Proton-ionizable crown compounds. 1. Synthesis, complexation properties, and structural studies of macrocyclic polyether-diester ligands containing a triazole subcyclic unit

A series of macrocyclic polyether-diester ligands containing a proton-ionizable triazole subcyclic unit has been prepared. The crystal structure of one ligand shows that it forms a hydrate with the water molecule located in the macrocyclic cavity. The water is coordinated by hydrogen bonding to two oxygen atoms of the macrocycle and to the NH group of the triazole moiety. These macrocycles also form complexes with amines. These amine complexes are kinetically more stable than complexes formed by the triazole ligands with the corresponding alkylammonium perchlorate salts. The crystal structure of one of these complexes shows that the triazole ring has donated a proton to the amine group. 41 references, 4 figures, 2 tables.