Molar Range Research Articles

Aspects of electron transfer processes in vanadium redox-flow batteries

The electrochemical processes in vanadium redox-flow batteries (VRFBs) include conversions of vanadium species in acidic electrolytes with total vanadium concentrations over molar range. The majority of currently available data on electrode kinetics of vanadium reactions, and on the role of electrode surface chemistry are obtained for diluted electrolyte solutions and are very controversial. In this minireview, we consider the interpretations of electrochemical kinetic data for vanadium electrode reactions and mechanistic concepts, which have been reported in the literature. Thereby, the gap between electrochemical kinetics in “diluted” and “concentrated” solutions is in the focus of the review.

Design, synthesis, and biological evaluation of 1-substituted -2-aryl imidazoles targeting tubulin polymerization as potential anticancer agents

A series of novel 1-substituted-2-aryl imidazoles (SAI) were designed and synthesized based on our previously reported ABI (2-Aryl-4-Benzoyl Imidazole) analogs and on the structure of combretastatin A-4 (CA-4). These compounds showed potent antiproliferative activities against six human cancer cell lines with IC50 values in nano molar range. Among them, compound 3X exhibited the best anticancer activity with an average IC50 value of ∼100 nM. The compound maintains the mechanism of action by inhibiting tubulin polymerization, thus causing cell arrest at G2/M phase and apoptosis. In vivo efficacy studies indicated that 3X was highly effective in suppressing tumor growth in a MDA-MB-468 xenograft model of nude mouse with a TGI (Tumor Growth Suppression) of 77% at 60 mg/kg without causing significant toxicity. In addition, 3X displayed significantly better water solubility (36.70 μg/mL) than CA-4 (2.83 μg/mL). Molecular modeling study indicated that 3X binds well to the colchicine binding site in tubulin. Our results suggest that the novel SAI analogs deserve further investigation as potential anticancer agents.

Synthesis and Spectroscopic study of some transition metal complexes with 2-(4-Iodo Phenyl Azo)-4,5- Diphenyl Imidazol

This work deals with the preparation and identification of azo dye, 2-(4-Iodo phenyl azo)- 4.5-diphenyl imidazole (4-IPAI).The characterization of this ligand was done by elemental analysis is (C.H.N) mass spectra, Uv-vis. and IR techniques. The complexes of Co(II), Ni(II), and Cu(II) with (4-IPAI) have been prepared. The preparation were performed after fixing the optimum conditions of pH and molar concentration using Uv-Vis spectra of mixed solutions of the above ions with (4-IPAI). A wide range of pH and molar concentration in the ranges obeyed Lambert-Beers law were studies, and the stability (stability constant) were studied at optimum conditions of pH, molar concentration and mole ratio for all complex. The structure of these complexes were deduced according to the mole ratio method which were obtained from the spectroscopic studies of the complex solutions of the above ions. However ratio 1:2 metal: ligand were obtained. Uv-Vis absorption spectra of ethanol solution of the studied complexes showed bathochromic shift in the visible region compared with that of the ligand. The IR. Spectra of these complexes showed some changes in the band shape and density compared with those of the free ligands. New bands have been observed which may indicate that the coordinated with the metal ions. The elemental analysis (C.H.N) agreed with our results, the flame atomic absorption spectroscopy has also been used to determine the metal ion percentages. The percentages of metal ions were determined using flame atomic absorption spectroscopy, good agreement were obtained between the found and calculated percent values. Conductivity measurements have shown non-ionic character of complexes in ethanol and DMF solution. From all above observations the proposed geometrical structures of these complexes were octahedral [M(4-IPAI)2Cl2].

Influence of molecular design on the morphology of nanoparticles formed from 1-alkyl-6-alkoxy-quinolinium cations and 4-sulfonatocalix[n]arenes

In order to reveal the influence of the guest molecular structure, the interactions between 4-sulfonatocalix[n]arene (SCXn) cavitands (n = 4 or 6) and two series of quinolinium derivatives were studied in neutral aqueous solutions at 298 K. For this, the long alkyl chain of the quinoliniums was attached either to the heterocyclic nitrogen (CmC1OQ+ m = 10, 12, or 14) or to the oxygen located in position 6 of the aromatic system (C1CmOQ+ m = 8, 10, or 12). All the quinolinium derivatives self-assembled with SCXn into nanoparticles (NP), whose size, zeta potential and composition were determined over a large molar mixing ratio range. Isothermal titration calorimetry showed that host-guest binding assisted the formation of negatively charged NPs in exothermic processes. The enthalpy gain in these associations significantly increased with the lengthening of the 1-alkyl group but was insensitive to the size of the SCXn macrocycle. The morphology of NPs was studied by cryo-TEM method. CmC1OQ+ organization with SCXn led to spherical NPs without regular inner structure. In contrast, C1CmOQ+-SCXn nanoaggregates usually had various shapes and the original morphologies exhibited lamellar domains with ~3 nm layer thickness. The different orientation of CmC1OQ+ and C1CmOQ+ in the cavitand was proposed to rationalize the morphological alterations.

Study on solute-solvent interactions in the aqueous solutions containing guaifenesin drug, sodium chloride and potassium chloride salts in viewpoint of volumetric, electrical conductivity properties and quantum computing

Sodium and potassium ions have an important role in controlling the blood pressure in the body. Potassium ion along with sodium ion regulates the water and the acid-base balances in the tissues and blood. In this work, solute-solvent interactions in the aqueous solutions containing the guaifenesin drug (GG), NaCl and KCl salts were studied. To reach this purpose, the density and electrical conductivity data for GG drug in water and aqueous solutions of NaCl and KCl were measured within salt and drug molality range of (0.05, 0.1, and 0.15) mol kg−1 at T = (298.15, 308.15 and 318.15) K. The apparent molar volumes (Vφ) were calculated from density data. These data were analysed with Redlich–Meyer equation to find the limiting apparent molar volume. The low concentration Chemical Model (lcCM) was used for evaluating the limiting values of the molar conductivity (Λ0), the association constant (Ka) and the standard Gibbs energy for the ion-association process. We also optimized the structures and calculated the Gibbs energies of considered molecules in gas phase with Gaussian 03 W using the Hartree-Fock approximation with 6-311G basis set. Tomasi’s polarized continuum model (PCM) with basis set of 6-311G was used for optimizing and calculating the Gibbs energies of molecules in aqueous phase. The calculated solvation Gibbs energies were used for elucidating the solute-solvent interactions.

Modified carbon-paste-surface electrode for NaCl and KCl solution measurements

In this work, we report on the research results of electrical impedance spectroscopy using a surface printed electrode with superficial modification using graphite nanoparticles and polymethyl-metaacrylate in three concentrations. The experiments used saline solutions of NaCl and KCl with a molar range between 0.287 to 3 M. Three parameters with nonlinear behaviour were used to adjust the molar concentration (MC); the correlation coefficients show a higher relationship (r2 > 0.9). This behavior depends on frequency, graphite and MC. The proposed electrode was found to have lower sensitivity to lower levels of NaCl or KCl which, in turn, might be a good electrical characteristic in order to detect a higher concentration in a solution. The modified electrode has advantages such as low cost, easy construction and lower saturation surface; future application of this sensor could be an industrial process or corrosion with brine water.

New kinetic analysis of the Fenton reaction: Critical examination of the free radical – chain reaction concept

Using [H2O2] in the molar range, the reaction with Fe2+ has two phases: in the first rapid phase, only a small fraction of the total O2 is evolved; the bulk of the gas is formed in a slow second phase. In interpretations based on the free radical model of Barb et al., the first phase has been identified with the ‘Fenton reaction’ (reaction of Fe2+with H2O2), while the second with catalytic decomposition of H2O2 by Fe3+ ions. This interpretation is not correct. A new analysis of the model shows that (1) it is a chain reaction having no termination steps and (2) the ‘Fenton part’ alone consists of two phases. It starts with rapid evolution of O2 via a five-membered chain reaction (first phase). When [Fe2+] becomes low, evolution of O2 continues in a three-membered chain reaction at a greatly reduced rate (second phase). In later stages of the second phase, Fe3+ catalysis contributes to O2 evolution. Thus, the amount of O2 formed in the rapid phase cannot be identified with the total amount formed in the ‘Fenton reaction’ but only with that formed in its first phase. Computer simulations of O2 evolution based on the model of Barb et al. and rate constants show a definite dependence of this quantity on the initial [H2O2] – in contrast to the experimentally found independence. More satisfactory, but not complete, agreement with measured data could be reached in simulations using a non-radical model. Some of the difficulty has been due to the determination of the exact position of the end of the first phase. The transition between the two phases of the reaction occurs in a short, but finite time interval. It has been shown that the quantity ‘total amount of O2 evolved in the Fenton reaction’ (subtracting the part due to Fe3+catalysis) is not accessible to experimental determination nor to theoretical calculation.

SYNTHESIS AND OPTICAL PROPERTIES OF NANOCOMPOSITES BASED ON LIQUID CRYSTAL WITH BIMETALLIC Au + Ag NANOPARTICLES OF ALLOY TYPE.

In this work, we have carried out a research which aimed to obtain complex nanoparticles of noble metals Au + Ag in the form of bimetallic alloys. Bimetallic nanoparticles were synthesized directly in a liquid-crystalline cadmium caprylate melt in an argon atmosphere in the temperature range of mesophase existence by the simultaneous chemical reduction of cations of gold (Au3+) and silver (Ag+) from their compounds, tetrachloroaurate acid (H[AuCl4]×3Н2О) and silver nitrate AgNO3, respectively.
 The effect of synthesis duration (3 and 5 hours) on the spectral behavior of binary nanoparticles have been studied. It has been shown that when the synthesis duration is 3 h, mainly homogeneous bimetallic alloys are obtained, and when it is 5 h, both homogeneous and gradient alloys can be obtained. The absorption spectra of homogeneous alloys are characterized by the presence of one surface plasmon resonance (SPR) peak, which occupies an intermediate position relative to the SPR peaks for monometallic nanoparticles, i.e. between 425 and 560 nm. When forming heterogeneous alloys, which are formed in the molar ratio range where the amount of silver ions predominates, the absorption spectra exhibit two SPR peaks which relate to nanoparticles with different metallic silver content. The formation of metallic nanoparticles containing different metals may be due both to the different mobility of noble metals ions in the liquid crystal matrix and to the different rate of rearrangement of metals in the new formed heteronanoparticle.
 It has been found by electron spectroscopy and transmission electron microscopy that the nanoparticles in this matrix have mostly a spherical shape with a mean diameter of 15 nm. The possibility of the fine control of the position of SPR peak of bimetallic nanoparticles in a liquid crystal matrix over a wide optical range of 422–580 nm is shown.

Chemical speciation of aqueous hydrogen fluoride at various temperatures from 298.15 K to 353.15 K

The chemical speciation of aqueous hydrofluoric acid solutions was investigated at various temperatures. The experimental results and calculations were carried out to study a qualitative and quantitative speciation of the system HF-H2O. Literature review of thermodynamic and speciation studies of aqueous hydrogen fluoride were reported and revealed some deficiencies at various temperatures. The dissociation of HF in the aqueous solution is not complete, which exhibits a concentration-dependent stoichiometric coefficient and directly influences the thermodynamic properties. Neglecting this concentration dependence leads to erroneous osmotic coefficients for solutions of weak electrolytes. The water activities of the HF-H2O system were measured within the molality range from 0.10 mol kg−1 to 6.00 mol kg−1 at different temperatures from 298.15 K to 353.15 K using the hygrometric method. From these measurements, on the basis of the fluorine 19F nuclear magnetic resonance and the chemical equilibriums, the qualitative and quantitative speciation aqueous hydrofluoric acid solutions were performed respectively. The deployed approach was developed based on ion interaction model to describe the behavior of HF aqueous solutions, considering a polyelectrolyte system HF−H−F−HF2−H2F3−H2O. The calculated species HF(aq), H+, F−, HF2− and H2F3−were determined at various temperatures. From the complementary techniques and the developed model, the results reflect the present species and allow describing the behavior of hydrofluoric acid aqueous solutions.

Site-Resolved and Quantitative Characterization of Very Weak Protein-Ligand Interactions.

Very weak interactions between small organic molecules and proteins have long been predicted and are expected to have dissociation constants of hundreds of millimolar and above. Unfortunately, quantitative evaluation of binding in a high-resolution structural context for this affinity regime is particularly difficult and often impossible using existing experimental approaches. Here, we show that nanoscale encapsulation of single protein molecules within the water core of reverse micelles enables the detection and evaluation of weak binding interactions at atomic resolution using solution NMR spectroscopy. This strategy is used to survey the interactions of a set of small molecules with the cytokine interleukin-1β (IL-1β). The interaction of IL-1β with these molecules is found to vary from more diffuse and weak binding modes to more specific and with a relatively higher affinity. The interactions detected here cover a large portion of the protein surface and have dissociation constants mostly in the low molar range. These results illustrate the ability of a protein to interact productively with a variety of small molecule functional groups and point to a broader potential to target even relatively featureless protein surfaces for applications in chemical biology and drug discovery.

Evolutionary Steps in the Analytics of Primordial Metabolic Evolution.

Experimental studies of primordial metabolic evolution are based on multi-component reactions which typically result in highly complex product mixtures. The detection and structural assignment of these products crucially depends on sensitive and selective analytical procedures. Progress in the instrumentation of these methods steadily lowered the detection limits to concentrations in the pico molar range. At the same time, conceptual improvements in chromatography, nuclear magnetic resonance (NMR) and mass spectrometry dramatically increased the resolution power as well as throughput, now, allowing the simultaneous detection and structural determination of hundreds to thousands of compounds in complex mixtures. In retrospective, the development of these analytical methods occurred stepwise in a kind of evolutionary process that is reminiscent of steps occurring in the evolution of metabolism under chemoautotrophic conditions. This can be nicely exemplified in the analytical procedures used in our own studies that are based on Wächtershäuser’s theory for metabolic evolution under Fe/Ni-catalyzed volcanic aqueous conditions. At the onset of these studies, gas chromatography (GC) and GC-MS (mass spectrometry) was optimized to detect specific low molecular weight products (<200 Da) in a targeted approach, e.g., methyl thioacetate, amino acids, hydroxy acids, and closely related molecules. Liquid chromatography mass spectrometry (LC-MS) was utilized for the detection of larger molecules including peptides exceeding a molecular weight of 200 Da. Although being less sensitive than GC-MS or LC-MS, NMR spectroscopy benefitted the structural determination of relevant products, such as intermediates involved in a putative primordial peptide cycle. In future, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) seems to develop as a complementary method to analyze the compositional space of the products and reaction clusters in a non-targeted approach at unprecedented sensitivity and mass resolution (700,000 for m/z 250). Stable isotope labeling was important to differentiate between reaction products and artifacts but also to reveal the mechanisms of product formation. In this review; we summarize some of the developmental steps and key improvements in analytical procedures mainly used in own studies of metabolic evolution.

Novel morpholine containing cinnamoyl amides as potent tyrosinase inhibitors

Tyrosinase enzyme plays a crucial role in melanin biosynthesis and enzymatic browning process of vegetables and fruits. Hence, tyrosinase inhibitors are important in the fields of medicine, cosmetics and agriculture. In this study, novel N-(2-morpholinoethyl)cinnamamide derivatives bearing different substituents on phenyl ring were designed, synthesized and evaluated for their tyrosinase diphenolase inhibitory activity. The compounds were found to be better tyrosinase inhibitors (IC50s were in micro molar range) than cinnamic acid. (E)-3-(3-chlorophenyl)-N-(2-morpholinoethyl)acrylamide (B6) exhibited the highest inhibition with IC50 value of 15.2 ± 0.6 μM which was comparable to that of kojic acid. The inhibition kinetic analysis of B6 indicated that the compound was a mixed-type tyrosinase inhibitor. In silico ADME prediction indicated that B6 might show more skin penetration than kojic acid. Molecular docking analysis confirmed that the active inhibitors well accommodated in the mushroom tyrosinase active site and it was also revealed that B6 formed the most stable drug-receptor complex with the target protein. Therefore, cinnamamide B6 could be introduced as a potent tyrosinase inhibitor that might be a promising lead in cosmetics, medicine and food industry.

Pharmacological investigation of quinoxaline-bisthiazoles as multitarget-directed ligands for the treatment of Alzheimer’s disease

Alzheimer’s disease (AD) is the most prevalent disease of old age leading to dementia. Complex AD pathogenesis involves multiple factors viz. amyloid plaque formation, neurofibrillary tangles and inflammation. Herein we report of a new series of quinoxaline-bisthiazoles as multitarget-directed ligands (MTDLs) targeting BACE-1 and inflammation concurrently. Virtual screening of a library of novel quinoxaline-bisthiazoles was performed by docking studies. The most active molecules from the docking library were taken up for synthesis and characterized by spectral data. Compounds 8a-8n showed BACE-1 inhibition in micro molar range. One of the compounds, 8n showed BACE-1 inhibition at IC50 of 3 ± 0.07 µM. Rat paw edema inhibition in acute and chronic models of inflammation were obtained at 69 ± 0.45% and 55 ± 0.7%, respectively. Compound 8n also showed noteworthy results in AlCl3 induced AD model. The treated rats exhibited excellent antiamnesic, antiamyloid, antioxidant, and neuroprotective properties. Behavioural parameters suggested improved cognitive functions which further validates the testimony of present study. Moreover, compound 8n was found to have inherent gastrointestinal safety. This new string of quinoxaline-bisthiazoles were identified as effective lead for the generation of potent MTDLs and compound 8n was found to showcase qualities to tackle AD pathogenesis.

Reversible adsorption of oxygen as superoxide ion on cerium doped zirconium titanate

Zirconium titanate (ZrTiO4) modified via cerium ions insertion in the oxide lattice has been successfully prepared via Sol-Gel synthesis forming solid solutions in the molar range between 0 and 10%. Cerium ions are hosted both as Ce4+ and Ce3+ ions whose ratio depends on the treatment undergone by the solid, with trivalent cerium always abundantly present even in strong oxidative conditions. Surface exposed Ce3+ ions are capable to adsorb O2 in the range of temperature between 273 K and 77 K, as superoxide anion (O2−), having side-on structure and characterized by complete surface-to-molecule electron transfer (about 98% of spin density on O2 molecule). Surprisingly such abundant adsorption is pressure dependent and fully reversible opening the perspective of applications of this system in the field of oxygen separation from gas mixtures.

Volume-related solvation and pair interaction parameters for dilute solutions of urea and tetramethylurea in ethylene glycol between 288.15 K and 328.15 K: A comparative analysis

The densities of urea (U) and tetramethylurea (TMU) solutions in ethylene glycol (EG) at the solute molality range up to 1.5 mol·kg−1 were measured with the uncertainty of 0.03 kg·m−3 at T = (288.15, 298.15, 308.15, 318.15 and 328.15) K and p = 99.6 kPa using a vibrating-tube densimeter. The standard partial molar volumes and isobaric expansibilities as well as parameters of the solvent-induced solute–solute pair interactions for both ureas were calculated. The results were discussed in terms of hydrophilic and hydrophobic nature of U and TMU, respectively, and also on the background of the suggestion that EG, like liquid water, forms the hydrogen bond spatial network.

Determination of water activity, osmotic coefficients, activity coefficients, solubility and excess Gibbs free energies of NaCl-sucrose-H2O mixture at 298.15 K

The relative humidities on ternary NaCl-sucrose-H2O solution of 0.5, 1.0, 2.0, 4.0 and 5.5 mol·kg−1 of sucrose have been determined by the hygrometric method at 298.15 K in the molality range from 0.5 to 6.0 mol·kg−1 of NaCl. The obtained data allow the deduction of the water activities and osmotic coefficients. The experimental results are compared with the predictions of the extended composed additivity (ECA) rule, the Lin et al. equation, and Lietzke and Stoughton (LS II) models. The obtained results were interpreted by using Pitzer-Simonson-Clegg model. The four mixture parameters are determined and used to predict the activity coefficients of NaCl and sucrose in the mixed solution. The solubility, excess Gibbs energy and The Gibbs energies of transfer of sodium chloride are also calculated for this system.

Properties of Micellar Solutions of Sodium Decyl Sulfate at Relatively High Concentrations

Heat capacities of aqueous solutions of anionic surfactant sodium decyl sulfate in the 0.28–0.42 mol kg−1 range of molar concentrations and the 278–363 K range of temperatures are studied via precision adiabatic differential scanning microcalorimetry. Specific and apparent heat capacities of solutions at intervals of 0.01 mol kg−1, partial molar heat capacities of the solute and the solvent, and excess partial molar heat capacities are plotted as functions of concentration and temperature. The Kraft boundary is determined. Analysis of the characteristic changes in the above properties reveals structural changes in sodium decyl sulfate micelles that correspond to their shape transforming from cylindrical to plate-like in the region of the third critical micelle concentration.

Cyclosporine‐A Enhances Mitochondrial Calcium Buffering to Delay mPTP Opening

Regulation of intra‐mitochondrial (matrix) free calcium ([Ca2+]m) is critical for cellular Ca2+ homeostasis. While mitochondria have the capacity to store a large amount of Ca2+, the availability of [Ca2+]m is maintained within a sub‐micro molar range at steady‐state by the dynamic balance between Ca2+ uptake, buffering, and efflux. Excessive matrix Ca2+ with oxidative stress induces permanent opening of a nonselective inner membrane pore, the mitochondrial permeability transition pore (mPTP), which leads to cell death. Cyclosporine A (CsA), a well‐known inhibitor of the mPTP, is thought to suppress pore opening, in part, by binding to cyclophilin D (CypD) and inhibiting its peptidyl‐prolyl cis‐trans isomerase (PPIase) activity in the presence of high [Ca2+]m. It is not known if the CsA mediated delay in mPTP opening involves regulation of [Ca2+]m as a potential mechanism for mPTP inhibition. In the present study, we tested a novel hypothesis that CsA enhances matrix Ca2+ buffering and consequently modulates the [Ca2+]m threshold for mPTP opening. To test this hypothesis, we investigated the effects of CsA on mitochondrial Ca2+ handling and bioenergetics in K+ pyruvate energized mitochondria isolated from the guinea pig hearts. We quantitatively determined mitochondrial Ca2+ uptake by monitoring both the disappearance of the extra‐matrix ([Ca2+]e) and the increase in [Ca2+]m, using the fluorescent dyes Fura‐4 penta‐K+ salt and Fura‐4 AM, respectively. Mitochondria suspended in Na+ free buffer, to obviate mitochondrial Na+/Ca2+ exchanger, containing 40 μM EGTA, were challenged with repeated boluses of CaCl2 (20 μM) every 5 minutes until mitochondria could not take up or retain the additional Ca2+. Key mitochondrial bioenergetics variables, membrane potential (ΔΨm), matrix pH and NADH (redox state), were also monitored using specific fluorescent dyes. We found that treatment of mitochondria with CsA, before adding boluses of CaCl2, significantly increased the amount of Ca2+ uptake and sequestration, maintained [Ca2+]m at a steady‐state level, and markedly delayed mPTP opening. The extent of matrix Ca2+ buffering, as determined by the bound/free Ca2+ ratio, was strikingly higher for CsA treated mitochondria vs. control. In addition, by enhancing matrix Ca2+ buffering, CsA preserved ΔΨm, matrix pH, and redox state. Interestingly, when CsA was added to mitochondrial suspension just before the onset of mPTP opening, it inhibited pore opening, in part, by promoting the buffering of [Ca2+]m, which reduced the [Ca2+]m and rescued bioenergetics variables to normal values. Since inorganic phosphate (Pi) is vital for Ca2+ sequestration in the matrix, we conducted experiments in Pi‐depleted mitochondria and in Pi free buffer condition. We found that in the absence of Pi, the CsA mediated buffering of [Ca2+]m was abrogated, and mitochondrial bioenergetics were compromised. These results suggest that CsA delays mPTP opening by a novel mechanism that involves enhanced matrix Ca2+ buffering primarily by induction of a PO43− ‐dependent matrix Ca2+ sequestration system.Support or Funding InformationNational Institutes of Health (R01 HL131673‐01A1) and the Veterans Administration (BX‐002539‐01).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

New methylpyridinium ionic liquids – Influence of the position of –CH3 group on physicochemical and structural properties

In this work, the three newly synthesized pyridinium based ionic liquids (ILs) are investigated in order to show the structure-property relationship and the possibility of fine-tuning based on a change of –CH3 position on cation heterocycle. Studied ILs are N-hydroxypropyl-n-methylpyridinium chloride, [N-C3OH-n-mpy][Cl] (n is 2, 3 or 4 position of –CH3 on pyridinium ring). The relationship between molecular structure and properties for these pure ILs is explored by a combination of experimentally obtained physicochemical properties, as well as molecular dynamics and quantum chemistry. How the change in the position of the –CH3 group affects the volumetric and viscosimetric properties of aqueous solutions of these ILs is also reported in this work. Density and viscosity measurements were performed in the temperature range from T = (293.15 to 313.15) K at atmospheric pressure and in the molality range from m ~ (0.10000 to 0.50000) mol·kg−1. Based on physicochemical characterization supported with computational simulations for pure ILs and their aqueous solutions, the interactions between these different ILs and water were discussed and more precisely viewed the impact of the position of the methyl substitute on the pyridinium ring.

Study of Strength of Interaction between Solute and Solvent Molecules in Aqueous Solutions of Ethylene Glycol, D-Mannitol, D-Fructose, Sucrose, and Maltose at 294.15, 298.15, and 303.15 K and Atmospheric Pressure using Refractometry

In this research work, we measured the refractive indices for aqueous solutions of ethylene glycol, D-mannitol, D-fructose, sucrose, and maltose at T = 294.15, 298.15, and 303.15 K and atmospheric pressure entire wide range of molar concentrations. These measurements were done in order to investigate the power of interactions between solute and solvent molecules as well as the effect of temperature in these interactions. For these mixtures, the experimental values of refractive index were correlated with experimental equation and constants of this equation (Kr) were applied to investigate on power of interactions between solute species in solutions of this study.