Tricarbonyltechnetium(i) and tricarbonylrhenium(i) complexes of amino acids: crystal and molecular structure of a novel cyclic dimeric Re(CO)3-amino acid complex comprised of the OON donor atom set of the tridentate ligand

Abstract

Radiolabeled complexes of monoamino polycarboxylic, polyamino monocarboxylic and thiol containing amino acid ligands were prepared from a fac-[(99m)Tc(CO)3(H2O)3](+) precursor.The overall radiochemical yield was 94-98%. The complexes exhibited substantial in vitro and in vivo stability. The corresponding Re(I) complexes of the ligands DAPA, Asp and CysH were prepared and characterized by means of IR, NMR, and MS spectroscopic studies, as well as X-ray crystallography (for those containing D,L-DAPA and D,L-Asp). The rhenium complexes have been structurally correlated with the technetium complexes by means of HPLC studies. The reaction of Re(CO)5Cl with D,L-Asp in presence of triethylamine led to the formation of a new class of cyclic dimeric complexes formed by the OON donor atom set of the tridentate ligands. The amino carboxylate ligand system formed well defined complexes with a fac-[M(CO)3(H2O)3](+) core and shows good promise in (99m)Tc(CO)3 tracer development.

New leads for fragment-based design of rhenium/technetium radiopharmaceutical agents

“…S1). The third available position is occupied by the O atom (-carboxylate) from a second Asp unit (Nayak et al, 2013). The Re-O 1 (-carboxylate) and Re-O(-carboxylate) bond distances are both 2.149 (4) Å .…”

Formation of a highly dense tetra-rhenium cluster in a protein crystal and its implications in medical imaging

“…99m Tc remains an important radionuclide for diagnostic nuclear medicine with $80% of current radiopharmaceuticals administered clinically containing this radioisotope (Liu, 2004;Kluba & Mindt, 2013). The rhenium homolog is regularly utilized as a model for the technetium complex of interest to confirm its coordination and structure, with the advantages that accompany working with a nonradioactive complex (Bordoloi et al, 2015;Nayak et al, 2013Nayak et al, , 2015. However, the medical advantages of rhenium should not be underestimated when considering the radionuclides of 186 Re and 188 Re.…”

Synthesis and Evaluation of Tricarbonyl 99mTc-Labeled 2-(4-Chloro)phenyl-imidazo[1,2-a]pyridine Analogs as Novel SPECT Imaging Radiotracer for TSPO-Rich Cancer

“…In addition, the tricarbonyl technetium-99m ( 99m Tc-(CO) 3 ) unit has been shown to be useful for introducing 99m Tc into biomolecules because of its high chemical stability and small size. In order to take advantage of molecular imaging techniques with 99m Tc-(CO) 3 , many low-molecular weight 99m Tc(I)-complex with tridentate ligands have been developed and used for the preparation of 99m Tc-(CO) 3 -labeled radiotracers [19,20,21,22,23,24]. …”