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Thermodynamics, Structure, and Intermolecular Interactions in Solutions

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Physical Chemistry".

Deadline for manuscript submissions: closed (31 May 2023) | Viewed by 21039

Special Issue Editors

Tianjin Key Laboratory of Brine Chemical Engineering and Ecological Utilization of Resources, Tianjin Engineering Center of Marine Chemical Engineering & Technology, College of Chemical Engineering and Materials Science, Tianjin University of Science and Technology, Tianjin 300457, China
Interests: crystallization thermodynamics; crystallization kinetics, involved nucleation, and crystal growth kinetics; functional crystal materials; self-assembly materials; chiral separation (typically by using crystallization technology); brine chemical engineering and the ecological utilization of resources; crystal engineering (polymorphism, co-crystal, salt, solvates); separation and purification technology
Special Issues, Collections and Topics in MDPI journals
School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China
Interests: solubility enthalpy; entropy dissolution; solubility enhancement; solution chemistry
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The key issues of structural evolution and intermolecular interactions in molecular thermodynamics, statistical thermodynamics, and molecular self-assembly play important roles in a range of multidisciplinary fields such as chemistry, materials science, crystal engineering, pharmaceutical science, environmental science, and earth science. Robust discussion on the evolution of molecular structures and intermolecular interactions in solution has already resulted in vast leaps in science and technology, and will undoubtedly lead to further insights and open new horizons in relation to molecular thermodynamics and phase transition mechanisms and kinetics.

Therefore, we encourage scientists to submit papers describing fundamental studies devoted to thermodynamics and phase transitions at the molecular level. The manuscripts might relate to, but are by no means limited to, the following topics:

  1. Experimental, theoretical, or combined perspective views on molecular thermodynamics or molecular simulation in organic, inorganic or physical chemistry;
  2. The exploitation of different experimental techniques (NMR, IR, Raman, UV-vis spectroscopy, etc.) for the characterization of intermolecular interactions or solution species;
  3. Physical interpretations or molecular insights into the molecular self-assembly process.

For this Special Issue, we invite scientists working in different experimental and theoretical fields to contribute their work in order to achieve deeper insight into the issues of structural evolution, intermolecular interactions in molecular thermodynamics, statistical thermodynamics, and molecular self-assembly processes.

Dr. Shijie Xu
Dr. Tao Li
Guest Editors

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • thermodynamics
  • intermolecular interactions
  • statistical thermodynamics
  • molecular simulation
  • physical chemistry
  • phase transition
  • solution species
  • thermodynamic descriptor
  • thermodynamic model
  • molecular self-assembly

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Published Papers (14 papers)

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Research

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18 pages, 4138 KiB  
Article
Removal of Heavy Metal Ions from Aqueous Solution Using Biotransformed Lignite
by Jianguo Cheng, Shanfei Zhang, Chen Fang, Litong Ma, Jianguo Duan, Xu Fang and Rihong Li
Molecules 2023, 28(13), 5031; https://doi.org/10.3390/molecules28135031 - 27 Jun 2023
Cited by 1 | Viewed by 1100
Abstract
Heavy metal pollution caused by industrial wastewater such as mining and metallurgical wastewater is a major global concern. Therefore, this study used modified lignite as a low-cost adsorbent for heavy metal ions. Pingzhuang lignite was dissolved and modified using Fusarium lignite B3 to [...] Read more.
Heavy metal pollution caused by industrial wastewater such as mining and metallurgical wastewater is a major global concern. Therefore, this study used modified lignite as a low-cost adsorbent for heavy metal ions. Pingzhuang lignite was dissolved and modified using Fusarium lignite B3 to prepare a biotransformed-lignite adsorbent (BLA). The O, H, and N contents of the BLA increased after transformation, and the specific surface area increased from 1.81 to 5.66 m2·g−1. Various adsorption properties were investigated using an aqueous solution of Cu(Ⅱ). The kinetic and isothermal data were well-fitted by pseudo-second-order and Langmuir models, respectively. The Langmuir model showed that the theoretical Cu(II) adsorption capacity was 71.47 mg·g−1. Moreover, large particles and a neutral pH were favorable for the adsorption of heavy metal ions. The adsorption capacities of raw lignite and BLA were compared for various ions. Microbial transformation greatly improved the adsorption capacity, and the BLA had good adsorption and passivation effects with Cu(II), Mn(II), Cd(II), and Hg(II). Investigation of the structural properties showed that the porosity and specific surface area increased after biotransformation, and there were more active groups such as –COOH, Ar–OH, and R–OH, which were involved in the adsorption performance. Full article
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19 pages, 4551 KiB  
Article
Measurement and Correlation of Solubility of Thiamine Nitrate in Three Binary Solvents and Thermodynamic Properties for the Solutions in Different Binary Mixtures at (278.15–313.15) K
by Xinda Li, Zhengjiang Wang, Jing Wang, Jiaqi Lu, Jin Mao, Dandan Han and Kangli Li
Molecules 2023, 28(13), 5012; https://doi.org/10.3390/molecules28135012 - 27 Jun 2023
Viewed by 873
Abstract
The solubility of thiamine nitrate in {(methanol, acetone, isopropanol) + water} solvents will provide essential support for crystallization design and further theoretical studies. In this study, the solubility was experimentally measured over temperatures ranging from 278.15 to 313.15 K under atmospheric pressure using [...] Read more.
The solubility of thiamine nitrate in {(methanol, acetone, isopropanol) + water} solvents will provide essential support for crystallization design and further theoretical studies. In this study, the solubility was experimentally measured over temperatures ranging from 278.15 to 313.15 K under atmospheric pressure using a dynamic method. The solubility increased with increasing temperature at a constant solvent composition. The dissolving capacity of thiamine nitrate in the three binary solvent mixtures at constant temperature in the low ratio of water ranked as water + methanol > water + acetone > water + isopropanol generally. Interestingly, in the high ratio of water systems, especially when the molar concentration of water was greater than 0.6, the dissolving capacity ranked as water + acetone > water + methanol > water + isopropanol. Additionally, the modified Apelblat equation, λh equation, van’t Hoff equation and NRTL model were used to correlate the solubility data in binary mixtures. It turned out that all the selected thermodynamic models could give satisfactory results. Furthermore, the thermodynamic properties of the dissolution process of thiamine nitrate were also calculated based on the modified van’t Hoff equation. The results indicate that the dissolution process of the thiamine nitrate in the selected solvents is all endothermic. Full article
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20 pages, 22717 KiB  
Article
Eu(III) and Cm(III) Complexation by the Aminocarboxylates NTA, EDTA, and EGTA Studied with NMR, TRLFS, and ITC—An Improved Approach to More Robust Thermodynamics
by Sebastian Friedrich, Claudia Sieber, Björn Drobot, Satoru Tsushima, Astrid Barkleit, Katja Schmeide, Thorsten Stumpf and Jerome Kretzschmar
Molecules 2023, 28(12), 4881; https://doi.org/10.3390/molecules28124881 - 20 Jun 2023
Cited by 2 | Viewed by 1793
Abstract
The complex formation of Eu(III) and Cm(III) was studied via tetradentate, hexadentate, and octadentate coordinating ligands of the aminopolycarboxylate family, viz., nitrilotriacetate (NTA3−), ethylenediaminetetraacetate (EDTA4−), and ethylene glycol-bis(2-aminoethyl ether)-N,N,N′,N′-tetraacetate (EGTA4− [...] Read more.
The complex formation of Eu(III) and Cm(III) was studied via tetradentate, hexadentate, and octadentate coordinating ligands of the aminopolycarboxylate family, viz., nitrilotriacetate (NTA3−), ethylenediaminetetraacetate (EDTA4−), and ethylene glycol-bis(2-aminoethyl ether)-N,N,N′,N′-tetraacetate (EGTA4−), respectively. Based on the complexones’ pKa values obtained from 1H nuclear magnetic resonance (NMR) spectroscopic pH titration, complex formation constants were determined by means of the parallel-factor-analysis-assisted evaluation of Eu(III) and Cm(III) time-resolved laser-induced fluorescence spectroscopy (TRLFS). This was complemented by isothermal titration calorimetry (ITC), providing the enthalpy and entropy of the complex formation. This allowed us to obtain genuine species along with their molecular structures and corresponding reliable thermodynamic data. The three investigated complexones formed 1:1 complexes with both Eu(III) and Cm(III). Besides the established Eu(III)–NTA 1:1 and 1:2 complexes, we observed, for the first time, the existence of a Eu(III)–NTA 2:2 complex of millimolar metal and ligand concentrations. Demonstrated for thermodynamic studies on Eu(III) and Cm(III) interaction with complexones, the utilized approach is commonly applicable to many other metal–ligand systems, even to high-affinity ligands. Full article
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21 pages, 2910 KiB  
Article
Thermodynamic and Thermal Analyze of N,N-Dimethylformamide + 1-Butanol Mixture Properties Based on Density, Sound Velocity and Heat Capacity Data
by Magdalena Tyczyńska, Aleksandra Dentkiewicz and Małgorzata Jóźwiak
Molecules 2023, 28(12), 4698; https://doi.org/10.3390/molecules28124698 - 11 Jun 2023
Cited by 2 | Viewed by 1011
Abstract
The present paper contains data on the density (ρ), sound velocity (u), and specific heat capacity cp of the mixture of N,N-dimethylformamide + 1-butanol (DMF + BuOH) determined in the entire concentration range [...] Read more.
The present paper contains data on the density (ρ), sound velocity (u), and specific heat capacity cp of the mixture of N,N-dimethylformamide + 1-butanol (DMF + BuOH) determined in the entire concentration range of solution and in the temperature range (293.15–318.15) K. The analysis of thermodynamic functions such as isobaric molar expansion, isentropic and isothermal molar compression, isobaric and isochoric molar heat capacity, as well as their excess functions (Ep,mE,KS,mE,KT,mE,Cp, mE,CV, mE) and also VmE was undertaken. The analysis of changes in the physicochemical quantities was based on consideration of the system in terms of intermolecular interactions and resulting changes in the mixture structure. The results available in the literature were confusing during the analysis and became the reason for our decision to thoroughly examine the system. What is more, for a system whose components are widely used, there is very scarce information in the literature regarding the heat capacity of the tested mixture, which was also achieved and presented in this publication. The conclusions drawn from so many data points allow us to approximate and understand the changes that occur in the structure of the system due to the repeatability and consistency of the obtained results. Full article
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16 pages, 975 KiB  
Article
Europium(III) Meets Etidronic Acid (HEDP): A Coordination Study Combining Spectroscopic, Spectrometric, and Quantum Chemical Methods
by Anne Heller, Christian Senwitz, Harald Foerstendorf, Satoru Tsushima, Linus Holtmann, Björn Drobot and Jerome Kretzschmar
Molecules 2023, 28(11), 4469; https://doi.org/10.3390/molecules28114469 - 31 May 2023
Cited by 3 | Viewed by 1505
Abstract
Etidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP, H4L) is a proposed decorporation agent for U(VI). This paper studied its complex formation with Eu(III), an inactive analog of trivalent actinides, over a wide pH range, at varying metal-to-ligand ratios (M:L) and total concentrations. Combining [...] Read more.
Etidronic acid (1-Hydroxyethylidene-1,1-diphosphonic acid, HEDP, H4L) is a proposed decorporation agent for U(VI). This paper studied its complex formation with Eu(III), an inactive analog of trivalent actinides, over a wide pH range, at varying metal-to-ligand ratios (M:L) and total concentrations. Combining spectroscopic, spectrometric, and quantum chemical methods, five distinct Eu(III)−HEDP complexes were found, four of which were characterized. The readily soluble EuH2L+ and Eu(H2L)2 species with log β values of 23.7 ± 0.1 and 45.1 ± 0.9 are formed at acidic pH. At near-neutral pH, EuHL0s forms with a log β of ~23.6 and, additionally, a most probably polynuclear complex. The readily dissolved EuL species with a log β of ~11.2 is formed at alkaline pH. A six-membered chelate ring is the key motif in all solution structures. The equilibrium between the Eu(III)–HEDP species is influenced by several parameters, i.e., pH, M:L, total Eu(III) and HEDP concentrations, and time. Overall, the present work sheds light on the very complex speciation in the HEDP–Eu(III) system and indicates that, for risk assessment of potential decorporation scenarios, side reactions of HEDP with trivalent actinides and lanthanides should also be taken into account. Full article
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13 pages, 2398 KiB  
Article
Stability of the Inclusion Complexes of Dodecanoic Acid with α-Cyclodextrin, β-Cyclodextrin and 2-HP-β-Cyclodextrin
by Zdzisław Kinart
Molecules 2023, 28(7), 3113; https://doi.org/10.3390/molecules28073113 - 30 Mar 2023
Cited by 1 | Viewed by 1489
Abstract
In the presented work, the stability of the formation of inclusion complexes of dodecanoic acid (lauric acid) with three cyclodextrins, α-cyclodextrin, β-cyclodextrin and 2-HP-β-cyclodextrin, was analyzed from the point of view of the size of the cavity in cyclodextrins, their molar mass and [...] Read more.
In the presented work, the stability of the formation of inclusion complexes of dodecanoic acid (lauric acid) with three cyclodextrins, α-cyclodextrin, β-cyclodextrin and 2-HP-β-cyclodextrin, was analyzed from the point of view of the size of the cavity in cyclodextrins, their molar mass and the structure of the studied fatty acid. The measurements were made in a wide temperature range of 283.15–318.15K. The conductometric method was used for these studies. The results obtained allowed us to determine the value of the theoretical limiting molar conductivity (Λm0) of the studied complexes, the values of the inclusion complex formation constants (Kf) and the values of thermodynamic functions (ΔG0, ΔH0 and ΔS0) describing the complexation process in the studied temperature range. Full article
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14 pages, 1463 KiB  
Article
Composition of the Solvation Shell of the Selected Cyclic Ethers (1,4-Dioxane, 12-Crown-4, 15-Crown-5 and 18-Crown-6) in a Mixture of Formamide with Water at Four Temperatures
by Małgorzata Jóźwiak, Monika A. Trzmielak, Michał Wasiak and Katarzyna Łudzik-Dychto
Molecules 2023, 28(5), 2169; https://doi.org/10.3390/molecules28052169 - 26 Feb 2023
Cited by 1 | Viewed by 851
Abstract
The solution enthalpy of 15-crown-5 and 18-crown-6 ethers in the mixture of formamide (F) and water (W) was measured at four temperatures: 293.15 K, 298.15 K, 303.15 K, 308.15 K. The standard molar enthalpy of solution, ΔsolHo, depends on [...] Read more.
The solution enthalpy of 15-crown-5 and 18-crown-6 ethers in the mixture of formamide (F) and water (W) was measured at four temperatures: 293.15 K, 298.15 K, 303.15 K, 308.15 K. The standard molar enthalpy of solution, ΔsolHo, depends on the size of cyclic ethers molecules and the temperature. With increasing temperature, the values of ΔsolHo become less negative. The values of the standard partial molar heat capacity Cp,2o of cyclic ethers at 298.15 K have been calculated. The Cp,2o=f(xW) curve shape indicates the hydrophobic hydration process of cyclic ethers in the range of a high-water content in the mixture with formamide. The enthalpic effect of preferential solvation of cyclic ethers was calculated and the effect of temperature on the preferential solvation process was discussed. The process of complex formation between 18C6 molecules and formamide molecules is observed. The cyclic ethers molecules are preferentially solvated by formamide molecules. The mole fraction of formamide in the solvation sphere of cyclic ethers has been calculated. Full article
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23 pages, 3437 KiB  
Article
The Group Contribution to the Function Derived from Density and Speed-of-Sound Measurements for Glymes in N,N-Dimethylformamide + Water Mixtures
by Małgorzata Jóźwiak, Marlena Komudzińska and Magdalena Tyczyńska
Molecules 2023, 28(4), 1519; https://doi.org/10.3390/molecules28041519 - 04 Feb 2023
Viewed by 815
Abstract
The density and speed of sound of pentaglyme and hexaglyme in the N,N-dimethylformamide + water mixture at four temperatures are presented. The limiting apparent molar volumes (VΦ,m0=Vm0), the isobaric molar [...] Read more.
The density and speed of sound of pentaglyme and hexaglyme in the N,N-dimethylformamide + water mixture at four temperatures are presented. The limiting apparent molar volumes (VΦ,m0=Vm0), the isobaric molar thermal expansion (Ep,m0), the isentropic compressibility (κS), and the limiting partial molar isentropic compression (KS,Φ,m0 = KS,m0) were calculated. Changes in the values obtained from the physicochemical parameters, as functions of composition and temperature, were analyzed in terms of the molecular interactions and structural differentiation of the investigated systems. The hydrophobic hydration process of the studied glymes was visible in the area of high water content in the mixture. The hydration number of glymes in water at four temperatures was calculated and analyzed. The contribution of the –CH2– and –O– group to the functions describing the volume and acoustic properties of the investigated system was calculated. The calculated values of the functions analyzed using the group contribution are in agreement with the values obtained from the experimental data. Thus, such contributions are valuable for wide ranges of data, which can be used to analyze the hydrophobic hydration and preferential solvation processes, as well as to calculate the values of these functions for other similar compounds. Full article
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14 pages, 1480 KiB  
Article
Conductometric Studies of Formation the Inclusion Complexes of Phenolic Acids with β-Cyclodextrin and 2-HP-β-Cyclodextrin in Aqueous Solutions
by Zdzisław Kinart
Molecules 2023, 28(1), 292; https://doi.org/10.3390/molecules28010292 - 29 Dec 2022
Cited by 2 | Viewed by 1383
Abstract
An attempt was made to evaluate the possibility of creating and assessing the stability of inclusion complexes of selected phenolic acids [trans-4-hydroxycinnamic acid (trans-p-coumaric acid), trans-3,4-dihydroxycinnamic acid (trans-caffeic acid), trans-4-hydroxy-3-methoxycinnamic acid, (trans-ferulic acid) [...] Read more.
An attempt was made to evaluate the possibility of creating and assessing the stability of inclusion complexes of selected phenolic acids [trans-4-hydroxycinnamic acid (trans-p-coumaric acid), trans-3,4-dihydroxycinnamic acid (trans-caffeic acid), trans-4-hydroxy-3-methoxycinnamic acid, (trans-ferulic acid) and trans-3-phenylacrylic acid (trans-cinnamic acid)] with β-cyclodextrin and 2-HP-β-cyclodextrin in aqueous solutions in a wide temperature range 283.15 K–313.15 K. On the basis of the values of the limiting molar conductivity CDNaDod), calculated from the experimental data, the values of the formation constants and the thermodynamic functions of formation (standard enthalpy, entropy, and Gibs standard enthalpy) of the studied complexes were determined. It has been found that the stability of the studied complexes increases with lowering of the molar mass of cyclodextrin and lowering of the temperature. Full article
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17 pages, 1542 KiB  
Article
The Lyotropic Nature of Halates: An Experimental Study
by Mert Acar, Duccio Tatini, Barry W. Ninham, Federico Rossi, Nadia Marchettini and Pierandrea Lo Nostro
Molecules 2022, 27(23), 8519; https://doi.org/10.3390/molecules27238519 - 03 Dec 2022
Cited by 2 | Viewed by 1256
Abstract
Unlike halides, where the kosmotropicity decreases from fluoride to iodide, the kosmotropic nature of halates apparently increases from chlorate to iodate, in spite of the lowering in the static ionic polarizability. In this paper, we present an experimental study that confirms the results [...] Read more.
Unlike halides, where the kosmotropicity decreases from fluoride to iodide, the kosmotropic nature of halates apparently increases from chlorate to iodate, in spite of the lowering in the static ionic polarizability. In this paper, we present an experimental study that confirms the results of previous simulations. The lyotropic nature of aqueous solutions of sodium halates, i.e., NaClO3, NaBrO3, and NaIO3, is investigated through density, conductivity, viscosity, and refractive index measurements as a function of temperature and salt concentration. From the experimental data, we evaluate the activity coefficients and the salt polarizability and assess the anions’ nature in terms of kosmotropicity/chaotropicity. The results clearly indicate that iodate behaves as a kosmotrope, while chlorate is a chaotrope, and bromate shows an intermediate nature. This experimental study confirms that, in the case of halates XO3, the kosmotropic–chaotropic ranking reverses with respect to halides. We also discuss and revisit the role of the anion’s polarizability in the interpretation of Hofmeister phenomena. Full article
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9 pages, 1475 KiB  
Article
Sublimation and Diffusion Kinetics of 2,4,6-Trinitrotoluene (TNT) Single Crystals by Atomic Force Microscopy (AFM)
by Walid M. Hikal, Sanjoy K. Bhattacharia, Mark W. Vaughn and Brandon L. Weeks
Molecules 2022, 27(17), 5482; https://doi.org/10.3390/molecules27175482 - 26 Aug 2022
Cited by 2 | Viewed by 1124
Abstract
In this article, we report the in-situ nanoscale experimental measurement of sublimation rates, activation energy of sublimation, and diffusion coefficients of 2,4,6-trinitrotoluene (TNT) single crystals in air using atomic force microscopy (AFM). The crystals were prepared by slow evaporation at 5 °C using [...] Read more.
In this article, we report the in-situ nanoscale experimental measurement of sublimation rates, activation energy of sublimation, and diffusion coefficients of 2,4,6-trinitrotoluene (TNT) single crystals in air using atomic force microscopy (AFM). The crystals were prepared by slow evaporation at 5 °C using acetone-dissolved TNT. The mass loss was calculated by monitoring the shrinkage of the surface area of layered islands formed on the surface of the TNT crystals due to sublimation upon isothermal heating at temperatures below the melting point. The results suggest the sublimation process occurs via two-dimensional detachment of TNT molecules from the non-prominent facets on the crystal surface which imitates the nucleation and crystal growth process. Sublimation rates are one order of magnitude smaller than previously reported values. However, the calculated activation energy (112.15 ± 3.2 kJ/mol) and temperature-dependent sublimation rates agree well with the reported values for TNT thin films and microcrystals determined by UV-vis absorbance spectroscopy and quartz crystal microscopy (QCM) (90–141 kJ/mol). The average diffusion coefficient is (4.35 × 10–6 m2/s) which is within the range of the reported theoretical values with an average of 5.59 × 10–6 m2/s, and about 25% less than that determined using thermogravimetric analysis for powder TNT. Full article
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12 pages, 2753 KiB  
Article
Studies of the Formation of Inclusion Complexes Derivatives of Cinnamon Acid with α-Cyclodextrin in a Wide Range of Temperatures Using Conductometric Methods
by Zdzisław Kinart and Renato Tomaš
Molecules 2022, 27(14), 4420; https://doi.org/10.3390/molecules27144420 - 10 Jul 2022
Cited by 2 | Viewed by 1265
Abstract
The electrical conductivities of aqueous solutions of sodium salts of trans-4-hydroxycinnamic acid (trans-p-coumaric acid), trans-3,4-dihydroxycinnamic acid (trans-caffeic acid), trans-4-hydroxy-3-methoxycinnamic acid, (trans-ferulic acid) and trans-3-phenylacrylic acid (trans-cinnamic acid) with α-cyclodextrin [...] Read more.
The electrical conductivities of aqueous solutions of sodium salts of trans-4-hydroxycinnamic acid (trans-p-coumaric acid), trans-3,4-dihydroxycinnamic acid (trans-caffeic acid), trans-4-hydroxy-3-methoxycinnamic acid, (trans-ferulic acid) and trans-3-phenylacrylic acid (trans-cinnamic acid) with α-cyclodextrin were measured in the temperature range of 288.15 K–318.15 K. For the first time in the literature, using the limiting molar conductivity (Λmo) obtained from conductivity measurements, the values of the complexation constants (Kf) of the salts of phenolic acid derivatives with α-cyclodextrin were determined using a modified low concentration chemical model (IcCM). An attempt was also made to analyze the individual thermodynamic functions ΔGo, ΔHo and ΔSo describing the complexation process as a function of temperature changes. The obtained results show that the process of formation of inclusion complexes is exothermic and is spontaneous. Full article
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18 pages, 24854 KiB  
Article
Insight into the Nucleation Mechanism of p-Methoxybenzoic Acid in Ethanol-Water System from Metastable Zone Width
by Guangle Wang, Zeren Shang, Mingdi Liu, Weibing Dong, Haichao Li, Haiqing Yin, Junbo Gong and Songgu Wu
Molecules 2022, 27(13), 4085; https://doi.org/10.3390/molecules27134085 - 24 Jun 2022
Cited by 3 | Viewed by 1321
Abstract
The metastable zone width (MSZW) of p-methoxybenzoic acid (PMBA) in an ethanol-water system was measured using the polythermal method. The nucleation order m obtained by the Nývlt’s model indicates the nucleation of PMBA following a progressive nucleation mechanism at low saturation temperature [...] Read more.
The metastable zone width (MSZW) of p-methoxybenzoic acid (PMBA) in an ethanol-water system was measured using the polythermal method. The nucleation order m obtained by the Nývlt’s model indicates the nucleation of PMBA following a progressive nucleation mechanism at low saturation temperature (m = 3.18–7.50) and an instantaneous nucleation mechanism at high saturation temperature (m = 1.46–2.55). Then, combined with the metastable zone experiment and the Sangwal model, we found that the MSZW and the interfacial energy reached the maximum when the mass fraction of ethanol was 0.8, which resulted in the smallest crystal product size. Meanwhile, the maximum rcrit and ΔGcrit obtained based on the modified Sangwal model indicating the PMBA needs to overcome a higher nucleation barrier in the ethanol mass fraction of 0.8. Finally, we proposed a preferential strategy for adjusting MSZW by correlating the interfacial energy with the change in ethanol mass fraction, saturation temperature, and cooling rate, respectively. Full article
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Review

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29 pages, 2055 KiB  
Review
Strategies for Improving Bioavailability, Bioactivity, and Physical-Chemical Behavior of Curcumin
by Levente Zsolt Racz, Csaba Pal Racz, Lucian-Cristian Pop, Gheorghe Tomoaia, Aurora Mocanu, Ioana Barbu, Melinda Sárközi, Ioana Roman, Alexandra Avram, Maria Tomoaia-Cotisel and Vlad-Alexandru Toma
Molecules 2022, 27(20), 6854; https://doi.org/10.3390/molecules27206854 - 13 Oct 2022
Cited by 23 | Viewed by 4237
Abstract
Curcumin (CCM) is one of the most frequently explored plant compounds with various biological actions such as antibacterial, antiviral, antifungal, antineoplastic, and antioxidant/anti-inflammatory properties. The laboratory data and clinical trials have demonstrated that the bioavailability and bioactivity of curcumin are influenced by the [...] Read more.
Curcumin (CCM) is one of the most frequently explored plant compounds with various biological actions such as antibacterial, antiviral, antifungal, antineoplastic, and antioxidant/anti-inflammatory properties. The laboratory data and clinical trials have demonstrated that the bioavailability and bioactivity of curcumin are influenced by the feature of the curcumin molecular complex types. Curcumin has a high capacity to form molecular complexes with proteins (such as whey proteins, bovine serum albumin, β-lactoglobulin), carbohydrates, lipids, and natural compounds (e.g., resveratrol, piperine, quercetin). These complexes increase the bioactivity and bioavailability of curcumin. The current review provides these derivatization strategies for curcumin in terms of biological and physico-chemical aspects with a strong focus on different type of proteins, characterization methods, and thermodynamic features of protein–curcumin complexes, and with the aim of evaluating the best performances. The current literature review offers, taking into consideration various biological effects of the CCM, a whole approach for CCM-biomolecules interactions such as CCM-proteins, CCM-nanomaterials, and CCM-natural compounds regarding molecular strategies to improve the bioactivity as well as the bioavailability of curcumin in biological systems. Full article
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