Technetium and Rhenium – Fundamental Research and Nuclear Medical Applications
Ulrich Abram, Freie Universität Berlin, Institute of Chemistry and Biochemistry
Technetium is an artificial element and has no appreciable natural resources. Nevertheless,
99mTc (pure gamma emitter, half-life: 6 hours) is the workhorse of diagnostic nuclear
medicine and more than 80 per cent of all routine applications (about 35 million clinical
studies per year) are done with this metastable nuclear isomer. The heavier congener of
technetium, the element rhenium, is not just an interesting element for catalysis, but also
frequently used as non-radioactive mimic for technetium chemistry. Additionally, it has two
--emitting isotopes (186Re and 188Re), which possess potential for therapeutic nuclear
medicine.
The talk will cover recent work on rhenium and technetium bioconjugates on the basis of
oxorhenium(V) and oxotechnetium(V) complexes with tetra- and pentadentate ligands,
nitrosyl and fluorido complexes of the two elements as well as organometallic compounds
with N-heterocyclic carbene, aryl and cyclopentadienyl units. The compounds have been
isolated in crystalline form with the long-lived isotope 99Tc (half-life: 200.000 years) or
natural rhenium and studied by conventional spectroscopic methods and X-ray diffraction.
When appropriate, corresponding 99mTc compounds were prepared and tested for their
biological behavior.