Structures of aza-macrocyclic ligands with polyphosphonated dangling groups

Two phosphonated hexaaza-macrocycles with 24- and 26-membered rings have been synthesized via a Mannich reaction and characterized. The novel crystal structures of the macrocyclic ligands show the extended 3-D hydrogen bonded structure in their solid states. These ligands have unusual ring conformations with two or four pendent arms wrapping around the macrocycle with alternating up and down orders. Strong hydrogen bonding between the protonated phosphonate groups and the deprotonated phosphonated groups was observed in those structures together with the complicated solvent hydrogen bonding networks.