Materials Chemistry, Short Talk
Mat-023

Excited-state charge transfer interaction in a benzothiadiazole/benzodithiophene supramolecular assembly

I. Kolly1, P. Debnath2*, S. M. Langenegger1*, A. Cannizzo2*, R. Häner1*, S. X. Liu1*
1Department of Chemistry, Biochemistry and Pharmaceutical Sciences, W. Inäbnit Laboratory for Molecular Quantum Materials and WSS-Research Center for Molecular Quantum Systems, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland, 2Institute for Applied Physics, University of Bern, Sidlerstrasse 5, CH-3012 Bern

Benzodithiophene/benzothiadiazole-based trimers have been synthesized and characterized. In aqueous conditions, the oligomers self-assemble into distinct nanostructures, which was observed by AFM and DLS measurements. UV-vis spectroscopy was performed and showed, that the supramolecular polymers (SPs) are formed at 20°C, whereas at 80 °C the oligomers are disassembled. Fluorescence spectroscopy revealed that the emission of the electron-accepting benzothiadiazole moiety is efficiently quenched through the presence of the electron-donating benzodithiophene moiety. This excited-state charge transfer interaction seems to take place via photoinduced electron transfer, which was further analyzed by TAS measurements and confirmed the interaction of the non-conjugated donor-acceptor moieties upon photoexcitation.[1] The charge transfer interaction in SPs can be altered by changing the donor-acceptor sequence in the trimer. A-D-A and D-A-D trimers are compared to get a closer insight into this phenomenon.

[1]        S.-Y. Kim, Y.-J. Cho, A.-R. Lee, H. Son, W.-S. Han, D. W. Cho, S. O. Kang, Phys. Chem. Chem. Phys. 2016, 19, 426