Isostructural nuclear and luminescent probes derived from stabilized [2 + 1] rhenium(I)/technetium(I) organometallic complexes

A convenient method to prepare ^99mTc analogues of a class of rhenium(I) luminophores was developed, creating isostructural pairs of nuclear and optical probes. A two-step procedure and a new one-pot procedure were used to produce a series of [2 + 1] complexes of the type [Tc(CO)₃(bipy)L] ⁺ in greater than 80% yield. The plasma stability of the reported compounds was evaluated, where the basicity of the monodentate pyridine type ligand (L) has a significant impact with half-lives ranging from 2 to 20 h. The ability to generate the radioactive complexes makes it possible to quantitate cell uptake of Re luminophores, which was demonstrated in MCF-7 breast cancer cells using ^99mTc analogues of two Re(I)-based mitochondrial targeting dyes.