Biomedical Engineering Reference
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Fig. 5 CVs of (a) a 2.0 mM 4
solution in 0.10 M Bu
4
NPF
6
/
MeCN. (b) A 2.0 mM 5
solution in 0.10 M Bu
4
NPF
6
/
MeCN. Potential scan rate of
100 mV/s
Bharadwaj et al
.
[
19
], no significant reduction wave in the cyclic voltammogram of
Cu
2+
·3 in the
1.0 to 1.0 range (vs
.
SCE) was observed and the absence of the redox
process Cu
2+
Cu
+
!
in the complex could explain the enhanced fluorescence
observed in Cu
2+
·3.
On the other hand, the red shift of the fluorescence emission is too large
(
200 nm) to be due only to a metal ion-induced change in polarity around
the fluorophore. This shift in emission could well result from the modification in the
dihedral angle induced by the complexation process. This possibility is supported by
the complex's great stability (log
K
D
l
¼
¼
0.2 in acetonitrile (MeCN) for a 1:1
complex). There are similar reasons that could explain the shift observed for Pb
2+
·1.
Related compounds 4 and 5 are able to act as electrochemical sensors for Zn
2+
and Cd
2+
[
20
].
6.30
N
N
N
N
O
O
O
O
O
O
N
O
O
O
O
CO
CO
O
N
O
O
N
O
O
O
O
O
O
N
N
N
N
5
6
7
4
The CV response of compound 4 (10
3
mM solution in 0.10 M Bu
4
NPF
6
/
MeCN) at the platinum electrode consists of three anodic peaks which overlap at
+0.74 (Ia), +0.92 (IIa), and +1.09 V (IIIa), coupled with their cathodic counterparts
at +0.72 (Ic), +0.84 (IIc) (Fig.
5a
).
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