Crown ether-appended calix[2]triazolium[2]arene as a macrocyclic receptor for the recognition of the H2PO4- anion.

A crown ether-appended calix[2]triazolium[2]arene, which exhibits excellent selectivity for H2PO4- compared to other anions, has been designed and synthesized. The selectivity of the prepared receptor for H2PO4- is caused by the stabilization of H2PO4- by the neighboring triazolium hydrogen bond donors and crown ether hydrogen bond acceptors.