Premium
Structural, Photophysical, and Magnetic Circular Dichroism Studies of Three Rigidified meso ‐Pentafluorophenyl‐Substituted Hexaphyrin Analogues
Author(s) -
Ishida Masatoshi,
Furuyama Taniyuki,
Lim Jong Min,
Lee Sangsu,
Zhang Zhan,
Ghosh Sudip K.,
Lynch Vincent M.,
Lee ChangHee,
Kobayashi Nagao,
Kim Dongho,
Sessler Jonathan L.
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201700759
Subject(s) - antiaromaticity , protonation , chemistry , conjugated system , redox , absorption (acoustics) , circular dichroism , magnetic circular dichroism , electronic structure , photochemistry , crystallography , computational chemistry , molecule , aromaticity , materials science , inorganic chemistry , organic chemistry , ion , polymer , spectral line , physics , astronomy , composite material
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 [4 n ] and [4 n +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.