Issue 23, 2016

Blue-shifted emission and enhanced quantum efficiency via π-bridge elongation in carbazole–carborane dyads

Abstract

Carbazole–carborane linear dyads and di(carbazole)–carborane V-shaped dyads with phenyleneethynylene-based bridges have been synthesized. The V-shaped dyads display the expected red-shifts in the location of their UV-Vis absorption maxima on bridge-lengthening, but show unusual blue-shifts in charge-transfer (CT) emission on the same π-system lengthening. These blue-shifts can be attributed to the 2n + 3 electron count within the carborane cluster in the excited state. The linear dyads luminesce via a combination of local excited (LE) and CT emission, with a red-shift in LE emission and a blue-shift in CT emission accompanying π-bridge elongation. A quantum efficiency as high as 86% in the solution state is achieved from the hybrid LE/CT emission. Time-dependent density functional theory (TD-DFT) calculations at the excited state of these compounds have clarified the photoluminescence blue-shift and suggested a typical cluster C–C bond elongation in the V-shaped dyads. Calculations on the elongated linear dyads have suggested that the electron density is localized at the phenyleneethynylene-containing bridge.

Graphical abstract: Blue-shifted emission and enhanced quantum efficiency via π-bridge elongation in carbazole–carborane dyads

Supplementary files

Article information

Article type
Paper
Submitted
29 Apr. 2016
Accepted
20 Maijs 2016
First published
20 Maijs 2016
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2016,18, 15719-15726

Author version available

Blue-shifted emission and enhanced quantum efficiency via π-bridge elongation in carbazole–carborane dyads

Z. Wang, P. Jiang, T. Wang, G. J. Moxey, M. P. Cifuentes, C. Zhang and M. G. Humphrey, Phys. Chem. Chem. Phys., 2016, 18, 15719 DOI: 10.1039/C6CP02870E

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