Mechanofluorochromism of 1-Alkanoylaminopyrenes.
To create a new series of mechanofluorochromic materials and to elucidate the mechanism of the phenomenon of mechanofluorochromism, 1-alkanoylaminopyrenes including 1-acetylaminopyrene (AAPy), 1-octanoylaminopyrene (OAPy), and 1-stearoylaminopyren (SAPy) were prepared. It was found that these materials exhibited mechanofluorochromism with emission colors in the crystalline samples changing reversibly from bluish purple to yellowish green, which could be induced by mechanical grinding. X-ray crystal structure analysis, electronic absorption, and fluorescence spectroscopies, as well as fluorescence lifetime analysis and powder X-ray diffraction analysis of AAPy suggested that the present mechanofluorochromism was caused by developing crystal defects through grinding. Intermolecular hydrogen bonds were suggested to play an important role in the occurrence of mechanofluorochromism, suppressing the face-to-face overlapping of pyrene moieties to form excimers in the pristine crystal.
Department of Applied Chemistry, Muroran Institute of Technology, 27-1, Mizumoto-cho, Muroran, Hokkaido 050-8585 (Japan).
Eisuke
E
Nagata
Department of Applied Chemistry, Muroran Institute of Technology, 27-1, Mizumoto-cho, Muroran, Hokkaido 050-8585 (Japan).
Shugo
S
Takeuchi
Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan).
Takayuki
T
Nakanishi
Faculty of Engineering, Hokkaido University, N13 W8, Kita-ku, Sapporo, Hokkaido 060-8628 (Japan).
Yasuchika
Y
Hasegawa
Research Center for Environmentally Friendly Materials Engineering, Muroran Institute of Technology, 27-1, Mizumoto-cho, Muroran, Hokkaido 050-8585 (Japan).
Yasuteru
Y
Mawatari
Department of Applied Chemistry, Muroran Institute of Technology, 27-1, Mizumoto-cho, Muroran, Hokkaido 050-8585 (Japan). nakano@mmm.muroran-it.ac.jp.
Hideyuki
H
Nakano
alkanoylaminopyrene; excimers; fluorescence; hydrogen bonds; mechanofluorochromism