Preparation and characterization of technetium complexes with Schiff base and phosphine coordination. 1. complexes of technetium-99g and -99m with substituted acac 2en and trialkyl phosphines (where acac 2en = N,N′-ethylenebis[acetylacetone iminato

Abstract

A series of 23 technetium(III) complexes of the type [TcL(PR 3) 2]+, where L represents a tetradentate Schiff base ligand in the equatorial plane and PR 3 represents the axial phosphine ligands, are reported. Full ligand syntheses and characterizations are included. The technetium complexes were prepared with 99mTc 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 99gTc or 99gTc/99mTc (designated as carrier-added) to allow macroscopic characterization. Equivalence of the 99gTc and 99mTc 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 to 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.