Electrochemistry in Supramolecular Science
Transcript of Electrochemistry in Supramolecular Science
Date 27.01.2009
Faculty of Mathematics
and Natural Sciences
Stratingh Institute for Chemistry
Electrochemistry in Supramolecular Science
Wesley R Browne
Supramolecular AIO course
Groningen, 1st /2nd of February
www.browne.fmns.rug.nl
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Background1. Basic concepts in electrochemistry
2. Cyclic and thin layer voltammetry
3. Experimental conditions & Electrochemical cells
4. Spectroelectrochemistry
5. Other techniques
Applications1. Electrochemistry of SAMs and Electropolymers
2. Electrochemistry and molecular structure
3. Electrochemical STM
4. SERS on roughened electrodes
Date 27.01.2009
Faculty of Mathematics
and Natural Sciences
Stratingh Institute for Chemistry
Background
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Basic concepts in electrochemistry
Potential
+
-
Energy level
of electrons Occupied
MO
Vacant
MO
Electrode Solution
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Basic concepts in electrochemistry
Potential
+
-
Energy level
of electrons Occupied
MO
Vacant
MO
Electrode Solution Electrode Solution
e-
Reduction: A + e- A-
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
Potential
+
-
Energy level
of electrons Occupied
MO
Vacant
MO
Electrode Solution Electrode Solution
e-
Oxidation: A - e- A+
Basic concepts in electrochemistry
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
The Nernst Equation
Walther Hermann Nernst (25 June 1864 – 18 November 1941). German physical
chemist who is known for his theories behind the calculation of chemical affinity as
embodied in the third law of thermodynamics, for which he won the 1920 Nobel Prize
in chemistry. Nernst helped establish the modern field of physical chemistry and
contributed to electrochemistry, thermodynamics, solid state chemistry and
photochemistry. His career was cut short by his opposition to Hitler and the Nazi party
Red Ox + ne-
[ ]ln
[ ]
o
meas A
RT OxE E where F N e
nF red
Basic concepts in electrochemistry
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Electrode Solution
e-
Basic concepts in electrochemistry
[ ]ln
[ ]
o
meas
RT OxE E
nF red
Formally only at low concentrations, <10 mM
lno Oxmeas
red
RTE E
nF
Date 27.01.2009
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0.4 0.6 0.8 1.0 1.2 1.420.0µ
10.0µ
0.0
-10.0µ
-20.0µ
-30.0µ
Compound
gets reduced
Compound
gets oxidized
START
Cu
rre
nt
/A
Potential vs SCE
Cyclic voltammetry is a powerful tool in following
redox processes in solution and on surfaces
Potential
+
-
Energy level
of electrons Occupied
MO
Electrode Solution
Cyclic voltammetry
Pote
ntial
Time
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
1 -2 mm
Base of cell
Working electrode
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
-12.0µ
-10.0µ
-8.0µ
-6.0µ
-4.0µ
-2.0µ
0.0
2.0µ
4.0µ
6.0µ
Cu
rre
nt in
A
potential vs. SCE
0.001 V s-1
diffusion controlled
Co
nc
Potential
Cyclic voltammetry
Date 27.01.2009
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and natural sciences
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1 -2 mm
Base of cell
Working electrode
Potential
Co
nc
Thin Layer Voltammetry
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
-12.0µ
-10.0µ
-8.0µ
-6.0µ
-4.0µ
-2.0µ
0.0
2.0µ
4.0µ
6.0µ
Cu
rre
nt in
A
potential vs. SCE
0.001 V s-1
pseudo thin layer
0.001 V s-1
diffusion controlled
Cyclic voltammetry
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
Diffusable species
Non-diffusion (surface confined)
3 1 15 *2 2 2(2.69 10 )p o oi n AD C v
5 2 *(9.39 10 )p oi n v A
Cyclic voltammetry
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
Two electrode cell
V
Power supplyi
Working electrodereference electrode
Experimental conditions & Electrochemical cells
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
Three electrode cell
V
Power supply i
Working
electrode
reference
electrode
counter
electrode
Current flow (ions not
electrons)
Potential
difference
N.B. iR drop = cell resistance
Experimental conditions & Electrochemical cells
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
Four electrode cell
V
Power supply i
Working
electrode1
reference
electrode
counter
electrode
Current flow (ions not
electrons)N.B. iR drop = cell resistance
V
Working
electrode2
Experimental conditions & Electrochemical cells
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Electrodes
Reference electrodes
SCE (Hg/HgCl2/KClsat.aq.)
NHE (Pt/H2)
SCE (Hg/HgSO4/K2SO4sat.aq.)
Ag/Ag+ (non-aqueous)
Ag/AgCl electrode (aqueous)
Pseudo reference electrodes
Ag wire
Pt wire
Pd wire
Counter electrode
Typically platinum gauze or wire
Experimental conditions & Electrochemical cells
Working electrodes
Pt wire/disc/gauze
Au wire/disc/bead/gauze (bead gives Au111
surface)
Glassy Carbon disc
Vitreous carbon (usually for bulk
electrolysis)
Diamond (boron doped)
ITO (indium tin oxide, transparent)
Hg (polarography)
Electrode size/shape
Mini – 0.1-1 cm2
Micro-/Ultramicro electrode 1-100 mm
IDE (interdigitated microelectrodes)
Date 27.01.2009
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stratingh institute for chemistry
Solvents
Solvent window
Region in which solvent/electrolyte
are redox inactive. Depends also on
electrode type – e.g. platinum is
very active for H2 evolution whereas
Hg is not.
Solvent type
The more polar the better in order to
help dissociation of electrolyte and
increase conductivity.
N.B. Polarity is temperature
dependent. CH2Cl2 increases in
polarity with decreasing
temperature.
Experimental conditions & Electrochemical cells
Electrolyte
In non-aqueous apolar media
TBAPF6, TOAHSO4, NaBArF (good for
electrochemistry in diethylether)
In non-aqueous polar media
KPF6, NaBF4 (can be a source of F-),
NaClO4 (can be explosive in very dry
solvent)
In aqueous media
KCl, NaCl, Na2SO4
Date 27.01.2009
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stratingh institute for chemistry
UV.Vis Spectroelectrochemistry
Spectroelectrochemistry
Date 27.01.2009
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FTIR Spectroelectrochemistry
Spectroelectrochemistry
Thin Gold Electrode
In transmission mode an adapted Liquid IR cell is very useful using CaF2 windows
See for example SPECACTM
Date 27.01.2009
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Spectrograph
with CCD
Laser
sample
Basic Raman/fluorescence spectroscopic setup:
Spectroelectrochemistry
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
Raman spectro-electrochemistry of the polymer on a gold bead electrode. Signals are baseline corrected. Solvent
signals are present as a reference. At 0.2 Volts only solvent signals are observed as the neutral form of the polymer
doesn’t give resonance enhancement.
400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.3 V
0.3 V
Ab
s.
wavelenght (nm)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
The electrode double layer
Electrode (positively charged)
Solution
Helmholtz or Stern
layer--
Specifically
adsorbed anion
= Solvent
molecule
+
Solvated cation
+
+Non-specifically
adsorbed anion
Outer
Inner
Diffuse layer
Experimental conditions & Electrochemical cells
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
-15.0µ
-10.0µ
-5.0µ
0.0
5.0µ
10.0µ
15.0µ
20.0µ
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0
Dc3+
Dc2+
Potential (V vs SCE)
Curr
ent (A
)
Dc2+
Dc+
Dc
Desorption spike
Dc2+
Dc+
Dc
Dc3+
Dc2+
(qr)
Dc Dc2-
-10.0µ
-5.0µ
0.0
5.0µ
10.0µ
15.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0
Potential (V vs SCE)
Cu
rre
nt
(A)
Dc2+
Dc+
Dc
Dc2+
Dc+
Dc
Dc Dc2-
Adsorption to electrodes
Dr J. H. Jurenkamp, Ph.D. Thesis Groningen 2008
Experimental conditions & Electrochemical cells
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
-10.0µ
-5.0µ
0.0
5.0µ
10.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Po
Potential (V vs SCE)
Cu
rre
nt
(A)
Pc3+
Pc2+
Po1+
Pc2+
Pc+
Pc
Pc3+
(Po3+
)
Pc Pc-
Pc2-
Pc Pc-
Pc2-
-10.0µ
-5.0µ
0.0
5.0µ
10.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Pc2-
Potential (V vs SCE)
Curr
ent (A
)Pc
3+ Pc
2+ Pc
+ Pc
Pc3+
Pc2+
Pc+
Pc
Pc2+
Pc Pc-
Pc2-
Pc Pc-
Pc2-
Pc3-
Pc2- Pc
3-
Dr J. H. Jurenkamp, Ph.D. Thesis Groningen 2008
Other techniques
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
-10.0µ
-5.0µ
0.0
5.0µ
10.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Po
Potential (V vs SCE)
Curr
ent (A
)
Pc3+
Pc2+
Po1+
Pc2+
Pc+
Pc
Pc3+
(Po3+
)
Pc Pc-
Pc2-
Pc Pc-
Pc2-
-10.0µ
-5.0µ
0.0
5.0µ
10.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Pc2-
Potential (V vs SCE)
Curr
ent (A
)
Pc3+
Pc2+
Pc+
Pc
Pc3+
Pc2+
Pc+
Pc
Pc2+
Pc Pc-
Pc2-
Pc Pc-
Pc2-
Pc3-
Pc2- Pc
3-
-16.0µ
-12.0µ
-8.0µ
-4.0µ
0.0
4.0µ
8.0µ
12.0µ
16.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Potential (V vs SCE)
Curr
ent (A
)
-8.0µ
-4.0µ
0.0
4.0µ
8.0µ
-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Potential (V vs SCE)
Curr
ent (A
)
Cyclic voltammetry of the open (left) and closed (right) form of PerSPer 7 (PerSPer open (Po), PerSPer closed (Pc)) in CH2Cl2 / 0.1 M TBAPF6 vs SCE at 0.1 V s-1.
Differential pulse voltammetry of the open (left) and closed (right) form of PerSPer 7 in CH2Cl2 / 0.1 M TBAPF6 vs SCE.
Dr J. H. Jurenkamp, Ph.D. Thesis Groningen 2008
Other techniques – Differential Pulse Voltammetry
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
-16.0µ
-12.0µ
-8.0µ
-4.0µ
0.0
4.0µ
8.0µ
12.0µ
16.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Potential (V vs SCE)
Curr
ent (A
)
Other techniques – Differential Pulse Voltammetry
Pote
ntial
Time
Cyclic voltammetry
Pote
ntial
Time
Pulse voltammetry
Wait
Change potential
Sample current
-10.0µ
-5.0µ
0.0
5.0µ
10.0µ-2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5
Po
Potential (V vs SCE)
Curr
ent (A
)
Pc3+
Pc2+
Po1+
Pc2+
Pc+
Pc
Pc3+
(Po3+
)
Pc Pc-
Pc2-
Pc Pc-
Pc2-
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Applications
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S SMe
Me
RRS SMe
Me
RR
UV
Vis
M. Irie, Chem. Rev., 2000, 100, 1685; H. Tian, S. Yang, Chem. Soc. Rev. 2004, 33, 85;
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
SSR R
SSR RSSR R S+S+R R
S.
+S.+R R
-e-
-2e-
hv313 nm
hv > 400 nm
+e-
-e-
+e-
isomerisation
-2e-
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Self assembled monolayers and polymer
modified electrodes
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S
S
CONH
Si(OEt)3
Toluene
S SO
O
O
Si (CH2)3CONH
Contact angle 80o
+ITO
J. Areephong, W. R. Browne, N. Katsonis, B. L. Feringa, Chem. Commun., 2006, 3930-3932.
Self assembled monolayers and
polymer modified electrodes
Electrochemistry of SAMs
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S
S
CONH
Si(OEt)3
Toluene
S SO
O
O
Si (CH2)3CONH
Contact angle 30o
Contact angle 80o
+ITO
a) AFM image andb) phase contrast (1x1 mm2).
Electrochemistry of SAMs
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
-4.0µ
-2.0µ
0.0
2.0µ
4.0µ
6.0µ
8.0µ
10.0µ
12.0µ
14.0µ
16.0µ
Initial scan
2c 2c+ 2c
2+
2o2+
2c 2c+ 2c
2+
2c2+
2o
Curr
ent (A
)
Potential (V vs SCE)
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
-10.0µ
0.0
10.0µ
20.0µ
30.0µ
Initial scan
1c-ITO 1c1+
-ITO
1c2+
-ITO
1c2+
-ITO
1o-ITO
Curr
ent
(A)
Potential (V vs SCE)
Solution SAM
J. Areephong, W. R. Browne, N. Katsonis, B. L. Feringa, Chem. Commun., 2006, 3930-3932.
S SMe
Me
RRS SMe
Me
RR
UV
Vis
Electrochemistry of SAMs
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
-0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5
30.0µ
20.0µ
10.0µ
0.0
-10.0µ
-20.0µ
-30.0µ
-40.0µ
Curr
ent (A
)
Potential (V vs SCE)
Photochemical switching of ITO switch modified electrode followed by electrochemistry
Photochemical switching - open/close cycling
-0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
5.0µ
10.0µ
15.0µ
20.0µ
25.0µ
30.0µ
35.0µ
40.0µ
b
a
Cu
rre
nt
(A)
Cycles
Electrochemistry of SAMs
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
P. Wesenhagen, J. Areephong, T. Fernandez Landaluce, N. Heureux, N. Katsonis, J. Hjelm, P. Rudolf, W. R. Browne, B. L. Feringa, Langmuir, 2008, 24, 6334-6342.
Self assembled monolayers and
polymer modified electrodes
SS
OMeMeO
Polymerisable unit
Photochromic unit
Spacer
SS
OMeMeO
Electrochemistry of Redox polymers
Date 27.01.2009
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and natural sciences
stratingh institute for chemistry
300 400 500 600 7000.0
0.2
0.4
0.6
0.8
1.0
1.2
2o
2c
Ab
s
Wavelength in nm
a)
-0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.220.0µ
10.0µ
0.0
-10.0µ
-20.0µ
-30.0µ
-40.0µ
-50.0µ
-60.0µ
+e-
+e-
-2e-
-e-
2c
2c 2c+
2c+
2c2+
2c2+
2c2+
2o2+
Cu
rre
nt
in A
Potential in V vs SCE
2o
-e-
b)
SS
OMeMeO
Polymerisable unit
Photochromic unit
Spacer
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
0.0 0.3 0.6 0.9 1.2 1.530.0µ
20.0µ
10.0µ
0.0
-10.0µ
-20.0µ
-30.0µ
-40.0µ
Curr
ent
(A)
Potential V vs SCE
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
0.0 0.3 0.6 0.9 1.2 1.530.0µ
20.0µ
10.0µ
0.0
-10.0µ
-20.0µ
-30.0µ
-40.0µ
Curr
ent
(A)
Potential V vs SCE
0.0 0.2 0.4 0.6 0.8 1.0 1.2
40.0µ
20.0µ
0.0
-20.0µ
-40.0µ
Cu
rre
nt
(A)
Potential V vs SCE
0.0 0.2 0.4 0.6 0.8 1.0 1.20
5
10
15
20
25
30
35
40
Cu
rre
nt
in m
A
scan rate (V s-1)
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
SS
OMeMeO2o
-2e- S+S+
OMeMeO2o2+
S+S+
OMeMeO 2c2+
S+S+
OMeMeO
-2e-
++
2c4+
S+S+
poly-2c2+
1.2 V
1.5 V
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
>Limited layer thickness – lessons about conductivity of polymers
electrode
polymer
monomer monomer+
e-
monomermonomer+
e-polymer+
+
monomermonomer+
e-
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S S
F6
S S
S S S S
F6
S
n
J. Areephong, T. Kudernac, J. J. D. de Jong, G. T. Carroll, D. Pantorotta, J. Hjelm, W. R.
Browne, B. L. Feringa, J. Am. Chem. Soc. 2008, 130, 12850-12851.
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S S
F6
S S
S S
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
0.0
-5.0µ
-10.0µb)
Cu
rren
t (A
)
Potential (V vs SCE)
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
0.0 0.2 0.4 0.6 0.8 1.0 1.2
1.0n
0.0
-1.0n
-2.0n
-3.0n
-4.0n
a)
0.0 0.2 0.4 0.6 0.8 1.0 1.2
5.0n
4.0n
3.0n
2.0n
1.0n
0.0
-1.0n
-2.0n
-3.0n
-4.0n
-5.0n
-6.0n
Cu
rre
nt
in A
Potenial in V (vs SCE)
Cu
rre
nt in
A
Potenial in V (vs SCE)
0 5 10 15 20 25
-500.0p
0.0
500.0p
1.0n
1.5n
2.0n
2.5n
b)
Cu
rre
nt /A
cycle number
0.73
Cyclic voltammetric scanning electropolymerization of monomer in 0.1 M TBAPF6/CH2Cl2 cycled at 0.1 Vs-1 on gold micro electrode (10 mm diameter) Inset: Cyclic volatammogram of the polymer coated gold electrode in monomer-free 0.1 M TBAPF6/CH2Cl2
Increase in current at 0.73 V vs SCE with number of cycles.
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Raman spectro-electrochemistry of the polymer on a gold bead electrode. Signals are baseline corrected. Solvent
signals are present as a reference. At 0.2 Volts only solvent signals are observed as the neutral form of the polymer
doesn’t give resonance enhancement.
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
-0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
20.0µ
10.0µ
0.0
-10.0µ
-20.0µ
-30.0µ
Cu
rre
nt (A
)
Potential (V vs SCE)
S S
F6
S SS
S
S
H3C
F6
S
S S CH3
SS
S S
F6
S SS
S
UV
Vis
Electrochemistry of Redox polymers
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Electrochemistry & molecular structure
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Yan-Li Zhao; William R. Dichtel; Ali Trabolsi; Sourav Saha; Ivan Aprahamian;
J. Fraser Stoddart; J. Am. Chem. Soc. 2008, 130, 11294-11296.
Cyclic voltammetry of [2]rotaxane (black, 1.1 mM) and
dumbbell 6(red, 1.1 mM) in 0.1 M LiClO4/H2O at scan rate =
100 mV s−1.
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
X
X
Anti-folded
Orthogonal
Syn-folded
X
X
X
X
X
X
Twisted
See for example: Mills, N. S.; Benish, M. A.; Ybarra, C. J. Org. Chem. 2002, 67, 2003-2012., Levy, A.;
Biedermann, P. U.; Cohen, S.; Agranat, I. J. Chem. Soc., Perkin Trans. 2, 2001, 2329-2341.
Bistricyclic aromatic enylidenes
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S
S
Me
Me
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
250 300 350 400 450 500 5500.00
0.05
0.10
0.15
0.20
0.25
Abs
Wavelength /nm
Abs LumS
S
Me
Me
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.42.0µ
0.0
-2.0µ
-4.0µ
-6.0µ
-8.0µ
-10.0µ
-12.0µ
Curr
ent in
A
potential vs. SCEAt 1 mV s-1 in CH3CN/TBAPF6, GC (WE), Pt (CE), SCE (RE)
S
S
R
R
Anti-folded
Kissinger, P. T.; Holt, P. T.; Reilley, C. N. J. Electro. Anal. Chem. 1971, 33, 1-12.
Evans, D. H.; Busch, R. W. J. Am. Chem. Soc. 1982, 104, 5057-5062.
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.46.0µ
4.0µ
2.0µ
0.0
-2.0µ
-4.0µ
-6.0µ
Curr
ent / A
V vs. SCE
S
S
S
S
1.21 V- 2e-
0.36 V+ 2e-
R
R
R
R
Thin layer Cyclic voltammetry
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.46.0µ
4.0µ
2.0µ
0.0
-2.0µ
-4.0µ
-6.0µ
Curr
ent / A
V vs. SCE
S
S
S
S
1.21 V- 2e-
0.36 V+ 2e-
R
R
R
R
Thin layer Cyclic voltammetry
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
300 400 500 600 7000.0
0.2
0.4
0.6
0.8
1.0
Abs (
AU
)
Wavelength /nm
Electrochromism
S
S
S
S
R
R
R
R
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
300 400 500 600 7000.0
0.2
0.4
0.6
0.8
1.0
Abs (
AU
)
Wavelength /nm
Fluorescence – blue/red
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
400 600 800 10000.00
0.05
0.10
0.15
0.20
12+
1A 12+
1A 12+
1.15 V1.15 V 0.35 V0.35 V 0.35 VA
bso
rba
nce
Time / s (1 s = 10 mV)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
400 600 800 10000.00
0.05
0.10
0.15
0.20
12+
1B 1A 12+
1B 1A 12+
1B
1.15 V1.15 V 0.35 V0.35 V 0.35 VA
bsorb
ance
Time / s (1 s = 10 mV)
Spectroelectrochemistry
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
250 300 350 400
0.00
0.05
0.10
0.15
0.20
0.25
Ab
s
Wavelength /nm
S
S
hv
R
R
Anti-foldedSyn-folded
S
S
R
R
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
250 300 350 400
0.00
0.05
0.10
0.15
0.20
0.25
Abs
Wavelength /nm
S
S
hv
R
R
Anti-foldedSyn-folded
S
S
R
R
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S
S
hv
MeO
OMe
Anti-folded
Syn-folded
S
S
MeO
OMe0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
0.0
-1.0µ
-2.0µ
-3.0µ
-4.0µ
-5.0µ
-6.0µ
Curr
ent (A
)
Potential (V vs. SCE)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
0.0
-1.0µ
-2.0µ
-3.0µ
-4.0µ
-5.0µ
-6.0µ
Curr
ent (A
)
Potential (V vs. SCE)
S
S
hv
MeO
OMe
Anti-folded
Syn-folded
S
S
MeO
OMe
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Cyclic voltammetry of 1A before (black) and after conversion to 1B (blue) by irradiation with 365 nm light and after thermal reversion
of the photoproduct to 1A (red). Initial scan direction cathodic, scan rate 0.1 V s-1.
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
6.0µ
4.0µ
2.0µ
0.0
-2.0µ
-4.0µ
-6.0µ
-8.0µ
-10.0µ
-12.0µ
Cu
rre
nt
(A)
Potential (V vs SCE)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Cyclic voltammetry of 1A before (black) and after conversion to 1B (blue) by irradiation with 365 nm light and after thermal reversion
of the photoproduct to 1A (red). Initial scan direction cathodic, scan rate 0.1 V s-1.
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
6.0µ
4.0µ
2.0µ
0.0
-2.0µ
-4.0µ
-6.0µ
-8.0µ
-10.0µ
-12.0µ
Cu
rre
nt
(A)
Potential (V vs SCE)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Cyclic voltammetry of 1A before (black) and after conversion to 1B (blue) by irradiation with 365 nm light and after thermal reversion
of the photoproduct to 1A (red). Initial scan direction cathodic, scan rate 0.1 V s-1.
-0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
6.0µ
4.0µ
2.0µ
0.0
-2.0µ
-4.0µ
-6.0µ
-8.0µ
-10.0µ
-12.0µ
Cu
rre
nt
(A)
Potential (V vs SCE)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
S
S
S
S
S
S
1.21 V- 2e-
0.36 V+ 2e-
hv
R R
R
R R
R
Anti-foldedBlue fluorescent
OrthogonalRed fluorescent
Syn-foldednon-fluorescent
1.10 V- 2e-
W. R. Browne, M. M. Pollard, B. de Lange, A. Meetsma, B. L. Feringa, J. Am. Chem. Soc., 2006, 126, 12412
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Electrochemical STM
ii
Ref electrodeAuxillary electrode
moleculesubstrate
STM tip
Han Vos (Dublin city University)
Johan Hjelm (University of Denmark)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
>Electrochemical STM
Tim Albrecht, Adrian Guckian, Alexander M. Kuznetsov, Johannes G. Vos, and Jens
Ulstrup, J. Am. Chem. Soc., 2006, 128, 17132–17138
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
>Electrochemical STM
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Self-assembled monolayers
Surface Enhanced Raman Spectroscopy
on roughened gold electrodesYvonne Halpin (Dublin City University)
Hella Logtenberg (RUG)
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Surface enhanced Raman spectroscopy
› Surface coverage = 6.5 * 10-12 mol/cm2
› Raman spot size = 100 µm2
› Roughly we are looking at 6.5 * 10-18 mol analyte
SERS effect:
› Raman enhancement
by surface plasmon
› Charge transfer effect
between metal and monolayer
0
0.7
0.2
0.4
0.6
200 900400 600 800
Abs
Wavelength [nm]
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
SERS on electrodes
>Au-beads (electrochemically cleaned and roughened)
>Prepare SAM from solution
>Raman microscope
>785 nm and 633 nm excitation
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Roughened bead
5x 20x 50x
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Recommended Texts
Electrochemical Methods- Fundamentals and applications, Allen J. Bard, Larry R. Faulkner
Electrode Dynamics - (Oxford Chemistry Primers) by A. C. Fisher
Electrochemistry for Chemists- by Donald T. Sawyer, Andrzej Sobkowiak, and Julian L. Roberts
Supramolecular Electrochemistry- By Angel E. Kaifer
Experimental Electrochemistry for Chemists- by Donald T. Sawyer
Date 27.01.2009
faculty of mathematics
and natural sciences
stratingh institute for chemistry
Any questions?