rming an amide or ester linkage with each adjacent chelant moiety A (with any substituting moiety preferably being chosen to enhance solubility or biodistribution of the resultant compound, such as -OH, --NH2 or --CO2 H, a peptide residue, a polypeptide or protein such as a plasma protein, antibody or antigen, or other suitable moiety)); each A is independently a chelant moiety; and Z is a multipl