Phosphonoacetic acid as a building block in supramolecular chemistry: salts with organic polyamines

Phosphonoacetic acid, (HO)(2)P(O)CH2COOH, forms adducts with a range of amines. The acid component in these adducts may be the neutral molecule C2H5O5P, the mono-anion (C2H4O5P)(-) or the di-anion (C2H3O5P)(2-). The substructure formed by the acid component takes the form of simple chains in compounds (1)-(3), which are the 1:1 adducts formed with 1,4-diazabicyclo[2.2.2]octane, 4,4'-bipyridyl and 1,3-trimethylenedipiperidine, respectively. These adducts contain C2H5O5P, (C2H4O5P)(-) and (C2H3O5P)(2-), respectively, although (3) is solvated by a mixture of methanol and water. The (C2H4O5P)(-) anion substructure in (4), which is the adduct formed with meso-5,5,7,12,12,14-hexa-C-methyl-1,4,8,11-tetraazacyclotetradecane, is a chain of spiro-fused rings, while the substructure in (5), which is the adduct formed with 2,2'- dipyridylamine, is a chain of edge-fused rings. In (6), the adduct formed with 1,2-bis(4'-pyridyl)ethane, the anion substructure is two-dimensional. The chain substructures are linked by the amine units into two-dimensional structures in (1) and (4) and into three-dimensional frameworks in (2), (3) and (5), while the anion sheets in (6) are likewise linked by the amine units into a three-dimensional framework.