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Bis(merocyanine) Hetero-Folda-Dimers: Evaluation of Exciton Coupling between Different Types of π-Stacked Chromphores |
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| Authors: | Dr Eva Kirchner Dr David Bialas Prof Frank Würthner |
| Institution: | 1. Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany;2. Institut für Organische Chemie, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
Center for Nanosystems Chemistry, Universität Würzburg, Theodor-Boveri-Weg, 97074 Würzburg, Germany |
| Abstract: | Exciton coupling between different types of chromophores has been rarely investigated. Herein, a systematic study on the exciton coupling between merocyanine chromophores of different conjugation length with varying excited state energies is presented. In this work well-defined hetero-dimer stacks were obtained upon folding of bis(merocyanine) dyes in nonpolar solvents. They show distinctly different absorption properties in comparison with the spectra of the single chromophores, revealing a significant coupling between the different chromophores. The simulated absorption spectra obtained from time-dependent density functional theory (TD-DFT) calculations are in good agreement with the experimental spectra. Our theoretical analysis based on an extension of Kasha's exciton theory discloses strong coupling between the dyes’ transition dipole moments despite of an excited-state energy difference of 0.60 eV between the chromophores. |
| Keywords: | aggregates dyes/pigments exciton coupling foldamers merocyanines |