Synthesis and preliminary biological evaluation of the first 99m Tc(I)‐specific semi‐rigid tridentate ligand based on a click chemistry strategy

A novel bifunctional chelating agent based on a click chemistry strategy has been synthesized and characterized on the basis of spectroscopic techniques. The metal chelating part of this new class of tridentate N 2 O ligand combined a triazole unit and an aromatic ring. This latter semi‐rigid framework induced a pre‐organization of the chelating cavity, improving the stability of the corresponding metallic complexes (M =  99m Tc, Re). Thus, the 99m Tc(CO) 3 complex, obtained with good yield and excellent radiochemical purity (>90%), exhibited a high in vitro serum stability. Tissue biodistribution in normal mice showed a rapid clearance, no long‐term retention in organs and no in vivo reoxidation of technetium‐99m, making this compound a promising 99m Tc‐chelating system. Copyright © 2014 John Wiley & Sons, Ltd.