Synthesis of β-Bromo-Substituted Cu(II) Tetraphenylporphyrinates

Article abstract of DOI:10.1134/S0036023618060062

Bromination reactions of Cu(II) 5,10,15,20-tetraphenylporphyrinate with N-bromosuccinimide in chloroform and chloroform–dimethylformamide mixture and complexation of 2-bromo-5,10,15,20-tetraphenylporphyrin and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with copper(II) acetate in dimethylformamide have been studied. Mono-, tetra-, and octabromo-substituted Cu(II) porphyrinates have been synthesized. Obtained compounds have been identified by electronic absorption spectroscopy, IR spectroscopy, mass spectrometry, and elemental analysis.

Full text of DOI:10.1134/S0036023618060062

ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2018, Vol. 63, No. 6, pp. 732–735. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © N.V. Chizhova, A.V. Shinkarenko, A.V. Zav’yalov, N.Zh. Mamardashvili, 2018, published in Zhurnal Neorganicheskoi Khimii, 2018, Vol. 63, No. 6,
pp. 695–699.
SYNTHESIS AND PROPERTIES
OF INORGANIC COMPOUNDS
Synthesis of β-Bromo-Substituted Cu(II) Tetraphenylporphyrinates
N. V. Chizhovaa, *, A. V. Shinkarenkob, A. V. Zav’yalovb, and N. Zh. Mamardashvilia
aKrestov Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, 153040 Russia
bIvanovo State University of Chemistry and Technology, Ivanovo, 153000 Russia
*e-mail: nvc@isc-ras.ru
Received April 20, 2017
Abstract⎯Bromination reactions of Cu(II) 5,10,15,20-tetraphenylporphyrinate with N-bromosuccinimide
in chloroform and chloroform–dimethylformamide mixture and complexation of 2-bromo-5,10,15,20-tet-
raphenylporphyrin and 2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin with copper(II) acetate in
dimethylformamide have been studied. Mono-, tetra-, and octabromo-substituted Cu(II) porphyrinates have
been synthesized. Obtained compounds have been identified by electronic absorption spectroscopy, IR spec-
troscopy, mass spectrometry, and elemental analysis.
DOI: 10.1134/S0036023618060062
Interest in the synthesis and study of copper porphy- at the pyrrole rings and the reactions of metal exchange
rin complexes is caused by the possibility of their appli-
cation in biomedicine and catalysis. Copper(II) chloro-
phyll complexes are extensively studied at present. The
potential areas of application of copper chlorophyll
derivative include the treatment of malignant tumors,
hemopoietic system, respiratory organs, and the use as
photosensitizer. Radiation sensitizers based on copper
complex with tetraphenylporphyrins are under study.
The first reduction potential (E1/2) of obtained com-
pounds was shown to increase on passing from copper
tetraphenylporphyrin complex (1.2 V) to its β-octa-
bromo-substituted derivative (0.59 V). Copper com-
plexes with electron-withdrawing nitro groups and flu-
orine atoms were prepared for higher antitumor effi-
ciency. Pigments and dyes based on copper
phthalocyanines and porphyrins are widely known [1].
of their cadmium complexes with zinc and copper(II)
acetates in dimethylformamide (DMF) were studied.
Kinetic parameters of the studied reactions were deter-
mined [9].
In this work, we studied bromination reactions of
Cu(II) 5,10,15,20-tetraphenylporphyrinate 5 with
NBS in chloroform and chloroform–dimethylform-
amide mixture and complexation reactions of porphy-
rins 2 and 3 with copper acetate in DMF.
EXPERIMENTAL
2-Bromo-5,10,15,20-tetraphenylporphyrin 2 and
2,3,12,13-tetrabromo-5,10,15,20-tetraphenylporphyrin 3
were prepared by procedures [2–4]. Spectral charac-
teristics of bromo-substituted porphyrins 2 and 3 were
reported in the work [7]. Chemicals used in the work
were 5,10,15,20-tetraphenylporphyrin manufactured
by Porphychem, N-bromosuccinimide from Acros,
aluminum oxide from Merck, DMF, hexane, and ace-
tonitrile of reagent grade. Cu(II) tetraphenylporphyri-
nate was obtained by the method by Adler [10]. Elec-
tronic absorption spectra (EAS) were recorded on a
Cary-100 spectrophotometer. IR spectra were regis-
tered on a Vertex 80v Fourier-transform spectrometer
as KBr pellets. Mass spectra were obtained on a Maldi
TOF Shimadzu Biotech Axima Confidence mass
spectrometer (dihydroxybenzoic acid as a matrix).
Elemental analysis was performed on a Flash EA 1112
Previously, the reaction of 5,10,15,20-tetraphenyl-
porphyrin 1 with N-bromosuccinimide (NBS) in boil-
ing chloroform resulted in 2-bromo-5,10,15,20-tetrap-
henylporphyrin
2 [2] and 2,3,12,13-tetrabromo-
5,10,15,20-tetraphenylporphyrin 3 [3, 4]. The bromina-
tion of copper–tetraphenylporphyrin complex with Br2
in chloroform–carbon tetrachloride–pyridine mixture
led to tetrabromo-substituted Cu(II) porphyrinate [5].
2,3,7,8,12,13,17,18-Octabromo-5,10,15,20-tetraphen-
ylporphyrin 4 was obtained by the treatment of copper
complex with perchloric acid. The reaction of porphy-
rins 3 and 4 with copper acetate in chloroform–metha-
nol mixture resulted in the synthesis of the correspond-
ing Cu(II) porphyrinates [4, 5]. The complexation of
β-bromosubstituted tetraphenylporphyrins with cobalt(II)
acetate, manganese(II) and platinum(II) chlorides gave
rise to preparation of the corresponding Со(II, III),
Mn(III), Pt(II, IV) porphyrinates [6–8]. Complexation
reactions of tetraphenylporphyrins bromo-substituted analyzer.
732

SYNTHESIS OF β-BROMO-SUBSTITUTED Cu(II)
733
R3
R3
R1
R1
R3
R2
R3
R2
R1
R3
R1
R3
NH
N
N
N
N
Cu
N
N
HN
R2
R2
R3
R3
R1 = R2 = R3 = H 1,
R1 = R2 = R3 = H 5,
R1 = Br, R2 = R3 = H 2,
R1 = R2 = Br, R3 = H 3,
R1 = R2 = R3 = Br 4,
R1 = Br, R2 = R3 = H 6,
R1 = R2 = Br, R3 = H 7,
R1 = R2 = R3 = Br 8,
Сopper(II)
5,10,15,20-tetraphenylporphyrinate
(c) A mixture of 0.02 g (0.0288 mmol) of porphyrin
(5). A mixture of 0.04 g (0.065 mmol) of porphin 1 and 2 and 0.052 g (0.288 mmol) of Cu(OAc)2 was dissolved
0.118 g (0.65 mmol) of Cu(OAc)2 in 40 mL of dimeth-
in 10 mL of DMF, the reaction mixture was heated to
ylformamide was heated under reflux for 15 s. The reflux, cooled, poured into water, solid NaCl was
reaction mixture was cooled, water and solid NaCl was added, the precipitate was separated by filtration,
added, the precipitate was separated by filtration, washed with water, dried, and chromatographed on
washed with water, dried, and chromatographed on aluminum oxide using chloroform as an eluent. Yield
aluminum oxide using chloroform as an eluent to give 0.02 g (0.0265 mmol), 85%.
0.038 g (0.0562 mmol) (86%) of compound 5.
MS (m/z (Irel, %)): 675 (97) [M]+; for C44H28N4Cu
calcd.: 676.
MS (m/z (Irel, %)): 754 (56) [M]+; for
C44H27N4BrCu calcd.: 755.
IR (ν, cm–1): 2926 s, 2855 m ν(C–H, Ph), 1790 w,
1680 w, 1488 s ν(C=C, Ph), 1457 m ν(C=N), 1366 m,
1345 s ν(C–N), 1193 s, 1169 w, 1146 m, 1072 m δ(C–
H, Ph), 1005 s ν(С–С), 861 s, 796 s γ(C–H, pyrrole
ring), 749 s, 702 s, 689 m γ(С–Н, Рh).
For C44H27N4BrCu anal. calcd. (%): C, 69.98; N,
7.42; H, 3.60; Br, 10.58.
IR (ν, cm–1): 2926 s, 2855 m ν(C–H, Ph), 1694 w,
1598 m 1489 s ν(C=C, Ph), 1441 m ν(C=N), 1371 m,
1346 s ν(C–N), 1146 s, 1071 s δ(C–H, Ph), 1005 s
ν(С–С), 861 m, 794 m γ(C–H, pyrrole ring), 742 m,
696 m γ(С–Н, Рh), 480 ν(Cu–N).
Copper(II) 2-bromo-5,10,15,20-tetraphenylpor-
phyrinate (6). (a) N-Bromosuccinimide (0.0131 g,
0.0737 mmol) was added with stirring to a solution of
0.02 g (0.0296 mol) of complex 5 in 10 mL of chloro-
form and the reaction mixture was heated under reflux
for 5 min. The mixture was cooled, water was added,
the organic layer was separated, washed with water,
dried with Na2SO4, concentrated, chromatographed
on aluminum oxide (using hexane, chloroform–hex-
ane 1 : 2, and then chloroform as eluent), and repre-
cipitated from ethanol. Yield 0.016 g (0.0212 mmol),
72%.
Found (%): C, 69.72; N, 7.30; H, 3.65; Br 9.67.
Сopper(II) 2,3,12,13-tetrabromo-5,10,15,20-tet-
raphenylporphyrinate (7). (a) N-Bromosuccinimide
(0.026 g, 0.148 mmol) was added with stirring in four
portions to a solution of 0.02 g (0.0296 mmol) of com-
plex 5 in 10 mL of chloroform. After addition of NBS
portion, the reaction mixture was heated under reflux
for 5 min. The mixture was cooled, water was added,
the organic layer was separated, washed with water,
dried with Na2SO4, concentrated to minimal volume,
chromatographed on aluminum oxide (using hexane,
chloroform–hexane 1 : 2, and then chloroform as elu-
ent), and reprecipitated from ethanol. Yield 0.02 g
(0.0202 mmol), 69%.
(b) N-Bromosuccinimide (0.00788 g, 0.0444 mmol)
was added with stirring to a solution of 0.02 g
(0.0296 mmol) of complex 5 in a mixture of 10 mL of
chloroform and 1 mL of DMF, the reaction mixture
(b) N-Bromosuccinimide (0.0315 g, 0.177 mmol)
was kept at ambient temperature for 35 min. The mix- was added with stirring to a solution of 0.02 g
ture was treated similarly to method a. Yield 0.017 g (0.0296 mmol) of complex 5 in a mixture of 10 mL of
(0.0225 mmol), 76%.
chloroform and 1 mL of DMF. The reaction mixture
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 63 No. 6 2018

734
CHIZHOVA et al.
was stirred at ambient temperature for 3.5 h. The mix-
ture was treated similarly to method a. Yield 0.021 g
(0.0212 mmol), 72%.
1
3.0
2.5
2.0
1.5
1.0
0.5
0
2
A mixture of 0.02 g (0.0215 mmol) of porphyrin 3
and 0.038 g (0.215 mmol) of Cu(OAc)2 was dissolved
in 10 mL of DMF and the reaction mixture was heated
to reflux. The mixture was cooled, poured into water,
solid NaCl was added, the precipitate was separated by
filtration, washed with water, dried, and chromato-
graphed on aluminum oxide using chloroform as an
eluent. Yield 0.018 g (0.0182 mmol), 86%.
400
500
600
λ, nm
700
800
MS (m/z (Irel, %)): 991 (53) [M]+; for C44H24N4Br4Cu
calcd.: 992.
Fig. 1. Electronic absorption spectra of bromo-substituted
copper porphyrinates in chloroform: (1) 6, (2) 7.
IR (ν, cm–1): 2925 s, 2854 m ν(C–H, Ph), 1614 w,
1489 s ν(C=C, Ph), 1466 w, 1457 m ν(C=N), 1367 m,
1351 m ν(C–N), 1193 s, 1169 m, 1145 m, 1039 m δ(C–
H, Ph), 1013 m ν(С–С), 862 s, 775 m γ(C–H, pyrrole
ring), 749 m, 693 m γ(С–Н, Рh).
RESULTS AND DISCUSSION
Our study showed that the reaction of complex 5
with NBS (molar ratio 1 : 2.5) in boiling chloroform
for 5 min results in Cu(II) 2-bromo-5,10,15,20-tetra-
phenylporphyrinate 6. Electronic absorption spec-
trum of sample dissolved in chloroform shows bands
with λmax 542 and 418 nm (Fig. 1). The long-wave-
length shift of absorption bands for compound 6 in
comparison with initial complex 5 was ~4–5 nm
(Table 1). The mass spectrum of compound 6 displays
a peak of molecular ion at m/z 754 (calculated for
C44H27N4BrCu: 755). The bromination of complex 5
with NBS (at molar ratio 1 : 1.5) in chloroform–DMF
mixture (10 : 1) at ambient temperature for 35 min
leads to formation of compound 6. It was shown in the
work [2] that reaction at molar ratio tetraphenylpor-
phyrinate to NBS of 1 : 2 in boiling chloroform gives
rise to 2-bromo-5,10,15,20-tetraphenylporphyrin 2.
We obtained Cu(II) complex 6 also by heating of
dimethylformamide solution of compound 2 and cop-
per acetate to boiling point. The spectral characteris-
tics of compound 6 obtained by different methods
coincide.
For C44H24N4Br4Cu anal. calcd. (%): С, 53.28; N,
5.65; H, 2.44; Br, 32.22.
Found (%): С, 53.02; N, 5.53; H, 2.48; Br, 32.08.
Сopper(II)
2,3,7,8,12,13,17,18-octabromo-
5,10,15,20-tetraphenylporphyrinate (8). (a) N-Bro-
mosuccinimide (0.105 g, 0.592 mmol) was added with
stirring to a solution of 0.02 g (0.0296 mmol) of com-
plex 5 in a mixture of 10 mL of chloroform and 1 mL
of DMF, the mixture was stirred at ambient tempera-
ture for 8 h. The reaction mixture was concentrated to
minimal volume, 10 mL of DMF, water, and solid
NaCl were added, the precipitate was separated by fil-
tration, washed with water, acetonitrile, dried, chro-
matographed on aluminum oxide using chloroform as
an eluent, and reprecipitated from ethanol. Yield
0.026 g (0.0199 mmol), 68%.
MS (m/z (Irel, %)): 1306.6 (98) [M]+; for
C44H20N4Br8Cu calcd.: 1307.5.
IR (ν, cm–1): 2925 s, 2853 m ν(C–H, Ph), 1680 w,
1488 m ν(C=C, Ph), 1467 w, 1444 w ν(C=N), 1366 w,
1351 w ν(C–N), 1175 m, 1145 w, 1108 w δ(C–H, Ph),
1024 s ν(С–С), 924 m, 858 m γ(C–H, pyrrole ring),
756 m, 734 m, 695 m γ(С–Н, Рh).
The bromination of compound 5 with NBS (molar
ratio 1 : 20) in boiling chloroform for 20 min leads to
formation of Cu(II) 2,3,12,13-tetrabromo-5,10,15,20-
tetraphenylporphyrinate 7. The electronic absorption
spectrum of compound 7 in chloroform exhibits bands
at λmax 593, 553, and 427 nm, while the bands of the
initial compound with λmax 575, 538, and 413 nm dis-
For С44Н20N4Br8Cu anal. calcd. (%): С, 40.42; N,
4.29; H, 1.54; Br, 48.89.
Found (%): С, 40.15; N, 4.16; H, 1.59; Br, 48.71.
Table 1. Electronic absorption spectra of Cu(II) tetraphenylporphyrinates in chloroform (λ, nm (logε))
Complex
Band I
Band II
Soret band
Reference
5
6
7
7
8*
8
575 (4.20)
578 sh
593.6 (3.68)
593 sh
625 sh
538 (4.72)
413 (5.68), 394 (4.92)
418 (5.56), 398 (4.87)
427.7 (4.96)
427 (5.43)
466 (5.12), 448 sh
467 (5.21), 447 sh
542 (4.48)
554 (3.91)
553 (4.36)
581 (4.25)
581 (4.33)
[4]
[5]
626 sh
* In dichloromethane.
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY
Vol. 63
No. 6
2018

SYNTHESIS OF β-BROMO-SUBSTITUTED Cu(II)
735
solutions of porphyrins 2 and 3 with copper acetate to
1
2.5
2.0
1.5
1.0
0.5
0
boiling point.
2
The table shows characteristics of electronic
absorption spectra for the prepared compounds in
comparison with those described in the literature. The
spectral characteristics of compounds 7 and 8 coin-
cides with data reported in the works [4, 5] (Table 1).
The sequential increase in the number of bromine
atoms in the pyrrole rings of complexes 6–8 leads to
bathochromic shift of bands in electronic absorption
spectra as compared with unsubstituted complex 5.
The effect of bromine atoms in the β positions of the
pyrrole rings (compounds 6–8) appears in IR spec-
trum as a shift, emergence of new or amplification of
certain bands as compared with Cu(II) tetraphenyl-
porphyrinate.
400
500
600
λ, nm
700
800
Fig. 2. Electronic absorption spectra in chloroform: (1)
compound 5, (2) compound 8.
ACKNOWLEDGMENTS
appear. The reaction of complex 5 with six-fold excess
of NBS in chloroform–DMF mixture (10 : 1) at ambi-
ent temperature for 3.5 h also leads to compound 7
(Fig. 1). It was shown in the works [3, 4] that 2,3,12,13-
tetrabromo-5,10,15,20-tetraphenylporphyrin 3 forms at
molar ratio tetraphenylporphyrin to NBS of 1 : 6 in
boiling chloroform. We obtained Cu(II) porphyrinate
7 by heating of dimethylformamide solution of por-
phyrin 3 and copper acetate (at molar ratio 1 : 10) to
boiling point.
This work was performed with the use of equip-
ment of the Shared Facility Center “The Upper Volga
Regional Center for Physicochemical Research.”
REFERENCES
1. Porphyrins: Spectroscopy, Electrochemistry, and Applica-
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chloroform–DMF mixture at ambient temperature
for 8 h leads to formation of Cu(II) 2,3,7,8,12,13,17,18-
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dron Lett. 44, 4849 (2003).
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octabromo-5,10,15,20-tetraphenylporphyrinate
8.
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The electronic absorption spectrum of compound 8 in
chloroform displays bands at λmax 626, 581, 467, and
447 nm. Figure 2 shows electronic absorption spec-
trum of the initial complex 5 and octabromo-substi-
tuted compound 8. The time of formation of copper
porphyrinate 8 is reduced to 7 min in boiling chloro-
form–DMF mixture.
5. P. Bhyrappa and V. J. Krishnan, Inorg. Chem. 30, 239
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tetraphenylporphyrinate 5 with N-bromosuccinimide
in boiling chloroform leads to mono- and tetrabromo-
substituted copper porphyrinates. The bromination of
compound 5 with NBS in chloroform–DMF mixture
allows preparation of mono- tetra- and octabromo-
substituted Cu(II) porphyrinates under mild condi-
tions. Mono- and tetrabromo-substituted compound
6 and 7 readily form on heating of dimethylformamide
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Translated by I. Kudryavtsev
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 63 No. 6 2018