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Charge Transfer Reaction and Solvation Dynamics in Ionic Liquid. Satoe MORISHIMA MIYASAKA laboratory. Contents. Introduction ✦ What is ionic liquid? My project ✦ Sample , charge transfer reaction ✦ Solvation
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Charge Transfer Reaction and Solvation Dynamics in Ionic Liquid Satoe MORISHIMA MIYASAKA laboratory
Contents Introduction ✦ What is ionic liquid? My project ✦ Sample , charge transfer reaction ✦ Solvation ✦ Time-resolved Fluorescence ✦ Result and Discussion ✦ Recent work
1-ethyl-3-methylimidazolium (emim+) trihexyl(tetradecyl)phosphonium 1-butyl-3-methylpyridinium DEME BF4 bis(trifluoromethylsulfonyl)imide (TFSI-) tetrafluoroborate What is Ionic liquid ? Ionic liquid is・・・ Melted salt at room temperature Constructed from organiccation and anion NaCl N,N-Diethyl-N-methyl-N-(methoxyethyl) ammonium
Ionic liquids Application Biochemistry Bioreactor • Electric conductivity • Vapor pressure • nearly 0 Energy device a fuel cell actuator • Hard to burn • High viscosity • Heat-resist • ・・・etc material Heat-resist gel Green chemistry Solvent for synthesis refining
Synthesized in1992 by J.S.Wilkes and M.J.Zawarotko Measurement of Solvation dynamics in 2002 by Karmakar. R and Samanta. A ?? Sergei Arzhantsev, Huii jin, Gray A. Baker, and Mark Maroncelli J. Phys. Chem. B2007, 111, 4978-4989 Background rotation diffusion hn hn : dipole
About My project
BA 9,9’-bianthryl ADMA 4-(9-anthryl)-N,N’-dimethylaniline C153 coumarin153 δ+ δ- charge transfer reaction CT reaction electrically symmetric Locally excited :LE Charge transfer : CT electrically asymmetric reference dye
CTstate LE state hν ground state Background & Motivation cyclohexane DEME BF4 cP: g / cm・s
Ground state time Time-resolvedFluorescence - principle - Time-resolved spectroscopy time Excited state energy Red shift hn Directly observation of SolvationDynamics ! time Solvation coordinate
Counts time Time-resolvedFluorescence - Time-correlated single photon counting (TCSPC) - Laser pulse t t’ photon 125 ns Light source: Ti: Sapphire laser Exciting λ: absorption peak (second harmonic Ti: Sapphire laser) System response time: ~36 ps (FWHM) Step size: 4 ps temperature: 295K
Decay Rise Result (1) time (2) (1) (2) LE to CT reaction already finished !
64 % 25 % 65 % Result & Discussion The image of Solvation in ionic liquid Normalized (10 ps ~30 ns)
Recent work (1) fstransientAbsorption (2) TCSPC under row temperature condition Fitting with multi-exponential function Why rise ?
Summary The degree of solvent orientation at ground state makes for the ultra-fast solvation dynamics after excitation In the range of 10 ps~30 ns, the solvation time of ADMA is not so different from that of BA. Result suggested that initial solvent orientation in the ground state strongly affects the ultra-fast portion of the solvation process (<25 ps).
Sn monitor pulse S1 pump pulse S0 TransientAbsorption (TA) (1) I0 I (2) pump pulse (λ: const.) monitor pulse detector (1) (2) ⊿t
Viscosity and Ion size Stokes-Einstein equation D =kBT / 6πηR
Application to synthesis Huvddleston,J.G, Willauer,H.D., Swayloski, R.P., Vsser,A.E., Rogers,R.D., Chem.Commun., 1998, 1765-1766
Application to refining 2 C.Lee et al., J.Chem.Research (s), 122 (2002)
cathode anode cathode anode Application to energy device O2 H2 H2O H2O O2 H2 H2O Imidazole
Il: Intensity at observation λ Intl: Integration at observation λ Ipeak: Intensity at peak λ Intpeak: Integration at peak λ
I0 : ピーク強度 b : 非対称パラメータ νp : ピーク波数 Δ : スペクトルパラメータ Dynamics Stokes shift Fitting with log-normalFunction →Fluo.Max / cm-1
Solvation time Correlation function Multi-exponential function n (t):peak wavenumber at Time=t n (0): peak wavenumber at Time=0 n (∞):peak wavenumber at Time=∞ Ai : Intensity τi : life time 溶媒和応答関数解析結果 Observed Solvation Times Derived from the time dependent Stokes Shift of CT
Potential energy アトキンス 物理化学(下) 第6版 22章 p716