Technetium-99m is the most commonly used radionuclide in nuclear medicine, but has no stable nuclides. Studying cold rhenium compounds as analogs for technetium derivatives has long been a standard means of searching for radiopharmaceutical candidates. More recently, as rhenium-188 (half-life of 17 hours with �- = 2.1 MeV) becomes available carrier free, and a clinically relevant formulation becomes available for the 188Re(CO)3+ core, there is interest in theranostic treatments, where a matched pair of 99mTc and 188Re compounds would target the same location for diagnostic and therapeutic uses, respectively.We have previously prepared novel compounds as possible target-specific radiopharmaceuticals. But we have also prepared candidates of novel metal-essential radiopharmaceuticals compounds. One avenue we've examined is the use of neutral tripodal ligands bound to Re(CO)3+ to create lipophilic compounds that will stand up to biological nucleophiles. We have previously prepared Re(CO)3+ derivatives with methane-derivatized tripodal derivatives with amine, pyrazole, imidazole and pyridine donor groups.In the current study we present results showing that imidazole based-ligands are inferior to corresponding pyridine-based ligands as the tris-imidazole ligands often act only as k2-donors. In each case the methane-derivatized tris-2-pyridine ligand acts as a k3-donor and strongly resists replacement by biological nucleophiles.Finally, we present new compounds with a pendant ether ligand that will help create lipophilic compounds that might have biological use. Novel compounds were characterized by spectroscopic and crystallographic means.

Rhenium(I) compounds bound by tripodal ligands of pyridine and N-methylimidazole

245th National Meeting (2013)

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