Mono-, di-, and tetraazido derivatives of (thia)calix[4]arenes with free phenolic hydroxy groups

Abstract

A thiacalix[4]arene with four azido groups on the upper rim and free hydroxy groups on the lower rim was synthesized for the first time by the diazotization reaction. A procedure for the synthesis of diazido derivatives of calix[4]arenes and thiacalix[4]arenes with free phenolic hydroxy groups via benzoyl protection of OH groups was developed and optimized. A similar technique was used to synthesize a monoazido derivative of calix[4]arene, the parent compound for the biscalix[4]arenes with ethylene glycol and dihydroxyphenylene linkers obtained by the azide-alkyne cycloaddition reaction. It was demonstrated that these biscalix[4]arenes can bind the cationic dye rhodamine 6G, which is not observed for the starting de-tert-butylated calix[4]arene. It was established that the biscalix[4]arene—rhodamine 6G system can be used for the recognition of cationic surfactants and that the more lipophilic the surfactant, the more pronounced the system’s response.