Preparation and characterization of technetium(IV)-complexes with diethylenetriaminepentaacetic acid and ethylenediaminetetraacetic acid as ligands

Complexation of rhenium with ethylenediaminetetraacetic acid: studies of technetium analogue using Raman spectroscopy

The complexation of rhenium, to the polyamino-polycarboxylate EDTA was investigated using Raman spectroscopy. Complexation occurred when ReVIIO4 - was placed in the presence of a Sn(II) reducing agent and EDTA. Rhenium complexation was confirmed by the Raman and UV/Vis spectra of the solution samples. Binding modes were assigned using the Raman spectra of a solid-phase sample. Three complexes are proposed, a six-coordinate dimer H4[Re2(μO)2(EDTA)2], a seven-coordinate monomer H2[ReO(EDTA)(OH2)2] and a mono-oxorhenium [ReO(EDTA)] 2- . The solubility of Re(IV)-EDTA complexes is greater than that of ReO4. If this behaviour is analogous to Tc, it is proposed that complexation to EDTA by Tc(IV) may increase the solubility and enhance the environmental transport of 99Tc from geological repositories.

Technetium-99m complex of N-(2-pyridylmethyl)iminodiacetic acid as a new renal radiopharmaceutical

A tetradentate chelating agent constituting of an iminodiacetic acid group and a nitrogen atom of pyridine, N-(2-pyridylmethyl)iminodiacetic acid (PMIDA), was coordinated with 99mTc and evaluated as a renal functional agent. The complex of PMIDA with 99mTc was prepared by using a stannous chloride solution as a reducing agent. The chelating efficiency was analyzed by thin layer chromatography and electrophoresis. Chelation with 99mTc resulted in a single radiochemical product. Biological studies were performed in mice and rats. 99mTc-PMIDA was removed from the circulation solely by the kidneys. Clearance of 99mTc-PMIDA from the blood and the kidneys was as rapid as that of 99mTc-diethylenetriaminepentaacetic acid. The rate of blood clearance was unaffected by the administration of probenecid (a test for tubular secretion by the weak-acid mechanism), so that the glomerular filtration rate could be estimated by measuring its clearance from the blood. The results in animals with myohemoglobinuric acute renal failure suggested that 99mTc-PMIDA might be a useful renal function radiopharmaceutical.