Preparation and characterization of technetium complexes with Schiff base and phosphine coordination.: 1.: Complexes of technetium-99g and-99m with substituted acac2en and trialkyl phosphines (where acac2en = N,N′-ethylenebis[acetylacetone iminatol])

A series of 23 technetium(III) complexes of the type [TcL(PR3)(2)]+, where L represents a tetradentate Schiff base ligand in the equatorial plane and PR3 represents the axial phosphine ligands, are reported. Full ligand syntheses and characterizations are included. The technetium complexes were prepared with Tc-99m to study the organ distribution in guinea pigs at 5 and 60 min postinjection. Four prototypical complexes of the series were also prepared with either Tc-99g gp Tc-99g/99mTc (designated as carrier-added) to allow macroscopic characterization. Equivalence of the Tc-99g and Tc-99m complexes was demonstrated by dual detection high performance liquid chromatography (HPLC) techniques. The development of a one-step preparation from the standard two step method is discussed for some complexes. Biodistribution data are related Co structure and lipophilicity. None of the complexes in the series exhibited a tendency for in vivo reduction. Myocardial uptake was favorable for a number of complexes. The optimal agent from this series for further imaging development was chosen based on myocardial uptake, rapid blood and liver clearance, and ability to be formulated as a one-step kit. NUCL MED BIOL 26;7:755-710, 1999. (C) 1999 Elsevier Science Inc. All rights reserved.