[Re]Re- and [Tc]Tc-Tricarbonyl Metal Complexes with 1,4,7-Triazacyclononane-Based Chelators Bearing Amide, Alcohol, or Ketone Pendent Groups.

1,4,7-Triazacyclononane (TACN)-based chelators, such as NOTA and NODAGA, have shown great promise as bifunctional chelators for [M(CO)] cores (M = Tc and Re) in radiopharmaceutical development. Previous investigations of TACN-based chelators bearing pendent acid and ester arms demonstrated the important role the pendent arms have in successful coordination of the [M(CO)] core with the TACN backbone nitrogens. In this work, we introduce three TACN-based bifunctional chelators bearing amide, alcohol, and ketone pendent arms and evaluate their (radio)labeling efficiency with the [M(CO)] core as well as the stability and hydrophilicity of the resulting radiometal complexes.