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ISRN Physical Chemistry
Volume 2012 (2012), Article ID 103817, 7 pages
http://dx.doi.org/10.5402/2012/103817
Research Article

Substitution Effects of C-C Triple Bonds on Deactivation Processes from the Fluorescent State of Pyrene Studied by Emission and Transient Absorption Measurements

1Department of Chemistry and Chemical Biology, Graduate School of Engineering, Gunma University, Gunma, Kiryū 376-8515, Japan
2Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Osaka, Sakai 599-8531, Japan
3Division of Material Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kanazawa 920-1192, Japan
4Graduate School of Material Science, Nara Institute of Science and Technology, Nara, Ikoma 630-0192, Japan

Received 14 August 2012; Accepted 6 September 2012

Academic Editors: H. Pal and E. Yeow

Copyright © 2012 Minoru Yamaji et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Pyrenes substituted with tert-butylethynyl, trimethylsilylethynyl, and trimethylsilylbutadiynyl groups were prepared, and the fluorescence yields ( ), lifetimes, and triplet-triplet absorption were measured in cyclohexane. Upon introduction of the groups possessing triple bond(s) to the pyrene skeleton, the fluorescence rate ( ) increased. The variation of the terminating groups did not appreciably affect the and values. Increasing the number of the triple bond, the values increased by the magnitude of order whereas the were not varied. The effect of the ethynyl groups on the values was rationalized by the Strickler-Berg equation considering an increase of the 1 transition moment. Triplet-triplet absorption spectra of pyrene derivatives were obtained. The intersystem crossing rates ( ) increased upon increasing the number of triple bonds terminated with the trimethylsilyl group whereas those between ethynylpyrenes were independent of the terminating groups. Heavy atom effect failed to rationalize the enhancement of the values upon adding the triple bond to the pyrene moiety.