Citation:
Cho, J. W. ; Yoo, H. ; Lee, J. E. ; Yan, Q. ; Zhao, D. *; Kim, D. *. Intramolecular Interactions of Highly Π-Conjugated Perylenediimide Oligomers Probed by Single-Molecule Spectroscopy. J. Phys. Chem. Lett. 2014, 5, 3895-3901.
摘要:
Highly pi-conjugated perylenediimide (PDI) oligomers are promising low band gap organic materials for various applications in optoelectronics. In this work, individual fluorescence dynamics of ethynylene- and butadiynylene-bridged dimeric and trimeric PDIs (PEP, PBP, and PEPEP) were monitored and analyzed by single-molecule fluorescence spectroscopy to gain information on the degree of extension of pi-conjugation through the acetylene bridge in PDI multichromophores. The simultaneous measurements of fluorescence intensity, lifetime, and spectrum indicate a sequential decrease in pi-conjugation upon photobleaching of PDI monomer units. Furthermore, Huang-Rhys (HR) factors, S, are obtained to evaluate the degree of electronic coupling in view of pi-conjugation and overall rigidity between the PDI units in PDI oligomers at the single-molecule level. In addition, butadiynylene-bridged dimeric PDI (PBP) reveals conformational heterogeneity due to the long butadiynylene linker. These results suggest a new way to control the photophysical properties of the PDI multichromophoric system by expansion of pi-conjugation and modification with different linker groups.[GRAPHICS]See also: 2014