Chemistry Reference
In-Depth Information
Fe
Fe
NH
NH
H
3
C
Si
CH
3
H
3
C
Si
3
CH
3
HN
Si
Fe
H
3C
Si
CH
3
CH
3
Si
Fe
Si
NH
CH
3
CH
3
Si
CH
3
CH
3
HN
Si
Fe
Si
CH
3
CH
3
CH
3
Si
CH
3
Si NH CH
2
CH
2
CH
3
Fe
CH
3
Si
CH
3
+
A
NH
H
3
C
Si
CH
3
NH
Fe
Fe
FIGURE 8.2
Schematic representation of dihydrogenphosphate recognition by ferrocenyl
dendrimer
5
receptor, bearing SiNH peripheral groups.
to a new wave but only a progressive cathodic shift of the initial wave is observed.
The fact that the most striking changes of the CVs, caused by strong interactions [54],
are obtained for large and tetrahedral anions such as H
2
PO
4
and HSO
4
are attributed
to the presence of cavities in the receptor with complementary dimensions to these
anions. The selectivity of the receptor in the electrochemical recognition was
established by competition experiments. The CV recorded when H
2
PO
4
is added
FIGURE 8.3
(a) CVof dendrimer
5
(1.25
10
5
M) in the absence (—), and presence (- - -) of
0.5 equiv. of [n-Bu
4
N][H
2
PO
4
] per ferrocene center. (b) Oxidation potential shift of the
ferrocene redox couple versus equivalents of anion added.
