1,4,7-Triazacyclononane

1,4,7-Triazacyclononane (TACN) is a versatile platform from which various ligands can be derived to form effective chelators for (radio)copper(II) complexation. The ability of TACN-derivatives to form highly stable complexes with copper(II) is greatly influenced by the number and type of substituents on the macrocyclic ring. The formed copper(II) complexes show a broad variability in their thermodynamic stability and kinetic inertness, varying in structure from square-pyramidal to distorted octahedral. TACN-based BFCAs have also been used for indirect radiolabelling of biomolecules, rendering them suitable for imaging and therapy.