Helicate self-assembly from heterotopic ligand strands of specific binding site sequence

Linear ligands containing a sequence of three bipyridine B and terpyridine T units form homo- or hetero-nuclear duplex helicates with CuI, CuII and FeII ions; of particular interest is the case of a [(BTB)CuIICuIICuII(TBT)] combination which amounts to the translation of one strand into the other one by virtue of the B–T correspondence established by the five-coordinate CuII ions.