X-ray-Triggered Thermoluminescence and Density Functional Theory Characterization of a gem-Diphenyltrimethylenemethane Biradical

Hiroshi Ikeda; Yasunori Matsui; Ikuko Akimoto; Ken-ichi Kan’no; Kazuhiko Mizuno

doi:10.1071/CH10167

RESEARCH ARTICLE

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X-ray-Triggered Thermoluminescence and Density Functional Theory Characterization of a gem-Diphenyltrimethylenemethane Biradical

Hiroshi Ikeda ^A ^B ^D , Yasunori Matsui ^A , Ikuko Akimoto ^C ^D , Ken-ichi Kan’no ^C and Kazuhiko Mizuno ^A ^B ^D

+ Author Affiliations

- Author Affiliations

^A Department of Applied Chemistry, Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.

^B The Research Institute for Molecular Electronic Devices (RIMED), Osaka Prefecture University, Sakai, Osaka 599-8531, Japan.

^C Department of Material Science and Chemistry, Faculty of Systems Engineering, Wakayama University, Sakaedani 930, Wakayama 640-8510, Japan.

^D Corresponding authors. Email: ikeda@chem.osakafu-u.ac.jp; akimoto@sys.wakayama-u.ac.jp; mizuno@chem.osakafu-u.ac.jp

Australian Journal of Chemistry 63(9) 1342-1347 https://doi.org/10.1071/CH10167
Submitted: 20 April 2010 Accepted: 15 May 2010 Published: 9 September 2010

Abstract

Thermoluminescence (TL) from the excited triplet state of a gem-diphenyltrimethylenemethane biradical (³4^••*) is triggered by X-irradiation at 77 K followed by annealing to ~140 K. The new X-irradiation method reported here is simpler and more convenient than the previously employed γ-irradiation method. The TL spectrum of ³4^••* is similar to the photoluminescence spectrum of the 1,1-diphenylethyl radical (5^•). The results of density functional theory (DFT) and time-dependent-DFT calculations of the ground state biradical ³4^•• suggest that no significant electronic interaction takes place between the diphenylmethyl and allyl radical moieties owing to its twisted geometry. Accordingly, the results also suggest that the excited state biradical ³4^••* has a similar molecular geometry and electronic structure as the triplet ground state. Both the experimental and computational results obtained for ³4^•• and 5^• confirm that the main fluorophore of ³4^••* is the diphenylmethyl radical moiety.

Acknowledgement

The study was supported by the Cooperation for Innovative Technology and Advanced Research in Evolutional Area (CITY AREA) program by the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. H.I. acknowledges financial support in the form of a Grant-in-Aid for Scientific Research on Priority Areas ‘New Frontiers in Photochromism’ (Nos. 20044027 and 21021025 in the Area No. 471) and Innovative Areas ‘π-Space’ (No. 21108520 in the Area No. 2007), the Scientific Research (B) (No. 20044027), and the Challenging Exploratory Research (No. 21655016) from the MEXT of Japan. H.I. also thanks the Iketani, Shorai, and Mazda Foundations for support.

References

X-ray-Triggered Thermoluminescence and Density Functional Theory Characterization of a gem-Diphenyltrimethylenemethane Biradical

Abstract

Acknowledgement

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