Electronic Properties of π-conjugated Materials II - Universität ...

Oral Presentations – 1 π 2011
Optical Transitions and Excitonic Coupling in a Covalently
linked Spiroindolone Bichromophore
A. Wohlert and J. Tatchen
Universität Düsseldorf
We present a quantum chemical study of the electronic excitation spectrum of a novel luminescent
bichromophoric dye [1] which is made up of a diphenylbutadiene and a dihydroindolone
unit which is carrying a dansyl moiety. Experimentally, a broad fluorescence band with a maximum
at 511 nm has been observed [1] which could in principle result as emission from either one
of the chromophores or from both (dual fluorescence). In order to unravel the mechanism behind
the luminescence, we calculate absorption and emission spectra employing time-dependent density
functional theory. Minima on the excited state potential energy surfaces are identified which
correspond in good approximation to local excitations. Strictly local excitations are generated by
means of the fragment molecular orbital approach [2, 3]. Possibilities will be explored for obtaining
excitonic couplings within the covalently linked system from the strictly local excitations.
References
[1] D. M. D’Souza, A. Kiel, D.-P. Herten, F. Rominger, T. J. J. Müller, Chem. Eur. J. 14, 529 (2008),
J. Schönhaber, Dissertation, Düsseldorf (2010)
[2] K. Kitaura, E. Ikeo, T. Asada, T. Nakano, M. Uebayasi, Chem. Phys. Le�. 313, 701 (1999)
[3] M. Chiba, D. G. Fedorov, K. Kitaura, J. Chem. Phys. 127, 104108 (2007)
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