A thermodynamic study of reactions of amino acids with crown ethers in nonaqueous media as examples of guest-host molecular complex formation

作者：Usacheva T R; Sharnin V A^*

来源：Russian Chemical Bulletin, 2015, 64(11): 2536-2544.

DOI：10.1007/s11172-015-1189-7

• amino acids
• aqueous organic solvents
• crown ethers
• 18-crown-6
• molecular complexes
• thermodynamics

Our findings and the literature data on the effect of binary aqueous organic solvents on the enthalpy and entropy of molecular complexation reactions of 18-crown-6 with glycine, D,L-alanine, and L-phenylalanine and on the stability of the resulting complexes were reviewed. The relationships between the thermodynamic parameters of the complexation reactions and the reactant solvation were analyzed to reveal the key factors that are crucial for the stability of the complexes and the increasing exothermicity of the processes under study in water-ethanol, water-DMSO, and water-acetone. The changes in the stability of 18-crown-6 complexes with amino acids were assumed to be predicted from the Gibbs energy changes in the transsolvation of the amino acids. This criterion was proposed as a basic thermodynamic parameter for estimating the changes in the stability of 18-crown-6 complexes with peptides and ammonium-type cations (structurally related to amino acids) when the composition of the binary aqueous organic solvent is varied.

• 出版日期2015-11