Synthesis and structural characterizations of MESO-tetraphenyl porphyrin

Article abstract of DOI:10.14233/ajchem.2014.16659

In this paper, tetraphenyl porphyrin (H₂TPP) was synthesized by using pyrrole and benzaldehyde as raw materials under the catalysis of p-nitrobenzoic acid. The prepared tetraphenyl porphyrin was re-crystallized in a mixed system of methanol and

Full text of DOI:10.14233/ajchem.2014.16659

Asian Journal of Chemistry; Vol. 26, No. 10 (2014), 3050-3052
ASIAN JOURNAL OF CHEMISTRY
http://dx.doi.org/10.14233/ajchem.2014.16659
Synthesis and Structural Characterizations of meso-Tetraphenyl Porphyrin
1
1
1
1
TIANXIANG ZHAO , JIANBIN ZHANG1,2,*, XIAOXIA YANG , QIUXIA XU and GONGJIA LAN
1College of Chemical Engineering, Inner Mongolia University of Technology, Huhhot 010051, P.R. China
2Department of Applied Chemistry, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P.R. China
*Corresponding author: Tel/Fax: +86 471 6575722; E-mail: tadzhang@pku.edu.cn
Received: 8 November 2013;
Accepted: 7 January 2014;
Published online: 10 May 2014;
AJC-15179
In this paper, tetraphenyl porphyrin (H2TPP) was synthesized by using pyrrole and benzaldehyde as raw materials under the catalysis of
p-nitrobenzoic acid. The prepared tetraphenyl porphyrin was re-crystallized in a mixed system of methanol and methylene chloride
(CH2Cl2) and the yield of tetraphenyl porphyrin is 34.2 %. Tetraphenyl porphyrin was characterized by using FTIR, UV-visible, 1H NMR
and fluorescence spectrophotometer. The effects on the yield of tetraphenyl porphyrin at different volumes of dimethylbenzene as solvent
were explored.
Keywords: Tetraphenylporphyrin, Recrystallization, Structural characterization.
and methylene chloride. Tetraphenyl porphyrin was charac-
terized by using FTIR, UV-visible, 1H NMR and fluorescence
spectrophotometer. Meanwhile, the effect on the yield of tetra-
phenyl porphyrin at different volumes of solvent of dimethyl-
benzene was explored.
INTRODUCTION
Porphyrin is a special kind of macrocyclic conjugated
aromatic system, which received widespread attention as a
result of having many special physiological activities. One of
the most wide spread of all naturally occurring prosthetic group
is the class of highly coloured pigments known as porphyrin.
These tetrapyrrolic macrocycles play critical roles in a wide
range of biological processes, including electron transfer,
oxygen transfer and photosynthetic processes and they have a
statement of "life pigment"1-3. Tetraphenyl porphyrin (H2TPP)
is precursors for the synthesis of many metal-porphyrin
compounds and its synthesis and applications have received
continuous attention due to their special structures and
properties. The synthesis method of tetraphenyl porphyrin was
proposed by Zhang4 and the method was proved to be time-
consuming and a low production rate. Previous workers5-7
proposed that tetraphenyl porphyrin can be synthesized by
the method of condensation of pyrrole and benzaldehyde under
the protection of N2, with boron trifluoride and ether complex
[(C2H5)2O·BF3] as catalyst; however, due to many steps and
harsh reaction conditions, the method was not used. Guo et al.8
proposed a synthetic method using AlCl3 as catalyst; in the
process, although the yield could reach 30 %, AlCl3 easily
react with water to cause the difficulties of product separation.
In this work, tetraphenyl porphyrin was synthesized by
using pyrrole and benzaldehyde as raw materials under the
catalysis of p-nitrobenzoic acid. The prepared tetraphenyl
porphyrin was recrystallized in a mixed system of methanol
EXPERIMENTAL
UV-visible spectra were obtained on a Shimadzu 2450
spectrometer in CH2Cl2 at room temperature. Infrared spectra
(4000-400) cm-1 of solid samples were taken as 1 % dispersion
between two KBr pellets using a Nexus 670 spectrophotometer.
Fluorescence spectra were determined by using an F-4500
fluorescence spectrometer. 1H NMR spectra were acquired by
using a BrukerARX-400 nuclear magnetic resonance spectro-
meter and CDCl3 was used as a NMR solvent.All solid reagents
were weighed using a Sartorius BS224S electric balance.
Product obtained after filtration was dried under vacuum dried
at 80 °C under the DZF-6053 vacuum drying oven.
Pyrrole (≥ 99 %) was purchased from Shanghai Sinopharm
Co., Ltd. Dichloromethane (≥ 99.5 %) was purchased from Tianjin
Siyou Co., Ltd. Dimethylbenzene (≥ 99 %) was purchased
from Tianjin Fuyu Co., Ltd. All other reagents and solvents
were reagent grade and used as received.
General procedure: Tetraphenyl porphyrin was synthe-
sized by using pyrrole and benzaldehyde and the reaction
device and experimental mechanism as shown in Fig. 1.
A solution of 0.02 mol pyrrole, 0.02 mol benzaldehyde
and 0.01 mol p-nitrobenzoic acid as catalyst in 100 mL
dimthylbenzene was refluxed for 1.5 h in a 250 mL three-

Vol. 26, No. 10 (2014)
Synthesis and Structural Characterizations of meso-Tetraphenyl Porphyrin 3051
90
80
70
N2
PNB
NH
N
N
4
4
CHO +
+ 4H2O
N
H
HN
dimethylbenzene
60
50
40
30
20
Fig. 1. Reaction equipment and mechanism of tetraphenylporphyrin
necked round-bottom flask at 134 °C. The reaction started with
N2 purge protection and stopped with N2 until the temperature
to stabilize. The colour of reaction system soon changes into
dark purple from light yellow. After the reaction, the tempe-
rature of the system decreased by 80 °C, adding 100 mL of
methanol and standing for 2 h with shaking in a refrigerator at
-5 °C. Purple black solid was obtained by air pump filtration
and washed several times with methanol. The resulting solid
was dissolved in a mixed solvent of CH2Cl2 and CH3OH and
recrystallized, then the bright purple product obtained after
filtration was dried under vacuum at 80 °C for 5 h. In the process,
the weight of product is 1.0512 g with a yield of 34.2 %.
Under the conditions of pyrrole 0.02 mol, benzaldehyde
0.02 mol, p-nitrobenzoic acid 0.01 mol and the reaction tempe-
rature at 134 °C, the effects on the yield of dimethylbenzene
in the different volumes were explored. Yield of tetraphenyl
porphyrin synthesized at different volumes of dimethylbenzene
as shown in Table-1. When the volume of dimethylbenzene is
100 mL, the yield of tetraphenyl porphyrin can arrive at larger
value. Little solvent will result in incomplete reaction or
formation of by-products. In contrast, the purification is not
conducive to the precipitation of crystals.
1500
1000
500
Wavenumbers (cm–1)
90
80
70
60
50
40
4000
3500
3000
2500
2000
Wavenumbers (cm–1)
Fig. 2. FTIR spectra of product
3.0
2.5
2.0
1.5
1.0
0.5
0.0
418 nm
TABLE-1
YIELD OF H2TPP AT DIFFERENT VOLUMES
OF DIMETHYLBENZENE
Dimethylbenzene (mL)
H2TPP (g)
0.6825
1.0512
0.7283
0.5258
Yield (%)
22.2
80
100
120
150
34.2
23.7
17.1
RESULTS AND DISCUSSION
300
0.2
350
400
450
Wavelength (nm)
500
550
600
650
700
Infrared spectra (4000-400) cm-1 of solid samples were
taken as 1 % dispersion between two KBr pellets. As shown
in the Fig. 2: 3313 and 959 cm-1 for N-H stretching vibration
and in-plane bending vibration on the porphine ring, 3052
cm-1 is =CH- stretching vibration, 1542 cm-1 is C=C skeleton
vibration on the pyridine ring, 1459 cm-1 is C=C stretching
vibration peak on the aryl ring, 1342 cm-1 for the C=N stret-
ching vibration, 795 cm-1 is skeleton vibration peak on the
benzene ring, 841 cm-1 is C-N stretching vibration peak. The
514 nm
0.1
549 nm
590 nm
647 nm
results are consistent with the literatures9-13
.
UV spectra were determined by using CH2Cl2 as reference,
the results shown in Fig. 3. The UV spectral results showed
that the Soret absorption band of synthetic products appeared
a strong absorption peak of 418 nm9-13, which is consistent
with the ultraviolet absorption peak of tetraphenyl porphyrin
at Soret absorption band. Product of the absorption band in Q
0.0
450
500
550 600
Wavelength (nm)
650
700
Fig. 3. UV-visible spectra of product

3052 Zhao et al.
Asian J. Chem.
had 4 absorption peaks as follows: 515 nm, 549 nm, 590 nm
and 646 nm, which is consistent with the features of tetraphenyl
acid was used as catalyst at 134 °C for 1.5 h. Tetraphenyl
1
porphyrin was characterized by using FTIR, UV-visible, H
porphyrin in this absorption band9-13
.
NMR and fluorescence spectrophotometer. When the volume
of dimethylbenzene is 100 mL and pyrrole and benzaldehyde
is at 0.2 mol/L, the yield arrived at 34.2 %.
Fluorescence spectra of product CH2Cl2 solution were
determined under a concentration of 1.952 × 10-5 mol/L, when
the excitation wavelength was set at 515 nm with the slit for
5 nm. Under this condition, the intensity of emission spectrum
was strong, as shown in Fig. 4. The maximum length of exci-
tation synthetic of product can be determined to be 515 nm,
which confirmed that the product was tetraphenyl porphyrin9.
ACKNOWLEDGEMENTS
This work was supported by Foundation of the "Western
Light" Visiting Scholar Plan, Inner Mongolia Autonomous
Region's Educational Commission (No. NJZZ11068), the
Program for New Century Excellent Talents in University
(NCET-12-1017), the Program for Grassland Excellent Talents
of Inner Mongolia Autonomous Region, the Inner Mengolia
Science & Technology Plan, the program for Young Talents
of Science and Technology in Universities of Inner Mongolia
Autonomous Region (NJYT-12-B13), the Natural Science
Foundation of Inner Mongolia Autonomous Region
(2011BS0601, China), the Inner Mongolia Talented People
Development Fund and Yongfeng Boyuan Industry Co., Ltd.
(Jiangxi Province, China).
500
400
300
200
100
0
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550
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650
Wavelength (nm)
Fig. 4. Fluorescence spectrum of product
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1
In H NMR spectrum, it is notable that tetraphenyl
porphyrin are aromatic compounds and the ring current in
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Conclusion
Experiments show that tetraphenyl porphyrin (H2TPP) can
synthesize in 100 mL of dimethylbenzene when p-nitrobenzoic