Two kit preparations of the organometallic precursor [ 188 Re(H 2 O) 3 (CO) 3 ] + in aqueous media are presented. Method A uses gaseous carbon monoxide and amine borane (BH 3 ‚NH 3 ) as the reducing agent. In method B CO(g) is replaced by K 2 [H 3 BCO 2 ] that releases carbon monoxide during hydrolysis. Both procedures afford the desired precursor in yields >85% after 10 min at 60 °C. HPLC and TLC analyses revealed 7 ( 3% of unreacted 188 ReO 4and <5% of colloidal 188 ReO 2 . Solutions of up to 14 GBq/mL Re-188 have been successfully carbonylated with these two methods. The syntheses of two tailor-made bifunctional ligand systems for the precursor [ 188 Re(H 2 O) 3 (CO) 3 ] + are presented. The tridentate chelates consist of a bis[imidazol-2-yl]methylamine or an iminodiacetic acid moiety, respectively. Both types of ligand systems have been prepared with alkyl spacers of different length and a pendent primary amino or carboxylic acid functionality, enabling the amidic linkage to biomolecules. The tridentate coordination of the ligands to the rhenium-tricarbonyl core could be elucidated on the macroscopic level by X-ray structure analyses and 1D and 2D NMR experiments of two representative model complexes. On the nca level, the ligands allow labeling yields >95% with [ 188 Re(H 2 O) 3 (CO) 3 ] + under mild reaction conditions (PBS buffer, 60 °C, 60 min) at ligand concentrations between 5 × 10 -4 M and 5 × 10 -5 M. Thus, specific activities of 22-220 GBq per µmol of ligand could be achieved. Incubation of the corresponding Re-188 complexes in human serum at 37 °C revealed stabilities between 80 ( 4% and 45 ( 10% at 24 h, respectively, and 63 ( 3% and 34 ( 3% at 48 h postincubation in human serum depending on the chelating system. Decomposition product was mainly 188 ReO 4 -. The routine kit-preparation of the precursor [ 188 Re(H 2 O) 3 (CO) 3 ] + in combination with tailormade ligand systems enables the organometallic labeling of biomolecules with unprecedented high specific activities.

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Sjmposium Abstracts. S809 68Zn: 0.03% 6jZn, 0.09 % 66Zn, 0.75% 67Zn ,98,32% 68Zn, 0.81% 70Zn 70Zn: 0.07% -Zn ,0.006% 66Zn , 0.01% 67Zn , 6.06% 68Zn ,93.92% "Zn "".Zn: 48.6% @Zn , 27.9% 66Zn , 4.1% 67Zn , 18.8% 68Zn , 0.6% 70Zn .

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