title: 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.
authors.affiliation: Department of Chemistry, Yonsei University, Seoul 120-749, Korea.
authors.forename: Hyejin
authors.initials: H
authors.lastname: Yoo
authors.forename: Shu
authors.initials: S
authors.lastname: Furumaki
authors.forename: Jaesung
authors.initials: J
authors.lastname: Yang
authors.forename: Ji-Eun
authors.initials: JE
authors.lastname: Lee
authors.forename: Heejae
authors.initials: H
authors.lastname: Chung
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Oba
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kobayashi
authors.forename: Boris
authors.initials: B
authors.lastname: Rybtchinski
authors.forename: Thea M
authors.initials: TM
authors.lastname: Wilson
authors.forename: Michael R
authors.initials: MR
authors.lastname: Wasielewski
authors.forename: Martin
authors.initials: M
authors.lastname: Vacha
authors.forename: Dongho
authors.initials: D
authors.lastname: Kim
mesh_terms: D007094:Imides / Q000737:chemistry*; D008856:Microscopy, Fluorescence; D015335:Molecular Probes / Q000737:chemistry*; D015394:Molecular Structure; D010569:Perylene / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: D007094:Imides; D015335:Molecular Probes; C521332:perylenediimide; D010569:Perylene