Dibenzoborole-containing pi-electron systems: remarkable fluorescence change based on the "on/off" control of the p(pi)-pi* conjugation.
A series of dibenzoborole derivatives with various groups such as (N,N-diphenylamino)phenyl, thienyl, and bithienyl groups at the 3,7-positions have been synthesized and their photophysical properties studied. These new pi-electron systems show significant solvatochromism in the fluorescence spectra. Thus, about 100-140 nm blue shifts in the emission maxima and 20-30-fold increments in the quantum yields are observed upon changing the solvent from THF to DMF. Similar fluorescence changes are observed upon the addition of n-Bu4NF to their THF solutions, demonstrating their sensing abilities toward a fluoride ion. These fluorescence changes result from the "on/off" control of the ppi-pi* conjugation in their LUMO by the coordination of donor solvents or fluoride ion to the boron atom in the dibenzoborole skeleton.
Yamaguchi
Shigehiro
S
Institute for Chemical Research, Kyoto University, and PRESTO, Japan Science and Technology Corporation, Uji, Kyoto 611-0011, Japan. shige@scl.kyoto-u.ac.jp
Shirasaka
Toshiaki
T
Akiyama
Seiji
S
Tamao
Kohei
K