Synthesis of heptadentate (N4O3) amine-phenol ligands and radiochemical studies with technetium-99m

Heptadentate amine-phenol ligands with N4O3 donor atoms for coordination were synthesized by condensing tris(2-aminoethyl)amine with salicylaldehyde or acetophenone and reducing the Schiff bases formed with NaBH4. The ligands were characterized by 1H and 13C nuclear magnetic resonance spectroscopy. Radiochemical studies were carried out with no-carrier-added 99mTc and 99mTc spiked with 0.1-100 microM of 99Tc. Complexation yields were estimated from thin layer chromatography, paper electrophoresis, and solvent extraction studies. 99mTc complexes were formed in yields better than 90% with the amine-phenol ligands. The complexes were found to be neutral and lipophilic. Biodistribution studies of the 99mTc complexes showed that clearance was mainly through the hepatobiliary system.