Crown Ethers

Used as complexing agents for the selective solvation of cations.

 

 

Crown Ether Cavity Size/Å[12] Favored Alkali Ion[13] Effective Ion Radii/Å[14]
12-crown-4 0.6-0.75 Li+ 0.76
15-crown-5 0.86-0.92 Na+ 1.02
18-crown-6 1.34-1.55 K+ 1.38
21-crown-7 1.7-2.1 Cs+ 1.67