derivative with the meso-carbons replaced by nitrogens) [76]. Nevertheless, the
vibrational properties of the free-base corroles have not been described yet, except
for a few complex corroles [77, 78]. The free-base corroles synthesized and presented in [62] are quite similar to each other—the difference lies in one of the
substituents while the main core of the molecules remain unchanged. This allows
predicting a lot of similarities in the vibrational spectra of the samples with some
differences related to the changed group. The previous vibrational study of the
corrole-fullerene dyad showed that the B3LYP functional with a 6-31G basis set is
effective in the interpretation of experimentally observed vibrational bands [77]. For
that reason, we decided to use the same method for calculations of the set of
free-base corroles. The corrole macroring of the DFT optimized free-base corroles
is not planar, especially the NH containing part. Beenken et al. [60] performed DFT
calculations on meso-pyrimidinylcorrole and also obtained the non-flat geometry of
the corrole macroring. Moreover, this is in agreement with the experimental X-ray
results obtained by Gross et al. for TpFPC-H3 corrole [79]. The surface of the C 6 F 5
substituents of the samples 1–6 (respectively named as:
• 1–10-(4,7-Dimethoxynaphthalen-1-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 2–10-(2,7-Dimethoxynaphthalen-1-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 3–10-(8-Methoxyquinolin-4-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 4–10-(7,8-Dimethoxycoumarin-4-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 5–5,10,15-Tris(pentafluorophenyl)-corrole,
• 6–10-(4-nitrophenyl)-5,15-bis(pentafluorophenyl)-corrole [62])
is inclined with respect to the macroring surface; however, the angle between
them is about 45°. The third substituent in 5 and 6 has similar inclination angle. The
remaining molecules (1–4) have the double ring structure as the third substituent
which is oriented more or less perpendicularly to the macroring surface. Beenken
et al. [60] suggested that massive groups attached to the aryl substituents are
responsible for perpendicular orientation between the substituent and the macroring
surface. Our results seem to confirm that suggestion. In Fig. 3.4, the exemplary
infrared absorption spectra of two investigated corroles recorded in KBr matrix are
presented. For comparison, an appropriate calculated spectrum of each molecule is
added in every panel. The relatively good agreement between the calculated data
and experimental spectra is clearly visible. A small shift of the calculated bands
toward higher wave numbers is typical and originates from the approximations used
for calculations (harmonic vibrations, isolated molecule). The most characteristic
feature is the double band observed in the spectra of both samples at about
1500 cm
–1 (1497 and 1522 cm
–1 ).
This band is related to the symmetrical (lower wave number) and asymmetrical
(higher wave number) stretching vibrations of the C–F bonds and stretching of the
C–C bonds in the corrole macroring. In the calculated spectra, this band appears as
a single band; however, it contains two normal modes mentioned above. The
similar band has been observed in the spectra of previously investigated corrole at
1521 cm
–1 [77]. Wasbotten et al. also observed those two bands in the spectra of
108
D. Wróbel and B. Barszcz
vibrational properties of the free-base corroles have not been described yet, except
for a few complex corroles [77, 78]. The free-base corroles synthesized and presented in [62] are quite similar to each other—the difference lies in one of the
substituents while the main core of the molecules remain unchanged. This allows
predicting a lot of similarities in the vibrational spectra of the samples with some
differences related to the changed group. The previous vibrational study of the
corrole-fullerene dyad showed that the B3LYP functional with a 6-31G basis set is
effective in the interpretation of experimentally observed vibrational bands [77]. For
that reason, we decided to use the same method for calculations of the set of
free-base corroles. The corrole macroring of the DFT optimized free-base corroles
is not planar, especially the NH containing part. Beenken et al. [60] performed DFT
calculations on meso-pyrimidinylcorrole and also obtained the non-flat geometry of
the corrole macroring. Moreover, this is in agreement with the experimental X-ray
results obtained by Gross et al. for TpFPC-H3 corrole [79]. The surface of the C 6 F 5
substituents of the samples 1–6 (respectively named as:
• 1–10-(4,7-Dimethoxynaphthalen-1-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 2–10-(2,7-Dimethoxynaphthalen-1-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 3–10-(8-Methoxyquinolin-4-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 4–10-(7,8-Dimethoxycoumarin-4-yl)-5,15-bis(pentafluorophenyl)-corrole,
• 5–5,10,15-Tris(pentafluorophenyl)-corrole,
• 6–10-(4-nitrophenyl)-5,15-bis(pentafluorophenyl)-corrole [62])
is inclined with respect to the macroring surface; however, the angle between
them is about 45°. The third substituent in 5 and 6 has similar inclination angle. The
remaining molecules (1–4) have the double ring structure as the third substituent
which is oriented more or less perpendicularly to the macroring surface. Beenken
et al. [60] suggested that massive groups attached to the aryl substituents are
responsible for perpendicular orientation between the substituent and the macroring
surface. Our results seem to confirm that suggestion. In Fig. 3.4, the exemplary
infrared absorption spectra of two investigated corroles recorded in KBr matrix are
presented. For comparison, an appropriate calculated spectrum of each molecule is
added in every panel. The relatively good agreement between the calculated data
and experimental spectra is clearly visible. A small shift of the calculated bands
toward higher wave numbers is typical and originates from the approximations used
for calculations (harmonic vibrations, isolated molecule). The most characteristic
feature is the double band observed in the spectra of both samples at about
1500 cm
–1 (1497 and 1522 cm
–1 ).
This band is related to the symmetrical (lower wave number) and asymmetrical
(higher wave number) stretching vibrations of the C–F bonds and stretching of the
C–C bonds in the corrole macroring. In the calculated spectra, this band appears as
a single band; however, it contains two normal modes mentioned above. The
similar band has been observed in the spectra of previously investigated corrole at
1521 cm
–1 [77]. Wasbotten et al. also observed those two bands in the spectra of
108
D. Wróbel and B. Barszcz