Hexaaza-18-crown-6 is the

macrocyclic ligand In coordination chemistry, a macrocyclic ligand is a macrocyclic ring having at least nine atoms (including all hetero atoms) and three or more donor sites that serve as ligands. Crown ethers and porphyrins are prominent examples. Macrocyclic lig ...

with the formula (CH₂CH₂NH)₆. A white solid, this compound has attracted attention as the N6-analogue of 18-crown-6. It functions as a

hexadentate ligand A hexadentate ligand in coordination chemistry is a ligand that combines with a central metal atom with six bonds. One example of a hexadentate ligand that can form complexes with soft metal ions is TPEN. A commercially important hexadentate ligan ...

coordination chemistry A coordination complex is a chemical compound consisting of a central atom or ion, which is usually metallic and is called the ''coordination centre'', and a surrounding array of chemical bond, bound molecules or ions, that are in turn known as ' ...

. It is the parent hexa

aza-crown ether In organic chemistry, an aza-crown ether is an aza analogue of a crown ether (cyclic polyether). That is, it has a nitrogen atom (amine linkage, or ) in place of each oxygen atom (ether linkage, ) around the ring. While the parent crown ethers ...

. Its protonated derivatives bind anions via multiple hydrogen bonds.{{cite journal , doi=10.1016/j.inoche.2008.01.028, title=Binding of Fluoro-Containing Anions to Hexaazamacrocyclic Ligand: Competitive Interactions of Fluoride and Tetrafluoroborate Anions with Hexaprotonated [18]aneN6, year=2008, last1=Fonari, first1=Marina S., last2=Ganin, first2=Eduard V., last3=Gelmboldt, first3=Vladimir O., last4=Basok, first4=Stepan S., last5=Luisi, first5=Brian S., last6=Moulton, first6=Brian, journal=Inorganic Chemistry Communications, volume=11, issue=5, pages=497–501

References

Polyamines Ethyleneamines Chelating agents Macrocycles Hexadentate ligands