Optical and electronic properties of air-stable organoboron compounds with strongly electron-accepting bis(fluoromesityl)boryl groups
Zhang, Zuolun and Edkins, Robert M. and Nitsch, Jörn and Fucke, Katharina and Steffen, Andreas and Longobardi, Lauren E. and Stephan, Douglas W. and Lambert, Christoph and Marder, Todd B. (2015) Optical and electronic properties of air-stable organoboron compounds with strongly electron-accepting bis(fluoromesityl)boryl groups. Chemical Science, 6 (1). pp. 308-321. ISSN 2041-6539 (https://doi.org/10.1039/c4sc02410a)
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Abstract
Three compounds with phenyl (1), 4-tert-butylphenyl (2) and 4-N,N-diphenylaminophenyl (3) groups attached to bis(fluoromesityl)boryl ((FMes)2B) through B-C bonds have been prepared. The restricted rotation about the B-C bonds of boron-bonded aryl rings in solution has been studied by variable-temperature 19F NMR spectroscopy, and through-space F-F coupling has been observed for 3 at low temperature. Steric congestion inhibits binding of 1 by Lewis bases DABCO and tBu3P and the activation of H2 in their presence. Photophysical and electrochemical studies have been carried out on 2, 3, and an analogue of 3 containing a bis(mesityl)boryl ((Mes)2B) group, namely 4. Both 2 and 3 show bright emission in nonpolar solvents and in the solid-state, very strong electron-accepting ability as measured by cyclic voltammetry, and good air-stability. In addition, 2 displayed unusually long-lived emission (τ = 2.47 s) in 2-MeTHF at 77 K. The much stronger acceptor strength of (FMes)2B than (Mes)2B leads to significantly red-shifted emission in solution and the solid state, stronger emission solvatochromism, and significantly lower reduction potentials. Theoretical calculations confirm that 2 and 3 tend to form highly twisted excited states with good conjugation between one FMes group and the boron atom, which correlate well with their blue-shifted solid-state emissions and low kr values in solution. This journal is
ORCID iDs
Zhang, Zuolun, Edkins, Robert M. ORCID: https://orcid.org/0000-0001-6117-5275, Nitsch, Jörn, Fucke, Katharina ORCID: https://orcid.org/0000-0002-6885-5457, Steffen, Andreas, Longobardi, Lauren E., Stephan, Douglas W., Lambert, Christoph and Marder, Todd B.;-
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Item type: Article ID code: 71979 Dates: DateEvent1 January 2015Published1 October 2014Published Online1 October 2014AcceptedSubjects: Science > Chemistry Department: Faculty of Science > Pure and Applied Chemistry
Faculty of Science > Strathclyde Institute of Pharmacy and Biomedical SciencesDepositing user: Pure Administrator Date deposited: 06 Apr 2020 16:01 Last modified: 16 Nov 2024 23:22 Related URLs: URI: https://strathprints.strath.ac.uk/id/eprint/71979