By using single-molecule fluorescence spectroscopy, we have investigated the electronic interaction of ethyne-bridged porphyrin arrays (ZNE) depending on their structure. The fluorescence dynamics of ZNE show a large amount of one-step photobleaching behaviors, indicating the high degree of π-conjugation. The ratio of one-step photobleaching behavior decreased as the number of porphyrin units increased. This behavior indicates that the linear and shortest Z2E shows a strong electronic coupling between constituent porphyrin moieties. Structural properties and orientation of ZNE were also measured by wide-field excitation fluorescence spectroscopy (ExPFS) and defocused wide-field imaging (DWFI). The ExPFS and DWFI show that the structure of absorbing and emitting units of Z2E and Z3E are linear. On the other hand, star-shaped pentamer with five porphyrins acts as an absorbing unit, but unidirectional trimer moiety acts as an emitting unit in the Z5E molecule. Collectively, these studies provide further information on the electronic interaction depending on their structure and length.
Bibliographical noteFunding Information:
We thank Prof. Chen-Yu Yeh at National Chung Hsing University for providing us with a series of ZNE investigated in this study. The work at Yonsei University was supported by Global Research Laboratory (2013K1A1A2A02050183) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT (Information and Communication Technologies) and Future Planning.
© 2016 American Chemical Society.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry