Acid–Base Properties of Polyhalogenated Tetraphenylporphyrins

Article abstract of DOI:10.1134/S1070428020060147

Abstract: [2,3,7,8,12,13,17,18-Octabromo-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]zinc(II)and[2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]zinc(II)were synthesized by halogenation of[5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]zinc(II) with N-bromosuccinimide and N-chlorosuccinimide, respectively, in a mixture of chloroformwith methanol. Treatment of the halogenated zinc porphyrins with trifluoroaceticacid in chloroform gave the corresponding free ligands. The isolated compoundswere identified by electronic absorption, ¹H NMR, andmass spectra. The acid–base properties of5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin,2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin,and2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinwere studied in acetonitrile at 298 K. Their acidity and basicity constants andconcentration ranges of their ionized forms were determined.

Full text of DOI:10.1134/S1070428020060147

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2020, Vol. 56, No. 6, pp. 1054–1061. © Pleiades Publishing, Ltd., 2020.
Russian Text © The Author(s), 2020, published in Zhurnal Organicheskoi Khimii, 2020, Vol. 56, No. 6, pp. 957–965.
Acid–Base Properties of Polyhalogenated Tetraphenylporphyrins
Yu. B. Ivanovaa,*, N. V. Chizhovaa, I. A. Shumilovab,
A. I. Rusanovb, and N. Zh. Mamardashvilia
a Krestov Institute of Solution Chemistry, Russian Academy of Sciences, Ivanovo, 153040 Russia
b Ivanovo State University of Chemistry and Technology, Ivanovo, 153460 Russia
*e-mail: jjiv@yandex.ru
Received January 29, 2020; revised February 26, 2020; accepted February 28, 2020
Abstract—[2,3,7,8,12,13,17,18-Octabromo-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]zinc(II) and
[2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]zinc(II) were synthesized
by halogenation of [5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]zinc(II) with N-bromosuccinimide and
N-chlorosuccinimide, respectively, in a mixture of chloroform with methanol. Treatment of the halogenated zinc
porphyrins with trifluoroacetic acid in chloroform gave the corresponding free ligands. The isolated compounds
1
were identified by electronic absorption, H NMR, and mass spectra. The acid–base properties of
5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin, 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,6-di-
chlorophenyl)porphyrin, and 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin
were studied in acetonitrile at 298 K. Their acidity and basicity constants and concentration ranges of their
ionized forms were determined.
Keywords: halogen-substituted tetraphenylporphyrins, bromination and chlorination, spectral and acid–base
properties
DOI: 10.1134/S1070428020060147
Porphyrins and their metal complexes proved to be
efficient semiconductors, components of solar cells,
photodynamic therapy agents, and sensors for various
substrates [1]. Introduction of electron-withdrawing
substituents into porphyrin molecules gives rise to
materials with enhanced n-conductivity [2]. Halogen-
substituted porphyrins are of particular interest among
compounds containing electron-withdrawing substit-
uents in the macrocycle. They can be used in the manu-
facture of new materials with nonlinear optical and
catalytic properties [3].
octachlorotetraphenylporphyrins [6] were reported
previously.
With the goal of studying spectral and acid–base
properties of polyhalogenated tetraphenylporphyrins,
in this work we performed bromination and chlorina-
tion of zinc porphyrin 1 with NBS and NCS in a mix-
ture of chloroform with methanol. The free ligands,
2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,6-
dichlorophenyl)porphyrin (4) and 2,3,7,8,12,13,17,18-
octachloro-5,10,15,20-tetrakis(2,6-dichlorophenyl)-
porphyrin (5), were synthesized by treatment of the
corresponding zinc porphyrins with trifluoroacetic acid
(Scheme 1). Initial complex 1 was prepared by two
methods: (1) complexation of 5,10,15,20-tetrakis(2,6-
dichlorophenyl)porphyrin (6) with zinc(II) acetate and
(2) metal exchange of [5,10,15,20-tetrakis(2,6-di-
chlorophenyl)porphyrinato]cadmium(II) (7) with
zinc(II) chloride in boiling DMF [7]. It was found that
the synthesis of 1 by the transmetalation method [8]
takes much less time (by an order of magnitude) than
the complexation method.
As shown in [4], the bromination of [5,10,15,20-tet-
rakis(2,6-dichlorophenyl)porphyrinato]zinc(II) (1) with
N-bromosuccinimide (NBS) in a boiling methanol
suspension gave 45% of [2,3,7,8,12,13,17,18-octa-
bromo-5,10,15,20-tetrakis(2,6-dichlorophenyl)por-
phyrinato]zinc(II) (2). Likewise, heating of 1 with
N-chlorosuccinimide (NCS) in methanol for 11 h gave
[2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis-
(2,6-dichlorophenyl)porphyrinato]zinc(II) (3). The
synthesis and acid–base properties of β-octabromo-
substituted unsymmetrical nitrophenylporphyrins [5]
and isomeric tetrachlorooctabromo- and tetrabromo-
The mass spectrum of 1 (see Supplementary Mate-
rials) contained the molecular ion peak at m/z 952.9
1054

ACID–BASE PROPERTIES OF POLYHALOGENATED TETRAPHENYLPORPHYRINS
1055
Scheme 1.
Cl
Cl
R
Cl
Cl
R
R
Cl
R
Cl
Cl
Cl
Cl
Cl
NBS or NCS
CHCl3, MeOH
N
N
N
N
N
N
N
N
Zn
Zn
Cl
Cl
R
R
Cl
Cl
R
R
Cl
Cl
1
2, 3
R
Cl
Cl
R
R
R
Cl
Cl
NH
N
N
TFA, CHCl3
HN
Cl
R
Cl
R
Cl
Cl
R
R
4–6
4, R = Br; 5, R = Cl; 6, R = H.
1
(calculated for C44H20Cl8N4Zn: 953.7). The H NMR
spectrum of 1 in CDCl3 showed a singlet at δ 8.75 ppm
from the pyrrole ring protons, a doublet at δ 7.80 ppm
from protons in the meta positions of the phenyl rings,
and a triplet at δ 7.70 ppm from protons in the para
position (Fig. 1a).
5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrinato]-
zinc(II) (3). The reaction time was approximately two
times shorter than that given in [4]. The H NMR
1
spectrum of 3 in CDCl3 showed a multiplet at δ 7.73–
7.65 ppm due to protons in the 2,6-dichlorophenyl
rings, and its mass spectrum (see Supplementary Mate-
rials) contained the molecular ion peak at m/z 1231.04
(calculated for C44H12Cl16N4Zn: 1229.3).
By heating complex 1 with 20 equiv of in a boiling
chloroform–methanol mixture (1:1) for 50 min we
obtained β-octabromo-substituted zinc porphyrin 2.
The yield of 2 isolated by chromatography on basic
Parameters of the electronic absorption spectra of
halogen-substituted zinc and cadmium porphyrins are
given in Table 1.
1
alumina was 70%. In the H NMR spectrum of 2 in
CDCl3 we observed a multiplet in the region δ 7.71–
7.62 ppm from meta- and para-protons in the phenyl
rings (Fig. 1b). The mass spectrum of 2 (see Supple-
mentary Materials) showed the molecular ion peak at
m/z 1584.7 (calculated for C44H12Br8Cl8N4Zn: 1584.9).
Treatment of a solution of 2 in chloroform with tri-
fluoroacetic acid for 30 min gave doubly protonated
form (H4P2+) of the free porphyrin ligand, which
displayed absorption bands with their maxima at λ 696,
636, and 494 nm in the electronic spectrum (CHCl3).
The neutral ligand, 2,3,7,8,12,13,17,18-octabromo-
5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin (4)
was obtained by treatment of H4P2+ with aqueous
The reaction of 1 with N-chlorosuccinimide at
a molar ratio of 1:20 under similar conditions (reaction
time 5 h) afforded [2,3,7,8,12,13,17,18-octachloro-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 6 2020

IVANOVA et al.
1056
Fig. 1. 1H NMR spectra of compounds (a) 1 and (b) 2 in CDCl3.
sodium hydrogen carbonate. The electronic absorption
The acid–base properties of porphyrins 4 and 5, as
well as of tetrakis(2,6-dichlorophenyl)porphyrin (6)
and previously reported halogenated tetraphenylpor-
phyrins [6], were studied by spectrophotometric titra-
tion [9] in the systems acetonitrile–perchloric acid and
acetonitrile–1,8-diazabicyclo[5.4.0]undec-7-ene
(DBU) at 298 K.
spectrum of 4 in chloroform showed bands at λmax 644,
1
559, and 463 nm. Its H NMR spectrum (CDCl3)
contained signals of the meta- and para-protons in the
region δ 7.71–7.67 ppm, and the NH protons resonated
at δ –1.26 ppm The molecular ion of 4 was observed in
the mass spectrum (Fig. 2) at m/z 1523.7 (calculated
for C44H14Br8Cl8N4: 1521.6). Likewise, treatment of
complex 3 with trifluoroacetic acid in chloroform
afforded 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-
tetrakis(2,6-dichlorophenyl)porphyrin (5). Its mass
spectrum is shown in Fig. 3.
Porphyrins (H2P) in organic solvents behave as am-
photeric compounds capable of undergoing protonation
in the presence of acids and deprotonation in the pres-
ence of bases at the inner nitrogen atoms (Scheme 2).
Fig. 2. Mass spectrum of 2,3,7,8,12,13,17,18-octabromo-
5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin (4).
Fig. 3. Mass spectrum of 2,3,7,8,12,13,17,18-octachloro-
5,10,15,20-tetrakis(2,6-dichlorophenyl)porphyrin (5).
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 6 2020

ACID–BASE PROPERTIES OF POLYHALOGENATED TETRAPHENYLPORPHYRINS
1057
Table 1. Electronic absorption spectra of zinc porphyrins 1–3 and cadmium porphyrin 7, λ, nm (logε)
Compound no.
Solvent
DMF
Soret band
Q band
1
1
2
2
3
3
7a
405 (4.66), 426 (5.50)
405 (4.64), 425 (5.53)
368 (4.52), 474 (5.31)
368 (4.64), 469 (5.45)
364 (4.66), 455 (5.40)
362 (4.63), 451 (5.45)
418 (4.77), 438 (5.53)
559 (4.35), 594 sh
557 (4.32), 592 sh
CHCl3
DMF
612 (4.16), 660 (4.06)
604 (4.35), 656 (4.16)
592 (4.34), 643 sh
CHCl3
DMF
CHCl3
DMF
584 (4.38), 635 sh
578 (4.34), 620 (3.98)
a Data of [7].
Scheme 2.
Materials) show variations of the electronic absorption
spectra of porphyrins 4–6 in acetonitrile upon titration
with 0.01 M HClO4 and of 4 and 5 upon titration with
0.01 M DBU.
Kb1
H4P2+
H3P+
H2P
H3P+
H2P
HP–
P2–
+
H+
(1)
(2)
(3)
(4)
Kb2
Ka1
Ka2
+
H+
The presence of two families of isosbestic points in
the electronic absorption spectra is typical of stepwise
protonation processes. However, the spectrophoto-
metric titration curves plotted on the basis of the
experimental data displayed no clearly defined steps,
except for the titration curves obtained for compound 6.
This does not rule out stepwise process but implies
close protonation constants in each step [10]. The
observed variations of the electronic absorption spectra
suggest that the ratio of the ionized forms in equilibria
(1)–(4) does not change as the concentrations of two
absorbing centers of the porphyrin molecule change.
+
H+
HP–
+
H+
Here, H2P, HP–, P2–, H3P+, and H4P2+ are, respec-
tively, neutral, singly and doubly deprotonated, and
singly and doubly protonated forms.
Analysis of the electronic absorption spectra
showed that increase of the concentration of HClO4 or
1,8-diazabicyclo[5.4.0]undec-7-ene gave rise to two
families of spectral curves with their own sets of isos-
bestic points. Figures 4 and 5 (see also Supplementary
The molar absorption factors of all porphyrin
species involved in equilibria (1)–(4) were determined
from the electronic spectra parameters and overall
ꢂɚꢃ
A
ꢂEꢃ
A
Ⱥ
ꢀɚꢁ
ꢀEꢁ
Ⱥ
1.4
1.0
0.6
0.2
1.4
1.0
0.6
1.8
1.5
–6 –5 –4 –3 –2
0.9
–7 –6 –5 –4 –3 –2
logcDBU (M)
logcDBU (M)
ȜꢀꢁQP
400
600
700
400
500
600
700 ȜꢂꢃQP
500
Fig. 4. (a) Variation of the electronic absorption spectrum
and (b) spectrophotometric titration curve (λ 502 nm) of
2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(2,6-di-
chlorophenyl)porphyrin (4) in the system MeCN–DBU; c4 =
5.41×10–6 M; cDBU = 0–3.31×10–2 M; temperature 298 K.
Fig. 5. (a) Variation of the electronic absorption spectrum
and (b) spectrophotometric titration curve (λ 449 nm) of
2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetrakis(2,6-di-
chlorophenyl)porphyrin (5) in the system MeCN–DBU; c5 =
1.34×10–5 M; cDBU = 0–3.31×10–2 M; temperature 298 K.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 6 2020

IVANOVA et al.
1058
concentration of each porphyrin (Table 2). The overall
protonation constant [equilibria (1) and (2)] was cal-
culated by Eq. (5):
The acidity constants [equilibria (3) and (4)] were
calculated by Eq. (6):
logKa1,2 = logI + nlogcan,
(6)
pKb1,2 = –logK = logI + pH,
(5)
where Ka is the overall acidity constant, can is the
analytical concentration of DBU in solution, I is the
indicator ratio P2–/H2P, and n is the number of released
protons (n = 2); pKa1,2 = –logKa1,2. The error in the
determination of the acidity and basicity constants did
not exceed 3–5% (Table 2).
where K is the overall protonation constant for the
first and second steps, and I is the indicator ratio
[H2P]/[H4P2+]. Using the previous data of potentio-
metric study of the pH function of a glass electrode
(ESL 43-07) in acetonitrile and temperature calibration
of the electrode system ESL 43-07–silver chloride elec-
trode [EVL 1 M3, filled with a solution of Et4NCl and
saturated at 293 K with respect to m-nitroaniline
(pKa 7.6)] [11–14], we obtained the dependence
pH—log cHClO [15] which was used to calculate
protonation con4stants.
Analysis of the data presented in Table 2, in partic-
ular protonation and deprotonation constants of the
porphyrins under study and published data [6, 15–18]
on halogen-substituted tetraphenylporphyrins, showed
that the presence of electron-withdrawing chlorine
atoms both in the β-positions and in the meso-phenyl
Table 2. Electronic absorption spectra of halogenated porphyrins and their ionized forms and their acidity and basicity constants
in acetonitrile; temperature 298 K
Soret band,
λ, nm, (logε)
Porphyrin
H2TPP
Q Band, λ, nm, (logε)
pKb1,2
pKa1,2
413 (5.02) 512 (3.56), 546 (3.12), 589 (2.92), 646 (2.96) 19.8 [15, 16]
413 (5.01) 512 (3.69), 547 (3.42), 660 (3.47)
441 (5.04) 661 (4.17)
–
H3TPP+
H4TPP2+
H2Br8TPP
471 (5.14) 646 (4.16), 765 (3.92)
490 (5.19) 741 (4.52)
16.60 [6, 17]
10.77 [6, 17]
H4Br8TPP2+
Br8TPP2–
497 (5.30) 734 (4.80)
H2(3,5-BrPh)P
(3,5-BrPh)P2+
417 (5.01) 513 (3.91), 546 (3.67), 588 (3.66), 649 (4.59) 17.50 [18]
442 (4,95) 492 sh (3.76), 596 sh (3.72), 650 (4.06)
418 (5.03) 515 (3.84), 552 (3.70), 593 (3.62), 651 (3.75) 18.09 [18]
452 (4.90) 685 (4.21)
H2(4-MeO-3- BrPh)P
H4(4-MeO-3-BrPh)P2+
H2Br8(2,6-ClPh)P (4)
Br8(2,6-ClPh)P2+
Br8(2,6-ClPh)P2–
H2Cl8(2,6-ClPh)P (5)
HCl8(2,6-ClPh)P+
Cl8(2,6-ClPh)P2+
HCl8(2,6-ClPh)P–
Cl8(2,6-ClPh)P2–
H2T(2,6-ClPh)P (6)
T(2,6-ClPh)P2+
463 (5.13) 560 (4.21), 646 (3.92), 603 sh, 713 (3.73)
495 (5.08) 639 (4.02), 698 (4.06)
15.63
9.9
502 (4.97) 674 (3.90),729 (3.99)
13.25 (pKb1 9.63, 8.82 (pKb1 4.72,
pKb2 3.62)
449 (5.11) 548 (4.13), 590 sh, 636 (3.67), 706 (3.42)
465 (4.89) 643 (4.01), 710 (3.85)
pKb2 4.1)
483 (4.92) 629 (3.91), 688 (3.97)
454 (4.86) 548 (3.87), 591 (3.11)
461 (4.77) 599 (3.84), 643 (3.82)
409 (5.42) 510 (4.20), 543 sh, 586 (3.78)
425 (5.41) 574 (4.29), 620 (4.09)
17.04
–
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 6 2020

ACID–BASE PROPERTIES OF POLYHALOGENATED TETRAPHENYLPORPHYRINS
1059
rings is the main factor affecting the acid-base prop-
erties of porphyrins.
Thus, the results of our study have shown that
chemical modification of a porphyrin macrocycle is
an important tool for controlling their spectral and
acid–base properties, which makes it possible to create
systems with required physicochemical properties for
definite purposes.
In this case, the stepwise character of protonation
and deprotonation becomes more distinct, and separate
steps corresponding to processes (1)–(4) can be ob-
served for the “most acidic” porphyrin 5, which is
typical of a distorted porphyrin macrocycle. It is known
that distortion of the porphyrin macrocycle is com-
monly achieved via introduction of substituents into
the neighboring meso and β-positions and that the
degree of distortion increases in parallel with the
number and size of these substituents [15].
EXPERIMENTAL
Commercial 5,10,15,20-tetrakis(2,6-dichloro-
phenyl)porphyrin (Porphychem), N-bromosuccinimide,
N-chlorosuccinimide, trifluoroacetic acid (Acros),
aluminum oxide, solvents, cadmium acetate, zinc
acetate, and zinc chloride (Merck) were used without
further purification. The electronic absorption spectra
were recorded on a Varian Cary-100 spectrophotometer.
It should be noted that halogen-substituted por-
phyrins containing substituents only in phenyl rings
showed no acidic properties due to weak effect of
chlorine and bromine atoms on the electron density
transfer from the functional substituent to the reaction
center of porphyrin through the inductive mechanism.
Peripheral halogenation in combination with β-halo-
genation of porphyrins endowed them with acidic
properties. As noted above, introduction of chlorine
atoms exerted the strongest effect on the acid–base
properties of porphyrins.
1
The H NMR spectra were recorded on a Bruker AV
III-500 spectrometer at 500 MHz using CDCl3 as
solvent and tetramethylsilane as internal standard. The
mass spectra were obtained with a Shimadzu Biotech
Axima Confidence MALDI TOF spectrometer using
2,5-dihydroxybenzoic acid as matrix. The acid–base
properties were studied according to the procedure
described in [9, 10]. Solutions of 1,8-diazabicyclo-
[5.4.0]undec-7-ene (DBU) and perchloric acid with
a concentration of 0.01 M were prepared from dry
acetonitrile (Aldrich, water content 0.03%), DBU
(Aldrich, purity 98%), and perchloric acid (analytical
grade, 66.76% aqueous solution).
The maximum effect was observed for β-octachloro
derivative 5, and the difference in the basicity constants
of 5 and unsubstituted tetraphenylporphyrin (H2TPP)
was more than 6.5 orders of magnitude; analogous
difference between 5 and 2,3,7,8,12,13,17,18-octa-
bromotetraphenylporphyrin (H2Br8TPP) was more than
3 orders of magnitude. The corresponding differences
for octabromoporphyrin 4 were more than four orders
and one order of magnitude, respectively. Compound 6
showed a lower acidity due to specific features of the
system acetonitrile–DBU (larger titrant molecule), and
only compounds 4 and 5 displayed acidic properties.
However, stepwise deprotonation was observed in the
titration of 5 with DBU, so that we were able to
calculate acidity constants for each deprotonation step.
Leveling of the deprotonation processes in the case of
H2Br8TPP and compound 4 is likely to be related to
weaker effect of bromine atoms than chlorines. It is
interesting that introduction of bromine atoms into the
3,5-positions of meso-phenyl rings changes the basicity
by 0.5 order of magnitude relative to double ortho-
chlorine substitution in 6. Analogous pattern was ob-
served for 3-bromo-4-methoxy derivative. The basicity
of the latter is higher by 0.5 order of magnitude than
that of H2(3,5-BrPh)P and by an order of magnitude
than that of 6. These findings do not contradict clas-
sical views on substituent effects, but make it possible
to vary acid–base properties of porphyrin molecules.
[5,10,15,20-Tetrakis(2,6-dichlorophenyl)por-
phyrinato]cadmium(II) was synthesized according to
the procedure described in [7].
[5,10,15,20-Tetrakis(2,6-dichlorophenyl)por-
phyrinato]zinc(II) (1). a. A mixture of 0.04 g
(0.0225 mmol) of porphyrin 6 and 0.082 g
(0.450 mmol) of zinc(II) acetate in 30 mL of DMF was
refluxed for 30 min. The mixture was cooled and
poured into water, and the precipitate was filtered off,
washed with water, dried, and purified by alumina
chromatography using chloroform as eluent. Yield
0.035 g (0.0367 mmol, 82%).
b. A mixture of 0.04 g (0.040 mmol) of complex 7,
0.054 g (0.40 mmol) of zinc(II) chloride, and 25 mL of
DMF was refluxed for 2 min, and the product was
isolated as described above in a. Yield 0.034 g
1
(0.0357 mmol, 89%). H NMR spectrum (CDCl3), δ,
ppm: 7.70 t (4H, p-H, J = 7.65 Hz), 7.79 d (8H, m-H,
J = 7.6 Hz), 8.75 s (8H, β-H). Mass spectrum:
m /z 952. 9 (I re l 98%) [M] +. C a l c ul a t e d fo r
C44H20Cl8N4Zn: 953.7.
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 56 No. 6 2020

IVANOVA et al.
1060
[2,3,7,8,12,13,17,18-Octabromo-5,10,15,20-tetra-
CF3COOH), δ, ppm: –1.03 s (4H, NH), 7.85–7.79 m
(12H, Harom). Mass spectrum: m/z 1168.3 (Irel 96%)
[M + 2H]+. Calculated for C44H14Cl16N4: 1165.9.
kis(2,6-dichlorophenyl)porphyrinato]zinc(II) (2).
Complex 1, 0.02 g (0.021 mmol), was dissolved in
a mixture of 5 mL of chloroform and 5 mL of methanol,
0.075 g (0.420 mmol, 20 equiv) of NBS was added,
and the mixture was refluxed for 50 min. The mixture
was cooled and evaporated, the residue was dissolved
in methylene chloride, and the product was isolated by
alumina chromatography using first CH2Cl2 and then
CHCl3 as eluent. Yield 0.023 g (0.0145 mmol, 70%).
1H NMR spectrum (CDCl3), δ, ppm: 7.71–7.62 m
(Harom). Mass spectrum: m/z 1584.7 (Irel 98%)
[M – H]+. Calculated for C44H12Br8Cl8N4Zn: 1584.9.
ACKNOWLEDGMENTS
This study was performed using the equipment of joint
centers of the Institute of Organic Chemistry, Russian
Academy of Sciences, and of the Upper Volga Regional
Center for Physicochemical Studies.
FUNDING
This study was performed under financial support by the
Russian Science Foundation (project no. 19-73-20079).
[2,3,7,8,12,13,17,18-Octachloro-5,10,15,20-tetra-
kis(2,6-dichlorophenyl)porphyrinato]zinc(II) (3).
Complex 1, 0.02 g (0.021 mmol), was dissolved in
a mixture of 5 mL of chloroform and 5 mL of methanol,
0.028 g (0.21 mmol) of NCS was added, and the mix-
ture was refluxed for 2 h. An additional portion of
NCS, 0.028 g (0.210 mmol), was added, and the mix-
ture was refluxed for 3 h more, cooled, and evaporated.
The residue was treated as described above in the
synthesis of 2. Yield 0.017 g (0.0138 mmol, 66%).
1H NMR spectrum (CDCl3), δ, ppm: 7.73–7.65 m
(Harom). Mass spectrum: m/z 1231.04 (Irel 97%)
[M + 2H]+. Calculated for C44H12Cl16N4Zn: 1229.3.
CONFLICT OF INTEREST
The authors declare no conflict of interest.
SUPPLEMENTARY MATERIALS
Supplementary materials are available for this article at
https://doi.org/10.1134/S1070428020060147 and are acces-
sible for authorized users.
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