A dual lanthanide probe suitable for optical (Tb3+ luminescence) and magnetic resonance imaging (Gd3+ relaxometry)

A new polyaminocarboxylate ligand derived from N,C-pyrazolylpyridine was synthesized. The luminescence and relaxometry properties of its Tb3+ and Gd3+ chelates were investigated in aqueous solutions. The Tb3+ chelate is strongly luminescent having remarkable lifetime and quantum yield (τ = 1.82 ms and Φ = 0.42). The 1/T1 proton relaxivity at 20 MHz and 25 °C (5.3 s−1 mM−1) of the Gd3+ chelate was found to be comparable to that of the clinically used Gd-DTPA.