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Eisuke Takeuchi Miyasaka Lab.

Photoinduced Electron Transfer in Bianthryl and derivatives in Ionic Liquid. Eisuke Takeuchi Miyasaka Lab. Contents. Introduction What is ionic liquid (IL)? Charge transfer (CT) of bianthryl derivatives . Motivation Effect of pre-solvation on CT dynamics.

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Eisuke Takeuchi Miyasaka Lab.

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  1. Photoinduced Electron Transfer in Bianthryl and derivatives in Ionic Liquid Eisuke Takeuchi Miyasaka Lab.

  2. Contents IntroductionWhat is ionic liquid (IL)?Charge transfer (CT) of bianthryl derivatives. MotivationEffect of pre-solvation on CT dynamics. Experimental method Femtosecond transient absorption (TA) spectroscopy. My workComparison of symmetric and asymmetric bianthryl derivatives. Summary

  3. What is ionic liquid (IL)? Molten organic salt at room temperature, which consists of organic cations and inorganic anions Ionic Liquid : Ionic Liquid Inorganic salt Bmim TFSI m.p -4℃ Deme BF4 m.p 9℃ m.p 800℃ ex. NaCl

  4. What is ionic liquid (IL)? • Electric conductivity • Vapor pressure: nearly 0 • Hard to burn (fire resistant) • Heat-resistant • High viscosity • etc… Application in various fields. Safe and sustainable solvent （Green solvent） Electrochemical device（Electrolyte） Lubricant S. Kuwabata, et al., Chem. Lett. 35, 600 (2006) Science 302, 792 (2003) SEMimage of IL. IL does not vaporize even in vacuum.

  5. Solvation Dynamics（溶媒和ダイナミクス） Ionic Liquid Organic solvent δ+ δ- CH3CN : anion : cation hυ hυ

  6. Charge transfer (CT) of bianthryl derivatives hυ 9,9’-Bianthryl (BA) Locally Excited (LE) state Charge Transfer (CT) state

  7. Charge transfer (CT) of bianthryl derivatives Solute of this experiment Electron withdrawing group According to quantum chemical calculations lowering CT state 0.25eV in comparison with BA M. Jurczoket al. Chemical Physics. . 256, (2000) 137- 10-Cyano-9,9’-Bianthryl (CNBA) LE state BA CNBA CT state energy 0.25eV hυ LE emission CT emission solvation coordinate

  8. Motivation Peculiarity of solvation coordinate and dynamics effect reactivity of solute : anion : cation nonpolar molecule with a symmetric polar molecule Pre - solvation different ?

  9. delay time D t Detector Sample Femtosecond transient absorption (TA) spectroscopy Transient Absorption (過渡吸収) pulse2 pulse-duration : 30 fs pulse1 delay time D t : several fs~ 1 fs= 10-15 s = 0.000 000 000 000 001 seconds distance that light travels in 30 fs 1s globe 7.5 times ( 300,000 km ) pylori bacteria 3times ( 9 μm )

  10. My work 672nm Time constant: 0.063ps Delay time

  11. My work 720nm Time constant : 60ps - δ- Delay time + δ+

  12. Compare BA 680nm BA Time constant CNBA : 0.063ps BA : 1.25ps

  13. My work LE state * Time constant: 0.063ps CT state Time constant : 60ps - δ- Solvation (1.5ns) hυ + δ+ Grand state

  14. Summary Charge transfer in CNBA / Deme BF4 is more faster than charge transfer by solvationand unaffected by solvation  The ultrafast CT kinetics could be arising from the pre-solvation state caused by the polar nature of asymmetric CNBA, while for nonpolar symmetric BA, much drastic solvent reorganization is required.  BA CNBA LE state LE state CT state CT state ≈ 0 0.5 kcal / mol K. Tominaga et al. J. Phys. Chem. 95, 10485 (1991)

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