Artificial Tripeptide Scaffolds for Self-Assembly of Heteromultimetallic Structures with Tunable Electronic and Magnetic Properties

An artificial tripeptide containing pendant pyridine and bipyridine ligands has been synthesized using a solution-phase method analogous to divergent dendrimer synthesis, yielding a palindromic multifunctional peptide chain. When compared to conventional solid-phase peptide synthesis, this method rapidly yields the tripeptide in significantly greater quantities. The pendant pyridine ligands are coordinated with stoichiometric quantities of either [Pt(tpy)]2+ or [Cu(pda)] metal complexes. By addition of a second transition-metal ion, supramolecular structures are formed by chelation of the bipyridine ligands to create cross-links between oligopeptide strands. The resulting heteromultimetallic materials have unique optical, electrochemical, and magnetic properties that can be tuned by the choice of transition-metal ions.