Study of copper(II) polyazamacrocyclic complexes by electronic absorption spectrophotometry and EPR spectroscopy

Copper(II) mononuclear complexes with the polyazamacrocyclic ligands NOTA ( 1,4,7-triazacyclononane-N,N',N "-triacetate), DOTA (1,4,7,10-tetraazacyclo- dodecane-N,N',N ",N'''-tetraacetate), NOTP [1,4,7-triazacyclononane-N,N',N "-tris(methylenephosphonate)] and DOTP [1,4,7,10-tetraazacyclododecane-N,N' ,N ",N'''-tetrakis(methylenephosphonate)] were characterised in aqueous sol ution by electronic absorption spectrophotometry and electron paramagnetic resonance (EPR) spectroscopy. While two isomeric species were detected by E PR spectroscopy in frozen samples of the polycarboxylate complexes, only on e complex form was found for the poly(methylenephosphonate) systems. The re sults obtained are in accordance with a six-coordinate pattern for the meta l centre, yielding tetragonally distorted complexes in solution, in agreeme nt with previously reported studies on Cu-II complexes, both in solution an d in the solid state.