Sequence and Surface Confinement Direct Cooperativity in Catalytic Precision Oligomers.

ABSTRACT

Confinement and cooperativity are important design principles used by Nature to optimize catalytic activity in enzymes. In these biological systems, the precise sequence of the protein encodes for specific chain folding to preorganize critical amino acid side chains within defined binding pockets, allowing synergistic catalytic activation pathways to be expressed and triggered. Here we show that short synthetic precision oligomers with the optimal sequence of catalytic units, spatially arranged by dense surface grafting to form confined cooperative "pockets", display an up to 5-fold activity improvement compared to a "mismatched" sequence or free oligomers using the (pyta)Cu/TEMPO/NMI-catalyzed aerobic selective oxidation of alcohols as a model reaction. We thus demonstrate that, in analogy with enzymes, sequence definition combined with surface grafting induce the optimized distribution, both radially (interchain) and axially (intrachain), of a catalytic triad, and that the impressive improvement of catalytic efficiency results predominantly from "matched" interchain interactions in the surface-confined system, thereby outperforming the homogeneous system. The concept presented here hence uncovers a new paradigm in the design of multifunctional molecular assemblies to control functions at a level approaching biological precision.