Electron–electron repulsion in carbazole oligomer-attached <i>tris</i> (2,4,6-trichlorophenyl) methyl radicals
Abstract
Luminescent radicals are gathering much attention as a new class of luminescent material. We have synthesized a new carbazole oligomer (mono, di, tri, tetra) substituted luminescent tris (2,4,6-trichlorophenyl) methyl (TTM) radicals. The photoluminescence (PL) spectra showed emission stemmed from the excited state charge transfer character. Despite the increase in the highest occupied molecular orbital level of the carbazole oligomer associated with increasing the oligomer length, the PL maxima showed a blue shift from di- to tetra-oligomer substitution. This unexpected behavior was explained by quantum chemical calculations, including electron–electron repulsion. The electron–electron repulsion on the donor orbital decreases when the oligomer length increases and leads to the blue shift of the emission. The blue shift of the emission accompanied by an increase in the photoluminescence quantum yield by substituting a large π-conjugated donor to a TTM radical would be a unique method to control the photophysical property of the luminescent radical.
Article Details
Journal Info
The Journal of Chemical Physics
American Institute of Physics
Authors (9)
Kenshiro Matsuda
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University 1 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Wataru Ota
MOLFEX, Inc., 34-4 Takano Nishibiraki-cho, Sakyo-ku, Kyoto 606-8103, Japan
Keiko Yamaoka
Institute for Materials Chemistry and Engineering, Kyushu University 4 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Kosuke Anraku
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University 1 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Emiko Fujiwara
Fukui Institute for Fundamental Chemistry, Kyoto University 2 , Takano Nishibiraki-cho 34-4, Sakyo-ku, Kyoto 606-8103,
Kazuhiro Nakamura
Interdisciplinary Graduate School of Engineering Sciences, Kyushu University 1 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,
Takuya Hosokai
National Metrology Institute of Japan (NMIJ), National Institute of Advanced Industrial Science and Technology (AIST) 5 , Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565,
Tohru Sato
Fukui Institute for Fundamental Chemistry
Ken Albrecht
Institute for Materials Chemistry and Engineering, Kyushu University 4 , 6-1 Kasuga-Koen, Kasuga-shi, Fukuoka 816-8580,