The role of the capping bond effect on pyclen nat Y 3+ / 90 Y 3+ chelates: full control of the regiospecific N-functionalization makes the difference.

Thanks to a smart regiospecific N-functionalization, a pyclen based ligand bearing one picolinate and two acetate arms organized in a dissymmetric manner was synthesized for Y3+ complexation, and compared to its symmetric analogue. The nature of the capping bonds around the metal coordination environment has a dramatic effect on the properties of the chelate, the Y-nat(3+) and Y-90(3+) dissymmetric derivatives presenting enhanced thermodynamic stability and kinetic inertness.