A family of penta-and hexadentate metal ligating α-amino acids, suitably protected for Fmoc solid-phase chemistry, has been prepared. These residues incorporate the mono-amides of ethanolaminetriacetic acid, ethylenediaminetriacetic acid, and ethylenediaminetetraacetic acid as side chains. Side chains are tethered varying distances (n) from the Cα-carbon to allow metal binding events to occur at distinct distances from the peptide backbone. These ...