Photochromism of Diarylethene Single Molecules in Polymer Matrices

1. Photochromism of Diarylethene Single Molecules in Polymer Matrices Tuyoshi Fukaminato, Tohru Umemoto, Yasuhide Iwata, Satoshi Yokojima, Mitsuru Yoneyama, Shinichiro Nakamura, and Masahiro Irie J.AM.CHEM.SOC.2007,129,5932-5938 Miyasaka Lab. Toshiyuki Umesato

2. Contents • Introduction • - Photochromism • Digital fluorescent molecular photoswitch • Experimental • - Molecular Design of Fluorescent Photochromic Molecules • - Experimental Apparatus • Results and Disscusion • - Photochromism at the Single-Molecule Level • - Environmental Effect of the Reaction • Summary

3. A B Photochromism Photoinduced reversible transformation in a chemical species between two forms without changes of molecular weight. (at least, one pathway should be photoinduced.) hn hn’ or D Quick Property Change Absorption spectra, Dipole moment, Polarizability …. Optical memories, Optical switches

4. Photochromism Diarylethene derivatives UV Vis. Open form Closed form • Thermal stability ( 1900 years at 30 ℃ ) • Fatigue resistance ( 104 times ) • Photochromism in solid phase

5. OFF OFF ON ON Molecular Design of Fluorescent Photochromic Molecules SWICTH LIGHT Perylene bisimide Diarylethene

6. ON OFF Molecular Design of Fluorescent Photochromic Molecules Fluorescent unit

7. OFF ON Molecular Design of Fluorescent Photochromic Molecules OFF ON Energy Pump

8. soft rigid T Tg Experimental Section Sample preparation (spin-coat) 2×10-11 M solution Single molecule with polymer (2 wt %) Polymer film Cover glass (thickness = 50 ～100 nm) 4000 rpm Cover glass PnBMA PMMA Tg : glass transition temperature Tg= 21 ℃ Tg = 105℃

9. DM : Dichroic Mirror L : Lens P : Pinhole (80 ～ 100 mm) M : Mirror NF : Notch Filter LP : Long-pass Filter Experimental Section Single molecule fluorescence detection Objective Lens Sample L L L P DM APD NF LP Computer ND ND He-Cd Laser (325 nm) Ar-Ion Laser (488 nm)

10. Photochromism at the Single-Molecule Level Fluorescence intensity trajectory in polymerfilm ON-Time ON OFF OFF-Time cf. in solution J. AM. CHEM. SOC. VOL. 126, NO. 45, 2004

11. Photochromism at the Single-Molecule Level soft in PnBMA Tg= 21 ℃ ON-Time OFF-Time rigid in PMMA Tg = 105℃ ON-Time OFF-Time

12. Environmental Effect of the Reaction Normal model ( in PnBMA ) Multi-local minima model ( in PMMA )

13. 1-Pf Pf Environmental Effect of the Reaction Probabilit to induce the reaction for the first time after the N-th excitation soft Normal model rigid Multi-local minima model

14. Summary • Single-molecule photochromic reactions in various polymer matrices • were measured and analyzed. • A novel environmental effect in the photochromic reactions • of the single-molecule were found. • The multi-local minima model were proposed to explain the effect, • and this successfully reproduced the novel effect.

15. 1-Pf Pf Environmental Effect of the Reaction Quantum yield for N-th excitation soft Normal model Constant Quantum yield rigid Multi-local minima model Increasing Quantum yield

16. UV power 270 mW/cm2 54 mW/cm2 27 mW/cm2 T. Fukaminato, T. Umemoto, Y. Iwata, S. Yokojima, M. Yoneyama, S. Nakamura, and M. Irie, J. AM. CHEM. SOC. VOL. 129, NO. 18, 2007 5934

17. Photochromism at the Single-Molecule Level 1 2 FC-O : 4.1 × 10-5 FC-O : 1.4 × 10-3

18. Experimental Section Quantum yield constant Quantum yield increasing ON OFF

19. Photochromism at the Single-Molecule Level soft rigid PnBMA PMMA Zeonex Arton Tg= 21 ℃ Tg= 105 ℃ Tg≈ 130 ℃ Tg = 300 ℃ 環境の違いによって、分布が異なる。

20. a reversible transformation of a chemical species induced in one or both directions by absorption of electromagnetic radiation between two forms having different absorption spectra Increasing number of absorbed photons Increasing quantum yield

21. Photochromism at the Single-Molecule Level PnBMA Zeonex rigid soft Tg= 21 ℃ Tg≈ 130 ℃ ON-Time OFF-Time ON-Time OFF-Time Increasing number of absorbed photons Constant quantum yield Increasing quantum yield