Synthesis of [n]Cyclo-5,15-porphyrinylene-4,4'-biphenylenes Displaying Size-Dependent Excitation-Energy Hopping.
A set of 5,15-biphenylene-bridged porphyrin wheels, namely, [n]cyclo-5,15-porphyrinylene-4,4'-biphenylenes [n]CPB, have been synthesized through the platination of 5,15-bis(4-(pinacolboranyl)phenyl) nickel(II) porphyrin and subsequent reductive elimination of Pt(II) (cod)-bridged cyclic porphyrin intermediates. The calculated strain energies for [3]CPB, [4]CPB, [5]CPB, and [6]CPB are 49.3, 32.9, 23.5, and 16.0 kcal mol(-1) , respectively. UV/Vis absorption spectra and cyclic voltammetry indicated characteristic ring-size-dependent absorption-peak shifts and redox-potential shifts, which presumably reflect the degree of strain in the π-systems. Excitation-energy hopping (EEH) times were determined to be 5.1, 8.0, 8.0, and 9.6 ps for [3]CPB, [4]CPB, [5]CPB, and [6]CPB, respectively, in a pump-power-dependent TA experiment.
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan).
Hua-Wei
HW
Jiang
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan).
Takayuki
T
Tanaka
Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749 (Korea).
Taeyeon
T
Kim
Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749 (Korea).
Young Mo
YM
Sung
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan).
Hirotaka
H
Mori
Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 120-749 (Korea). dongho@yonsei.ac.kr.
Dongho
D
Kim
Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan). osuka@kuchem.kyoto-u.ac.jp.
Atsuhiro
A
Osuka
energy transfer; nickel; platination; porphyrin wheels; porphyrinoids