TRACE METAL ROLE ON CROWN ETHERS STABILITY BY DFT METHODS

Document Type: Original Article

Author

Department of Chemistry, Faculty of Science, University of Jiroft, Jiroft, Iran

Abstract

Crown ethers strongly bind certain cations, forming complexes. The oxygen atoms are well situated to coordinate with a cation
located at the interior of the ring, whereas the exterior of the ring is hydrophobic. The resulting cations often form salts that are
soluble in nonpolar solvents, and for this reason crown ethers are useful in phase transfer catalysis. The denticity of the polyether
influences the affinity of the crown ether for various cations. For example, 18-crown-6 has high affinity for potassium cation, 15-
crown-5 for sodium cation, and 12-crown-4 for lithium cation. The high affinity of 18-crown-6 for potassium ions contributes to its
toxicity. Crown ethers are not the only macrocyclic ligands that have affinity for the potassium cation. Ionophores such as
valinomycin also display a marked preference for the potassium cation over other cations. In this study different role of crown ethers
in stability of trace metal complexes were considered by DFT methods.


Keywords