Universität Siegen, Organische Chemie I,
Adolf-Reichwein-Str. 2, D-57068 Siegen,
Tel: +49 271 740 4340
e-mail: lin@chemie.uni-siegen.de
Hengwei Lin, Ravuri Kishore and Michael Schmittel
Introduction: Surface functionalization has, in recent years, grown into an ever expanding area of research.1 This has fueled a
constant need for universal, efficient, and robust strategies to fabricate various substances on the surface. Herein, we present a
simple but effective strategy to achieve surface functionalization by metal complexation as a post-electropolymerization step. This
method opens an exciting possibility of exploring a whole gamut of metal coordinated species on the surface and extends their
solution state applications to the surface.2
II Functionalization of 2 by crown ether-containing ruthenium
(II) phenanthroline complex
Monomer synthesis
HO-(CH2)12-OSi
Br
N
NaH, DMF
N
N
N
MeOH/H2O
N
N
O-(CH2)12-OH
N
N
Ru
O
O
O
O
N
N
N
O-(CH2)12-Br
N
N
O
N
N
O
1
Cl
2
N
O
S
O
O
Ru
N
(a)
O
O
Cl
N
O
O
O
N
O
O
DMF, 81%
O
N
O
S
S
S
n-BuLi,THF, 62%
O
N
N
55%
PBr3
O
O
KOH
O-(CH2)12-OSi
O
O
2
-0,4
-0,2
DMF, 120 °C, 24h
S
S
0,0
0,2
0,4
0,6
0,8
0,6
0,8
Potential (VFc)
n
n
S
S
Pt or ITO
The steps of surface functionalization
Pt or ITO
2
4
f
f
N
N
Step 1
N
N
Step 2
N
f
O
Electropolymerization on Pt
or ITO electrodes in 1.0 mM
CH2Cl2 solution
O
M
O
M = Ru(II), m = 2
or Cu(I), m = 1
f
n
S
S
S
S
m
f
Functionalization via a
coordination reaction
S
Pt or ITO
1
S
= Desired functionality
2
I Functionalization of 2 by ruthenium (II) phenanthroline
complex
N
N
N
450.
550.
0Wavelength0(nm)
650.
0
-0,2
0,0
0,2
0,4
Potential (VFc)
750.
0
Cyclic voltammograms of electropolymer 4 on ITO before (a) and after (b)
overoxidation of electropolymer 2 in
monomer-free acetonitrile solution.
III Functionalization of 2 by a porphyrin appended
phenanthroline copper (I) complex
N
Ru
N
N
Zn
N
N
2
O
-0,4
350.
0
Comparison of UV-Vis spectra:
Electropolymer 2 before complexation (blue line),
Ru (II) complex 4 on ITO (red line), and Ru (II)
complex 4 monomer in dichloromethane (brown line).
n
Pt or ITO
N
(b)
0.
6
0.
5
0.
Abs
4
0.
3
0.
2
0.
1
0.
0 250.
0
N
N
N
O
N
(a)
(a)
Br
Cl
N
N
Ru
2
N
N
Cu
Cl
O
N
N
Zn
N
S
0,0
n
S
S
Pt or ITO
n
0,4
0,8
N
N
1,2
N
Br
-0,2
Potential (VFc)
Pt or ITO
2
N
N
N
O
DMF, 120 °C, 24h
S
N
0,0
S
S
0,4
0,6
0,8
0,6
0,8
n
Pt or ITO
Pt or ITO
5
2
(b)
2.0
S
S
n
0,2
Potential (VFc)
DMF, 120 °C, 24h
3
1,8
(b)
1,5
1.5
1,2
Ab
s
1.0
Abs
0,9
0.5
0,3
0,0
0.0
0,6
300.0
400.0
500.0
600.0
700.0
800.0
0,4
0,8
1,2
Potential (VFc)
Comparison of UV-Vis spectra:
Electropolymer 2 before complexation (blue line),
Ru (II) complex 3 on ITO (brown line), and Ru (II)
complex 3 monomer in dichloromethane (green line).
0,0
-0,2
300
Wavelength (nm)
Cyclic voltammograms of electropolymer
2 on ITO before (a) and after (b)
overoxidation of electropolymer 2 in
monomer-free acetonitrile solution.
Acknowledgments:
We are greatly indebted to Deutsche Forschungsgemeinschaft for
financial support.
400
500
600
700
Wavelength (nm)
800
Comparison of UV-Vis spectra:
Electropolymer 2 before complexation (red line) and
porphyrin appended Cu (I) complex 5 on ITO
(brown line).
0,0
0,2
0,4
Potential (VFc)
Cyclic voltammograms of electropolymer 5
on ITO before (a) and after (b) overoxidation of electropolymer 2 in monomerfree acetonitrile solution.
Conclusions:
A simple 2-step surface functionalization procedure has been
developed. This method could be utilized effectively in modifying
coordination complexes on surfaces and exploring their properites.
References:
1 (a) Deronzier, A.; Moutet, J.-C. Coord. Chem. Rev. 1996, 147, 339-371. (b) Roncali, J. J. Mater. Chem. 1999, 9, 1875.
2 (a) Ng, P. K.; Gong, X.; Chan, S. H.; Lam, L. S. M.; Chan, W. K. Chem. Eur. J. 2001, 7, 4358-4367. (b)McQuade, D. T.; Pullen, A. E.; Swager, T. M. Chem.
Rev. 2000, 100, 2537-2574. (c) Schmittel, M.; Kishore, R. S. K. Org. Lett. 2004, 6, 1923-1926. (d) Gust, D.; Moore, A. L. Acc. Chem. Res. 2001, 34, 40-48.