title: Excited-state torsional relaxation dynamics of meso-meso directly linked corrole dimers: importance of linking position.
abstract: Herein, we present a combined spectroscopic and computational study on 5,5'-linked and 10,10'-linked corrole dimers, 5CD and 10CD, respectively, to reveal their strikingly different excited-state dynamics. The excited-state dynamics of 10CD indicate relatively small electronic interactions between the two corrole units, which is similar to the case of the meso-meso directly linked Zn(ii) porphyrin dimer. On the other hand, 5CD exhibits characteristic excitation-wavelength-dependent dual fluorescence. Transient absorption spectra of 10CD on the picosecond timescale showed torsional relaxation with a time constant of 25 ps, whereas the torsional relaxation of 5CD was faster, exhibiting a time constant of 10 ps. Quantum calculations have indicated that the eccentric dual fluorescence and the faster torsional relaxation process of 5CD are consequences of a large π-orbital coefficient at the connecting 5-position, which enhances the conjugative stabilization in the excited-state. In contrast, a small π-orbital coefficient at the 10-position and a larger torsional barrier of 10CD cause monomer-like characters in the excited-state.
authors: Spectroscopy Laboratory for Functional π-Electronic Systems, Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seoul 120-749, Korea. dongho@yonsei.ac.kr.
authors: Kyu Hyung
authors: KH
authors: Park
authors: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. osuka@kuchem.kyoto-u.ac.jp.
authors: Shota
authors: S
authors: Ooi
authors: Spectroscopy Laboratory for Functional π-Electronic Systems, Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seoul 120-749, Korea. dongho@yonsei.ac.kr.
authors: Taeyeon
authors: T
authors: Kim
authors: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. osuka@kuchem.kyoto-u.ac.jp.
authors: Takayuki
authors: T
authors: Tanaka
authors: Department of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. osuka@kuchem.kyoto-u.ac.jp.
authors: Atsuhiro
authors: A
authors: Osuka
authors: Spectroscopy Laboratory for Functional π-Electronic Systems, Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seoul 120-749, Korea. dongho@yonsei.ac.kr.
authors: Dongho
authors: D
authors: Kim