title: meso-3,5-Bis(trifluoromethyl)phenyl-substituted expanded porphyrins: synthesis, characterization, and optical, electrochemical, and photophysical properties.
abstract: Trifluoroacetic acid-catalyzed condensation of pyrrole with electron-deficient and sterically hindered 3,5-bis(trifluoromethyl)benzaldehyde results in the unexpected production of a series of meso-3,5-bis(trifluoromethyl)phenyl-substituted expanded porphyrins including [22]sapphyrin 2, N-fused [22]pentaphyrin 3, [26]hexaphyrin 4, and intact [32]heptaphyrin 5 together with the conventional 5,10,15,20-tetrakis(3,5-bis(trifluoromethyl)phenyl)porphyrin 1. These expanded porphyrins are characterized by mass spectrometry, (1)H NMR spectroscopy, UV/Vis/NIR absorption spectroscopy, and fluorescence spectroscopy. The optical and electrochemical measurements reveal a decrease in the HOMO-LUMO gap with increasing size of the conjugated macrocycles, and in accordance with the trend, the deactivation of the excited singlet state to the ground state is enhanced.
authors.affiliation: Department of Molecular Engineering, Graduate School of Engineering, Kyoto University, Nishikyo-ku, Kyoto (Japan).
authors.forename: Soonchul
authors.initials: S
authors.lastname: Kang
authors.forename: Hironobu
authors.initials: H
authors.lastname: Hayashi
authors.forename: Tomokazu
authors.initials: T
authors.lastname: Umeyama
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Matano
authors.forename: Nikolai V
authors.initials: NV
authors.lastname: Tkachenko
authors.forename: Helge
authors.initials: H
authors.lastname: Lemmetyinen
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imahori