Synthesis of cyclophane-like porphyrin-calix[4]pyrrole conjugates

Article abstract of DOI:10.1134/S107042801008021X

New cyclophane-like porphyrin-calix[4]pyrrole conjugates were synthesized on the basis of mesoethynyloctaethylporphyrin, and their physicochemical properties were studied. Pleiades Publishing, Ltd., 2010.

Full text of DOI:10.1134/S107042801008021X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2010, Vol. 46, No. 8, pp. 1246–1250. © Pleiades Publishing, Ltd., 2010.
Original Russian Text © O.M. Kulikova, N.Zh. Mamardashvili, 2010, published in Zhurnal Organicheskoi Khimii, 2010, Vol. 46, No. 8, pp. 1244–1248.
Synthesis of Cyclophane-Like Porphyrin–Calix[4]pyrrole
Conjugates
O. M. Kulikova and N. Zh. Mamardashvili
Institute of Solution Chemistry, Russian Academy of Sciences, ul. Akademicheskaya 1, Ivanovo, 153045 Russia
e-mail: ngm@isc-ras.ru
Received September 17, 2009
Abstract—New cyclophane-like porphyrin–calix[4]pyrrole conjugates were synthesized on the basis of meso-
ethynyloctaethylporphyrin, and their physicochemical properties were studied.
DOI: 10.1134/S107042801008021X
In the recent time, many compounds in which por-
phyrin fragments are covalently linked to crown ethers,
cyclodextrins, and calixarenes were synthesized and
found to possess interesting physicochemical prop-
erties [1–11]. We believed that new polyfunctional
supramolecules, namely calix[4]pyrrole–bis-porphyrin
conjugates, should be promising. The calix[4]pyrrole
fragment in their molecules may be capable of acting
simultaneously as complexing cavity (for selective
binding of anions) and scaffold endowing the molecule
with a definite geometric structure in which the reac-
tion centers in the porphyrin fragments are fixed at
a certain distance with respect to each other. The pres-
ence of tetrapyrrole chromophores in such supramole-
cules should considerably extend the set of spectral
methods for analysis of a broad spectrum of inter-
molecular interactions.
conjugates. The condensation of porphyrin–bis(dipyr-
romethane) (I) with acetone in the presence of boron
trifluoride–ether complex in strongly dilute solution
gave two stereoisomers II and III [12, 13] differing in
the orientation of meso-methyl groups in the calix[4]-
pyrrole macroring relative to the porphyrin ring plane
(Scheme 1). The yields of calix[4]pyrrole–porphyrins
II and III were 5 and 7%, respectively.
In the present work we synthesized cyclophane-like
calix[4]pyrrole–porphyrin conjugates in which the
calix[4]pyrrole fragment holds two porphyrin frag-
ments in the face-to-face mode. The structure of the
synthesized compounds was confirmed by their elec-
1
tronic absorption and H NMR spectra. The spectral
data indicated strong mutual effect of π-electron sys-
tems in the neighboring porphyrin macrocycles.
By the Sonogashira reaction [14] of meso-hexa-
methylbis(4-iodophenyl)calix[4]pyrrole (IV) with
5-ethynyloctaethylporphyrin (V) we synthesized calix-
We have found only one published example of syn-
thesis of chemically bonded calix[4]pyrrole–porphyrin
Scheme 1.
Me
NH HN
Me
NH HN
Me
NH
Me
Me
NH
NH
Me
O
NH
Me
Me
N
Mes
N
Mes
O
O
O
N
N
Ni
Ni
N
N
N
N
Mes
Mes
I
II, III
1246

SYNTHESIS OF CYCLOPHANE-LIKE PORPHYRIN–CALIX[4]PYRROLE CONJUGATES
1247
Scheme 2.
Et
Et
I
I
Et
Et
Et
Et
HN
N
N
Me
Me
Me
Me
+
2
H
N
H
N
CH
N
H
N
H
NH
Me
Me
Et
Et
IV
V
Et
Et
Et
N
M1
Et
N
N
Et
N
Et
Me
Me
NH
Me
Me
I
Et
Et
NH
Me
Me
Me
Me
Pd(PPh3)2Cl2
CuI
HN
HN
NH
HN
HN
NH
+
Et
Et
N
Et
Et
Me
Et
Me
Et
N
Me
Me
M2
M3
Et
Et
N
N
N
N
Et
Et
N
N
Et
Et
Et
Et
Et
Et
VI, VIII, X, XI
VII, IX
VI, M1 = M2 = H2, VIII, M1 = M2 = Cu; VII, M3 = H2; IX, M3 = Cu; X, M1 = Cu, M2 = H2; XI, M1 = Cu, M2 = Zn.
[4]pyrrole–bisporphyrin conjugate VI with the calix-
[4]pyrrole scaffold having 1,3-alternate conformation
(Scheme 2). The reaction was carried out in thoroughly
dried toluene in the presence of CuI, Pd(PPh3)2Cl2, and
triethylamine. The product was purified by chromatog-
raphy on aluminum oxide, followed by recrystalliza-
tion from methylene chloride–methanol (1 :1); the
yield of VI was 30%. Calix[4]pyrrole–porphyrin con-
jugate VII having only one porphyrin fragment was
formed as by-product. The reactions of compounds VI
and VII with copper acetate in dimethylformamide
gave the corresponding copper porphyrin complexes
VIII and IX in 95% yield.
In the porphyrin chemistry, of particular interest are
dimeric porphyrin complexes having different metal
cations in the coordination centers of the tetrapyrrole
macrorings. Such compounds can be successfully syn-
thesized following the above approach. The reaction of
equimolar amounts of calix[4]pyrrole–porphyrin IX
with 5-ethynyloctaethylporphyrin (V) gave 25% of
calix[4]pyrrole–bisporphyrin X. Complex formation of
the latter with zinc acetate in dimethylformamide
afforded bisporphyrinate XI in which the tetrapyrrole
macrorings contain zinc and copper cations.
1
The H NMR spectra of calix[4]pyrrole–porphyrins
VI–XI contained signals from protons in the calix[4]-
pyrrole and porphyrin fragments. Interactions between
π-electron systems in the neighboring tetrapyrrole
fragments in molecules VI, VIII, X, and XI gave rise
to upfield shift of signals from protons in the meso
positions (δΔ ≈ 0.2 ppm) and β-ethyl groups (δΔ ≈
0.08–0.25 ppm) relative to the corresponding signals in
the spectra of conjugates VII and IX having only one
porphyrin macroring. The observed shifts are consist-
ent with face-to-face orientation of the porphyrin frag-
ments in conjugates VI, VIII, X, and XI.
Protons in the p-phenylene fragments resonated in
the 1H NMR spectra as two doublets at δ ~6.55 (ortho)
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 8 2010

KULIKOVA, MAMARDASHVILI
1248
and ~6.30 ppm (meta). The signals from bisporphyrin
conjugates VI, VIII, X, and XI were located in
a stronger field than those of compounds VII and IX.
The NH protons in the calix[4]pyrrole fragment of VI–
XI gave rise to a broadened singlet at δ 7.2 ppm. All
CH protons in the pyrrole rings of the calix[4]pyrrole
macroring appeared as one well-resolved doublet at
about δ ~5.70 ppm.
The electronic absorption spectra of calix[4]pyr-
role–bisporphyrins VI, VIII, X, and XI were charac-
terized by a blue shift (Δλ = 4.5 nm), reduced intensity,
and considerable broadening of the Soret band as com-
pared to monoporphyrin analogs VII and IX. These
findings also indicate fairly strong interaction between
π-electron systems of the porphyrin fragments. In
going from methanol to toluene solution, the Soret
band in the electronic absorption spectra of calix[4]-
pyrrole–bisporphyrins VI, VIII, X, and XI is appreci-
ably displaced to longer wavelength (Δλ ≈ 12 nm).
Presumably, effective solvation of aromatic porphyrin
fragments by toluene molecules is accompanied by
increase in the distance between the tetrapyrrole
macrorings and weakening of interaction between their
π-electron system. The effect of solvent on the position
of absorption maxima in the electronic absorption
spectra of porphyrin analogs VII and IX is minimal.
phenyl)calix[4]pyrrole IV in 5 ml of toluene, the mix-
ture was stirred for 5 min, 4.76 mg (0.01 mmol) of
dichlorobis(triphenylphosphine)palladium(II) and
1.62 mg (0.01 mmol) of copper(I) iodide were added,
and the mixture was stirred for 24 h at 50°C. The
solvent was distilled off under reduced pressure, the
residue was dissolved in methylene chloride, and the
organic phase was washed twice with water, dried over
sodium sulfate, and evaporated to dryness under re-
duced pressure. The residue was subjected to chroma-
tography on aluminum oxide using methylene chlo-
ride–hexane (2:1) as eluent. The eluate was evaporated
under reduced pressure, and the product was recrystal-
lized from methylene chloride–methanol (1:1). Yield
29.1 mg (30%), Rf 0.53 (Al2O3, CH2Cl2–C6H14, 2:1).
Electronic absorption spectrum, λmax, nm (logε): in
toluene: 623.4 (3.58), 571.4 (3.72), 540.2 (3.62), 505.3
(4.01), 421.1 (4.97); in methanol: 618.8 (3.49), 565.3
(3.59), 539.2 (3.58), 502.1 (4.12), 411.8 (4.92).
1H NMR spectrum, δ, ppm: –3.23 br.s (4H, NH),
–0.41 s (6H, meso-CH3), 0.44 s (12H, meso-CH3),
1.40 t (12H, CH2CH3), 1.52 t (36H, CH2CH3), 3.71 m
(8H, CH2CH3), 3.29 q (24H, CH2CH3), 5.51 d (4H,
β-CH), 5.72 d (4H, β-CH), 6.23 d (4H, Harom), 6.53 d
(4H, Harom), 7.23 br.s (4H, NH), 9.83 s (2H, meso-H),
10.04 s (4H, meso-H). Mass spectrum: m/z 1665.1 [M]+.
Found, %: C 82.17; H 7.62; N 10.04. C114H128N12. Cal-
culated, %: C 82.21; H 7.69; N 10.10.
EXPERIMENTAL
10-(4-Iodophenyl)-20-[4-(2,3,7,8,12,13,17,18-
octaethylporphyrin-5-ylethynyl)phenyl]-5,5,10,15,-
15,20-hexamethylporphyrinogen (VII). Yield 5%,
Rf 0.56 (Al2O3, CH2Cl2–C6H14, 2:1). Electronic ab-
sorption spectrum, λmax, nm (logε): in toluene: 625.1
(3.60), 572.3 (3.70), 542.1 (3.63), 507.1 (4.22), 424.6
(5.07); in methanol: 623.5 (3.53), 570.5 (3.65), 541.9
meso-Hexamethylbis(4-iodophenyl)calix[4]pyrrole
(IV) was synthesized according to the procedure de-
scribed in [15], and 2,3,7,8,12,13,17,18-octaethyl-5-
ethynylporphyrin (V) was prepared as reported in [16].
Individual compounds were isolated by column chro-
matography on neutral aluminum oxide using toluene–
hexane (1:2) as eluent. Organic solvents were purified
by standard methods [17]. The progress of reactions
was monitored by TLC on Silufol UV-254 plates. The
1H NMR spectra were recorded on a Bruker VC-200
spectrometer (200 MHz) using benzene-d6 as solvent
and tetramethylsilane as internal reference. The mass
spectra (electron impact, 70 eV) were obtained on
an MKh-1310 instrument (ion source temperature 150–
200°C). The electronic absorption spectra were
measured from solutions in toluene and methanol on
a Varian Cary 100 spectrophotometer.
1
(3.61), 505.7 (4.20), 422.9 (5.01). H NMR spectrum,
δ, ppm: –2.97 s (2H, NH), –0.29 s (6H, meso-CH3),
0.59 s (12H, meso-CH3), 1.54 t (6H, CH2CH3), 1.59 t
(18H, CH2CH3), 3.38 q (12H, CH2CH3), 3.98 q (4H,
CH2CH3), 5.54 d (4H, β-CH), 5.73 d (4H, β-CH),
6.32 d (4H, Harom), 6.65 d (4H, Harom), 7.29 br.s (4H,
NH), 10.05 s (1H, meso-H), 10.27 s (2H, meso-H).
Mass spectrum: m/z 1259.3 [M]+. Found, %: C 80.95;
H 6.52; N 8.81. C78H83IN8. Calculated, %: C 81.00;
H 6.59; N 8.90.
10,20-Bis[4-(2,3,7,8,12,13,17,18-octaethylporphy-
rin-5-ylethynyl)phenyl]-5,5,10,15,15,20-hexamethyl-
porphyrinogen dicopper(II) complex (VIII). Yield
40.1 mg (95%), Rf 0.62 (Al2O3, CH2Cl2–C6H14, 2:1).
Electronic absorption spectrum, λmax, nm (logε): in
toluene: 425.6 (4.82), 549.9 (3.87), 592.3 (3.35); in
10,20-Bis[4-(2,3,7,8,12,13,17,18-octaethylporphy-
rin-5-ylethynyl)phenyl]-5,5,10,15,15,20-hexamethyl-
porphyrinogen (VI). Triethylamine, 5 ml, was added
under argon to a solution of 78.0 mg (0.14 mmol) of
compound V and 47.11 mg (0.07 mmol) of bis(4-iodo-
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 46 No. 8 2010

SYNTHESIS OF CYCLOPHANE-LIKE PORPHYRIN–CALIX[4]PYRROLE CONJUGATES
1249
methanol: 413.1 (4.76), 550.1 (3.81), 587.5 (3.36).
1H NMR spectrum, δ, ppm: –0.38 s (6H, meso-CH3),
0.43 s (12H, meso-CH3), 1.38 t (12H, CH2CH3), 1.50 t
(36H, CH2CH3), 3.30 q (24H, CH2CH3), 3.70 m (8H,
CH2CH3), 5.50 d (4H, β-CH), 5.73 d (4H, β-CH),
6.21 d (4H, Harom), 6.52 d (4H, Harom), 7.22 br.s (4H,
NH), 9.82 s (2H, meso-H), 10.02 s (4H, meso-H).
Mass spectrum: m/z 1788.3 [M]+. Found, %: C 76.49;
H 6.89; N 9.33. C114H124Cu2N12. Calculated, %:
C 76.55; H 6.94; N 9.40.
(2,3,7,8,12,13,17,18-Octaethyl-5-{4-[15-(4-Iodo-
phenyl)-5,10,10,15,20,20-hexamethylporphyrino-
gen-5-yl]phenylethynyl}porphyrinato)copper(II)
(IX). Yield 37.3 mg (91%), Rf 0.49 (Al2O3, CH2Cl2–
C6H14, 2:1). Electronic absorption spectrum, λmax, nm
(logε): in toluene: 420.9 (4.89), 547.2 (3.93), 594.2
(3.39); in methanol: 419.7 (4.85), 546.5 (3.90), 593.6
(3.41). 1H NMR spectrum, δ, ppm: –0.25 s (6H, meso-
CH3), 0.56 s (12H, meso-CH3), 1.52 t (6H, CH2CH3),
1.57 t (18H, CH2CH3), 3.36 q (12H, CH2CH3), 3.97 q
(4H, CH2CH3), 5.52 d (4H, β-CH), 5.69 d (4H, β-CH),
6.30 d (4H, Harom), 6.61 d (4H, Harom), 7.31 br.s (4H,
NH), 10.06 s (1H, meso-H), 10.28 s (2H, meso-H).
Mass spectrum: m/z 1320.5 [M]+. Found, %: C 70.87;
H 6.10; N 8.43. C78H81CuIN8. Calculated, %: C 70.93;
H 6.14; N 8.49.
10,20-Bis[4-(2,3,7,8,12,13,17,18-octaethylporphy-
rin-5-ylethynyl)phenyl]-5,5,10,15,15,20-hexamethyl-
porphyrinogen copper(II) complex (X). Triethyl-
amine, 5 ml, was added under argon to a solution of
87.6 mg (0.07 mmol) of compound IX and 39.5 mg
(0.07 mmol) of porphyrin V in 5 ml of toluene, the
mixture was stirred for 5 min, 2.38 mg (0.005 mmol)
of dichlorobis(triphenylphosphine)palladium(II) and
0.81 mg (0.005 mmol) of copper(I) iodide were added,
and the mixture was stirred for 24 h at 50°C. The
solvent was distilled off under reduced pressure, the
residue was dissolved in methylene chloride, and the
solution was washed twice with water, dried over sodi-
um sulfate, and evaporated to dryness under reduced
pressure. The residue was subjected to chromatog-
raphy on aluminum oxide using CH2Cl2–C6H14 (2:1)
as eluent. The eluate was evaporated under reduced
pressure, and the product was recrystallized from
CH2Cl2–MeOH (1:1). Yield 25.7 mg (25%), Rf 0.44
(Al2O3, CH2Cl2–C6H14, 2:1). Electronic absorption
spectrum, λmax, nm (logε): in toluene: 423.6 (4.85),
506.3 (4.07), 548.3 (3.73), 586.1 (3.53), 622.4 (3.50);
in methanol: 414.7 (4.80), 506.9 (4.01), 547.0 (3.70),
585.7 (3.51), 622.1 (3.49). 1H NMR spectrum, δ, ppm:
–3.21 s (2H, NH), –0.34 s (6H, meso-CH3), 0.47 s
(12H, meso-CH3), 1.47 t (12H, CH2CH3), 1.53 t (36H,
CH2CH3), 3.32 q (24H, CH2CH3), 3.70 m (8H,
CH2CH3), 5.50 d (4H, β-CH), 5.73 d (4H, β-CH),
6.27 d (4H, Harom), 6.52 d (4H, Harom), 7.20 br.s (4H,
NH), 9.85 s (2H, meso-H), 10.07 s (4H, meso-H).
Mass spectrum: m/z 1726.6 [M]+. Found, %: C 79.22;
H 7.23; N 9.68. C114H126CuN12. Calculated, %:
C 79.28; H 7.30; N 9.74.
10,20-Bis[4-(2,3,7,8,12,13,17,18-octaethylporphy-
rin-5-ylethynyl)phenyl]-5,5,10,15,15,20-hexamethyl-
porphyrinogen copper(II) zinc(II) complex (XI).
Compound X, 30 mg, was dissolved in 70 ml of di-
methylformamide, 10 equiv of zinc acetate was added,
and the mixture was heated for 30 min under reflux.
The mixture was cooled, diluted with an equal volume
of water, and filtered. The residue was dried and
subjected to chromatography on aluminum oxide using
CH2Cl2–C6H14 (1:1) as eluent. The eluate was evapo-
rated under reduced pressure, and the product was re-
crystallized from CH2Cl2–MeOH (1:1). Yield 26.2 mg
(85%), Rf 0.67 (Al2O3, CH2Cl2–C6H14, 1:1). Electronic
absorption spectrum, λmax, nm (logε): in toluene: 427.8
(4.77), 552.3 (3.77), 586.9 (3.33); in methanol: 418.2
1
(4.71), 551.9 (3.73), 585.5 (3.30). H NMR spectrum,
δ, ppm: –0.32 s (6H, meso-CH3), 0.50 s (12H, meso-
CH3), 1.43 t (12H, CH2CH3), 1.50 t (36H, CH2CH3),
3.23 q (24H, CH2CH3), 3.76 q (8H, CH2CH3), 5.53 d
(4H, β-CH), 5.70 d (4H, β-CH), 6.31 d (4H, Harom),
6.56 d (4H, Harom), 7.25 br.s (4H, NH), 9.84 s (2H,
meso-H), 10.07 s (4H, meso-H). Found, %: C 76.41;
H 6.88; N 9.33. C114H124CuN12Zn. Calculated, %:
C 76.47; H 6.93; N 9.39.
This study was performed under financial support
by the Russian Foundation for Basic Research
(project nos. 08-03-90000-Bel-a, 08-03-00009-a, 09-
03-97500-r_tsentr_a).
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