Toward Hypoxia-Selective Rhenium and Technetium Tricarbonyl Complexes

With the aim of preparing
hypoxia-selective imaging and therapeutic agents, technetium­(I) and
rhenium­(I) tricarbonyl complexes with pyridylhydrazone, dipyridylamine,
and pyridylaminocarboxylate ligands containing nitrobenzyl or nitroimidazole
functional groups have been prepared. The rhenium tricarbonyl complexes
were synthesized with short reaction times using microwave irradiation.
Rhenium tricarbonyl complexes with deprotonated p-nitrophenyl pyridylhydrazone ligands are luminescent, and this has
been used to track their uptake in HeLa cells using confocal fluorescent
microscopy. Selected rhenium tricarbonyl complexes displayed higher
uptake in hypoxic cells when compared to normoxic cells. A 99mTc tricarbonyl complex with a dipyridylamine ligand bearing a nitroimidazole
functional group is stable in human serum and was shown to localize
in a human renal cell carcinoma (RCC; SK-RC-52) tumor in a mouse.