The Co₃(CO)₉C moiety acts as an electroreducible marker for estradiol detection enhancement in the HPLC-ED technique

The tricobalt enneacarbonyl-ethynylestradiol derivative Co₃(CO)₉C-C≢C-E (E=estradiol) proved to be elusive, due to the strong electron-withdrawing properties of both the 17β OH and the Co₃(CO)₉C groups. However, the advantage of introducing the Co₃C core, which undergoes a reversible 1 e reduction, can be achieved by the interposition of a spacer arm, namely -C(O)NHC₆H₄-, generated in situ during the synthesis in the appropriate experimental conditions. The corresponding bioorganometallic product Co₃(CO)₉C-C(O)NHC₆H₄-C≢;C-E retains an acceptable relative binding affinity for estradiol receptor affording a new electrochemical marker suitable for biochemical analyses.