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.
Institute for Chemical Research, Kyoto University, and PRESTO, Japan Science and Technology Corporation, Uji, Kyoto 611-0011, Japan. shige@scl.kyoto-u.ac.jp
Shigehiro
S
Yamaguchi
Toshiaki
T
Shirasaka
Seiji
S
Akiyama
Kohei
K
Tamao