1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

3.2.7.6 Cyclic Voltammetry
Discussion and Results 3
Compounds 67-71 were investigated under the same conditions as the mono-exocyclic ones
53-58 (see paragraph 3.2.3.5). The obtained voltammograms are depicted in Figure 41.
-1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.6 0.8 1.0 1.2 1.4 E [V]
Figure 41. Cyclic voltammograms of 67 (almost identical to 69), 68 (almost identical to 70)
and 71 measured in CH2Cl2 solution (c = 10 -3 M) vs. ferrocene, E(Fc/Fc + = +0.53 V), as internal
standard. For further experimental details see paragraph 6.1, p. 139.
For the interpretation, the data have to been seen in comparison to those for 53 as
corresponding mono-annulated system on also to non-functionalized porphyrin 15
representing a standard tetraphenylporphyrin systems of that kind. The corresponding
5 μA
67 (69)
68 (70)
71
values for the obtained half-wave potentials are summarized in Table 22.
Concerning the anodic regions of the voltammograms, the oxidation potentials of the BCKPs
appear well comparable to standard porphyrins like 15 and also to mono-exocyclic system
53. Thus, also the presence of two electron withdrawing ketone groups seems to have no
effect on the oxidability of the porphyrin core. In contrast, the attachment of a second
ketone does clearly affect the cathodic region since the reductions steps are observed at
very high potentials, meaning an ease of reduction. The shift is that drastic compared to 15
that in all these systems both reductions are mostly completed at potentials higher than the
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