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(P(Ph)2N(Ph))2 (P(Ph)2N(Ph)=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(P(Ph)2N(APPA))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.