Effects of Substitution on Solid-State Fluorescence in 9-Aryl-9-methyl-9H-9-silafluorenes.
Aromatic groups were incorporated into 9H-9-silafluorene units at the 9-position (mono-9H-silafluorenes) and 9,9'-positions (di-9H-9-silafluorenes). The aryl substituents showed weak conjugation to the 9H-9-silafluorene for 9-aryl substituted ones 1-7 and a 9,9'-phenylene substituted one (compound 8) and they exhibited similar absorption and emission spectra. The 9H-9-silafluorene 10 containing a 5,5'-(2,2'-bithiophenyl) group showed a significantly red-shifted absorption and fluorescence maxima in the solid-state. Single-crystal X-ray diffraction studies found J-type aggregated structures formed by intermolecular CH-π interactions (ca. 2.6-2.7 Å). Density functional theory (DFT), time-dependent DFT (TD-DFT), and configuration interaction single (CIS) calculations were conducted to explain the observed optical properties.
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. yamanoi@chem.s.u-tokyo.ac.jp.
Yoshinori
Y
Yamanoi
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. k-nakashima@chem.s.u-tokyo.ac.jp.
Takayuki
T
Nakashima
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. shimada@chem.s.u-tokyo.ac.jp.
Masaki
M
Shimada
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. h-maeda@chem.s.u-tokyo.ac.jp.
Hiroaki
H
Maeda
Department of Chemistry, School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. nisihara@chem.s.u-tokyo.ac.jp.
Hiroshi
H
Nishihara
D005453:Fluorescence; D005456:Fluorescent Dyes / Q000138:chemical synthesis / Q000737:chemistry; D008956:Models, Chemical; D017646:Organosilicon Compounds / Q000138:chemical synthesis / Q000737:chemistry
D005456:Fluorescent Dyes; D017646:Organosilicon Compounds
9H-9-silafluorene; J-aggregation; UV absorption; single-crystal X-ray diffraction; solid-state emission; thiophene