Enzyme Design from the Bottom Up: An Active Nickel Electrocatalyst with a Structured Peptide Outer Coordination Sphere



Catalytic, peptide-containing metal complexes with a well-defined peptide structure have the potential to enhance molecular catalysts through an enzyme-like outer coordination sphere. Here, we report the synthesis and characterization of an active, peptide-based metal complex built upon the well-characterized hydrogen production catalyst [Ni(PPh2NPh)2]2+ (PPh2NPh=1,3,6-triphenyl-1-aza-3,6-diphosphacycloheptane). The incorporated peptide maintains its β-hairpin structure when appended to the metal core, and the electrocatalytic activity of the peptide-based metal complex (≈100,000 s−1) is enhanced compared to the parent complex ([Ni(PPh2NAPPA)2]2+; ≈50,500 s-1). The combination of an active molecular catalyst with a structured peptide provides a scaffold that permits the incorporation of features of an enzyme-like outer-coordination sphere necessary to create molecular electrocatalysts with enhanced functionality.