Synthetic Polymers To Promote Cooperative Cu Activity for O₂ Activation: Poly vs Mono

Abstract

We report polymer-promoted cooperative catalysis of Cu for oxygen activation. A series of random copolymers containing dipicolylamine as binding motifs are designed to coordinate type-3 Cu sites. The Cucopolymers show a 6−8-fold activity enhancement, compared to the molecular complex of Cu with an identical coordination site. Michaelis−Menten analysis demonstrates that the kinetic enhancement results from flexible polymer-promoted cooperative catalysis among multi-Cu sites despite the imposed thermodynamic barrier. These observations provide guidance for the bioinspired design of metallopolymers as soluble catalysts with high activity.Communication pubs.acs.org/JACS

Bioinspired Design of Hybrid Polymer Catalysts with Multicopper Sites for Oxygen Reduction

“…[25] To verify the role of polymer backbones, the activity of monomeric Cu, i. e., Cu complexed with (3dipicolylamino-2-hydroxy)propyl methacrylate (CuMon), was compared to CuPoly. [16] When varying the concentration of the two catalysts supported on CB, the ORR activity was mapped out ( Figures S8-S9). Interestingly, when the catalysts loading concentration was high (4.9 × 10 À 4 mmol Cu cm À 2 ), CuMon and CuPoly showed very similar activity in terms of their onset potential, peak current and peak potential ( Figure S9).…”

“…Dipicolyl amine (DPA) was used from a previously synthesized batch reported in our previous paper. [16] Glycidyl methacrylate (GMA) was passed through a short basic alumina column prior to use. AIBN was recrystallized twice from ethanol.…”

“…The μ ‐oxo‐bridge between two Cu atoms is the most common intermediate during O 2 activation [25] . To verify the role of polymer backbones, the activity of monomeric Cu, i. e ., Cu complexed with (3‐dipicolylamino‐2‐hydroxy)propyl methacrylate (CuMon), was compared to CuPoly [16] . When varying the concentration of the two catalysts supported on CB, the ORR activity was mapped out (Figures S8–S9).…”

“…Our group recently demonstrated that the proximity of Cu sites confined within individual polymer chains allows the cooperative catalysis. [16] There is a 6-8-fold enhancement of Cu activity for O 2 activation at an optimal Cu content. Therefore, Cu-containing polymer catalysts show great potential as an ORR catalyst.…”

“…When bound to polymer chains, the colligative state of Cu sites enhanced the localized concentration of Cu sites to promote cooperativity. Our group recently demonstrated that the proximity of Cu sites confined within individual polymer chains allows the cooperative catalysis [16] . There is a 6–8‐fold enhancement of Cu activity for O 2 activation at an optimal Cu content.…”