Comparison of tridentate ligands in competition experiments for their ability to form a [99mTc(CO)3] complex

Site-specific labeling of ‘second generation’ annexin V with 99mTc(CO)3 for improved imaging of apoptosis in vivo

“…A discussion about potential ligands for labeling with the 99m TcðCOÞ 3 þ moiety and the use of a His-tag can be found elsewhere. [27][28][29] Biechlin et al recently described advantages of a labeling of AnxV with 99m TcðCOÞ 3 þ . 30 But also their approach (a reaction between free amino residues of lysine and 2-iminothiolane) introduced a chelating group unspecifically as seen for N-succinimidyl-HYNIC, contrary to the site-specific conjugation we demonstrate here for the second generation AnxV.…”

Reactions of [Re(CO)3]+ with Histidylhistidine and Modified Histidines

“…[20,21] When combined in histidine, they make for a tightly binding tridentate ligand whose compounds resist challenges at 37°C by biomolecular nucleophiles. [22] Comparison of imidazole Re-N δ bond lengths of 1-3 shows they are mostly similar, except that the Re-N δ bond length of the imidazole rings on the Nterminal histidine 3 is shorter by about 0.02 Å; presumably, this offsets the relatively weaker bonding of the amine group and the acyl oxygen atom. The Re-OCO distance is slightly longer in 2 than in 1 or 3.…”

Preparation, characterization and biological evaluation of99mTc(CO)3-labelled cyclic polyamines

“…Polyamines are supposed to be among the best ligands for binding of a technetium tricarbonyl core. [22] In contrast with aliphatic polyamines, which can be labelled at room temperature and neutral pH, labelling of cyclic polyamines demands more drastic conditions (pH 11 and 1008C, Figure 1). A high pH is always favourable, as at lower pH protons compete with the technetium tricarbonyl precursor for binding to the amines.…”