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

ElectronTransferinHelicalPolyaromaticsLubomírPospíšil,*FilipTeplý,MiroslavGál,LouisAdriaenssens,MichalHoráček,LukášSeveraJ.HeyrovskýInstituteofPhysicalChemistryofASCR,.,PragueInstituteofOrganicChemistryandBiochemistryofASCR,.,Prague,CzechRepublicSpiral-shapedcompounds[5]helquatPreviouslyreportedhelicenes[7]helicene1-aza-[6]helicene2-aza-[6]helicene[6]helquat[5]helquat(7)Synthesis(a)TfOCH2CH2C.CH(3equiv),CCl4,CH2Cl2,40°C,23h,83%;(b)[Rh(PPh3)3Cl](5mol%),MeCN,MW,30min,90°C,99%;(c)

[Cp*Ru(cod)Cl](10mol%),H2O/DMSO(99/1),air,30min,100°C,94%.Tf

=trifluoromethanesulfonyl.Aimreversibleredoxpotentials&molecularstructureheterogeneouselectrontransferrates&Marcusmodelhomogeneousself-exchangeratetrendofredoxpropertiesinaseriesofmethylatedderivativesTworeversible1e-redoxstepsH2++e-

H++e-

H0

CorrelationofE1/2andLUMOenergy15WeakadsorptioninacetonitrileDelahay’scouplingofredox&adsorptionq...electrodechargeΓ...surfaceconcentrationsc...bulkconcentrationsk...electrontransferratesofoxidationorreductionAdsorptionimpednaceacomplicatedfunctionoflargenumberofparametersHeterogeneousrateconstants(cotgφ)E=YF’’/YF’(cotgφ)E=1+(D/2)1/2(ω)1/2/k0k0=Aexp(-G*/RT)G*=(o+i)/4Marcusmodelo=(Ne2/8πεo)(1/r-1/2d)(1/n2-1/)Compoundk01k0211.183.35

20.72

1.1

30.506

1.21

40.32

0.96

50.16

0.29

Experimentalheterogeneousrateconstantscm.s-1Heterogeneousrateand

solventreorganizationenergyH2++e-

↔H+DoublelayeraccelerationFrumkincorrectionktrue=k0

exp(-(-z)φ2F/RT)Homogeneousself-exchange

rateconstantH2++H+↔H++H2+[5]helquat,noMesubstituentsHomogeneousself-exchange

rateconstantAacceptorH2+DdonorH+

D+A↔[D,A]↔[D+,A-]↔D++A-BroadeningBofEPRlinesfordifferentconcentrationsofAatconstantconc.ofDyieldstherateconstantkET=2.4±0.5109M-1s-1Hyperfinesplittingofothercompounds

ismuchsmallerFFTSummaryAllderivativesarereducedintworeversibleone-electronstepsHeteogeneousredoxrateisfast,k0

approaches1cm-1.s-1

Thesecondredoxstepisfaster,k0

2>ko1k0

decreaseswiththeincreasingnumberofmethylgroupsRedoxpotentialsandheterogeneousratescorrelatewithmodelsRadicalcationformsthechargetransfercomplexwithdicationTheself-exchangeelectront