus on how to properly model the complexity of the solvation phenomenon, arising from dynamical aspects and specific, strong solute-solvent interactions. To this end, conformational and configurational sampling techniques, such as Molecular Dynamics, have to be coupled to accurate fully atomistic Quantum Mechanical/Molecular Mechanics (QM/MM) methodologies. By exploiting different illustrative applications, we show that an effective reproduction of experimental spectral signals can be achieved by delicately balancing exhaustive sampling, hydrogen bonding, mutual polarization, and nonelectrostatic effects.

Subsistence of diverse interactions of some biologically important molecules in aqueous ionic liquid solutions at various temperatures by experimental and theoretical investigation

To investigate significant molecular interactions, different Physico-chemical methodologies have been studied and measured for mixtures of aqueous Benzyltriethylammonium chloride with two amino acids (L-Cysteine and Glycine) at various concentrations and temperatures under atmospheric pressure. The origin of various interactions is exposed by evaluating the apparent molar volume (ϕV), limiting apparent molar volume (ϕV0), viscosity A and Bcoefficients, molar refraction (RM), limiting molar refraction (RM0), and detected strong solute-solvent interaction is predominating over the solute-solute and also solvent-solvent interactions in the ternary mixtures. The solute-solvent interaction is measured through (δϕE0/δT)P and (dB/dT) data which provide information like structure-breaking. The findings of 1H NMR spectroscopy show that, in addition to H-bonding interactions, the ionic liquid and amino acids have significant hydrophobic-hydrophobic interactions, which is confirmed by theoretical explanations. L-Cysteine-IL interactions are more prominent than Glycine-IL interactions, according to both experiment and theory.

The quantum chemical solvation of indole: accounting for strong solute-solvent interactions using implicit/explicit models.

In this paper, we investigate the efficacy of different quantum chemical solvent modelling methods of indole in both water and methylcyclohexane solutions. The goal is to show that one can yield good photophysical properties in strongly coupled solute-solvent systems using standard DFT methods. We use standard and linearly-corrected Polarisable Continuum Models (PCM), as well as explicit solvation models, and compare the different model parameters, including the choice of density functional, basis set, and number of explicit solvent molecules. We demonstrate that implicit models overestimate energies and oscillator strengths. In particular, for indole-water, no level inversion is observed, suggesting a dielectric medium on its own is insufficient. In contrast, energies are seen to converge fairly rapidly with respect to cluster size towards experimentally measured properties in the explicit models. We find that the use of B3LYP with a diffuse basis set can adequately represent the photophysics of the system with a cluster size of between 9-12 explicit water molecules. Sampling of configurations from a molecular dynamics simulation suggests that the single point results are suitably representative of the solvated ensemble. For indole-water, we show that solvent reorganisation plays a significant role in stabilisation of the excited state energies. It is hoped that the findings and observations of this study will aid in the choice of solvation model parameters in future studies.

Viscometric and thermodynamic study of aspirin in aqueous ethanol media at four different temperatures

The present study was conducted to investigate the effect of concentration and temperature on viscosity of aspirin solution. In order to achieve better bioavailability of drug, it is necessary to make it soluble. Aqueous ethanol solutions have been taken as solvents. Aspirin solutions with different concentrations were prepared in aqueous ethanol. Viscosity values of the solutions were determined experimentally by using Ostwald viscometer at four different temperatures. The viscosity (η) data were used to calculate relative viscosity (ηr), Jone-Dole’s coefficient (BJ) and Falken Hagen coefficient (AF). Activation energy of viscous flow for the solvent (Δμ10∗), as well as for the solute (Δμ20∗) and other thermodynamic parameters like entropies (ΔS20∗) and enthalpies (ΔH20∗) of viscous flow were also calculated. All these physico-chemical parameters are important for understanding the molecular interactions present in the drug solutions. It has been found that strong solute–solvent interactions prevail over solute–solute interactions in the drug solutions. Negative values of (dBJ/dT) reveal that the drug aspirin acts as a structure promoter for the solutions under study.

Understanding gas absorption in multivalent ionic liquids via solute-solvent interaction analyses

Solute-solvent interactions are often evaluated to understand and explain gas solubilities. This information is regularly used to interpret gas solubility and separation within ionic liquids (ILs). Here, we use several different quantum chemical and previous molecular dynamics simulation results to show that strong solute–solvent interactions neither lead to high solubility nor to high selectivity, with respect to other solutes. Instead, the solute–solvent interaction strength with different isolated IL ions is affected by the electrostatic extremes. Also, the solute–solvent interaction with different IL molecules is strongly correlated to the molecular volumes or polarizabilities (within a series of same-anion based ILs).

Fluorescence Spectral Properties of Methyl Orange in Homogeneous Media.

The methyl orange [C14H14N3SO3Na], an azo dye exhibited strong emission and large Stokes shift in various solvents, and the largest shift (Δλ = 125.51nm or Δν = 9297cm-1) was obtained in the water. The UV-visible spectra of the dye showed the absorption in the range (33,333 - 20,000) cm-1. We found that solvent effects on the absorption wavelength are consistent. The bathochromic shift in water and the hypsochromic shift in methanol observed in the absorption (43 nm) as well as in the fluorescence (42 nm) spectra predict the strong solute-solvent interaction. The fluorescence quantum yield (ɸf) was decreased from 24% in DMSO to 5% in water. The fluorescent properties of this dye are strongly solvent dependent, the wavelength of minimum fluorescence emission (λem = 435.51nm) shifts to the red. The maximum and minimum calculated oscillator strength is 32% with (Ɛmax = 29011 M-1cm-1) and 11% (Ɛmax = 6682 M-1cm-1) in methanol and DMSO, respectively. Protonated solvents without exception give a shorter lifetime and lower quantum yield. The average excited-state lifetime of the dye was found maximum (τav = 5.36 ns) in DMSO. Also, fluorescence lifetime was combined to deduce the radiative and non-radiative decay rate.

Temperature dependent physicochemical studies propylene and hexylene glycols in methanol solutions of chlorhexidine

The experimentally obtained density (ρ) and sound velocity (c) values of chlorhexidine (methanol solution) at a concentration of (0.0015, 0.0035 and 0.0055) mol∙kg-1 with propylene and hexylene glycols at the temperature of 288.15, 298.15, 308.15 and 318 K have been used to calculate the various physico-chemical properties. Apparent molar volume (Vϕ) and apparent molar isentropic compression (Kϕ,s) have been computed by using density and sound velocity data respectively. Partial molar volume (Vϕ0) and partial molar isentropic compression (Kϕ,s0) have been determined by using apparent molar properties. Empirical parameters and limiting apparent molar expansibilities have also been calculated. These parameters give information in the form of strong solute–solvent interactions which increases from propylene to hexylene glycols.

Study of Thermodynamic and Acoustic Properties of Niacin in Aqueous Hexylene Glycol and Propylene Glycol at Different Temperatures.

The densities and speed of sound for liquid mixtures containing vitamin B3 (niacin) at 0.01, 0.03, and 0.05 mol·kg–1 concentrations in aqueous propylene glycol and hexylene glycol at the variation of temperatures from 293.15 to 308.15 K have been measured using an Anton Paar DSA 5000 M. From volumetric experimental data, apparent molar volume (Vϕ), partial molar volume (Vϕ0), and partial molar volume of transfer (ΔVϕ0) are calculated along with the apparent molar isentropic compression (Kϕ, S), partial molar isentropic compression (Kϕ, S0), and partial molar isentropic compression of transfer (ΔKϕ0) using experimental acoustic data. The positive volumetric data (i.e., apparent molar volume and partial molar volume) indicates strong solute–solvent interactions inside the mixture. Along with these values, the empirical constants a, b, and c with the pair and triplet coefficients (VAB, VABB, KAB, KABB) are also calculated.

Volumetric and viscometric studies of molecular interactions in systems containing tartaric acid in water/aqueous-L-arginine solutions at 303.15 K

The densities and viscosities of aqueous solutions containing tartaric acid and L-Arginine were measured at 303.15 K. The densities were used to calculate the apparent molar volume of tartaric acid in water and aqueous-L-Arginine solutions. The apparent molar volumes were fitted to the linear fit Masson relation and relative viscosities were fitted to the Jones-Dole equation. From Masson relation, the partial molar volumes were determined and from Jones-Dole equation, the viscosity B-coefficients were determined. Strong solute-solvent interactions in aqueous solutions of tartaric acid solutions were observed from the transfer volumes and viscosity B-coefficient. The pH of these systems was also measured to understand the transfer of a proton from solute to cosolute. A weakening of solute-solvent interactions and loosening of the hydration sphere of tartaric acid on the addition of cosolute has been observed.

Evaluation of an Efficient 3D-RISM-SCF Implementation as a Tool for Computational Spectroscopy in Solution.

The 3D-RISM-SCF solvent-model implementation of Gusarov et al. [ J. Phys. Chem. A 2006, 110, 6083-6090] in the Amsterdam density functional program has been improved and extended. In particular, an accurate yet efficient representation of the solute electrostatic potential is provided. The Coulomb-potential fitting of many DFT codes can be used advantageously in this context. The extra effort compared to a point-charge representation is small for a given SCF cycle and compensated by faster SCF convergence. This allows applications to large solutes, as demonstrated by evaluation of the solvatochromism of Reichardt's dye. In general, TDDFT applications to excitation energies in solution stand out and are highlighted. Applications to the 17O NMR chemical shifts of N-methylformamide in different solvents also demonstrate the distinct advantages of 3D-RISM over continuum solvents. Limitations are observed in this case for water solvent, where the solvent shielding is overestimated. This shortcoming applies also to the 17O gas-to-liquid shift of water, where we used localized molecular orbital analyses for a deeper understanding. For such cases of extremely strong solute-solvent interactions, couplings between solute and solvent orbitals induced by the magnetic perturbation are relevant. These clearly require a quantum-mechanical treatment of the most closely bound solvent molecules. Except for such extreme cases, 3D-RISM-SCF is very well suited to treat solvent effects on NMR parameters. More serious limitations pertain to the treatment of vibrational spectra, where the absence of the coupling between solute and solvent vibrational modes limits the accuracy of applications of 3D-RISM-SCF. The reported extended, efficient, and numerically accurate 3D-RISM-SCF implementation should provide a useful tool to study chemical and spectroscopic properties of molecules of appreciable size in a realistic solvent environment.

Use of Masson's and Jones–Dole equations to study different types of interactions of three pharmacologically important drugs in ethanol

AbstractThe volumetric and viscometric study of three allopathic drugs (sodium valporate, benzalkonium chloride, and losartan potassium) in ethanol solvent is reported here. This study was carried out at four different temperatures that is, from 288.15 to 318.15 K. The accurately measured density values were used to calculate partial molar volume at infinite dilution, solute–solute interaction parameter, Hepler's constant, partial molar expansivity constant, and isobaric thermal expansion coefficient. The viscosity measurements were carried out for the calculation of constants of Jones–Dole equation and to calculate different thermodynamic parameters of viscous flow which include standard free energy change, standard enthalpy change, and standard entropy change of viscous flow. All these viscometric and volumetric parameters are useful for understanding the different types of interactions of drugs in solution and to study the drug action in body. The results of both volumetric and viscometric studies showed that all drugs had structure promoting effect on solvent, existing of strong solute–solvent interaction, and very weak solute–solute interaction. For all these drugs, solvophobic interaction was found to be dominant over electrostriction. Viscometric studies also showed the existing of stronger solute–solvent interaction in ground state as compared to that in transition state.

The hydration behavior of d-glucose in the choline chloride: Urea:water mixtures

The hydration behavior of d-glucose in aqueous solutions containing a deep eutectic solvent (DES) was studied in the temperature range: T = (293.15–313.15) K. For that, several volumetric, acoustic and viscometric properties were measured and calculated. The choline chloride + urea (1,2, molar ratio) eutectic mixture was chosen as co-solvent. The Hepler parameter and the viscosity B-coefficient showed that d-glucose in DES aqueous mixtures is a structure-making agent. Both the molar properties and the transfer properties suggested a strong solute-solvent interaction with predominance of the hydrophilic -hydrophilic contribution. Lastly, the calculated viscous flow activation parameters demonstrated high stability of the hydration structure.

Redox Potentials of Polyoxometalates from an Implicit Solvent Model and QM/MM Molecular Dynamics

The ability to electrochemically store energy is crucial for the integration of intermittent renewable energy sources such as wind and solar power into modern energy grids. Among a wide variety of possible solutions, redox flow batteries (RFBs) are especially attractive as their energy content and power output can be scaled independently, offering a high degree of flexibility. For RFBs, polyoxometalates (POMs) are very appealing as these transition metal oxide nanoclusters exhibit the ability to store multiple electrons in a reversible manner. However, despite the interest in their properties, the link between the POM structure and its redox properties remains unclear. In this contribution, we study the redox potentials of [SiW12O40]4– (SiW12) and [PV14O42]9– (PV14) using a number of different theoretical methods. We first adopt the thermodynamic cycle approach combined with quantum chemistry and implicit solvation to estimate the redox potentials. Subsequently, we use molecular dynamics to facilitate an explicit description of the solvent environment. The implicit solvation model is semiquantitative, and problems arise when strong solute–solvent interactions are present. Using two approaches, thermodynamic integration and fractional number of electrons methods, we show that explicitly including the solvent environment can improve the calculated redox potentials for strong solute–solvent interactions and also gives important atomistic insights into its nature and how it changes upon reduction. Our results illustrate the performance of these approaches for addressing the challenging problem of simulating the redox potentials in POMs and provides the framework to develop a more detailed understanding of the structure–property relationships that exist.

Molecular interactions of drug semicarbazide hydrochloride in aqueous-D-xylose/L-arabinose solutions at different temperatures: Volumetric, acoustic and viscometric study

The interactions of drug semicarbazide hydrochloride in water and in aqueous-carbohydrate (D-xylose/L-arabinose) solutions from their physicochemical behaviour are studied. Density, ρ, ultrasonic speed, u and viscosity, η of the drug semicarbazide hydrochloride in water and in aqueous-D-xylose/L-arabinose (5 wt% and 10 wt% of D-xylose/L-arabinose in water, w/w) solvents were measured as functions of concentrations at temperatures, T = (293.15 – 318.15) K and at atmospheric pressure, p = 101 kPa. The measured data have been utilized to calculate various properties like the apparent molar volume, Vφ from density measurements while apparent molar compressibility, Ks,ϕ, acoustic impedance, Z and intermolecular free length, Lf from ultrasonic speed measurements. The values obtained from these parameters indicate strong solute–solvent interactions within the solutions. The viscosity data have been analyzed using Jones-Dole equation and coefficients A and B were evaluated. The temperature derivative of B-coefficient, dB/dT together with activation parameters of viscous flow have also been determined. The results are discussed in terms of hydrophilic-hydrophilic and hydrophilic-hydrophobic interactions in these systems along with the structure breaking/making ability of the drug.

A review on conductometric studies of electrolytes in mixed solvent systems to understand ion-ion and ion-solvent interactions

The study of ion- solvent interaction is of much importance to investigate the nature of different solutions. Measurement of electrical conductivity and evaluation of physico-chemical properties, such as molar conductance, limiting molar conductance, ion-pair association, Walden product etc. shade light on different intermolecular interactions present in electrolyte solutions. Solvation properties can be varied by mixing two or more solvents. An extensive literature survey on conductometric studies has been carried out on different electrolytes dissolved in a wide range of mixed solvent systems. The reported results show that strong solute-solute, solute-solvent and solvent-solvent interactions are responsible for the physico- chemical behavior of a solution in mixed solvents.