Water soluble macrocyclic ligands with an unprecedented size-selectivity pattern for lanthanides ions. (a) Molecular structures for macrotripa and macrodipa. (b) Stability constants for Ln(III) complexes formed with macrotripa and macrodipa plotted versus lanthanides cations radii. (c) Depictions of the conformational toggles present in Ln(III)-macrodipa complex system with the representative crystal structures of [La(macrodipa)]⁺ and [Lu(macrodipa(OH₂)]⁺. Figure is recreated from Ref [153] by courtesy of the American Chemical Society.