Spectroscopic Analysis and Density Functional Theory Calculations of Mercaptobenzothiazole and Mercaptobenzimidazole Ligands and their Rhenium and Technetium Complexes

In this study, four complexes featuring the [ReO]3+ core by substituting precursors RO(citrate)2- and ReO(gluconate)2- were synthesized. The complex [ReO(MBT)2OH] was obtained through the direct reduction of ReO4- using sodium borohydride as the reducing agent. Characterization of these complexes was conducted using UV-Vis and IR spectroscopy, elemental analysis, 1H and 13C NMR spectroscopy, thermogravimetric analysis (TGA), and density functional theory (DFT) calculations.

At the technetium tracer level, a 99mTcO-complex was synthesized using 99mTc-gluconate as a precursor. The radiochemical purity of the complex exceeded 95%, as measured by thin-layer chromatography. In vitro studies demonstrated that the complex exhibited good stability under physiological conditions, with a partition coefficient indicating its hydrophilic nature. Biodistribution studies in mice revealed significant heart accumulation, with uptake at 10.23 ± 3.87% ID/g at 5 minutes and good retention at 6.86 ± 1.21% ID/g at 60 minutes. One-hour post-injection, the heart/liver, heart/lung, and heart/blood radioactivity ratios were 0.71, 1.1, and 0.95, respectively. These findings suggest that the complex may be suitable for myocardial imaging.