Volume 53, Issue 37 pp. 9856-9859
Communication

Ligand Modification Transforms a Catalase Mimic into a Water Oxidation Catalyst

Dr. Wei-Tsung Lee

Dr. Wei-Tsung Lee

Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, IN 47405 (USA)

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Salvador B. Muñoz III

Salvador B. Muñoz III

Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, IN 47405 (USA)

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Dr. Diane A. Dickie

Dr. Diane A. Dickie

Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, NM 87131 (USA)

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Prof. Jeremy M. Smith

Corresponding Author

Prof. Jeremy M. Smith

Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, IN 47405 (USA)

Department of Chemistry, Indiana University, 800 East Kirkwood Ave., Bloomington, IN 47405 (USA)Search for more papers by this author
First published: 15 July 2014
Citations: 135

Funding from Indiana University, the American Chemical Society (Petroleum Research Foundation, 50971-ND3), and the U.S. Department of Energy (Office of Basic Energy Sciences; DE-FG02-08ER15996) is gratefully acknowledged. J.M.S. is a Dreyfus Teacher-Scholar. S.B.M. acknowledges support from NIH-RISE (R25 GM06122211). We thank Song Xu, Dennis Chen, and Sara Skrabalak for experimental assistance.

Graphical Abstract

Ligand-controlled switch: Simple modification of the substituent on a pyridinophane macrocycle ligand converts the corresponding MnII complex from a hydrogen peroxide disproportionation catalyst into a water oxidation catalyst. Preliminary results indicate that the catalyst is mononuclear.

Abstract

The catalytic reactivity of the high-spin MnII pyridinophane complexes [(Py2NR2)Mn(H2O)2]2+ (R=H, Me, tBu) toward O2 formation is reported. With small macrocycle N-substituents (R=H, Me), the complexes catalytically disproportionate H2O2 in aqueous solution; with a bulky substituent (R=tBu), this catalytic reaction is shut down, but the complex becomes active for aqueous electrocatalytic H2O oxidation. Control experiments are in support of a homogeneous molecular catalyst and preliminary mechanistic studies suggest that the catalyst is mononuclear. This ligand-controlled switch in catalytic reactivity has implications for the design of new manganese-based water oxidation catalysts.

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