Calix[n]triazoles and Related Conformational Studies

Calix[n]triazoles are developed as new derivatives in the calixarene family. Calixtriazole compounds 2-4 are synthesized using an iterative convergent strategy including an inter-/intramolecular copper(I)-catalyzed azide-alkyne cycloaddition reaction. Solid-state structures are clearly refined to give 1,2-alternate and partial cone conformations for calix[4]triazole and calix[5]triazole, respectively. Theoretical studies based on density functional theory (DFT) calculations indicated that intermolecular interactions are crucial in determining the conformers of the crystals, and the most stable conformers of calix[4]triazole, calix[5]triazole, and calix[6]triazole in the monomeric forms are 1,3-alternate, 1,3-alternate, and 1,3,5-alternate, respectively.