Issue 1, 2015

Optical and electronic properties of air-stable organoboron compounds with strongly electron-accepting bis(fluoromesityl)boryl groups

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.

Graphical abstract: Optical and electronic properties of air-stable organoboron compounds with strongly electron-accepting bis(fluoromesityl)boryl groups

Supplementary files

Article information

Article type
Edge Article
Submitted
08 Aug 2014
Accepted
01 Oct 2014
First published
01 Oct 2014
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY-NC license

Chem. Sci., 2015,6, 308-321

Author version available

Optical and electronic properties of air-stable organoboron compounds with strongly electron-accepting bis(fluoromesityl)boryl groups

Z. Zhang, R. M. Edkins, J. Nitsch, K. Fucke, A. Steffen, L. E. Longobardi, D. W. Stephan, C. Lambert and T. B. Marder, Chem. Sci., 2015, 6, 308 DOI: 10.1039/C4SC02410A

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements