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Cooperative Electronic and Structural Regulation in a Bioinspired Allosteric Photoredox Catalyst

Lifschitz, Alejo M. and Young, Ryan M. and Mendez-Arroyo, Jose and McGuirk, C. Michael and Wasielewski, Michael R. and Mirkin, Chad A. (2016) Cooperative Electronic and Structural Regulation in a Bioinspired Allosteric Photoredox Catalyst. Inorganic Chemistry, 55 (17). pp. 8301-8308. ISSN 0020-1669.

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Herein, we report the first allosteric photoredox catalyst regulated via constructively coupled structural and electronic control. While often synergistically exploited in nature, these two types of control mechanisms have only been applied independently in the vast majority of allosteric enzyme mimics and receptors in the literature. By embedding a model of photosystem II in a supramolecular coordination complex that responds to chloride as an allosteric effector, we show that distance and electronic control of light harvesting can be married to maximize allosteric regulation of catalytic activity. This biomimetic system is composed of a Bodipy photoantenna, which is capable of transferring excited-state energy to a photoredox pair, wherein the excitation energy is used to generate a catalytically active charge-separated state. The structural aspect of allosteric regulation is achieved by toggling the coordination chemistry of an antenna-functionalized hemilabile ligand via partial displacement from a RhI structual node using chloride. In doing so, the distance between the antenna and the central photoredox catalyst is increased, lowering the inherent efficiency of through-space energy transfer. At the same time, coordination of chloride lowers both the charge of the Rh^I node and the reduction potential of the Rh^(II/I) couple, to the extent that electronic quenching of the antenna excited state is possible via photoinduced electron transfer from the metal center. Compared to a previously developed system that operates solely via electronic regulation, the present system demonstrates that coupling electronic and structural approaches to allosteric regulation gives rise to improved switching ratios between catalytically active and inactive states. Contributions from both structural and electronic control mechanisms are probed via nuclear magnetic resonance, X-ray diffraction, electrochemical, spectroelectrochemical, and transient absorption studies. Overall, this work establishes that intertwined electronic and structural regulatory mechanisms can be borrowed from nature to build stimuli-responsive inorganic materials with potential applications in sensing, catalysis, and photonic devices.

Item Type:Article
Related URLs:
URLURL TypeDescription Information
Wasielewski, Michael R.0000-0003-2920-5440
Mirkin, Chad A.0000-0002-6634-7627
Additional Information:© 2016 American Chemical Society. Received: January 13, 2016. Publication Date (Web): May 10, 2016. This material is based on the work supported by the following awards: National Science Foundation Grant CHE-1149314 and U.S. Army Grant W911NF-11-1-0229. J.M.-A. acknowledges a fellowship from Consejo Nacional de Ciencia y Tecnologia. Time-resolved spectroscopy was supported as part of the ANSER Center, an Energy Frontier Research Center, funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Award DE-SC0001059 (to M.R.W. and R.M.Y.). The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript. The authors declare no competing financial interest.
Funding AgencyGrant Number
Army Research Office (ARO)W911NF-11-1-0229
Consejo Nacional de Ciencia y Tecnología (CONACYT)UNSPECIFIED
Department of Energy (DOE)DE-SC0001059
Issue or Number:17
Record Number:CaltechAUTHORS:20160524-082055455
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Official Citation:Cooperative Electronic and Structural Regulation in a Bioinspired Allosteric Photoredox Catalyst Alejo M. Lifschitz, Ryan M. Young, Jose Mendez-Arroyo, C. Michael McGuirk, Michael R. Wasielewski, and Chad A. Mirkin Inorganic Chemistry 2016 55 (17), 8301-8308 DOI: 10.1021/acs.inorgchem.6b00095
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:67286
Deposited By: Tony Diaz
Deposited On:24 May 2016 16:46
Last Modified:09 Mar 2020 13:19

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