¹⁸⁸Re(III)-EDTA - a Multipurpose Starting Material for the Preparation of Relevant ¹⁸⁸Re Complexes under Mild Conditions

An easy and gentle method for the preparation of ¹⁸⁸Re(V) complexes with bidentate and tetradentate ligands is described starting from the precursor complex ¹⁸⁸Re(III)-EDTA. That complex is prepared at room temperature in acidic solution and reacts by a combined re-oxidation/ligand exchange reaction with appropriate ligands like DMSA or ECD (DMSA = dimercapto succinic acid, ECD = L,L-ethylene dicysteine diethyl ester) or en and cyclam (en = ethylene diamine, cyclam = 1,4,8,11-tetraazacyclotetradecane) to the ¹⁸⁸Re(V)-oxo- and dioxocomplexes, respectively. The chelates were unambiguously identified by chromatographic comparison with spectroscopically characterised samples or known ^99mTc-kit reconstitutions. The reaction succeeds under mild conditions (room temperature, short time, neutral or weak basic solutions) with high yields and has potential for labelling of sensitive biomolecules with ¹⁸⁸Re.