Tuning the Reactivity of Cofacial Porphyrin Prisms for Oxygen Reduction Using Modular Building Blocks.

Autor: Crawley MR; Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States., Zhang D; Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States., Oldacre AN; Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States., Beavers CM; Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States., Friedman AE; Department of Materials, Design, and Innovation, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States., Cook TR; Department of Chemistry, University at Buffalo, The State University of New York, Buffalo, New York 14260, United States.
Jazyk: angličtina
Zdroj: Journal of the American Chemical Society [J Am Chem Soc] 2021 Jan 20; Vol. 143 (2), pp. 1098-1106. Date of Electronic Publication: 2020 Dec 30.
DOI: 10.1021/jacs.0c11895
Abstrakt: We assembled eight cofacial porphyrin prisms using MTPyP (M = Co(II) or Zn(II), TPyP = 4-tetrapyridylporphyrin) and functionalized ruthenium-based "molecular clips" using coordination-driven self-assembly. Our approach allows for the rapid synthesis of these architectures in isolated yields as high as 98% for the assembly step. Structural and reactivity studies provided a deeper understanding of the role of the building blocks on the oxygen reduction reaction (ORR). Catalytic efficacy was probed by using cyclic and hydrodynamic voltammetry on heterogeneous catalyst inks in aqueous media. The reported prisms showed outstanding selectivity (>98%) for the kinetically hindered 4e - /4H + reduction of O 2 to H 2 O over the kinetically more accessible 2e - /2H + reduction to H 2 O 2 . Furthermore, we have demonstrated significant cofacial enhancement in the observed catalytic rate constant k s (∼5 orders of magnitude) over the mononuclear analogue. We conclude that the steric bulk of the clip plays an important role in the structural dynamics of these prisms, which in turn modulates the ORR reactivity with respect to selectivity and kinetics.
Databáze: MEDLINE
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