Evaluation of Gibbs free energy for the transfer of a highly hydrophilic ion from an acidic aqueous solution to an organic solution based on ion pair extraction

The molecular recognition in aqueous solution is extremely important because most biological processes occur in aqueous solution. Water-soluble members of the calix[n]arene family (e.g., p-sulfonato substituted) can serve as model systems for studying the nature and manner of interactions between biological receptors and small ions. The complex formation behavior of water-soluble p-sulfonatocalix[4]arene and thiacalix[4]arene and group IA, IIA and f-block metal cations has been investigated computationally by means of density functional theory computations in the gas phase and in aqueous environment. The calculated Gibbs free energy values of the complex formation reaction of these ligands with the bare metal cations suggest a spontaneous and energy-favorable process for all metal cations in the gas phase and only for Na+, Mg2+, Lu3+ cations in water environment. For one of the studied cations (La3+) a supramolecular approach with explicit solvent treatment has been applied in the study of the effect of metal hydration on the complexation process. The La3+ binding to the p-sulfonatocalix[4]arene host molecule (now in the metal’s second coordination shell) is still exergonic as evidenced by the negative Gibbs free energy values (ΔG 1 and ΔG 78). The combination of implicit/explicit solvent treatment seems useful in the modeling of the p-sulfonatocalix[4]arene (and thiacalix[4]arene) complexes with metal cations and in the prediction of the thermodynamic parameters of the complex formation reactions.

Download Full-text

GIBBS POTENTIAL, SYNONYM FOR GIBBS FREE ENERGY

A-to-Z Guide to Thermodynamics Heat and Mass Transfer and Fluids Engineering ◽

10.1615/atoz.g.gibpotsynforgibfreene ◽

2006 ◽

Vol g ◽

Keyword(s):

Free Energy ◽

Gibbs Free Energy ◽

Gibbs Potential

Download Full-text

Misconceptions arising from a Sign Discrepancy in Thermodynamic Data for the Gibbs Free Energy Profile of Ribonuclease A

Protein and Peptide Letters ◽

10.2174/0929866023408625 ◽

2002 ◽

Vol 9 (4) ◽

pp. 305-313

Author(s):

Paul Chun

Keyword(s):

Free Energy ◽

Gibbs Free Energy ◽

Thermodynamic Data ◽

Ribonuclease A ◽

Energy Profile ◽

Free Energy Profile

Download Full-text

Chemical equilibrium and chemical kinetics

10.1093/oso/9780198782957.003.0014 ◽

2018 ◽

Author(s):

Dennis Sherwood ◽

Paul Dalby

Keyword(s):

Free Energy ◽

Equilibrium Constant ◽

Gibbs Free Energy ◽

Chemical Kinetics ◽

Chemical Equilibrium ◽

First Principles ◽

Effect Of Temperature ◽

Total System ◽

Free Energies

Building on the previous chapter, this chapter examines gas phase chemical equilibrium, and the equilibrium constant. This chapter takes a rigorous, yet very clear, ‘first principles’ approach, expressing the total Gibbs free energy of a reaction mixture at any time as the sum of the instantaneous Gibbs free energies of each component, as expressed in terms of the extent-of-reaction. The equilibrium reaction mixture is then defined as the point at which the total system Gibbs free energy is a minimum, from which concepts such as the equilibrium constant emerge. The chapter also explores the temperature dependence of equilibrium, this being one example of Le Chatelier’s principle. Finally, the chapter links thermodynamics to chemical kinetics by showing how the equilibrium constant is the ratio of the forward and backward rate constants. We also introduce the Arrhenius equation, closing with a discussion of the overall effect of temperature on chemical equilibrium.

Download Full-text