Chemistry Reference
In-Depth Information
Fe
H
3
C
Si
Fe
CH
3
CH
3
CH
3
CH
3
Si
CH
3
CH
3
CH
3
CH
3
Si
CH
3
O
O
O
O
O
Si
CH
3
H
3
C
Si
O
Si
O
O
Si
CH
3
O
Si
Si
Si
Si
CH
3
CH
3
CH
3
CH
3
CH
3
CH
3
CH
3
H
3
C
Si
H
3
C
Si
Fe
Fe
Fe
Fe
39
Fe
Fe
Si
Si
H
3
C
Fe
H
3
C
Fe
CH
3
CH
3
CH
3
CH
3
Si
Si
CH
3
O
Si
O
Si
O
Si
CH
3
CH
3
H
3
C
Si
O
O
CH
3
CH
3
H
3
C
Si
H
3
C
Si
Fe
Fe
Fe
Fe
40
FIGURE 8.22
Siloxane-based copolymer
39
and homopolymer
40
containing interacting
ferrocenes.
properties of poly(siloxanes) (such as chemical stability, high permeability to gases
and low toxicity) is an interesting and useful strategy for controlling the physical and
redox properties of the resulting hybrid macromolecules. The polymers were
synthesized employing Karstedt-catalyzed hydrosilylation reactions of the poly
(methylhydrosiloxane)-poly(dimethylsiloxane) copolymer,
(Me
3
SiO)(Me
2
SiO)
m
(MeSiHO)
n
(Me
3
Si) (m
¼
70-75%, n
¼
25-30%), and poly(methylhydrosiloxane),
(Me
3
SiO)(MeSiHO)
n
(Me
3
Si) (n
35) with a wedge-shaped dendritic fragment such
as the silicon-bridged biferrocene, CH
2
¼
5
-C
5
H
4
)(
5
-C
5
H
5
)]
2
that con-
CHSiMe[Fe(
Z
Z
tains a reactive vinyl group at the focal point [29,119-121].
A CVof a film of homopolymer
electrodeposited on a Pt electrode is shown in
Figure 8.23. In solvents of low polarity such as CH
2
Cl
2
, the polymer film displays two
reversible and stable redox reactions. This response is due to the existence of
appreciable interactions between the two iron centers, which are linked together by
a bridging silicon atom. The initial oxidation takes place at nonadjacent ferrocene
sites, whichmakes the subsequent removal of electrons from the remaining ferrocenyl
centers, adjacent to those already oxidized more difficult. Pt electrodes modified by
electrodepositionwith the homopolymer
40
40
39
have shown to promote
the redox reactions of hydrogen peroxide. This electrocatalytic activity may be
favored by the capability of the mediators to accomplish bielectronic transfers. Based
on this property it has been possible to carry out the amperometric determination of
and copolymer
