title: Synthesis and electronic, photophysical, and electrochemical properties of a series of thienylcarbazoles.
abstract: A series of thienylcarbazoles were synthesized by Suzuki-Miyaura and Ullmann coupling reactions. In these compounds, the 2-thienyl or 2,2'-bithiophen-5-yl group is connected at the N-, 1,8-, 3,6-, 2,7-, 2,7,N-, or 1,8,N-positions of the carbazole ring. The effects of structural variations on their electronic, photophysical, and electrochemical properties were explored by UV-vis and fluorescence spectroscopies, cyclic voltammetry (CV), and DFT calculations in evaluation of their potential as material components. The thienyl substituents at the 2,7-positions in 4, 5, and 10 are responsible for a high degree of π-conjugation and strong emission with fluorescence quantum yields up to 0.61. The CV on a series of thienylcarbazoles revealed a good electron-donating ability of 3,6-substituted carbazoles 3 and 9. The number of thiophene units was found to affect the extent of π-conjugation, the resulting HOMO-LUMO gaps, and fluorescence efficiency. The crystal structures of 5 and 9 were also disclosed.
authors.affiliation: Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Kiryu, Gunma 376-8515, Japan.
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Kato
authors.forename: Satoru
authors.initials: S
authors.lastname: Shimizu
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Taguchi
authors.forename: Atsushi
authors.initials: A
authors.lastname: Kobayashi
authors.forename: Seiji
authors.initials: S
authors.lastname: Tobita
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Nakamura