Synthesis and characterization of organometallic rhenium(І) and technetium(І) bile acid complexes

Eight bile acid derivatives have been synthesized with alkyl chains of various length based tridentate ligand chelating system. These derivatives have been reacted with the precursor [Et4N]2[Re(CO)3Br3] and fac-[M(CO)3(H2O)3]+ (M = 99mTc, Re) in ethanol or ethanol–aqueous media to form water-soluble and stable organometallic complexes in good yields. 1H NMR, 13C NMR, IR and elemental analysis or HRMS spectroscopic analyses confirmed the tridentate complexation of the metal–tricarbonyl fragment exclusively via the tridentate chelates. In addition, the corresponding radioactive technetium-99m complexes were prepared successfully and challenged for stability in physiological phosphate buffer at 37 °C for 24 h. No decomposition of the complexes could be detected under the condition proving the stability of these complexes.