Synthesis and conformational structure of hydrazo-bridged homo calixpyridinetriazines†
Presented in this paper are the practical synthesis and conformational structure of hydrazo-bridged homo calixarenes. The step-wise fragment coupling method based on the nucleophilic aromatic substitution reaction of 2,6-dihydrazinylpyridine with 6-alkoxy-2,4-dichlorotriazine afforded effectively hydrazo-linked homo calixpyridinetriazines. The exhaustive methylation of –NHNH– linkages led to lipophilic macrocycles, while the introduction of a THP-protected triglyme moiety on a triazine ring produced a water soluble hydrazo-bridged homo calixpyridinetriazine. The acquired hydrazo-bridged homo calixarenes adopted a cone conformational structure with two nitrogen atoms of the hydrazine linkage forming respectively a conjugation system with pyridine and triazine rings. The unique macrocyclic conformation and multidentate binding sites would render hydrazo-bridged homo calixpyridinetriazines powerful hosts in molecular recognition and self-assembly.
- This article is part of the themed collection: Organic Chemistry Frontiers HOT articles for 2017