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Intramolecular excimer formation and delayed fluorescence in sterically constrained pyrene dimers

Lookup NU author(s): Professor Andrew Benniston, Emeritus Professor Anthony Harriman, Dr Sarah Howell, Craig Sams, Dr Yong-Gang Zhi

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Abstract

The synthesis is described for a series of five molecular dyads comprising pyrene-based terminals covalently linked through a 1,3-disubstituted phenylene spacer. The extent of through-space communication between the pyrene units is modulated by steric interactions imposed by bulky moieties attached at the 6,8-positions of each pyrene unit. For the control compound, only hydrogen atoms occupy the 6,8 positions (DPI), whereas the remaining compounds incorporate ethynylene groups terminated with either triisopropylsilyl (DP2), 1-tert-butylbenzene (DP3), 2,6-di-tert-butylbenzene (DP4) or 1-tert-butyl-3,5-dimethylbenzene (DPS) units. Each compound shows a mixture of monomer and excimer fluorescence in fluid solution at room temperature, but only monomer emission in a glassy matrix at 77 K. The ratio of monomer to excimer fluorescence depends markedly on the molecular structure; DP1 is heavily biased in favour of the excimer and DP4 is enriched with monomer fluorescence. Photophysical properties, including laser induced and delayed fluorescence data, are reported for each compound. Delayed fluorescence occurs by both intramolecular and bimolecular steps, but these events take place on different timescales. The possibility is raised for using intramolecular triplet-triplet annihilation as a means of molecular imaging. © 2007 Wiley-VCH Verlag GmbH & Co. KGaA.


Publication metadata

Author(s): Benniston AC, Harriman A, Howell SL, Sams CA, Zhi Y-G

Publication type: Article

Publication status: Published

Journal: Chemistry - A European Journal

Year: 2007

Volume: 13

Issue: 16

Pages: 4665-4674

Print publication date: 01/01/2007

ISSN (print): 0947-6539

ISSN (electronic): 1521-3765

Publisher: Wiley-Blackwell

URL: http://dx.doi.org/10.1002/chem.200601498

DOI: 10.1002/chem.200601498

PubMed id: 17285654


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