国际电化学会议报告PPT POSPISIL-Xian-ElectronTransfer.ppt

ElectronTransfer in Helical Polyaromatics Lubomír Pospí?il,* Filip Teply, Miroslav Gál, Louis Adriaenssens, Michal Horá?ek, Luká? Severa J. Heyrovsky Institute of Physical Chemistry of AS CR, v.v.i., Prague Institute of Organic Chemistry and Biochemistry of ASCR, v.v.i., Prague, Czech Republic Spiral-shaped compounds Previously reported helicenes Synthesis Aim reversible redox potentials molecular structure heterogeneous electron transfer rates Marcus model homogeneous self-exchange rate trend of redox properties in a series of methylated derivatives Two reversible 1 e- redox steps Correlation of E1/2 and LUMO energy Weak adsorption in acetonitrile Delahay’s coupling of redox adsorption Heterogeneous rate constants Heterogeneous rate andsolvent reorganization energy Homogeneous self-exchangerate constant Homogeneous self-exchangerate constant Hyperfine splitting of other compoundsis much smaller Summary All derivatives are reduced in two reversible one-electron steps Heteogeneous redox rate is fast, k0 approaches 1 cm-1.s-1 The second redox step is faster, k0 2 ko1 k0 decreases with the increasing number of methyl groups Redox potentials and heterogeneous rates correlate with models Radical cation forms the charge transfer complex with dication The self-exchange electron transfer is fast, kET = 2.4?109 M-1 s-1 Compounds are promising redox mediators with tunable properties Thank you for your attention * * [5]helquat [7]helicene 1-aza-[6]helicene 2-aza-[6]helicene [6]helquat [5]helquat(7) (a) TfOCH2CH2C.CH (3 equiv), CCl4, CH2Cl2, 40 °C, 23 h, 83 %; ( b) [Rh(PPh3)3Cl] (5 mol%), MeCN, MW, 30 min, 90 °C, 99 %; (c)?[Cp*Ru(cod)Cl] (10 mol%), H2O/DMSO (99/1), air, 30 min, 100 °C, 94 %. Tf?=trifluoromethanesulfonyl. H2+ + e - ? H+ ? + e - ? H0 1 5 q ... electrode charge Γ ... surface concentrations c ... bulk concentrations k ... electron transfer rates of oxidation or reduction Adsorption impednace a complicated functi