1.1 Porphyrins - Friedrich-Alexander-Universität Erlangen-Nürnberg

3 Discussion and Results
nitro compound 91, the signals are expectedly detected more upfield at 8.66 and 8.57 ppm
(ortho-H) and at 8.11 and 8.33 ppm (meta-H) while they are observed at 8.33 and 8.15 ppm
(ortho-H) and at 7.03 ppm (meta-H) in amino compound 92, respectively, due to the
switching from a strongly electron withdrawing to a strongly electron donating functionality.
The remainder resonances for the non-annulated phenyl ring, the tethered phenyl ring, the
tether itself and the t-butyl groups appear unaffected and are found in nearly exactly the
same spectral position as they are observed in non-functionalized 53. While the signal for
the inner ring amine protons in 92, being found at -1.61 ppm, i.e. comparable to that in 53,
the resonance is shifted upfield to -1.69 ppm in 91 again reflecting the impact of the
different functionalities on the substituent in 15 position. Further NMR-data is included in
the experimental section.
Also the UV/Vis spectra (Figure 46) appear almost identical in comparison to the non-
functionalized system 53. Only for amino derivative 92, the bands are slightly
bathochromically shifted by 3 to 5 nm. The extinction coefficients (Table 23) obtained for 91
and 92 are almost identical to those of 53 except the SORET band of 92 which shows a slightly
lower extinction.
2.5·10 5
ε
[M -1 ·cm -1 ]
2.0·10 5
1.5·10 5
1.0·10 5
0.5·10 5
118
0
ε
[M -1 ·cm -1 ]
1.2·10 3
8.0·10 3
4.0·10 3
0
500 600 700
400 500 600 700
λ[nm]
λ[nm]
Figure 46. UV/Vis spectra
of 91 and 92 opposed to
the one of 53. All
measurements were
done in CH2Cl2 solution.
Thus, it was expected that the photophysical parameters will not differ much from those
obtained for 53 since also computational studies showed that the phenyl substituents on
positions 10, 15 and 20 should be electronically decoupled from the porphyrin core system
as orbital interactions are concerned 100 being in contrast to the already discussed NMR data.
The results on corresponding measurements will be discussed in the following paragraph.
53
91
92