Thermal effects of dissolution of aluminium halogenides in acetonitrile and tetrahydrofuran

1980 ◽  
Vol 45 (8) ◽  
pp. 2300-2307 ◽  
Author(s):  
Miriam Gálová ◽  
Daniela Kladeková
Keyword(s):  
Organic Solvents ◽  
Thermal Effects ◽  
Preferential Solvation ◽  
Inert Atmosphere ◽  
Water Molecules ◽  
Air Humidity ◽  
Enthalpies Of Dissolution ◽  
Heat Of Dissolution ◽  
As Effects

Molar enthalpies of dissolution of aluminium chlorides, bromides, and iodides in acetonitrile and tetrahydrofuran at 295 K have been determined experimentally. results of the measurements carried out in presence of air humidity point to the fact that both solvents preferential solvation of the solute by water molecules takes place. In an inert atmosphere, all the values obtained are negative. molar heat of dissolution has for AlCl3 the lowest negative value: -181 kJ mol-1 in acetonitrile and -107.8 kJ mol-1 in tetrahydrofuran. For AlBr3 and AlI3 exothermicity of dissolution is considerably higher: -817 and -887 kJ mol-1 for acetonitrile, and -489 and -713 kJ mol-1 for tetrahydrofuran. The transfer from water into both organic solvents has an endothermic character for AlCl3 only; for AlBr3 and AlI3, the character of transfer is unambiguously exothermic. The obtained results are interpreted as effects of interaction between the solute and the solvent.

scholarly journals Exploring EPR Parameters of 99Tc Complexes for Designing New MRI Probes: Coordination Environment, Solvent, and Thermal Effects on the Spectroscopic Properties

2017 ◽  
Vol 2017 ◽  
pp. 1-8 ◽  
Author(s):  
Bruna T. L. Pereira ◽  
Érika Ferreira Silva ◽  
Mateus A. Gonçalves ◽  
Daiana T. Mancini ◽  
Teodorico C. Ramalho
Keyword(s):  
Thermal Effects ◽  
Hyperfine Coupling ◽  
Hyperfine Coupling Constant ◽  
Spectroscopic Properties ◽  
Water Molecules ◽  
Coupling Constant ◽  
Coordination Environment ◽  
Epr Parameters ◽  
Dynamics Simulations ◽  
Explicit Water

We have evaluated the solvent and thermal effects on spectroscopic parameters of 99Tc complexes coordinated to explicit water molecules. Molecular dynamics simulations were performed followed by hyperfine coupling constant calculations (Aiso). Our results show a significant increase of Aiso, which demonstrates that the studied compounds can be promising contrast agents in MRI.

scholarly journals Theoretical Investigation into the Change in the Number of Water Molecules in Solvent Inaccessible Region of an Enzyme and Enzyme-substrate Complex

2019 ◽  
pp. 1-17
Author(s):  
Ikechukwu Iloh Udema ◽  
Abraham Olalere Onigbinde
Keyword(s):  
Free Energy ◽  
Equilibrium Constant ◽  
Preferential Solvation ◽  
Energy Difference ◽  
Theoretical Research ◽  
Water Molecules ◽  
Free Energy Difference ◽  
Substrate Complex ◽  
Enzyme Substrate ◽  
Theoretical Issues

Background: There may be dry enzymes, but water remains indispensable for the catalytic action of enzymes. There is not as much interest in how the presence of a drug such as aspirin and a psychoactive compound such as ethanol may affect the water-mediated role of the enzyme. Objectives: The objectives of this research are: 1) To assess the changes in the number of water molecules interacting with the enzyme-substrate complex and the solvent inaccessible region of a protein, 2) to determine the free energy difference due to preferential solvation and hydration, and 3) to re-examine theoretical issues in literature and relate them to the interpretation of the results. Methods: A major theoretical research and minor experimentation using Bernfeld method. Results and Discussion: The presence of ethanol/aspirin alone yielded only dehydration of the osmolyte inaccessible region and the enzyme substrate complex (ES). There was positive free energy difference (DDG) if the equilibrium constant for hydration change (Keq(1))> the equilibrium constant for folding-unfolding transition (Keq(3)); it is negative where Keq(3)> Keq(1). Analysis of various models made them valuable for the interpretation of result for feature application. Conclusion: The change in the number of water molecules in an osmolyte inaccessible region of the enzyme and those interacting with the ES may be either positive or negative due respectively to sucrose and ethanol/aspirin. The spontaneity of two processes, hydration and folding-unfolding transition, the free energy difference, differs. The model for water stripping, preferential interaction concept, and the KBI for osmolation and hydration can guide the interpretation of the effects of any cosolute.

Preferential Solvation in 2-Propanol/Water Mixtures: Relationship between Solvatochromic Parameters and Ionization and Transfer Thermodynamics of Nalidixic Acid Antibiotic

2002 ◽  
Vol 216 (10) ◽  
Author(s):  
I. Shehatta
Keyword(s):  
Nalidixic Acid ◽  
Thermodynamic Parameters ◽  
Organic Solvents ◽  
Preferential Solvation ◽  
Potentiometric Method ◽  
Ionization Constants ◽  
Solvatochromic Parameters ◽  
Different Temperatures ◽  
Transfer Thermodynamics

Precise ionization constants for nalidixic acid have been obtained in various binary 2-propanol/water mixtures at four different temperatures using a potentiometric method. The thermodynamic parameters of ionization and transfer of nalidixic acid from water to aquo-organic solvents were calculated. The variation of p

Probing solvent–solvent and solute–solvent interactions in surfactant binary mixtures: solvatochromic parameters, preferential solvation, and quantum theory of atoms in molecules analysis

RSC Advances ◽  
2016 ◽  
Vol 6 (22) ◽  
pp. 18515-18524 ◽  
Author(s):  
Mona Kohantorabi ◽  
Mostafa Fakhraee ◽  
Hadi Salari ◽  
Mohammad Reza Gholami
Keyword(s):  
Quantum Theory ◽  
Binary Mixtures ◽  
Organic Solvents ◽  
Preferential Solvation ◽  
Atoms In Molecules ◽  
Solvatochromic Parameters ◽  
Solvent Interactions ◽  
Solvent Solvent

The behaviour of solvatochromic absorbance probes within binary mixtures of TX-100/organic solvents.

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