Cooperative Electronic and Structural Regulation in a Bioinspired Allosteric Photoredox Catalyst

Journal Article · Tue May 10 00:00:00 EDT 2016 · Inorganic Chemistry

DOI:https://doi.org/10.1021/acs.inorgchem.6b00095· OSTI ID:1388175

Lifschitz, Alejo M. ^[1]; Young, Ryan M. ^[2]; Mendez-Arroyo, Jose ^[1]; McGuirk, C. Michael ^[1]; Wasielewski, Michael R. ^[2]; Mirkin, Chad A. ^[2]

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1. Northwestern Univ., Evanston, IL (United States). International Inst. for Nanotechnology
2. Northwestern Univ., Evanston, IL (United States). International Inst. for Nanotechnology and Argonne-Northwestern Solar Energy Research (ANSER) Center

Here in this article, 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 Rh^I 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.

• Research Organization: Energy Frontier Research Centers (EFRC) (United States). Argonne-Northwestern Solar Energy Research Center (ANSER)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); U.S. Army
• Grant/Contract Number: SC0001059; W911NF-11-1-0229; CHE-1149314
• OSTI ID: 1388175
• Journal Information: Inorganic Chemistry, Vol. 55, Issue 17; Related Information: ANSER partners with Northwestern University (lead); Argonne National Laboratory; University of Chicago; University of Illinois, Urbana-Champaign; Yale University; ISSN 0020-1669
• Publisher: American Chemical Society (ACS)
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
catalysis (homogeneous)
catalysis (heterogeneous)
solar (photovoltaic)
solar (fuels)
photosynthesis (natural and artificial)
bio-inspired
hydrogen and fuel cells
electrodes - solar
defects
charge transport
spin dynamics
membrane
materials and chemistry by design
optics
synthesis (novel materials)
synthesis (self-assembly)