Synthesis of Tetraazacalix[2]arene[2]triazines: Tuning the Cavity by the Substituents on the Bridging Nitrogen Atoms

A number of tetraazacalix[2]arene[2]triazines bearing different substituents on the bridging nitrogen atoms were synthesized efficiently using a fragment coupling strategy. The N-arylation of the parent azacalix[2]arene[2]triazine afforded tetra(arylaza)calix[2]arene[2]triazine in 91% yield. The introduction of different substituents on the bridging positions led to the regulation of the cavity of the resulting macrocyclic molecules.