Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy

Abstract
Perylenediimide (PDI) molecules are promising building blocks for photophysical studies of electronic interactions within multichromophore arrays. Such PDI arrays are important materials for fabrication of molecular nanodevices such as organic light-emitting diodes, organic semiconductors, and biosensors because of their high photostability, chemical and physical inertness, electron affinity, and high tinctorial strength over the entire visible spectrum. In this work, PDIs have been organized into linear (L3) and trefoil (T3) trimer molecules and investigated by single-molecule fluorescence microscopy to probe the relationship between molecular structures and interchromophoric electronic interactions. We found a broad distribution of coupling strengths in both L3 and T3 and hence strong/weak coupling between PDI units by monitoring spectral peak shifts in single-molecule fluorescence spectra upon sequential photobleaching of each constituent chromophore. In addition, we used a wide-field defocused imaging technique to resolve heterogeneities in molecular structures of L3 and T3 embedded in a PMMA polymer matrix. A systematic comparison between the two sets of experimental results allowed us to infer the correlation between intermolecular interactions and molecular structures. Our results show control of the PDI intermolecular interactions using suitable multichromophoric structures. © 2012 American Chemical Society.

Citation
Yoo H, Furumaki S, Yang J, Lee J-E, Chung H, et al. (2012) Excitonic Coupling in Linear and Trefoil Trimer Perylenediimide Molecules Probed by Single-Molecule Spectroscopy. J Phys Chem B 116: 12878–12886. Available: http://dx.doi.org/10.1021/jp307394x.

Acknowledgements
The authors thank Dr. Satoshi Habuchi (currently at KAUST, Saudi Arabia) for helpful discussions. This research was financially supported by World Class University (R32-2010-000-10217) and Midcareer Researcher (2010-0029668) Programs from the Ministry of Education, Science, and Technology (MEST) of Korea (D.K.), by a Grant-in-Aid for Scientific Research No. 23651107 of the Japan Society for the Promotion of Science (M.V.), and by a Research Grant of Ogasawara Foundation (M.V.). Research at Northwestern University was supported by the Chemical Sciences, Geosciences, and Biosciences Division, Office of Basic Energy Sciences, DOE under grant no. DE-FG02-99ER14999 (M.R.W.).

Publisher
American Chemical Society (ACS)

Journal
The Journal of Physical Chemistry B

DOI
10.1021/jp307394x

PubMed ID
23003328

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