NMR and Luminescence Binding Studies of Ytterbium, Thulium, and Europium Macrocyclic Complexes with Phosphorus(V) Oxy Anions

The binding of a series of phosphate anions to coordinatively unsaturated macrocyclic complexes of Yb, Tm, and Eu was studied by 1H‐NMR, emission and circularly polarized luminescence (CPL) spectroscopy. Each ternary adduct was distinguished by its spectral profile. With O‐phosphorylated amino acids and peptides, chemoselective ligation of the phosphate moiety was favored by Eu over chelation involving the terminal amino group, which was competitive for Tm and Yb. A preference for binding O‐phosphono‐L‐tyrosine sites was found with various Eu complexes, and was signalled by ratiometric changes in metal‐based emission and CPL spectra.