Biomedical Engineering Reference
In-Depth Information
Fig. 18 SQWVs at a Pt
electrode of (a) 0.48 mM 17,
(b) 2.16 mM Cd
2+
plus
1.69 mM 17 solutions in
MeCN (0.10 M Bu
4
NPF
6
).
Potential step increment of
4 mV, square wave amplitude
of 25 mV, frequency of 15 Hz
a
+22
+20
C
1
C
2
+18
+16
+14
+12
+10
+8
+6
+4
+1.0
+0.5
0
-0.5
Potential, V
-1.0
-1.5
-2.0
b
+6.6
C
6
+6.0
+5.4
C
1
+4.8
+4.2
C
5
+3.6
+3.0
+2.4
+1.8
+1.2
+1.0
+0.5
0
-0.5
Potential, V
-1.0
-1.5
-2.0
2.2 Recognition and Sensing of Anions
Demand for chemosensors which are selective for specific anions continuously
increases [
5
,
8
,
10
,
27
-
35
]. With this in mind, one especially important group is
sensors that monitor small organic anions of biological interest. Inside this group,
we are interested in
-dicarboxylates as they play key roles in different biochem-
ical process [
36
-
38
]. Major efforts have centered on the design and application of
chemosensors based on the binding site-signaling unit approach for anion recogni-
tion using ureas, thioureas, or their amido derivatives, given their ability to act as
H-bond donors. Moreover, they are highly suitable for carboxylate recognition with
the appropriate geometry [
39
,
40
].
As we indicate above, biphenyl moieties have demonstrated that the conforma-
tional changes induced by modifying the dihedral angle have a strong influence on
the fluorescent properties of sensors. A similar behavior has been observed in
bipyridines, and for this reason, ligands based on this system have been also
considered.
As a first approach to colorimetric sensors of anions, the selective sensing of
fluoride was studied. Thus, amide-based macrocyclic amine sensors 18-20 were
a
,
o
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