Structural, Photophysical, and Magnetic Circular Dichroism Studies of Three Rigidified meso-Pentafluorophenyl-Substituted Hexaphyrin Analogues.
Detailed electronic, structural, photophysical, and redox studies of a series of meso-pentafluorophenyl-substituted hexaphyrins, namely amethyrin (1), rosarin (2), and rubyrin (3), are described. In prior work, it was found that the electronic states of the antiaromatic hexapyrrolic macrocycle, [24]rosarin 2, could be modified by exposure to several Brønsted acids (e.g., HCl, HBr and HI) to produce either one- and two-electron reduced species, or both. In an effort to gain further insights into the reactivity of hexaphyrins possessing different π-conjugation pathways, the β-dodecamethyl-substituted [24]amethyrin 1 was prepared and its electronic structure was analyzed along with that of the o-phenylene-bridged [26]rubyrin 3 and rosarin 2 The [4n] and [4n+2] π-conjugated formulations of 2 and 3, respectively, were inferred from steady-state, fs-transient absorption and two photon absorption measurements. Similar photophysical analyses lead to the conclusion that 1 is best considered as nonaromatic or weakly antiaromatic. Magnetic circular dichroism (MCD) spectroscopic analyses of hexaphyrins 1 and 3, as well as comparisons to 2, and theoretical perimeter MO diagram analyses provided support for the electronic assignments. In contrast to what was found for 2, simple protonation of 1 and 3 by halohydric acids did not induce an evident, redox-based change in the electronic structure of the macrocycle.
Department of Chemistry, Yonsei University, Seoul, 03722, Korea.|Department of Chemistry and Biochemistry, Graduate School of Engineering, and Center for Molecular Systems, Kyushu University, Fukuoka, 819-0395, Japan.
Masatoshi
http://orcid.org/0000-0002-1117-2188
M
Ishida
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.|Graduate School of Natural Science and Technology, Kanazawa University, Kakuma-machi, Kanazawa, 920-1192, Japan.
Taniyuki
T
Furuyama
Department of Chemistry, Yonsei University, Seoul, 03722, Korea.|Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford, OX1 3QZ, UK.
Jong Min
JM
Lim
Department of Chemistry, Yonsei University, Seoul, 03722, Korea.
Sangsu
S
Lee
Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street-A5300, Austin, Texas, 78712-1224, USA.|Institute for Supramolecular and Catalytic Chemistry, Shanghai University, Shanghai, 200444, P. R. China.
Zhan
Z
Zhang
Department of Chemistry, Yonsei University, Seoul, 03722, Korea.|Department of Chemistry, Techno India University, EM/4, Sector-V, Salt Lake, Kolkata, 700091, West Bengal, India.
Sudip K
SK
Ghosh
Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street-A5300, Austin, Texas, 78712-1224, USA.
Vincent M
VM
Lynch
Department of Chemistry, Kangwon National University, Chun-Cheon, 24341, Korea.
Chang-Hee
CH
Lee
Department of Chemistry, Graduate School of Science, Tohoku University, Sendai, 980-8578, Japan.|Faculty of Textile Science and Technology, Shinshu University, Tokida, Ueda, 386-8567, Japan.
Nagao
N
Kobayashi
Department of Chemistry, Yonsei University, Seoul, 03722, Korea.
Dongho
D
Kim
Department of Chemistry, Yonsei University, Seoul, 03722, Korea.|Department of Chemistry, The University of Texas at Austin, 105 E. 24th Street-A5300, Austin, Texas, 78712-1224, USA.
Jonathan L
http://orcid.org/0000-0002-9576-1325
JL
Sessler
aromaticity; electrochemistry; expanded porphyrinoids; magnetic circular dichroism; photophysics; porphyrinoids; protonation