Synthesis and Structure of Azacalix[2]pyrimidine[2]triazines and Their Self‐assembly in the Solid State

Abstract

A number of azacalix[2]pyrimidine[2]triazines were synthesized in moderate to good yields from both a step-wise fragment coupling approach and a one-pot reaction strategy starting from 4,6-diaminopyrimidines and cyanuric chloride. Nucleophilic aromatic substitution reaction of resulting dichloro-substituted azacalix[2]pyrimidine[2]triazines with NH 4 Cl led to the formation of NH 2 -bearing azacalix[2]pyrimidine[2]triazine analogs. Azacalix[2]pyrimidine[2]triazines adopted symmetric 1,3-alternate conformations in solution while twisted 1,3-alternate conformations were observed in the solid state. In the presence of different additives during the growth of single crystals, azacalix[2]pyrimidine[2]triazines containing amino (-NH 2 ) groups gave varied self-assembled structures due to the formation of different intermolecular hydrogen bond motifs.