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Ferrocenyl Diquat Derivatives: Nonlinear Optical Activity, Multiple Redox States, and Unusual Reactivity

Coe, Benjamin J. and Fielden, John and Foxon, Simon P. and Asselberghs, Inge and Clays, Koen and Van Cleuvenbergen, Stjn and Brunschwig, Bruce S. (2011) Ferrocenyl Diquat Derivatives: Nonlinear Optical Activity, Multiple Redox States, and Unusual Reactivity. Organometallics, 30 (21). pp. 5731-5743. ISSN 0276-7333.

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Four new dipolar cations have been synthesized, containing ferrocenyl electron donor groups and diquaternized 2,2′-bipyridyl (diquat) acceptors. To our knowledge, these are the first organometallic diquat derivatives to be reported and have been characterized as their PF_6^– salts by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. UV–vis spectra show multiple intramolecular charge-transfer bands, and three reversible redox processes are observed for each compound. Molecular quadratic nonlinear optical (NLO) responses have been determined by using hyper-Rayleigh scattering at 1064 nm and Stark (electroabsorption) spectroscopic studies on the intense π→ π^* intraligand and d → π^* metal-to-ligand charge-transfer bands. The most active compounds have estimated, Stark-derived β0 values approaching that of the chromophore in the technologically important material (E)-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate. Single-crystal X-ray structures have been obtained for three of the salts, with one adopting the orthorhombic space group Aba2 and having potential for bulk NLO behavior due to its polar structure. Attempted crystallizations of the remaining chromophore revealed that it undergoes an unusual intermolecular formal Michael cycloaddition between an activated methyl group and a double bond, forming a dimeric species. This diastereomeric cyclic complex has also been characterized via single-crystal X-ray diffraction.

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URLURL TypeDescription DOIArticle
Coe, Benjamin J.0000-0002-5998-3895
Fielden, John0000-0001-5963-7792
Brunschwig, Bruce S.0000-0002-6135-6727
Additional Information:© 2011 American Chemical Society. Received: July 8, 2011. Published: October 12, 2011. We thank the EPSRC for support (grants EP/E000738 and EP/D070732) and also the Fund for Scientific Research-Flanders (FWO-V, G.0312.08), the University of Leuven (GOA/2006/3), and the NSF (grant CHE-0802907, “Powering the Planet: an NSF Center for Chemical Innovation”). I.A. is a postdoctoral fellow of the FWO-V. We thank Ayele Teshome of the University of Leuven for technical assistance with the HRS measurements, and Dr Simon Teat of the Advanced Light Source at the University of California Berkeley for collecting the X-ray data for [6][PF6][OTf].
Group:CCI Solar Fuels
Funding AgencyGrant Number
Engineering and Physical Sciences Research Council (EPSRC)EP/E000738
Engineering and Physical Sciences Research Council (EPSRC)EP/D070732
Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO)G.0312.08
University of LeuvenGOA/2006/3
Issue or Number:21
Record Number:CaltechAUTHORS:20111213-110615737
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Official Citation:Ferrocenyl Diquat Derivatives: Nonlinear Optical Activity, Multiple Redox States, and Unusual Reactivity Benjamin J. Coe, John Fielden, Simon P. Foxon, Inge Asselberghs, Koen Clays, Stijn Van Cleuvenbergen, and Bruce S. Brunschwig Organometallics 2011 30 (21), 5731-5743
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28446
Deposited By: Ruth Sustaita
Deposited On:13 Dec 2011 22:37
Last Modified:03 Oct 2019 03:32

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