Chemistry Reference
In-Depth Information
Table 7 Electrochemical
properties of 64a-c [
92
]
red
E
1/2
(V)
ox
E
1/2
(V)
Compound
64a
1.71
0.58
64b
1.66
-
64c
1.59 0.80
Potentials (V) vs Fc/Fc
+
, 0.1 M TBAPF
6
in CH
2
Cl
2
, 100 mVs
Table 8 Electrochemical properties of 66a-g [
95
], 68a, and 70a [
95
]
Compound
red
E
1,1/2
(V)
red
E
2,1/2
(V)
ox
E
1,1/2
(V)
ox
E
2,1/2
(V)
66a
1.60
2.17
0.87
1.06
66b
1.53
2.17
0.97
1.16
66c
1.63
2.21
0.35
0.72
66d
1.23
1.85
-
-
66e
1.62
2.18
0.87
0.98
66f
1.66
2.24
0.81
1.13
66g
1.38
1.74
0.94
1.05
68a
1.52
2.06
0.55
1.14
70a
1.79
2.26
0.73
1.11
Potentials (V) vs Ag/Ag
+
, 0.1 M TBAClO
4
in DMF, 100 mVs
Table 9 Electrochemical and optical properties of 74a and 81-84 [
98
]
Compound
red
E
1,1/2
(V)
red
E
2,1/2
(V)
l
max
(nm)
74a
1.41
1.96
447
81
a
1.33
1.65
550
82
a
1.34
1.71
534
83
1.56
1.89
476
84
1.64
2.19
479
Potentials (V) vs Fc/Fc
+
, 0.1 M TBAPF
6
in CH
2
Cl
2
, 100 mVs
a
tert-
Butyl substituted
one-electron reduction, while 64a and 64c both also undergo a reversible one-
electron oxidation (Table
7
)[
92
].
Many of the DAPs synthesized by Kawase and coworkers, 66a-g, exhibit four-
stage redox properties (Table
8
)[
94
]. Notably, 66c undergoes a reversible first
oxidation and a pseudoreversible second oxidation at very low potentials. The
electron-donating methoxy substituents at the benzene rings increase the energy
of the HOMO, an effect also evident in absorption spectra of 66a-d where 66d
experiences a large bathochromic shift. The opposite effect is seen in the reduction
potential of carbonyl-substituted 66d and 66g, undergoing reduction at more
positive potentials than the other derivatives. DAPs with aryl substituents in
5,10-position, 66e, f, undergo only a small bathochromic shift of approximately
50 nm compared to 66a-c.
The extended DAPs 68a and 70a showed improved oxidative ability over their
shorter counterparts [
95
]. The first oxidation and reduction waves for 68a and 70a
were both reversible (Table
8
). Angular 68a was both oxidized and reduced more
