“…Bifunctional chelators designed to accommodate the structural preferences of the [ReO] 3+ offer a more reliable strategy. Use and further design [20] of tetradentate ligands containing a combination of amino/amido and thiolate donors [21] such as MAG3 [22] (Figure 3a) and cysteine-containing amino acid sequences [23,24] (Figure 2), developed in the 1990s, [11] have remained popular for attachment to lipids [25,26] and peptides, [22,[27][28][29][30][31][32] or simple complexes designed for rapid renal excretion in the context of radionuclide therapy during balloon angioplasty, [33,34] has continued. Re analogues were synthesised and shown to have identical structure and isomerism [6,7] (Figure 3b) and biodistribution (targeting medullary thyroid carcinoma and bone metastases in prostate, lung and breast cancer) [4,5].…”