Solvent Parameters Research Articles

Determination of calcium in water samples by using Au-electrode in HCl solution in the absence and presence of a crystal violet and environmental studies

The hydrochloric acid (HCl 0.1 M) supporting electrolyte was used in the electrochemical estimation cyclic voltammetry for CaCl2 concentrations also using crystal violet dye or (hexamethyl pararosaniline) as ligand. For oxidation and reduction waves, the potential range is 0.5 V, -0.5 V. The interaction of calcium ions with crystal violet was examined using several analytical estimates, and kinetic and thermodynamic parameters. The analytical concentration for calcium ions in different samples especially in Nile River were estimated in the range from 1.6 to 14.3 mmol. The estimation of calcium ion concentrations was achieved up to 11.49 mmol in waste water in Mansoura University. Applications were made for calcium estimation of different water samples and molecular docking of the calcium-crystal violet complex against the Hepatitis C viral proteins (4i33, 4KTC), roving strong bonds of interaction were observed. And anti-bacterial effect on calcium complex with crystal violet and face mask N-95 tissue.
 KEY WORDS: Calcium ions, Thermodynamic properties, Solvation parameters, Nile water samples, Anti-bacterial, Molecular docking
 Bull. Chem. Soc. Ethiop. 2024, 38(1), 43-54. DOI: https://dx.doi.org/10.4314/bcse.v38i1.4

Solubility, correlation, Hansen solubility parameter and thermodynamic analysis of 2,4-dinitroanisole in three binary mixed solvents

Melt cast explosive is the most widely used type of military explosives. Then 2,4-dinitroanisole (DNAN) is a liquid phase carrier of melt cast explosives, and it is the most promising substitute for TNT. In this study, the solubility of DNAN in three binary mixed solvents (MeOH + water, EtOH + water, i-PrOH + water) at the temperature range of 298.15 ∼ 333.15 K at atmospheric pressure (0.1 MPa) was measured by laser dynamic method. The experimental results show that the solubility of DNAN increase with increasing temperature and the fraction of the organic solvents. In order to expand the applicability of solubility, Apelblat equation, van't Hoff equation, λh equation and modified Jouyban-Acree model were used to correlate the solubility, and satisfactory results were obtained. The Apelblat equation have best correlation with the solubility data of DNAN. The solubility parameters of DNAN and binary mixed solvents were calculated through Hansen solubility parameter and Materials Studio. The solubility of DNAN in three binary mixed solvents show a regular pattern of i-PrOH + H2O > EtOH + H2O > MeOH + H2O. The above pattern is consistent with the solubility parameters prediction results and prove that the solubility data is true and effective. In addition, according to the experimental data, the standard solubility enthalpy ΔHdis° degree, standard entropy ΔSdis° degree, standard Gibbs free energy ΔGdis°, the enthalpy %ξH and the entropy %ξS were calculated and discussed.

Insights into Hildebrand Solubility Parameters - Contributions from Cohesive Energies or Electrophilicity Densities?

We introduce certain concepts and expressions from conceptual density functional theory (DFT) to study the properties of the Hildebrand solubility parameter. The original form of the Hildebrand solubility parameter is used to qualitatively estimate solubilities for various apolar and aprotic substances and solvents and is based on the square root of the cohesive energy density. Our results show that a revised expression allows the replacement of cohesive energy densities by electrophilicity densities, which are numerically accessible by simple DFT calculations. As an extension, the reformulated expression provides a deeper interpretation of the main contributions and, in particular, emphasizes the importance of charge transfer mechanisms. All calculated values of the Hildebrand parameters for a large number of common solvents are compared with experimental values and show good agreement for non- or moderately polar aprotic solvents in agreement with the original formulation of the Hildebrand solubility parameters. The observed deviations for more polar and protic solvents define robust limits from the original formulation which remain valid. Likewise, we show that the use of machine learning methods leads to only slightly better predictability.

A polemic on the use of reversed-phase liquid chromatography to determine descriptors for the solvation parameter model

Revised descriptors for 74 varied compounds recommended for the characterization of reversed-phase silica columns using the solvation parameter model are assigned by the Solver method from experimental retention factors for calibrated gas-liquid and reversed-phase liquid chromatographic (RPLC) and biphasic liquid-liquid partition systems. These descriptors are taken as the best estimate of the true descriptor values and used to evaluate several RPLC systems as a single-technique approach for descriptor assignments. Various combinations of isocratic single column and multiple mobile phase compositions, multiple columns with a single mobile phase composition, and multiple columns and multiple mobile phase compositions are evaluated. A multiple column (Discovery HS C18 and HS F5, Fluophase-RP, and XBridge Shield RP18, Phenyl, and C18) with acetonitrile- and methanol-water mobile phases provided the best results with an absolute average deviation (AAD) of 0.043 for the electron lone pair interaction descriptor E, 0.047 for the dipole-type interaction descriptor S, 0.020 for the hydrogen-bond acid descriptor A, and 0.010 for the hydrogen-bond base descriptor B° for 46 varied compounds. These values compare favorably with the larger all columns and mobile phase composition RPLC dataset with the best estimate of the true descriptors, or all data set, with AAD = 0.026 for E, 0.044 for S, 0.027 for A, and 0.011 for B° for 74 varied compounds. The preferred RPLC systems for descriptor assignments contain columns identified as belonging to different selectivity groups that maximize the relative magnitude of the dipole-type contribution, s system constant, hydrogen-bond basicity, a system constant, and electron lone pair interactions, e system constant. RPLC systems are well suited to assigning the B° descriptor and, with proper system selection, the A and S descriptors. The E descriptor for compounds unavailable by calculation is more problematic and a few extreme values with an AAD > ± 0.1 were observed and can affect the reliability of the S descriptor assignments for these compounds. The likelihood of poor descriptor assignments using the Solver method can be identified by evaluating descriptor wells.

Musk ketone solubility in binary systems ethyl acetate with methanol, ethanol, and isopropanol: preferential solvation according to the inverse Kirkwood–Buff integrals method

ABSTRACT Three co-solvent mixtures {methanol (1) + ethyl acetate (2), ethanol (1) + ethyl acetate (2), and isopropanol (1) + ethyl acetate} were used to calculate the preferred solvation parameters () of musk ketone (MK) (2). In all co-solvent mixes, values vary non-linearly with the percentage of co-solvent (1). According to the study, values are negative in mixes rich in alcohol but positive in those high in ethyl acetate. The mixtures {methanol (1) + ethyl acetate (2)} and {ethanol (1) + ethyl acetate (2)} show the most favoured solvation of MK by ethyl acetate at 298.15 K and 293.15 K, respectively. When {isopropanol (1) + ethyl acetate (2)} is combined; it is maximum at 298.15 K. Since the values are positive, MK preferentially solvates with ethyl acetate. The most significant values for x 1 = 0.18–0.40 are obtained towards the non-polar regions of MK for the three co-solvent mixes.

Quantification of Heavy Metals and Chemical Stressors in Ground Water of Coal Mining Areas and Associated Human Health Risk

Acid mine drainage is one of the most obvious challenges in coal mining areas that is responsible for deteriorating soil and ground water quality of nearby communities thus posing serious human health risk. Objective: To quantify of heavy metals and chemical stressors in ground water and associated human health risk. Methods: Cross-sectional study with a combination of random sampling and Probability-Proportional-to-Size Sampling was used. Eight different sites were selected for water sample collection, and heavy metals were quantified. The analysis was carried out. Physicochemical properties of water were assessed using a portable photometer. Hematological parameters and antioxidants in the blood of study subjects were also measured. Results: Among the water samples, site S1 had the highest iron concentration at 0.354 ppm, exceeding the US limit of 0.3 ppm, with nickel being the next most abundant metal. Site S8 recorded the highest temperature at 36.4°C, while site S5 had the highest pH in the drinking water. The maximum electrical conductivity was found at S4 with 1387 s/m, and the total dissolved solvent parameter peaked at 1598 ppm in S8. Subjects exposed to acid mine drainage through water consumption displayed significant changes in antioxidant and blood parameters compared to the control group. In the exposed group, catalase (63.47), superoxide dismutase (33.26), and glutathione peroxidase (532.97) levels decreased, while malondialdehyde levels increased to 1.39. Conclusions: The physical and chemical properties of all water resources of mining areas were negatively altered due to heavy metals contamination thus poses a serious threat of oxidative stress in exposed subjects.

Donor-acceptor functionalized coumarin derivatives: Synthesis, fluorescence modulation, interaction with human serum albumin and acetylcholinesterase inhibition activity

A coumarin compound 7-diethylaminocoumarin (DEAC) and its substituted derivative coumarin-6-CF3 (CCF3) were synthesized, characterized and their photophysical behavior have been investigated by steady state and time resolved fluorescence spectroscopy. Both the investigated systems show appreciable modulation in photophysical properties depending on the nature of the solvent medium and in presence of sequestering agents like cyclodextrin nanocavities and/or human serum albumin (HSA). Quantitative estimation of different solvent parameters responsible for the modulated spectral features were done from multiple linear regression analysis of the experimental data based on Kamlet-Taft and Catalán formalisms. Significant modulation in fluorescence quantum yield in polar-protic medium and/or highly viscous glycerol solution for CCF3 in comparison with the model compound DEAC was due to donor–acceptor functionalization in the former. This additional excited state charge transfer possibility led to very large excited state dipole moment change in CCF3 and resulted almost ∼ 90 nm solvent dependent fluorescence peak shift. Multi-pronged experimental results in conjunction with molecular docking calculation revealed moderate binding affinity of the investigated systems towards HSA. Additionally, the coumarin derivatives were evaluated for its anticholinergic activity using in-vitro acetylcholinesterase enzymatic assay. The results demonstrated a significant inhibition of cholinergic activity, particularly for donor–acceptor functionalized CCF3, highlighting the potential therapeutic application of it. The study provides important insights into the molecular interactions and pharmacological properties of these promising coumarin derivatives, which could serve as a basis for the development of new drug candidates targeting cholinergic pathways.

Neural Network Models for Predicting Solubility and Metabolism Class of Drugs in the Biopharmaceutics Drug Disposition Classification System (BDDCS).

The biopharmaceutics drug disposition classification system (BDDCS) categorizes drugs into four classes on the basis of their solubility and metabolism. This framework allows for the study of the pharmacokinetics of transporters and enzymatic metabolization on biopharmaceuticals, as well as drug-drug interactions in the body. The objective of the present study was to develop computational models by neural network models and structural parameters and physicochemical properties to estimate the class of a drug in the BDDCS system. In this study, deep learning methods were utilized to explore the potential of artificial and convolutional neural networks (ANNs and CNNs) in predicting the BDDCS class of 721 substances. The structural parameters and physicochemical properties [Abraham solvation parameters, octanol-water partition (log P) and over the pH range 1-7.5 (log D), number of rotatable bonds, hydrogen bond acceptor numbers, as well as hydrogen bond donor count] are calculated with various software. These compounds were then split into a training set consisting of 602 molecules and a test set of 119 compounds to validate the models. The results of this study showed that neural network models using applied parameters of the drug, i.e., log D and Abraham solvation parameters, are able to predict the class of solubility and metabolism in the BDDCS system with good accuracy. Neural network models are well equipped to deal with the relations between the structural parameters and physicochemical properties of drugs and BDDCS classes. In addition, log D is a more suitable parameter compared with log P in predicting BDDCS.

Glyburide in a series co-solvent solutions: Solubility and modeling, solvation and quantum chemistry research

The shake-flask technique was used to test the solubility of glyburide in mixtures of acetone + water and ethyl acetate + methanol/ethanol/isopropanol under 101.0 kPa. For a fixed temperature, the glyburide solubility positively increased with the mass fraction of acetone in the acetone + water mixture, and reached a maximum value of 8.805 × 10−6 at 298.15 K. The solubility magnitudes reach their peak when the mass fraction of ethyl acetate in solutions containing ethyl acetate plus methanol/ethanol/isopropanol is approximately 0.3, which correspond to 5.703 × 10−4, 5.235 × 10−4 and 4.307 × 10−4, respectively, at 298.15 K. Two models-the Jouyban-Acree and modified van't Hoff-Jouyban-Acree were employed to correlate the solutility and produced the biggest relative average deviation of 7.78 %. The local composition (solvents) around the drug molecule was investigated at 298.15 K using an inverse Kirkwood-Buff integrals. The positive preferred solvation parameters of glyburide were observed in the medium and rich compositions of methanol/n-propanol/isopropanol/acetonitrile/PG/NMP (taken from published works)/acetone, signifying that glyburide was preferentially solvated by these solvents; while they had negative magnitudes in ethyl acetate + methanol/ethanol/isopropanol systems throughout the whole ethyl acetate compositions. The solubility of glyburide in the ten solutions was properly described by an extended Hildebrand solubility parameter approach, with relative average errors of no more than 5.32 %. In addition, the electrostatic characteristics of the basicity/acidity of glyburide molecule were highlighted with the help of quantitative study of molecular surface. Because of their lowest (-158.0 kJˑmol−1 to −136.6 kJˑmol−1) and largest (156.6 kJˑmol−1 to 182.8 kJˑmol−1) global electrostatic potentials, the > C = O and > NH groups are the main targets of electrophilic and nucleophilic assault. Visual examination of the weak interactions between glyburide and the neat solvents (methanol, ethanol, isopropanol, acetone, ethyl acetate, and water) was done using the Hirshfeld partition analysis-based independent gradient model.

Revised descriptors for polycyclic aromatic and related hydrocarbons for the prediction of environmental properties using the solvation parameter model

Revised descriptors for twenty-five polycyclic aromatic and related hydrocarbons (PAHs) forming a component of the Wayne State University (WSU) descriptor database are provided for use with the solvation parameter model. The descriptors are determined by the Solver method using experimental data for calibrated gas-liquid and reversed-phase liquid chromatographic retention factors and liquid-liquid partition constants in totally organic biphasic systems. The characteristic solvation properties of the PAHs are accounted for mainly by the additional dispersion interactions (E descriptor) and dipole-type interactions (S descriptor) resulting from the availability of easily polarizable electrons that complement typical dispersion interactions for saturated hydrocarbons. The descriptors afford acceptable prediction of the water-air partition constant (average absolute deviation AAD = 0.17, n = 22), octanol-air partition constant (AAD = 0.12, n = 20), and water-octanol partition constant (AAD = 0.10, n = 23). A two-parameter model containing only the V and B descriptors provides an unbiased prediction of aqueous solubility for the PAHs with an AAD = 0.26 (n = 22). The descriptors estimated by convenient chromatographic and partition constant measurements are demonstrated to be a viable alternative to the experimental determination of environmental properties otherwise only available by tedious, expensive, and low data throughput experimental techniques.

Research on solubility behavior of iminostilbene in twelve mono-solvents: Measurement, modeling, molecular simulation and thermodynamic properties

Iminostilbene (IMB) is an important pharmaceutical intermediate that can be used to prepare the antiepileptic drug omazepine. The measurement of solid–liquid equilibrium solubility parameters in various solvents can be employed for crystallization and separation processes of IMB. In this research, mole-fraction solubility of IMB in twelve individual organic solvents namely: “methyl acetate (MeAC), ethyl acetate (EtAC), n-propyl acetate (NPAC), isopropyl acetate (IPAC), n-butyl acetate (NBAC), isobutyl acetate (IBAC), N-methylpyrrolidone (NMP), acetone (DMK), N,N-dimethylformamide (DMF), acetonitrile (MeCN), N,N- dimethylacetamide (DMAC) and 1,4-dioxane (Diox)” was critically evaluated ranged from 278.15/288.15 K to 323.15 K at 0.1 MPa using laser monitoring method. Experimental solubility data had a general uptrend with the incremental temperature. Simultaneously, IMB solubility in selected mono-solvents showed an obvious order from high to low of: NMP > DMAC > DMF > Diox > DMK > NBAC > NPAC > EtAC > IBAC > IPAC > MeAC > MeCN. In order to explore dissolution behavior, Hirshfeld surface as well as molecular electrostatic potential surface (MEPs) were employed to analyze intermolecular interaction, and result indicated hydrogen bonding was easily formed on >NH group and its opposite position CHCH group. Meanwhile, Hansen solubility parameters (HSPs) were used to investigate solubility order, the result of which suggested that dispersion interaction could be the main factor influenced on solubility order in homologous solvents. Moreover, four activity coefficient models (Margules, UNIQUAC, NRTL, NRTL-SAC model) as well as a combined equation (Jouyban model) were applied for correlation of solubility data with twelve solvents. UNIQUAC model provided the highest regression accuracy among five models in terms of average relative deviation (ARD) lower than 1.178 % and root mean square deviation (RMSD) not higher than 1.176 ‰. Furthermore, based on UNIQUAC equation, thermodynamic properties including dissolution and mixing process were strictly evaluated for further research on solubility behavior. The results demonstrated that both of mixing and dissolution behaviors were spontaneous and entropically driven.

Selectivity comparison of acetonitrile-methanol-water ternary mobile phases on an octadecylsiloxane-bonded silica stationary phase.

The solvation parameter model was used in this study to investigate various intermolecular interactions that influence retention on the standard C18 stationary phase for the solvent system acetonitrile:methanol (ACN:MeOH, 1:1). In comparison to the organic mobile phase modifiers acetonitrile, acetone, methanol, 2-propanol, and tetrahydrofuran, the solvent strength for the ACN:MeOH (1:1) solvent system was evaluated. To facilitate the interpretation of various intermolecular interactions that contribute to retention on a standard C18 stationary phase for the solvent system ACN:MeOH (1:1), system maps were constructed and compared with those of acetone, tetrahydrofuran, acetonitrile, 2-propanol, and methanol. The solvation parameter models were constructed for the ternary solvent system ACN:MeOH (1:1)-water, and in the models constructed, the coefficient of determination values were from 0.998 to 0.999, the Fisher statistic values for the models were from 1687 to 4015, and the standard error of the estimate values ranged from 0.022 to 0.029. The solvent system ACN:MeOH (1:1) has retention properties more similar to methanol than acetonitrile, indicating methanol's influence is more dominant.

Preferential Solvation in Binary Liquid Mixtures with Norbornadiene

Norbornadiene has been found useful in organic and polymer synthesis and recently its mixtures have been found useful in solar energy storage. Structure factors S(0) help to identify structure and binding at microscopic level and also play a significant role in understanding and characterizing exchanges in liquid systems. Preferential solvation Parameter δij provides information about deviation from ideal behavior for the solvent. In this work structure factors S(0) and preferential solvation Parameter δij were evaluated of binary Liquid Mixtures of Norbornadiene with Benzene, Cyclohexane, Decane, and Carbon Tetrachloride using Kirkwood Buff formalism. For the said binary mixtures experimental data pertaining to the calculations were taken from literature. Obtained results indicate that molecules which tend to form dipole interactions or hydrogen bonds form favorable interactions as seen in Norbornadiene + carbon tetrachloride where the small molecule of CCl4 is not sterically hindered to approach the polar Norbornadiene molecule. Long chain and ring structure of carbon have a negative influence on hetero interactions. Studying these parameters will develop predictive techniques to determine the right composition for optimum performance of the liquid mixture.

Correlations of Surface Free Energy and Solubility Parameter with Dielectric Constant and Density for Inorganic Solids.

There should be some intrinsic correlations between the surface free energy (γ) and solubility (δ) parameters, called characteristic parameters here, of substances with their basic physical properties such as the relative dielectric constant (εr) and density (ρ), because they are all related to intermolecular interactions. Several correlations have been proposed empirically (or semiempirically) for liquids, but not for solids. It is essential to establish such correlations for solids because the estimation of γ and δ for solids is difficult and/or time-consuming. In the current work, the γ, δ, εr, and ρ data of 34 inorganic solids were chosen, and possible relationships between the characteristic parameters (γ and δ) and the physical quantities (εr and ρ) were explored by a trial-and-error fitting method based on the data of the solids. Six equations relating γ and δ to εr and δ were established. The γ parameters include total (γt), dispersive (γd), and polar (γp) ones, and the δ parameters include the Hildebrand parameter (δt) and the Hansen-dispersive (δd), polar (δp), and hydrogen-bonding (δh) ones. The empirical equations can be used to estimate the characteristic parameters of inorganic solids from their easily measurable physical quantities.

Reactivity Prediction of Cu-Catalyzed Halogen Atom Transfer Reactions Using Data-Driven Techniques.

In catalysis, linear free energy relationships (LFERs) are commonly used to identify reaction descriptors that enable the prediction of outcomes and the design of more effective catalysts. Herein, LFERs are established for the reductive cleavage of the C(sp3)-X bond in alkyl halides (RX) by Cu complexes. This reaction represents the activation step in atom transfer radical polymerization and atom transfer radical addition/cyclization. The values of the activation rate constant, kact, for 107 Cu complex/RX couples in 5 different solvents spanning over 13 orders of magnitude were effectively interpolated by the equation: log kact = sC(I + C + S), where I, C, and S are, respectively, the initiator, catalyst, and solvent parameters, and sC is the catalyst-specific sensitivity parameter. Furthermore, each of these parameters was correlated to relevant descriptors, which included the bond dissociation free energy of RX and its Tolman cone angle θ, the electron affinity of X, the radical stabilization energy, the standard reduction potential of the Cu complex, the polarizability parameter π* of the solvent, and the distortion energy of the complex in its transition state. This set of descriptors establishes the fundamental properties of Cu complexes and RX that determine their reactivity and that need to be considered when designing novel systems for atom transfer radical reactions. Finally, a multivariate linear regression (MLR) approach was adopted to develop an objective model that surpassed the predictive capability of the LFER equation. Thus, the MLR model was employed to predict kact values for >2000 Cu complex/RX pairs.

Neodymium based acylpyrazolone complexes: Synthesis and physicochemical characterizations

The electronic spectra of three neodymium acylpyrazolone complexes with the compositions [Nd(DMBPMP)3(H2O)(EtOH)] (Nd1), [Nd(DMMCPMP)3(H2O)(EtOH)] (Nd2), and [Nd(DMBPTMP)3(H2O)(EtOH)] (Nd3) have been analyzed. Utilizing ESI-mass, FT-IR, thermogravimetric, and single crystal X-ray diffraction methods, the structure of the DMBPTMP ligand and all three complexes were investigated. According to the single crystal analysis of Nd2, the complex is mononuclear and eight-coordinate (NdO8) with a distorted square antiprismatic geometry. A powder XRD pattern confirmed a similar structural arrangement of the other two complexes. The transition 4G5/2 ← 4I9/2, which is close to the centre of the visible spectrum (∼17,500 cm−1), exhibits hypersensitivity, which stands out in stark contrast to the behaviour of many other typically weak and reliably unchanging, typical 4f-4f transitions. Through a comparative analysis of calculated oscillator strength, Judd-Ofelt parameters, and covalency parameters in various solvents, hypersensitivity, symmetry characteristics, and covalency have been thoroughly investigated. The promotion of 4f-4f electric-dipole intensity has been found to be particularly successful with DMF, DMSO, pyridine and ethanol. Utilizing Judd-Ofelt parameter Ω4 values and Hirshfeld analysis, long-range secondary π⋯π stacking or H-bonding interactions were investigated. Using solid-state emission spectra, intensity of emission spectra and antenna effect energy diagram was examined.

Prediction of cosolvent effect on solvation free energies and analysis of intermolecular forces of tizanidine hydrochloride in ethyl acetate + methanol / ethanol mixtures

The solubility of small molecule drug in solvents can be dramatically affected by addition of a suitable cosolvent, which makes the screening of the best-suited cosolvent an important task for the purification and preparation. The present work aims to improve the fundamental understanding of tizanidine hydrochloride (TIZ HC) solvation by cosolvent. Solubility experimental data from TIZ HCl in mixtures of ethyl acetate + alcohols were obtained at different temperatures with the method of isothermal equilibrium. In the system of ethyl acetate + methanol, the solubility data increased firstly and then decreased with an increase in ethyl acetate content, however, the strictly monotonic decreasing of solubility in ethyl acetate + ethanol mixtures was observed. The solubility correlation fitting was performed with the Jouyban-Acree model and CNIBS/R-K model. The solvent effect analysis indicates that the hydrogen bond acidity, the polarity / polarizability and the cohesive forces of the solvent have a greater influence on the solubility, which was further validated by the local quantitative molecular surface analysis results of electrostatic potential (ESP). The dissolution process of TIZ HCl in systems with different solvent compositions was analyzed in the form of preferential solvation parameters, it was found that methanol is the preferred solvent in the solvation shell of TIZ HCl in methanol-rich and ethyl acetate-rich mixtures but the ethanol is preferred in intermediate compositions and ethyl acetate-rich mixtures. Moreover, the types of intermolecular solute–solvent interactions were discussed on the basis of the structural characteristics of TIZ HCl. The solvation free energy is a key parameter describing solvent effects, which is extremely important for understanding solution chemistry. For this part, with the aid of density functional theory (DFT) and molecular dynamics (MD) simulations, it was found that the cosolvent effect is consistent with the prediction trend of solvation free energy of TIZ HCl in each systems. The effect of the cavity formed by the solvent molecules and dipole moment of solute was calculated accordingly by the solvation model based on density (SMD) for explaining the former behavior.

Structural Features, Emission Analysis, and Covalency Comparison of Neodymium Acylpyrazolone Complexes using Oscillator Strengths, Covalency and Judd‐Ofelt Parameters**

AbstractThree distorted square antiprismatic eight coordinated neodymium acylpyrazolone complexes were synthesized having the compositions [Nd(L1)3(H2O)(EtOH)] (NdL1), [Nd(L2)3(H2O)(EtOH)] (NdL2), and [Nd(L3)3(H2O)(EtOH)] (NdL3). The structure of all three complexes was examined using ESI‐mass, FT‐IR, and thermogravimetric methods. According to the single crystal analysis of NdL1, the complex was found eight‐coordinated (NdO8) with a distorted square antiprismatic geometry. A powder XRD pattern confirmed a similar structural arrangement of the other two complexes. In electronic absorption spectra, the transition 4G5/2←4I9/2, which is close to the centre of the visible spectrum (~17,500 cm−1), exhibits hypersensitivity, which stands out in stark contrast to the behaviour of many other typically weak and reliably unchanging, typical 4f–4f transitions. Through a comparative analysis of calculated oscillator strength, Judd‐Ofelt parameters, root mean square deviation, radiative lifetime and covalency parameters in various solvents, hypersensitivity, symmetry characteristics, and covalency have been thoroughly investigated. The promotion of 4f–4f electric‐dipole intensity has been found to be particularly successful with ethanol, pyridine, DMF, and DMSO. Utilizing Judd‐Ofelt Ω4 values and Hirshfeld analysis, long‐range secondary π⋅⋅⋅π stacking or H‐bonding interactions were investigated. The intensity of emission spectra, quantum yield, stokes shift, and antenna effect energy diagram was examined using solid‐state emission spectra.

Solvatochromism in mixed-chelate of copper(II) with tetramethyl ethylenediamine and 2,4-dihydroxybenzophenone, experimental and computational study

A mixed-chelate copper(II) complex, [Cu(dhbp)(tmeda)(H2O)]ClO4, where dhbp = 2,4-dihydroxybenzophenone and tmeda = tetramethyl ethylenediamine, was synthesized and characterized using various techniques including elemental analysis, molar conductance, UV-Vis, IR spectroscopy, and computational study. The solvatochromic behavior of the complex was investigated by visible spectroscopy, revealing positive solvatochromism. To understand the interaction mechanism between the complex and solvent, six standard solvent parameters (DN, AN, α, β, π*, and ET(30)) were assigned using the stepwise multiple linear regression (SMLR) method. Statistical analysis indicated that the DN parameter of the solvent had the most significant contribution in changing the d-d absorption band of the complex. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were performed to study the electronic structure of the complex and gain insights into the solvatochromism processes. The results suggested that the approach of solvent molecules and coordination to the vacant site of the complex led to a change in its geometry from square pyramidal to octahedral. This geometric transformation caused the d-d transition band of the complex to shift towards the red region with increasing solvent DN, thus explaining the observed solvatochromism.

The influence of thermodynamic qualities of a solvent on the physicochemical properties of lentil protein concentrate – Second virial coefficient study

A protein concentrate (75.2%) was obtained from some Lens culinaris L. seeds. The osmotic, hydrodynamic and surface properties of protein concentrate aqueous solutions were studied with the help of membrane osmometry, dynamic light scattering, ζ-potential and the pendant drop method, in a wide range of protein concentrate concentrations and pH conditions. The second virial coefficient was determined in the range of pH 2–9. Two theta points (pH∼ 5 and pH∼ 8) were found. The change of the hydrodynamic radii as a function of pH and scattering vector was analysed. It was found that the change of the solvent parameters (pH) has a significant influence on the surface tension value. This phenomenon was related to the values of the second virial coefficient and the translational diffusion coefficient. The increase in the value of the diffusion coefficient (smaller hydrodynamic radius) resulted in faster interface formation at the gas–liquid interface.