New oxorhenium (V) complex with an imidazol [NN] /hydantoin [SN] mixed ligand system, and radiochemical behavior of its oxotechnetium (V) complex analog

Abstract

A [ReO(Imz)(Hyd)(H 2 O) 2 OH] complex was successfully synthesized by the ligand exchange method using oxorhenuim citrate and an imidazole /Hydanton mixed ligand system. Geometry optimization of complex has been carried out using DFT at the B3LYP/LANL2DZ functional in singlet state. B3LYP predicated infrared spectrum of the geometrically optimized structure using the same level of the theory and the same base set showed good agreement with experimentally observed values. The spin allowed singlet-singlet electronic transition of the [ReO(Imz)(Hyd) (H 2 O) 2 OH] complex was calculated with time dependent density function theory (TD-DFT) and the UV-Vis spectra has been discussed on this basis. The complex was characterized using microanalysis and IR, UVVis, NMR and mass spectroscopic. The technetium tracer [ 99m TcO(Imz)(Hyd) (H 2 O) 2 OH] has also been synthesized by two methods using 99m Tc-gluconate as a precursor or; by direct reduction. The radiochemical purity of the complex was over 95% as measured by thin layer chromatography. In vitro studies showed that the complex possessed good stability under physiological conditions. The partition coefficient indicated that the complex hydrophilic and the electrophoresis results showed that the complex cationic. Biodistrbution in mice showed that the complex accumulated in heart uptake of 9.53 ± 3.87% ID/gm at 5 min and good retention (6.37 ± 1.21)% ID/gm at 60 min. One hour after the injection, the heart/liver, heart/lung and heart/blood radioactivity ratios were 0.46, 1.04 and 0.56, respectively. These findings indicate that the complex might be suitable for myocardial imaging.