Macromolecular Engineering of the Outer Coordination Sphere of [2Fe-2S] Metallopolymers to Enhance Catalytic Activity for H2 Production

William P. Brezinski, Metin Karayilan, Kayla E. Clary, Keelee C. McCleary-Petersen, Liye Fu, Krzysztof Matyjaszewski, Dennis H. Evans, Dennis L Lichtenberger, Richard S Glass, Dong-Chul Pyun

Research output: Contribution to journalArticle

6 Scopus citations

Abstract

Small-molecule catalysts inspired by the active sites of [FeFe]-hydrogenase enzymes have long struggled to achieve fast rates of hydrogen evolution, long-term stability, water solubility, and oxygen compatibility. We profoundly improved on these deficiencies by grafting polymers from a metalloinitiator containing a [2Fe-2S] moiety to form water-soluble poly(2-dimethylamino)ethyl methacrylate metallopolymers (PDMAEMA-g-[2Fe-2S]) using atom transfer radical polymerization (ATRP). This study illustrates the critical role of the polymer composition in enhancing hydrogen evolution and aerobic stability by comparing the catalytic activity of PDMAEMA-g-[2Fe-2S] with a nonionic water-soluble metallopolymer based on poly(oligo(ethylene glycol) methacrylate) prepared via ATRP (POEGMA-g-[2Fe-2S]) with the same [2Fe-2S] metalloinitiator. Additionally, the tunability of catalyst activity is demonstrated by the synthesis of metallocopolymers incorporating the 2-(dimethylamino)ethyl methacrylate (DMAEMA) and oligo(ethylene glycol) methacrylate (OEGMA) monomers. Electrochemical investigations into these metallo(co)polymers show that PDMAEMA-g-[2Fe-2S] retains complete aerobic stability with catalytic current densities in excess of 20 mA·cm-2, while POEGMA-g-[2Fe-2S] fails to reach 1 mA·cm-2 current density even with the application of high overpotentials (η > 0.8 V) and loses all activity in the presence of oxygen. Random copolymers of the two monomers polymerized with the same [2Fe-2S] initiator showed intermediate activity in terms of current density, overpotential, and aerobic stability.

Original languageEnglish (US)
Pages (from-to)1383-1387
Number of pages5
JournalACS Macro Letters
Volume7
Issue number11
DOIs
Publication statusPublished - Nov 20 2018

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ASJC Scopus subject areas

  • Organic Chemistry
  • Polymers and Plastics
  • Inorganic Chemistry
  • Materials Chemistry

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