Rhenium(I) tricarbonil complexes with aminoacids in aqueous solution

Organometallic tricarbonyl complexes of Rhenium(I) and Technetium(I), fac−[M(H2O)3(CO)3]+ (M = Re, Tc), especially the aqueous complexes, have recently assumed an important role for diagnostic and therapeutic applications. In this regard, fac−[Re(H2O)3(CO)3]+ cation is readily conjugated to biomolecules which contain coordinating N, P, O, S atoms [1], where one or more water molecules can be replaced by ligands to obtain very stable d6 low−spin complexes [2]. Recently study has showed interaction between fac − [Re(H2O)3(CO)3]+ and histidine/imidazole molecule. Aim of this work is the study of the interaction among fac − [Re(H2O)3(CO)3]+ and some aminoacids that have been investigated using different instrumental techniques. Potentiometric titrations conducted with glass electrode in the pH range 2−10 estabilish that a complexation effect is observed. Information on complexes formation can be obtained also by spectrophotometric UV−VIS and fluorimetric measurements in solutions with different metal/ligand ratio.