Chemistry Reference
In-Depth Information
NaO
3
S
SO
3
Na
N
N
N
Co
N
N
N
N
N
NaO
3
S
(a)
SO
3
Na
SO
3
Na
N
N
Co
SO
3
Na
NaO
3
S
N
N
(b)
7.6
(a) Molecular structure of cobalt(II)tetrasulphonated-
phthalocyanine, sodium salt; (b) 5,10,15,20-tetrakis-(4-
sulphonatophenyl) porphyrin cobalt (II), tetrasodium salt.
SO
3
Na
0.6 V vs. Ag|AgCl in a pH = 12 buffer containing 8 ¥ 10
-3
mol l
-1
Co(II)TSPc
or Co(II)TSPor (for structures, see Fig. 7.6a and Fig. 7.6b, respectively).
In Fig. 7.7, cyclic voltammetric curves are shown of the oxidation of
sodium dithionite at a gold electrode (curves 1, 4), at a CoTSPc-modified
gold electrode (curves 2, 5) and at a CoTSPor-modified gold electrode
(curves 3, 6) for two different sodium dithionite concentrations. Several
observations indicate electrocatalytic behaviour. First, the voltammetric
waves are shifted towards less-positive potentials. This means that less
