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

k1 / cm.s-1
1
observed
0.1 0.01
5
1 32
4
true
1E-3 -0.086
-0.088 -0.090 -0.092
G* / eV. mol-1
-0.094
-0.096
H2+ + e- ↔ H+•
Double layer acceleration
Frumkin correction
q ... electrode charge Γ ... surface concentrations c ... bulk concentrations k ... electron transfer rates of oxidation or reduction
Heterogeneous rate constants
Y /F
Y( )
160 Hz
60
Y '' F
>
Y' F
Im 40
20
Re 0 -0 .5
-1 .0
-1 .5
E / V vs Fc
14 12 10
8
6
0.1
0.01
-2 .0
10
R Soln
C DL
Z ads
R CT
Y''/
Y'/
Y'' / blank
100
1000
frequency / Hz
derivatives
Two reversible 1 e- redox steps
ab so rb an ce
- i/ A
H2+ + e -
H+ • + e -
H0
0 .8
0 .4
DC
0 .0
CV
-0 .4
-0 .5
-1 .0
-1 .5
-2 .0
-2 .5
E / V vs Fc
iຫໍສະໝຸດ Baidutensity in a. u.
1 .0
0 .5
0 .0
200
400
600
800
1000
/ nm
0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3
3500
aH= 0.2 G aN= 2.4 G
3510
3520
H/G
3530
3540
Correlation of E1/2 and LUMO energy
1 5
Weak adsorption in acetonitrile
N+
N+
N+
N+
[6]helquat
[5]helquat(7)
Synthesis
N a)
2TfON+
b) or c)
2TfON+
N
N+
N+
5
6
4
(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.
kET = 2.4 ± 0.5 109 M1s-1
Hyperfine splitting of other compounds is much smaller
国际电化学会议报告PPT POSPISIL-Xian-ElectronTransfer
Spiral-shaped compounds
[5]helquat
Previously reported helicenes
N N
[7]helicene
1-aza-[6]helicene 2-aza-[6]helicene
ktrue= k0 exp(-(-z)φ2F/RT)
Homogeneous self-exchange rate constant
H2+ + H •+ ↔ H•+ + H2+
intensity in a. u. intensity in a. u.
0.2 0.1 0.0 -0.1 -0.2
3510
cotg
(cotg φ)E = YF’’ / YF’
1.2
(cotg φ)E = 1 + (D/2)1/2 (ω)1/2 / k0
Marcus model
1.1
k 0 = A exp(-G*/RT)
1.0
G*= (o+i)/4
0
50
100
150
1/2 / rad.s-1
o=(Ne2/8πεo)(1/r-1/2d)(1/n2-1/)
3520
H/G
3530
0.1
0.0
-0.1
-0.2 3519
3520
3521
H/G
3522
[5]helquat, no Me substituents
Homogeneous self-exchange rate constant
A acceptor H2+ D donor H•+
D + A ↔ [D,A] ↔ [D•+,A•-] ↔ D•+ + A•-
/ T
Broadening B of EPR lines for different
26
concentrations of A at constant conc.of D
yields the rate constant
24
22 20
kET(13pi)ecA(BB0)
0.0
0.5
1.0
1.5
C(12+ ) / mM
Experimental heterogeneous rate constants cm.s-1
Compound 1
k01 1.18
k02 3.35
2
0.72
1.1
3
0.506
1.21
4
0.32
0.96
5
0.16
0.29
Heterogeneous rate and solvent reorganization energy
10000
Delahay’s coupling of redox & adsorption
Adsorption impednace a complicated function of large number of parameters
ZAD S f E q, q o,x co ox ,x E k, q re,d cr re e,d d E k, .. .
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