Pub Date : 2023-08-18DOI: 10.1080/00319104.2023.2248345
Ramya Motati, W. Acree
ABSTRACT Abraham model solute descriptors have been determined for the zwitterionic forms of D-tryptophan and L-tyrosine based on published mole fraction solubility data. The calculated solute descriptors describe the observed solubility data to within standard errors of 0.122 log units (or less). Treatment of each amino acid as a non-zwitterionic molecular compound led to significantly larger standard errors than were observed for the zwitterion form.
{"title":"Abraham model solute descriptors for two additional α-amino acids: D-Tryptophan and L-Tyrosine","authors":"Ramya Motati, W. Acree","doi":"10.1080/00319104.2023.2248345","DOIUrl":"https://doi.org/10.1080/00319104.2023.2248345","url":null,"abstract":"ABSTRACT Abraham model solute descriptors have been determined for the zwitterionic forms of D-tryptophan and L-tyrosine based on published mole fraction solubility data. The calculated solute descriptors describe the observed solubility data to within standard errors of 0.122 log units (or less). Treatment of each amino acid as a non-zwitterionic molecular compound led to significantly larger standard errors than were observed for the zwitterion form.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"7 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89731460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This article summarizes a series of seventeen publications by the authors devoted to molecular dynamics modeling of various indicator dyes (molecular probes) enclosed in surfactant micelles. These dyes serve as generally recognized tools for studying various types of organized solutions, among which surfactant micelles in water are the simplest and most explored. The modeling procedure involves altogether 50 to 95 surfactant molecules, 16 to 28 thousand water molecules, and a single dye molecule. The presentation of the simulation results was preceded by a brief review of the state of experimental studies. This article consists of three parts. First, despite numerous literature data devoted to modeling the micelles itself, we decided to revisit this issue. The structure and hydration of the surface of micelles of surfactants, first of all of sodium n-dodecylsulfate, SDS, and cetyltrimethylammonium bromide, CTAB, were studied. The values of the electrical potential, Ψ, were estimated as functions of the ionic strength and distance from the surface. The decrease in the Ψ value with distance is gradual. Attempts to consider both DS− and CTA+ micelles in water without counterions result in a decay into two smaller aggregates. Obviously, the hydrophobic interaction (association) of the hydrocarbon tails balances the repulsion of the charged headgroups of these small “bare” micelles. The second part is devoted to the study of seven pyridinium N-phenolates, known as Reichardt’s dyes, in ionic micelles. These most powerful solvatochromic indicators are now used for examining various colloidal systems. The localization and orientation of both zwitterionic and (colorless) cationic forms are generally consistent with intuitive ideas about the hydrophobicity of substituents. Hydration has been quantitatively described for both the dye molecule as a whole and the oxygen atom. A number of markers, including the visible absorption spectra of Reichardt’s dyes, enable assuming a better hydration of the micellar surface of SDS than that of CTAB. However, our data show that it is more correct to speak about the more pronounced hydrogen-bonding ability of water molecules in anionic micelles than about better hydration of the SDS micelles as compared to CTAB ones. Finally, a set of acid–base indicators firmly fixed in the micellar pseudophase were studied by molecular dynamics. They are instruments for estimating electrostatic potentials of micelles and related aggregates as Ψ= 2.303RTF−1 (pKai − pKaapp), where pKai and pKaapp are indices of so-called intrinsic and apparent dissociation constants. In this case, in addition to the location, orientation, and hydration, the differences between values of pKaapp and indices of the dissociation constants in water were estimated. Only a semi-quantitative agreement with the experimental data was obtained. However, the differences between pKaapp of a given indicator in two micellar solutions do much better agree with the expe
{"title":"Solvatochromic and Acid–Base Molecular Probes in Surfactant Micelles: Comparison of Molecular Dynamics Simulation with the Experiment","authors":"N. Mchedlov-Petrossyan, V. Farafonov, A. Lebed","doi":"10.3390/liquids3030021","DOIUrl":"https://doi.org/10.3390/liquids3030021","url":null,"abstract":"This article summarizes a series of seventeen publications by the authors devoted to molecular dynamics modeling of various indicator dyes (molecular probes) enclosed in surfactant micelles. These dyes serve as generally recognized tools for studying various types of organized solutions, among which surfactant micelles in water are the simplest and most explored. The modeling procedure involves altogether 50 to 95 surfactant molecules, 16 to 28 thousand water molecules, and a single dye molecule. The presentation of the simulation results was preceded by a brief review of the state of experimental studies. This article consists of three parts. First, despite numerous literature data devoted to modeling the micelles itself, we decided to revisit this issue. The structure and hydration of the surface of micelles of surfactants, first of all of sodium n-dodecylsulfate, SDS, and cetyltrimethylammonium bromide, CTAB, were studied. The values of the electrical potential, Ψ, were estimated as functions of the ionic strength and distance from the surface. The decrease in the Ψ value with distance is gradual. Attempts to consider both DS− and CTA+ micelles in water without counterions result in a decay into two smaller aggregates. Obviously, the hydrophobic interaction (association) of the hydrocarbon tails balances the repulsion of the charged headgroups of these small “bare” micelles. The second part is devoted to the study of seven pyridinium N-phenolates, known as Reichardt’s dyes, in ionic micelles. These most powerful solvatochromic indicators are now used for examining various colloidal systems. The localization and orientation of both zwitterionic and (colorless) cationic forms are generally consistent with intuitive ideas about the hydrophobicity of substituents. Hydration has been quantitatively described for both the dye molecule as a whole and the oxygen atom. A number of markers, including the visible absorption spectra of Reichardt’s dyes, enable assuming a better hydration of the micellar surface of SDS than that of CTAB. However, our data show that it is more correct to speak about the more pronounced hydrogen-bonding ability of water molecules in anionic micelles than about better hydration of the SDS micelles as compared to CTAB ones. Finally, a set of acid–base indicators firmly fixed in the micellar pseudophase were studied by molecular dynamics. They are instruments for estimating electrostatic potentials of micelles and related aggregates as Ψ= 2.303RTF−1 (pKai − pKaapp), where pKai and pKaapp are indices of so-called intrinsic and apparent dissociation constants. In this case, in addition to the location, orientation, and hydration, the differences between values of pKaapp and indices of the dissociation constants in water were estimated. Only a semi-quantitative agreement with the experimental data was obtained. However, the differences between pKaapp of a given indicator in two micellar solutions do much better agree with the expe","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"65 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-08-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75254385","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The concept of “solvent polarity” is widely used to explain the effects of using different solvents in various scientific applications. However, a consensus regarding its definition and quantitative measure is still lacking, hindering progress in solvent-based research. This study hopes to add to the conversation by presenting the development of two linear regression models for solvent polarity, based on Reichardt’s ET(30) solvent polarity scale, using Abraham solvent parameters and a transformer-based model for predicting solvent polarity directly from molecular structure. The first linear model incorporates the standard Abraham solvent descriptors s, a, b, and the extended model ionic descriptors j+ and j−, achieving impressive test-set statistics of R2 = 0.940 (coefficient of determination), MAE = 0.037 (mean absolute error), and RMSE = 0.050 (Root-Mean-Square Error). The second model, covering a more extensive chemical space but only using the descriptors s, a, and b, achieves test-set statistics of R2 = 0.842, MAE = 0.085, and RMSE = 0.104. The transformer-based model, applicable to any solvent with an associated SMILES string, achieves test-set statistics of R2 = 0.824, MAE = 0.066, and RMSE = 0.095. Our findings highlight the significance of Abraham solvent parameters, especially the dipolarity/polarizability, hydrogen-bond acidity/basicity, and ionic descriptors, in predicting solvent polarity. These models offer valuable insights for researchers interested in Reichardt’s ET(30) solvent polarity parameter and solvent polarity in general.
{"title":"Reichardt’s Dye-Based Solvent Polarity and Abraham Solvent Parameters: Examining Correlations and Predictive Modeling","authors":"William E. Acree, Andrew S. I. D. Lang","doi":"10.3390/liquids3030020","DOIUrl":"https://doi.org/10.3390/liquids3030020","url":null,"abstract":"The concept of “solvent polarity” is widely used to explain the effects of using different solvents in various scientific applications. However, a consensus regarding its definition and quantitative measure is still lacking, hindering progress in solvent-based research. This study hopes to add to the conversation by presenting the development of two linear regression models for solvent polarity, based on Reichardt’s ET(30) solvent polarity scale, using Abraham solvent parameters and a transformer-based model for predicting solvent polarity directly from molecular structure. The first linear model incorporates the standard Abraham solvent descriptors s, a, b, and the extended model ionic descriptors j+ and j−, achieving impressive test-set statistics of R2 = 0.940 (coefficient of determination), MAE = 0.037 (mean absolute error), and RMSE = 0.050 (Root-Mean-Square Error). The second model, covering a more extensive chemical space but only using the descriptors s, a, and b, achieves test-set statistics of R2 = 0.842, MAE = 0.085, and RMSE = 0.104. The transformer-based model, applicable to any solvent with an associated SMILES string, achieves test-set statistics of R2 = 0.824, MAE = 0.066, and RMSE = 0.095. Our findings highlight the significance of Abraham solvent parameters, especially the dipolarity/polarizability, hydrogen-bond acidity/basicity, and ionic descriptors, in predicting solvent polarity. These models offer valuable insights for researchers interested in Reichardt’s ET(30) solvent polarity parameter and solvent polarity in general.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-08-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135016460","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-29DOI: 10.1080/00319104.2023.2234546
B. Siva Parvathi, M. Gowrisankar, R. Balaji, V. Anuradha
ABSTRACT The density (ρ), viscosity (η), and speed of sound (u) are reported for binary mixtures of N-methylpiperazine with aliphatic primary alcohols (propan-1-ol, 2-propen-1-ol, 2-propyn-1-ol) over the entire composition range from 303.15 K to 313.15 K and at atmospheric pressure 0.1 MPa. The excess parameters (VE,κs E), deviation in viscosity, and excess partial properties ( , and ) of the components at infinite dilution were calculated from the density, speed of sound, and viscosity at experimental temperatures. All the investigated systems exhibit positive values of ∆η and ∆G *E and negative values of VE and κs E over the whole composition range. The obvious deviations attribute to the association between the primary alcohols and N-methyl piperazine molecules through the hydrogen bond of O-H· · ·N. A good agreement is obtained between excess quantities and FTIR spectroscopic data.
本文报道了n-甲基哌嗪与脂肪族伯醇(丙烯-1-醇、2-丙烯-1-醇、2-丙烯-1-醇)二元混合物在303.15 K ~ 313.15 K和0.1 MPa大气压下的密度(ρ)、粘度(η)和声速(u)。根据实验温度下的密度、声速和粘度，计算了无限稀释条件下组分的过量参数(VE，κs E)、粘度偏差和过量偏性(和)。在整个组成范围内，各体系的∆η和∆G *E均为正值，而VE和κs E均为负值。这种明显的偏差归因于伯醇与N-甲基哌嗪分子之间通过O-H··N氢键的结合。过量量与FTIR光谱数据吻合较好。
{"title":"Thermodynamics and spectroscopic properties of N-methylpiperazine with propan-1-ol, 2-propen-1-ol, 2-propyn-1-ol","authors":"B. Siva Parvathi, M. Gowrisankar, R. Balaji, V. Anuradha","doi":"10.1080/00319104.2023.2234546","DOIUrl":"https://doi.org/10.1080/00319104.2023.2234546","url":null,"abstract":"ABSTRACT The density (ρ), viscosity (η), and speed of sound (u) are reported for binary mixtures of N-methylpiperazine with aliphatic primary alcohols (propan-1-ol, 2-propen-1-ol, 2-propyn-1-ol) over the entire composition range from 303.15 K to 313.15 K and at atmospheric pressure 0.1 MPa. The excess parameters (VE,κs E), deviation in viscosity, and excess partial properties ( , and ) of the components at infinite dilution were calculated from the density, speed of sound, and viscosity at experimental temperatures. All the investigated systems exhibit positive values of ∆η and ∆G *E and negative values of VE and κs E over the whole composition range. The obvious deviations attribute to the association between the primary alcohols and N-methyl piperazine molecules through the hydrogen bond of O-H· · ·N. A good agreement is obtained between excess quantities and FTIR spectroscopic data.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"10 1","pages":"386 - 404"},"PeriodicalIF":1.2,"publicationDate":"2023-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78474889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
ABSTRACT Mole fraction solubilities of 4-tert-butylbenzoic acid, 3-chlorobenzoic acid, 2-methyl-3-nitrobenzoic acid, 3-methyl-4-nitrobenzoic acid, 3,4,5-trimethoxybenzoic acid, isophthalic acid, 3-hydroxybenzoic acid, o-acetoacetaniside, 2,4-dihydroxybenzophenone, benzoin, paracetamol, and 1,4-dichloro-2-nitrobenzene in 2-pentanol at 298.15 K. Results of the experimental measurements, combined with published literature data, were used to calculated revised equation coefficients for the Abraham model correlations for the 2-pentanol solvent. Revised equation coefficients are also reported for the 3-methyl-1-butanol Abraham model correlations based on much larger data sets containing 95 experimental data points.
{"title":"Updated Abraham model correlations for describing solute transfer into both 2-Pentanol and 3-Methyl-1-butanol based on much larger data sets","authors":"Trisha Kandi, Ramya Motati, Saikiran Motati, Nikita Shanmugam, Amy Zhou, Emily Yao, Catherine Webber, W. Acree","doi":"10.1080/00319104.2023.2235709","DOIUrl":"https://doi.org/10.1080/00319104.2023.2235709","url":null,"abstract":"ABSTRACT Mole fraction solubilities of 4-tert-butylbenzoic acid, 3-chlorobenzoic acid, 2-methyl-3-nitrobenzoic acid, 3-methyl-4-nitrobenzoic acid, 3,4,5-trimethoxybenzoic acid, isophthalic acid, 3-hydroxybenzoic acid, o-acetoacetaniside, 2,4-dihydroxybenzophenone, benzoin, paracetamol, and 1,4-dichloro-2-nitrobenzene in 2-pentanol at 298.15 K. Results of the experimental measurements, combined with published literature data, were used to calculated revised equation coefficients for the Abraham model correlations for the 2-pentanol solvent. Revised equation coefficients are also reported for the 3-methyl-1-butanol Abraham model correlations based on much larger data sets containing 95 experimental data points.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"74 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75913770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-11DOI: 10.1080/00319104.2023.2234545
Deepa R. Parmar, M. Rani, Nuha Wazzan, Shruti Jain, Naveen Kumar
ABSTRACT Physicochemical properties of pure liquids and their liquid mixtures at different compositions and at different temperatures have a significant role in the optimisation of chemical processes. Present report involves the analysis of the physicochemical properties of 1,3-diaminopropane and alkyl acetate. The viscosity ( ) and refractive index ( ) of 1,3-Diaminopropane, 1,3-DAP (1), with alkyl acetates, AAc, (C1-C4) (2) were measured at different temperatures (T = 303.15 to 318.15 K) under the atmospheric pressure 0.1 MPa. Deviation in viscosity, , deviation in refractive index, , and excess Gibbs free energy of activation, for these binary mixtures were calculated from measured viscosity and refractive index data and fitted to Redlich-Kister polynomial equation (R.K.). The data were analysed in terms of the Graph theoretical approach (GTA) to study the interactions in binary mixtures. The values were also correlated by using Bloomfield and Dewan (BFD) model and various correlations. data were correlated by various relevant correlations.
纯液体及其液体混合物在不同组成和不同温度下的物理化学性质对化学工艺的优化具有重要作用。本文分析了1,3-二氨基丙烷和乙酸烷基酯的理化性质。测定了1,3-二氨基丙烷1,3- dap(1)与乙酸烷基酯AAc (C1-C4)(2)在不同温度(T = 303.15 ~ 318.15 K)和0.1 MPa大气压下的粘度()和折射率()。根据测量的粘度和折射率数据，计算了这些二元混合物的粘度偏差、折射率偏差和过量吉布斯自由活化能，并拟合到Redlich-Kister多项式方程(R.K.)中。用图理论方法(GTA)对数据进行分析，研究二元混合物中的相互作用。并利用Bloomfield and Dewan (BFD)模型和各种相关性对数值进行相关性分析。数据通过各种相关关系进行关联。
{"title":"Transport and optical properties of the binary liquid mixture containing 1,3-diaminopropane and alkyl acetates (C1-C4) at T= (303.15-318.15) K: experimental investigations and theoretical modelling","authors":"Deepa R. Parmar, M. Rani, Nuha Wazzan, Shruti Jain, Naveen Kumar","doi":"10.1080/00319104.2023.2234545","DOIUrl":"https://doi.org/10.1080/00319104.2023.2234545","url":null,"abstract":"ABSTRACT Physicochemical properties of pure liquids and their liquid mixtures at different compositions and at different temperatures have a significant role in the optimisation of chemical processes. Present report involves the analysis of the physicochemical properties of 1,3-diaminopropane and alkyl acetate. The viscosity ( ) and refractive index ( ) of 1,3-Diaminopropane, 1,3-DAP (1), with alkyl acetates, AAc, (C1-C4) (2) were measured at different temperatures (T = 303.15 to 318.15 K) under the atmospheric pressure 0.1 MPa. Deviation in viscosity, , deviation in refractive index, , and excess Gibbs free energy of activation, for these binary mixtures were calculated from measured viscosity and refractive index data and fitted to Redlich-Kister polynomial equation (R.K.). The data were analysed in terms of the Graph theoretical approach (GTA) to study the interactions in binary mixtures. The values were also correlated by using Bloomfield and Dewan (BFD) model and various correlations. data were correlated by various relevant correlations.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"103 1","pages":"365 - 385"},"PeriodicalIF":1.2,"publicationDate":"2023-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82132674","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-07-07DOI: 10.1080/00319104.2023.2234124
H. Yurtseven, O. Tari
ABSTRACT The Landau model is used to calculate the T – X phase diagram and the temperature dependence of the thermodynamic quantities near the phase transitions in the binary mixtures of tetradecane + hexadecane. The phase line equations are fitted to the experimental T – X phase diagram (liquidus + solid solution + solidus) and to the temperature dependence of the enthalpy for the solid (triclinic) solution + solid (rotator) solution from the literature for this binary mixture. By determining the fitted parameters, the thermodynamic quantities are calculated near the phase transitions in the tetradecane + hexadecane. Our T- X phase diagram explains the observed behaviour of the transitions for the binary mixtures studied. On the basis of the experimental enthalpy, calculated thermodynamic quantities exhibit the expected critical behaviour near the phase transitions from the Landau mean field model, which can be compared with the experimental data for tetradecane + hexadecane.
{"title":"Calculation of the T - X phase diagram and the thermodynamic quantities for the binary mixtures of Tetradecane + Hexadecane using the Landau mean field model","authors":"H. Yurtseven, O. Tari","doi":"10.1080/00319104.2023.2234124","DOIUrl":"https://doi.org/10.1080/00319104.2023.2234124","url":null,"abstract":"ABSTRACT The Landau model is used to calculate the T – X phase diagram and the temperature dependence of the thermodynamic quantities near the phase transitions in the binary mixtures of tetradecane + hexadecane. The phase line equations are fitted to the experimental T – X phase diagram (liquidus + solid solution + solidus) and to the temperature dependence of the enthalpy for the solid (triclinic) solution + solid (rotator) solution from the literature for this binary mixture. By determining the fitted parameters, the thermodynamic quantities are calculated near the phase transitions in the tetradecane + hexadecane. Our T- X phase diagram explains the observed behaviour of the transitions for the binary mixtures studied. On the basis of the experimental enthalpy, calculated thermodynamic quantities exhibit the expected critical behaviour near the phase transitions from the Landau mean field model, which can be compared with the experimental data for tetradecane + hexadecane.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"308 1","pages":"340 - 364"},"PeriodicalIF":1.2,"publicationDate":"2023-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77405343","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Yamaguchi, Nami Fukuyama, K. Yoshida, Y. Katayama, S. Machida, T. Hattori
The structure of electrolyte solutions under pressure at a molecular level is a crucial issue in the fundamental science of understanding the nature of ion solvation and association and application fields, such as geological processes on the Earth, pressure-induced protein denaturation, and supercritical water technology. We report the structure of an aqueous 2 m (=mol kg−1) MgCl2 solution at pressures from 0.1 MPa to 4 GPa and temperatures from 300 to 500 K revealed by X-ray- and neutron-scattering measurements. The scattering data are analyzed by empirical potential structure refinement (EPSR) modeling to derive the pair distribution functions, coordination number distributions, angle distributions, and spatial density functions (3D structure) as a function of pressure and temperature. Mg2+ forms rigid solvation shells extended to the third shell; the first solvation shell of six-fold octahedral coordination with about six water molecules at 0 GPa transforms into about five water molecules and one Cl− due to the formation of the contact ion pairs in the GPa pressure range. The Cl− solvation shows a substantial pressure dependence; the coordination number of a water oxygen atom around Cl− increases from 8 at 0.1 MPa/300 K to 10 at 4 GPa/500 K. The solvent water transforms the tetrahedral network structure at 0.1 MPa/300 K to a densely packed structure in the GPa pressure range; the number of water oxygen atoms around a central water molecule gradually increases from 4.6 at 0.1 MPa/298 K to 8.4 at 4 GPa/500 K.
{"title":"An X-ray and Neutron Scattering Study of Aqueous MgCl2 Solution in the Gigapascal Pressure Range","authors":"T. Yamaguchi, Nami Fukuyama, K. Yoshida, Y. Katayama, S. Machida, T. Hattori","doi":"10.3390/liquids3030019","DOIUrl":"https://doi.org/10.3390/liquids3030019","url":null,"abstract":"The structure of electrolyte solutions under pressure at a molecular level is a crucial issue in the fundamental science of understanding the nature of ion solvation and association and application fields, such as geological processes on the Earth, pressure-induced protein denaturation, and supercritical water technology. We report the structure of an aqueous 2 m (=mol kg−1) MgCl2 solution at pressures from 0.1 MPa to 4 GPa and temperatures from 300 to 500 K revealed by X-ray- and neutron-scattering measurements. The scattering data are analyzed by empirical potential structure refinement (EPSR) modeling to derive the pair distribution functions, coordination number distributions, angle distributions, and spatial density functions (3D structure) as a function of pressure and temperature. Mg2+ forms rigid solvation shells extended to the third shell; the first solvation shell of six-fold octahedral coordination with about six water molecules at 0 GPa transforms into about five water molecules and one Cl− due to the formation of the contact ion pairs in the GPa pressure range. The Cl− solvation shows a substantial pressure dependence; the coordination number of a water oxygen atom around Cl− increases from 8 at 0.1 MPa/300 K to 10 at 4 GPa/500 K. The solvent water transforms the tetrahedral network structure at 0.1 MPa/300 K to a densely packed structure in the GPa pressure range; the number of water oxygen atoms around a central water molecule gradually increases from 4.6 at 0.1 MPa/298 K to 8.4 at 4 GPa/500 K.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"EM-32 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84532325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The hydration of phosphate ions, an essential component of many biological molecules, is studied using all-atom molecular dynamics (MD) simulation and quantum chemical methods. MD simulations are carried out by employing a mean-field polarizable water model. A good linear correlation between the self-diffusion coefficient and phosphate anion concentration is ascertained from the computed mean-square displacement (MSD) profiles. The HB dynamics of the hydration of the phosphate anion is evaluated from the time-dependent autocorrelation function CHB(t) and is determined to be slightly faster for the phosphate–anion system as compared to that of the water–water system at room temperature. The coordination number (CN) of the phosphate ion is found to be 15.9 at 298 K with 0.05 M phosphate ion concentration. The average CN is also calculated to be 15.6 for the same system by employing non-equilibrium MD simulation, namely, the well-tempered meta-dynamics method. A full geometry optimization of the PO43−·16H2O cluster is investigated at the ωB97X-D/aug-cc-pVTZ level of theory, and the hydration of the phosphate anion is observed to have both singly and doubly bonded anion–water hydrogen bonds and inter-water hydrogen bonds in a range between 0.169–0.201 nm and 0.192–0.215 nm, respectively. Modified Stokes–Einstein relation is used to calculate the conductivity of the phosphate ion and is found to be in good agreement with the experimentally observed value.
{"title":"Hydration of Phosphate Ion in Polarizable Water: Effect of Temperature and Concentration","authors":"S. Verma, A. K. Pathak","doi":"10.3390/liquids3030018","DOIUrl":"https://doi.org/10.3390/liquids3030018","url":null,"abstract":"The hydration of phosphate ions, an essential component of many biological molecules, is studied using all-atom molecular dynamics (MD) simulation and quantum chemical methods. MD simulations are carried out by employing a mean-field polarizable water model. A good linear correlation between the self-diffusion coefficient and phosphate anion concentration is ascertained from the computed mean-square displacement (MSD) profiles. The HB dynamics of the hydration of the phosphate anion is evaluated from the time-dependent autocorrelation function CHB(t) and is determined to be slightly faster for the phosphate–anion system as compared to that of the water–water system at room temperature. The coordination number (CN) of the phosphate ion is found to be 15.9 at 298 K with 0.05 M phosphate ion concentration. The average CN is also calculated to be 15.6 for the same system by employing non-equilibrium MD simulation, namely, the well-tempered meta-dynamics method. A full geometry optimization of the PO43−·16H2O cluster is investigated at the ωB97X-D/aug-cc-pVTZ level of theory, and the hydration of the phosphate anion is observed to have both singly and doubly bonded anion–water hydrogen bonds and inter-water hydrogen bonds in a range between 0.169–0.201 nm and 0.192–0.215 nm, respectively. Modified Stokes–Einstein relation is used to calculate the conductivity of the phosphate ion and is found to be in good agreement with the experimentally observed value.","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"1 1","pages":""},"PeriodicalIF":1.2,"publicationDate":"2023-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87022370","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-06-19DOI: 10.1080/00319104.2023.2225205
B. Meenakshi, P. Bharath, S. Mubeena, M. G. Sankar, D. Ramachandran
ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy for activation of viscous flow for binary mixtures of 4-hydroxy-4-methyl-2-pentanone e (DAA) with 1-butanol (B1), 2-butanol(B2) and 2-methyl-2-propanol(B3) components selected compositions were determined from the measured values of densities (ρ), viscosities ( ), and speeds of sound (u) of pure components and their mixtures at from 303.15 K to 313.15 K. The results are analysed in terms of intermolecular interactions or hydrogen bonding or hetero-association interactions in the binary mixtures. Prigogine-Flory-Patterson (PFP) theory is applied to identify the predominant molecular interaction. Jouyban-Acree model results are discussed in terms of mean relative deviation (MRDs) and individual relative deviation (IRD) between calculated and experimental densities, speeds of sound and viscosities as an accuracy criterion
在303.15 K ~ 313.15 K范围内测定了4-羟基-4-甲基-2-戊酮e (DAA)与1-丁醇(B1)、2-丁醇(B2)和2-甲基-2-丙醇(B3)二元混合物的密度(ρ)、粘度()和声速(u)，确定了DAA与1-丁醇(B1)、2-丁醇(B2)和2-甲基-2-丙醇(B3)二元混合物的超摩尔体积、超等熵压缩率、粘度偏差和超吉布斯自由能。根据二元混合物中的分子间相互作用或氢键或异缔合相互作用对结果进行了分析。Prigogine-Flory-Patterson (PFP)理论被应用于识别主要的分子相互作用。对Jouyban-Acree模型结果进行了讨论，以计算密度、声速和粘度之间的平均相对偏差(MRDs)和个体相对偏差(IRD)作为精度准则
{"title":"Thermo physical properties of diacetone alcohol with isomer butanols at different temperatures and correlation with the Jouyban–Acree model","authors":"B. Meenakshi, P. Bharath, S. Mubeena, M. G. Sankar, D. Ramachandran","doi":"10.1080/00319104.2023.2225205","DOIUrl":"https://doi.org/10.1080/00319104.2023.2225205","url":null,"abstract":"ABSTRACT Excess molar volume, excess isentropic compressibility, deviation in viscosity and excess Gibbs free energy for activation of viscous flow for binary mixtures of 4-hydroxy-4-methyl-2-pentanone e (DAA) with 1-butanol (B1), 2-butanol(B2) and 2-methyl-2-propanol(B3) components selected compositions were determined from the measured values of densities (ρ), viscosities ( ), and speeds of sound (u) of pure components and their mixtures at from 303.15 K to 313.15 K. The results are analysed in terms of intermolecular interactions or hydrogen bonding or hetero-association interactions in the binary mixtures. Prigogine-Flory-Patterson (PFP) theory is applied to identify the predominant molecular interaction. Jouyban-Acree model results are discussed in terms of mean relative deviation (MRDs) and individual relative deviation (IRD) between calculated and experimental densities, speeds of sound and viscosities as an accuracy criterion","PeriodicalId":20094,"journal":{"name":"Physics and Chemistry of Liquids","volume":"54 1","pages":"312 - 327"},"PeriodicalIF":1.2,"publicationDate":"2023-06-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91350756","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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