Introduction Crown ethers are heteroaromatic compounds that act as host compounds in Host-Guest chemistry, and can form complexes with organic or inorganic cations or anions. Among the crown ethers, 18- Crown-6 has the potential to form stable complexes with cations such as K+, and NO+. These reagents have nanotube-like structures, their X-ray are presented in the following. Their preparation methods are given.