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22 pages, 2987 KiB

Open AccessArticle

A Machine Learning Free Energy Functional for the 1D Reference Interaction Site Model: Towards Prediction of Solvation Free Energy for All Solvent Systems

by Jonathan G. M. Conn, Abdullah Ahmad and David S. Palmer

Liquids 2024, 4(4), 710-731; https://doi.org/10.3390/liquids4040040 - 8 Nov 2024

Viewed by 256

Abstract

Understanding the interactions between solutes and solvents is vital in many areas of the chemical sciences. Solvation free energy (SFE) is an important thermodynamic property in characterising molecular solvation and so accurate prediction of this property is sought after. The One-Dimensional Reference Interaction [...] Read more.

Understanding the interactions between solutes and solvents is vital in many areas of the chemical sciences. Solvation free energy (SFE) is an important thermodynamic property in characterising molecular solvation and so accurate prediction of this property is sought after. The One-Dimensional Reference Interaction Site Model (RISM) is a well-established method for modelling solvation, but it is known to yield large errors in the calculation of SFE. In this work, we show that a single machine learning free energy functional for RISM can accurately model solvation thermodynamics in multiple solvents. A convolutional neural network is trained on solvation free energy density functions calculated by RISM for small organic molecules in approximately 100 different solvent systems. We achieve an average RMSE of 1.41 kcal/mol and an

R^{2}

of 0.89 across all solvent systems. We also compare the performance for the most and least commonly represented solvents and show that higher accuracy is generally seen with higher volumes of data, with RMSE values of 0.69–1.29 kcal/mol and

R^{2}

values of 0.78–0.97 for solvents with more than 50 data points. We have shown that machine learning can greatly improve solvation free energy predictions in RISM, while demonstrating that the methodology is generalisable across solvent systems. This represents a significant step towards a universal machine learning SFE functional for RISM. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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8 pages, 484 KiB

Open AccessArticle

On the Diffusion of Anti-Tuberculosis Drugs in Cyclodextrin-Containing Aqueous Solutions

by M. Melia Rodrigo, Ana M. T. D. P. V. Cabral, Sónia I. G. Fangaia, Afonso C. Nogueira, Artur J. M. Valente, Ana C. F. Ribeiro and Miguel A. Esteso

Liquids 2024, 4(4), 702-709; https://doi.org/10.3390/liquids4040039 - 12 Oct 2024

Viewed by 420

Abstract

In this work, we propose a comprehensive experimental study of the diffusion of isoniazid, one of the first-line anti-tuberculosis drugs, in combination with another drug (ethambutol dihydrochloride) and with different cyclodextrins as carrier molecules, for facilitated transport and enhanced solubility. For that, ternary [...] Read more.

In this work, we propose a comprehensive experimental study of the diffusion of isoniazid, one of the first-line anti-tuberculosis drugs, in combination with another drug (ethambutol dihydrochloride) and with different cyclodextrins as carrier molecules, for facilitated transport and enhanced solubility. For that, ternary mutual diffusion coefficients measured by the Taylor dispersion method (D₁₁, D₂₂, D₁₂, and D₂₁) are determined for aqueous solutions containing isoniazid and different cyclodextrins (that is, α–CD, β–CD, and γ–CD) at 298.15 K. From the significant effect of the presence of these carbohydrates on the diffusion of this drug, interactions between these components are suggested. Support for this arose from models, which shows that these effects may be due to the formation of 1:1 (CDs:isoniazid) complexes. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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13 pages, 2850 KiB

Open AccessArticle

Thermodynamic Properties of Two Cinnamate Derivatives with Flavor and Fragrance Features

by Vera L. S. Freitas, Carlos A. O. Silva and Maria D. M. C. Ribeiro da Silva

Liquids 2024, 4(4), 689-701; https://doi.org/10.3390/liquids4040038 - 11 Oct 2024

Viewed by 542

Abstract

The standard molar enthalpies of formation in the liquid phase for ethyl (E)-cinnamate and ethyl hydrocinnamate, two cinnamate derivatives with notable flavor and fragrance characteristics, were determined experimentally using combustion calorimetry in an oxygen atmosphere. To derive the gas-phase enthalpies of [...] Read more.

The standard molar enthalpies of formation in the liquid phase for ethyl (E)-cinnamate and ethyl hydrocinnamate, two cinnamate derivatives with notable flavor and fragrance characteristics, were determined experimentally using combustion calorimetry in an oxygen atmosphere. To derive the gas-phase enthalpies of formation for these derivatives, their enthalpies of vaporization were measured using a high-temperature Calvet microcalorimeter and the vacuum drop microcalorimetric technique. Additionally, a computational analysis employing the G3(MP2)//B3LYP composite method was conducted to calculate the gas-phase standard enthalpies of formation at T = 298.15 K for both compounds. These findings enabled a detailed assessment and analysis of the structural and energetic effects of the vinyl and ethane moieties between the phenyl and carboxylic groups in the studied compounds. Considering the structural features of ethyl (E)-cinnamate and ethyl hydrocinnamate, a gas-phase enthalpy of hydrogenation analysis was conducted to explore their energetic profiles more thoroughly. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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26 pages, 1298 KiB

Open AccessArticle

Quantum Chemical (QC) Calculations and Linear Solvation Energy Relationships (LSER): Hydrogen-Bonding Calculations with New QC-LSER Molecular Descriptors

by Costas Panayiotou

Liquids 2024, 4(4), 663-688; https://doi.org/10.3390/liquids4040037 - 4 Oct 2024

Viewed by 496

Abstract

A new method, based on quantum chemical calculations, is proposed for the thermodynamically consistent reformulation of QSPR-type Linear Free-Energy Relationship (LFER) models. This reformulation permits the extraction of valuable information on intermolecular interactions and its transfer in other LFER-type models, in acidity/basicity scales, [...] Read more.

A new method, based on quantum chemical calculations, is proposed for the thermodynamically consistent reformulation of QSPR-type Linear Free-Energy Relationship (LFER) models. This reformulation permits the extraction of valuable information on intermolecular interactions and its transfer in other LFER-type models, in acidity/basicity scales, or even in equation-of-state models. New molecular descriptors of electrostatic interactions are derived from the distribution of molecular surface charges obtained from COSMO-type quantum chemical calculations. The widely used and very successful Abraham’s Linear Solvation Energy Relationship (LSER) model is selected as the reference LSER model for the calculations in solute–solvent systems as well as in solute self-solvation. Hydrogen-bonding free energies, enthalpies, and entropies are now derived for a variety of common solutes. The capacity of the method to address the role of conformational changes in solvation quantities is discussed. The perspectives of the LSER model with the implementation of the new descriptors are also discussed. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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16 pages, 672 KiB

Open AccessArticle

Effect of Intramolecular Hydrogen Bond Formation on the Abraham Model Solute Descriptors for Oxybenzone

by Jocelyn Chen, Audrey Chen, Yixuan Yang and William E. Acree

Liquids 2024, 4(3), 647-662; https://doi.org/10.3390/liquids4030036 - 16 Sep 2024

Viewed by 465

Abstract

Solute descriptors derived from experimental solubility data for oxybenzone dissolved in 21 different organic solvents indicate that the hydrogen atom on the hydroxyl functional group forms an intramolecular hydrogen bond with the lone electron pair on the oxygen atom of the neighboring >C=O [...] Read more.

Solute descriptors derived from experimental solubility data for oxybenzone dissolved in 21 different organic solvents indicate that the hydrogen atom on the hydroxyl functional group forms an intramolecular hydrogen bond with the lone electron pair on the oxygen atom of the neighboring >C=O functional group. Group contribution methods developed for estimating the Abraham model solute descriptors from the molecule’s Canonical SMILES code significantly over-estimate the Abraham model’s hydrogen bond acidity solute descriptor of oxybenzone. An informed user-modified Canonical SMILES code is proposed to identify which hydrogen atoms are involved in intramolecular H-bond formation. The identified hydrogen atom(s) can be used to define a new functional/fragment group and numerical group contribution value. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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15 pages, 3117 KiB

Open AccessArticle

Nanoheterogeneity in Protic and Aprotic Alkylimidazolium Bistriflimide Ionic Liquids

by Timur I. Magsumov and Igor A. Sedov

Liquids 2024, 4(3), 632-646; https://doi.org/10.3390/liquids4030035 - 15 Sep 2024

Viewed by 426

Abstract

Many ionic liquids, including alkylimidazolium salts, form a nanoheterogeneous structure with polar and apolar domains in their liquid phase. Using molecular dynamics simulations, the influence of the structure of the cations of a series of aprotic ([C_nC₁Im][TFSI], [C_n [...] Read more.

Many ionic liquids, including alkylimidazolium salts, form a nanoheterogeneous structure with polar and apolar domains in their liquid phase. Using molecular dynamics simulations, the influence of the structure of the cations of a series of aprotic ([C_nC₁Im][TFSI], [C_nC_nIm][TFSI]) and protic ([HC_nIm][TFSI]) alkylimidazolium bistrilimides on the domain structure of their liquid phase was studied. The characteristic sizes of domains and the extent of domain segregation in different liquids have been compared. It has been shown that the latter, but not the former, is a key factor determining the magnitude of the Gibbs free energy of cavity formation in nanostructured ionic liquids, which in turn governs their solvation properties. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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8 pages, 267 KiB

Open AccessArticle

Calculation of Hydrogen Bonding Enthalpy Using the Two-Parameter Abraham Equation

by Boris N. Solomonov, Mansur B. Khisamiev and Mikhail I. Yagofarov

Liquids 2024, 4(3), 624-631; https://doi.org/10.3390/liquids4030034 - 6 Sep 2024

Viewed by 563

Abstract

In this work, an approach to the calculation of hydrogen bonding enthalpies is proposed. It employs the correlation proposed by M.H. Abraham, establishing the connection between the equilibrium constant (K_HB) and acidity (

α_{2}^{H}

) and basicity ( [...] Read more.

In this work, an approach to the calculation of hydrogen bonding enthalpies is proposed. It employs the correlation proposed by M.H. Abraham, establishing the connection between the equilibrium constant (K_HB) and acidity (

α_{2}^{H}

) and basicity (

β_{2}^{H}

) parameters: log K_HB = 7.354 ·

α_{2}^{H}

·

β_{2}^{H}

− 1.099. Hydrogen bonding enthalpy (Δ_HBH) is found using the compensation relationship with Gibbs energy (Δ_HBG): Δ_HBG = 0.66 · Δ_HBH + 2.5 kJ·mol⁻¹. This relationship enables the calculation of the enthalpy, Gibbs energy and entropy of hydrogen bonding. The validity of this approach was tested against 122 experimental hydrogen bonding enthalpies values available from the literature. The root mean square deviation and average deviation equaled 1.6 kJ·mol⁻¹ and 0.5 kJ·mol⁻¹, respectively. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

11 pages, 1820 KiB

Open AccessArticle

Vaporisation Thermodynamics: Are Triazolium Ionic Liquids a Real Alternative to Popular Imidazolium-Based Ionic Liquids?

by Sergey P. Verevkin and Dzmitry H. Zaitsau

Liquids 2024, 4(3), 581-591; https://doi.org/10.3390/liquids4030032 - 20 Aug 2024

Cited by 1 | Viewed by 443

Abstract

New experimental vapour pressures and vaporisation enthalpies of the ionic liquids [2,4-dimethyl-1,2,4-triazolium][NTf₂], [2-methyl-4-ethyl-1,2,4-triazolium][NTf₂], and [2-ethyl-4-methyl-1,2,4-triazolium][NTf₂] were measured using the Langmuir method in combination with the quartz crystal microbalance. New experimental vapour pressures and vaporisation enthalpies of the [...] Read more.

New experimental vapour pressures and vaporisation enthalpies of the ionic liquids [2,4-dimethyl-1,2,4-triazolium][NTf₂], [2-methyl-4-ethyl-1,2,4-triazolium][NTf₂], and [2-ethyl-4-methyl-1,2,4-triazolium][NTf₂] were measured using the Langmuir method in combination with the quartz crystal microbalance. New experimental vapour pressures and vaporisation enthalpies of the molecular liquids 1H-1,2,4-triazole, 1-methyl-1,2,4-triazole, 1-ethyl-1,2,4-triazole, and 1H-1,2,3-triazole were measured using the transpiration method. Structure–property relationships between molecular and ionic liquids were studied. These results will facilitate chemical engineering calculations of processes involving ILs. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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14 pages, 1992 KiB

Open AccessArticle

Solvation Enthalpies and Free Energies for Organic Solvents through a Dense Neural Network: A Generalized-Born Approach

by Sergei F. Vyboishchikov

Liquids 2024, 4(3), 525-538; https://doi.org/10.3390/liquids4030030 - 12 Aug 2024

Viewed by 649

Abstract

A dense artificial neural network, ESE-ΔH-DNN, with two hidden layers for calculating both solvation free energies ΔG°_solv and enthalpies ΔH°_solv for neutral solutes in organic solvents is proposed. The input features are generalized-Born-type monatomic and pair electrostatic [...] Read more.

A dense artificial neural network, ESE-ΔH-DNN, with two hidden layers for calculating both solvation free energies ΔG°_solv and enthalpies ΔH°_solv for neutral solutes in organic solvents is proposed. The input features are generalized-Born-type monatomic and pair electrostatic terms, the molecular volume, and atomic surface areas of the solute, as well as five easily available properties of the solvent. ESE-ΔH-DNN is quite accurate for ΔG°_solv, with an RMSE (root mean square error) below 0.6 kcal/mol and an MAE (mean absolute error) well below 0.4 kcal/mol. It performs particularly well for alkane, aromatic, ester, and ketone solvents. ESE-ΔH-DNN also exhibits a fairly good accuracy for ΔH°_solv prediction, with an RMSE below 1 kcal/mol and an MAE of about 0.6 kcal/mol. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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7 pages, 844 KiB

Open AccessArticle

AbraLlama: Predicting Abraham Model Solute Descriptors and Modified Solvent Parameters Using Llama

by Andrew S. I. D. Lang and Youngmin Lee

Liquids 2024, 4(3), 518-524; https://doi.org/10.3390/liquids4030029 - 2 Aug 2024

Cited by 2 | Viewed by 1337

Abstract

This study explores the application of fine-tuned large language models for predicting physicochemical properties, specifically focusing on Abraham model solute descriptors (E, S, A, B, V) and modified solvent parameters (e₀, s₀, a₀, b₀, v [...] Read more.

This study explores the application of fine-tuned large language models for predicting physicochemical properties, specifically focusing on Abraham model solute descriptors (E, S, A, B, V) and modified solvent parameters (e₀, s₀, a₀, b₀, v₀). By leveraging ChemLLaMA, a specialized version of the LLaMA model for cheminformatics tasks, we developed the AbraLlama-Solvent and AbraLlama-Solute models using curated datasets of experimentally derived solute descriptors and solvent parameters. Our findings demonstrate that AbraLlama-Solvent and AbraLlama-Solute predict modified solvent parameters and solute descriptors with high accuracy, comparable to existing methods. The AbraLlama-Solvent model shows varying prediction accuracy across different solvents, influenced by their position within the chemical space, while the AbraLlama-Solute model consistently predicts solute descriptors with high accuracy. Both models are available as applications on Hugging Face, facilitating easy predictions from SMILES strings. This research highlights the potential of LLMs in chemistry applications, offering practical tools for solvent comparison and expanding the applicability of Abraham solvation equations to a broader range of organic solvents. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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13 pages, 2549 KiB

Open AccessArticle

Unprecedented High Probe-Reported Polarity of Deep Eutectic Solvents Composed of Lanthanide Salts and Urea

by Anushis Patra, Vaishali Khokhar and Siddharth Pandey

Liquids 2024, 4(3), 505-517; https://doi.org/10.3390/liquids4030028 - 18 Jul 2024

Viewed by 976

Abstract

Deep eutectic solvents (DESs) have emerged as viable alternatives to toxic organic solvents. The most intriguing aspect of these solvents is perhaps the widely varying physicochemical properties emerging from the changes in the constituents that form DESs along with their composition. Based on [...] Read more.

Deep eutectic solvents (DESs) have emerged as viable alternatives to toxic organic solvents. The most intriguing aspect of these solvents is perhaps the widely varying physicochemical properties emerging from the changes in the constituents that form DESs along with their composition. Based on the constituents, a DES can be hydrophilic/polar or hydrophobic/non-polar, rendering a vastly varying spectrum of polarity a possibility. DESs formed by mixing urea (U) with hydrated lanthanide salts, lanthanum nitrate hexahydrate (La : U), cerium nitrate hexahydrate (Ce : U), and gadolinium nitrate hexahydrate (Gd : U), respectively, exhibit very high polarity as manifested via the probe-reported empirical parameters of dipolarity/polarizability (π*). The highest π* of 1.70 exhibited by the DES (Gd : U) in a 1 : 2 molar ratio is unprecedented. The π* ranges from 1.50 to 1.70 for these DESs, which is almost the highest reported for any solvent system. The π* decreases with an increasing amount of urea in the DES; however, the anomalous trends in H-bond donating acidity (α) and H-bond accepting basicity (β) appear to be due to the hydrated water of the lanthanide salt. The emission band maxima of the fluorescence probe of the “effective” dielectric constant (ε_eff) of the solubilizing media, pyrene-1-carboxaldehyde (PyCHO), in salt-rich DESs reflect higher cybotactic region dipolarity than that offered by water. Probe Nile red aggregates readily in these DESs to form non-fluorescent H-aggregates, which is a characteristic of highly polar solvents. The behavior of probe pyranine also corroborates these outcomes as the (lanthanide salt : urea) DES system supports the formation of the deprotonated form of the probe in the excited state. The (lanthanide salt : urea) DES system offers solubilizing media of exceptionally high polarity, which is bound to expand their application potential. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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15 pages, 793 KiB

Open AccessArticle

Abraham General Solvation Parameter Model: Predictive Expressions for Solute Transfer into Isobutyl Acetate

by Ramya Motati, Trisha Kandi, Jilawan Francis, Jocelyn Chen, Emily Yao, Saikiran Motati, Audrey Chen, Dhishithaa Kumarandurai, Nikita Shanmugam and William E. Acree, Jr.

Liquids 2024, 4(3), 470-484; https://doi.org/10.3390/liquids4030026 - 1 Jul 2024

Cited by 2 | Viewed by 836

Abstract

Mole fraction of solubilities are reported for the: o-acetoacetanisidide, anthracene, benzoin, 4-tert-butylbenzoic acid, 3-chlorobenzoic acid, 3-chlorobenzoic acid, 2-chloro-5-nitrobenzoic acid, 4-chloro-3-nitrobenzoic acid, 3,4-dichlorobenzoic acid, 2,3-dimethoxybenzoic acid, 3,4-dimethoxybenzoic acid, 3,5-dimethoxybenzoic acid, 3,5-dinitrobenzoic acid, diphenyl sulfone, 2-ethylanthraquinone, 2-methoxybenzoic acid, 4-methoxybenzoic acid, 2-methylbenzoic acid, [...] Read more.

Mole fraction of solubilities are reported for the: o-acetoacetanisidide, anthracene, benzoin, 4-tert-butylbenzoic acid, 3-chlorobenzoic acid, 3-chlorobenzoic acid, 2-chloro-5-nitrobenzoic acid, 4-chloro-3-nitrobenzoic acid, 3,4-dichlorobenzoic acid, 2,3-dimethoxybenzoic acid, 3,4-dimethoxybenzoic acid, 3,5-dimethoxybenzoic acid, 3,5-dinitrobenzoic acid, diphenyl sulfone, 2-ethylanthraquinone, 2-methoxybenzoic acid, 4-methoxybenzoic acid, 2-methylbenzoic acid, 3-methylbenzoic acid, 2-methyl-3-nitrobenzoic acid, 3-methyl-4-nitrobenzoic acid, 4-methyl-3-nitrobenzoic acid, 2-naphthoxyacetic acid, 3-nitrobenzoic acid, 4-nitrobenzoic acid, salicylamide, thioxanthene-9-one, 3,4,5-trimethoxybenzoic acid, and xanthene dissolved in isobutyl acetate at 298.15 K. The results of our experimental measurements, combined with the published literature data, were used to obtain Abraham model equations for isobutyl acetate. The mathematical correlations presented in the current study describe the observed molar solubility ratios of the solutes dissolved in isobutyl acetate to within an overall standard deviation of 0.12 log units or less. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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14 pages, 1186 KiB

Open AccessArticle

Vaporization Enthalpies and Vapor Pressures of 5α-Androstane and 5α-Cholestane by Correlation Gas Chromatography

by Christian Fischer-Lodike, Mohammad Albinsaad and James S. Chickos

Liquids 2024, 4(3), 456-469; https://doi.org/10.3390/liquids4030025 - 27 Jun 2024

Cited by 1 | Viewed by 496

Abstract

Vaporization enthalpies and vapor pressures of 5α-androstane and 5α-cholestane are reported using correlation gas chromatography (CGC). The results for 5α-cholestane are compared to both estimated and experimental values reported previously for 5α-cholestane. The results are generally in agreement with the literature within the [...] Read more.

Vaporization enthalpies and vapor pressures of 5α-androstane and 5α-cholestane are reported using correlation gas chromatography (CGC). The results for 5α-cholestane are compared to both estimated and experimental values reported previously for 5α-cholestane. The results are generally in agreement with the literature within the reported uncertainties. A simple method for reducing the amount of curvature in logarithm plots of vapor pressures as a function of K/T when using n-alkanes as standards in CGC experiments is also reported. This may prove useful in evaluating vapor pressures of rigid hydrocarbons at high temperatures. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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13 pages, 1559 KiB

Open AccessArticle

Dissolution Thermodynamics and Preferential Solvation of Phenothiazine in Some Aqueous Cosolvent Systems

by Fleming Martínez, María Ángeles Peña and Abolghasem Jouyban

Liquids 2024, 4(2), 443-455; https://doi.org/10.3390/liquids4020024 - 20 Jun 2024

Viewed by 594

Abstract

Published equilibrium mole fraction solubilities of phenothiazine in ethanol, propylene glycol and water as mono-solvents at several temperatures were investigated to find standard apparent thermodynamic quantities of dissolution mixing and solvation based on the van’t Hoff and Gibbs equations. Further, by processing the [...] Read more.

Published equilibrium mole fraction solubilities of phenothiazine in ethanol, propylene glycol and water as mono-solvents at several temperatures were investigated to find standard apparent thermodynamic quantities of dissolution mixing and solvation based on the van’t Hoff and Gibbs equations. Further, by processing the reported mole fraction solubility values of phenothiazine in some aqueous cosolvent mixtures at T/K = 298.2, the inverse Kirkwood–Buff integrals treatment demonstrated preferential hydration of phenothiazine in water-rich mixtures and preferential solvation of this agent by cosolvents in mixtures of 0.24 < x₁ < 1.00 in the {ethanol (1) + water (2)} mixed system and mixtures of 0.18 < x₁ < 1.00 in the {propylene glycol (1) + water (2)} mixed system. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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30 pages, 1558 KiB

Open AccessArticle

Calculation of the Three Partition Coefficients logP_ow, logK_oa and logK_aw of Organic Molecules at Standard Conditions at Once by Means of a Generally Applicable Group-Additivity Method

by Rudolf Naef and William E. Acree, Jr.

Liquids 2024, 4(1), 231-260; https://doi.org/10.3390/liquids4010011 - 1 Mar 2024

Cited by 1 | Viewed by 1173

Abstract

Assessment of the environmental impact of organic chemicals has become an important subject in chemical science. Efficient quantitative descriptors of their impact are their partition coefficients logP_ow, logK_oa and logK_aw. We present a group-additivity method that has proven [...] Read more.

Assessment of the environmental impact of organic chemicals has become an important subject in chemical science. Efficient quantitative descriptors of their impact are their partition coefficients logP_ow, logK_oa and logK_aw. We present a group-additivity method that has proven its versatility for the reliable prediction of many other molecular descriptors for the calculation of the first two partition coefficients and indirectly of the third with high dependability. Based on the experimental logP_ow data of 3332 molecules and the experimental logK_oa data of 1900 molecules at 298.15 K, the respective partition coefficients have been calculated with a cross-validated standard deviation S of only 0.42 and 0.48 log units and a goodness of fit Q² of 0.9599 and 0.9717, respectively, in a range of ca. 17 log units for both descriptors. The third partition coefficient logK_aw has been derived from the calculated values of the former two descriptors and compared with the experimentally determined logK_aw value of 1937 molecules, yielding a standard deviation σ of 0.67 log units and a correlation coefficient R² of 0.9467. This approach enabled the quick calculation of 29,462 logP_ow, 27,069 logK_oa and 26,220 logK_aw values for the more than 37,100 molecules of ChemBrain’s database available to the public. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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31 pages, 7460 KiB

Open AccessArticle

Evaluation of Thermodynamic and Kinetic Contributions to Over-Extraction of Extractables by Nonpolar Organic Solvents in Comparison to Lipids in Exhaustive and Exaggerated Extractions of Medical Devices Based on Abraham Solvation Model and Solvent–Material Interactions Using Low-Density Polyethylene as a Representative Material

by Jianwei Li

Liquids 2024, 4(1), 117-147; https://doi.org/10.3390/liquids4010006 - 23 Jan 2024

Cited by 2 | Viewed by 1551

Abstract

The thermodynamic and kinetic contributions to the over-extraction of extractables by nonpolar organic solvents relative to biological lipids in exhaustive and exaggerated extractions of medical devices are studied based on the Abraham solvation model and solvent–material interactions, using low-density polyethylene (LDPE) as an [...] Read more.

The thermodynamic and kinetic contributions to the over-extraction of extractables by nonpolar organic solvents relative to biological lipids in exhaustive and exaggerated extractions of medical devices are studied based on the Abraham solvation model and solvent–material interactions, using low-density polyethylene (LDPE) as an exemplary material. The thermodynamic effect is evaluated by the partition constant of extractables between LDPE and extraction solvents, hexane and lipids, defined as the concentration in the polymer phase divided by the concentration in the solvent phase. The Abraham solvation model is used to correlate the measured LDPE-lipid partition constant (

l o g_{10} P_{l d p e / l i p i d}

) to construct the predictive model. Similar models are also derived from the thermodynamic cycle conversion, using the system constants of LDPE-water and Lipid-water partition systems. These constructed models, together with the predictive LDPE-hexane (

l o g_{10} P_{l d p e / h e x a n e}

) model established from a previous study, are used to predict and compare the ranges and values of

P_{l d p e / s}

(s = lipids and hexane) for the observed LDPE extractables over a wide hydrophobicity range in

l o g_{10} P_{o / w}

from zero to 30. The solvent-LDPE interactions are examined by the degree of swelling of LDPE by hexane (or other nonpolar solvents) and lipids, including the solvent diffusion rates into the material. These parameters allow the evaluation of kinetic effect on the over-extraction. The extent of over-extraction is compiled directly by experimental “overall” or “specific” migration data or indirectly calculated by the diffusion coefficient of extractables when extracted by hexane or lipids. It is concluded from this study that the extractables distribution between LDPE and lipids highly favors the lipid phase thermodynamically (

P_{l d p e / l i p i d} < 1

), and the values of

P_{l d p e / l i p i d}

are always lower than those of

P_{l d p e / h e x a n e}

, thereby indicating that the thermodynamic effect is not the cause of over-extraction. It is the kinetic effect that dominantly contributes to the over-extraction, as supported by the material swelling and solvent diffusion rates. Finally, the extent of over-extraction has been established from a few folds to over a hundred-fold, and the median value is 7. Furthermore, the methods adopted and developed in this study can be invaluable tools in other disciplines such as the reliable prediction of extractables from other device materials and environmental sampling. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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Review

Jump to: Research

32 pages, 770 KiB

Open AccessReview

On the Solute-Induced Structure-Making/Breaking Phenomena: Myths, Verities, and Misuses in Solvation Thermodynamics

by Ariel A. Chialvo

Liquids 2024, 4(3), 592-623; https://doi.org/10.3390/liquids4030033 - 3 Sep 2024

Viewed by 675

Abstract

We review the statistical mechanic foundations of the fundamental structure-making/breaking functions, leading to the rigorous description of the solute-induced perturbation of the solvent environment for the understanding of the solvation process of any species regardless of the type and nature of the [...] Read more.

We review the statistical mechanic foundations of the fundamental structure-making/breaking functions, leading to the rigorous description of the solute-induced perturbation of the solvent environment for the understanding of the solvation process of any species regardless of the type and nature of the solute–solvent interactions. Then, we highlight how these functions are linked to unambiguous thermodynamic responses resulting from changes in state conditions, composition, and solute–solvent intermolecular interaction asymmetries. Finally, we identify and illustrate the pitfalls behind the use of surrogate approaches to structure-making/breaking markers, including those based on Jones–Dole’s B-coefficient and Hepler’s isobaric-thermal expansivity, while highlighting their ambiguities and lack of consistency and the sources of misinterpretations. Full article

(This article belongs to the Special Issue Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.)

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Recent Advances in the Behavior of Liquids in Honor of Prof. Dr. William Acree Jr.

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