New approach to the suppression of phthalocyanine aggregation: Synthesis of cobalt phthalocyanine complexes containing intramolecular bridges based on 2,7-disubstituted 9,9-bis(2,3-dicyanophenoxymethyl)fluorenes and study of their physical and catalytic p

Article abstract of DOI:10.1023/B:RUCB.0000030809.39833.30

A series of new cobalt monophthalocyanine complexes containing intramolecular bridges between the C(1(11)) and C(25(15)) carbon atoms of phthalocyanine with perpendicular rigid fluorenyl substituents was synthesized from 2,7-di(H,Bu^t)-9,9-bis(2

Full text of DOI:10.1023/B:RUCB.0000030809.39833.30

346
Russian Chemical Bulletin, International Edition, Vol. 53, No. 2, pp. 346—350, February, 2004
New approach to the suppression of phthalocyanine aggregation:
synthesis of cobalt phthalocyanine complexes containing
intramolecular bridges based on 2,7ꢀdisubstituted
9,9ꢀbis(2,3ꢀdicyanophenoxymethyl)fluorenes and study
of their physical and catalytic properties
A. L. Lyubimtsev and I. E. Nifant´evꢀ
Department of Chemistry, M. V. Lomonosov Moscow State University,
Leninskie Gory, 119992 Moscow, Russian Federation.
Fax: +7 (095) 939 4523. Eꢀmail: inif@org.chem.msu.ru
A series of new cobalt monophthalocyanine complexes containing intramolecular bridges
between the C(1(11)) and C(25(15)) carbon atoms of phthalocyanine with perpendicular rigid
fluorenyl substituents was synthesized from 2,7ꢀdi(H,But)ꢀ9,9ꢀbis(2,3ꢀdicyanophenoxyꢀ
methyl)fluorenes. The spectral and catalytic properties of the synthesized complexes and
cobalt 1,8(11),15(18),22(25)ꢀtetraethoxyphthalocyaninate were studied.
Key words: bisphthalodinitriles, phthalonitriles, cobalt phthalocyanines, oxidation, elecꢀ
tronic absorption spectra.
In recent time, phthalocyanine complexes became very
ture formed of parallel phthalocyanine rings. Based on
this concept, we obtained the series of phthalocyanines,
each containing two substituted or two unsubstituted
fluorenyl moieties, and showed that aggregation in these
phthalocyanines is completely suppressed.
This model was chosen due to two factors: simplicity
of the synthesis and a possibility to realize the proposed
concept with the maximum efficiency. In addition, as
shown by the theoretical calculation, tertꢀbutyl groups
substantially elongate the orthogonal substituent (fluorenyl
moiety) to make it, in addition, more bulky.
popular in different areas of science and technology. Due
to many useful physical and chemical properties, these
complexes found use in optical1,2 and semiconducting3
devices, electrochemistry,4 catalysis,5 and analytical
chemistry.6,7 The main disadvantage of using phthalocyaꢀ
nines is their enhanced affinity to aggregation and often,
as a consequence, low solubility. The main method for
the suppression of this phenomenon is the introduction of
additional bulky or dendrimeric substituents into the phꢀ
thalocyanine ring.8—10
In this work, we proposed an alternative method for
the suppression of aggregation by the creation of a rigid
structure with proportional substituents perpendicular (orꢀ
thogonal) to the phthalocyanine ring, which can strongly
prevent aggregation, i.e., formation of an infinite strucꢀ
Fluorene and 2,7ꢀdiꢀtertꢀbutylfluorene (3) 11 were used
for the synthesis of the respective 9,9ꢀbishydroxymethylꢀ
fluorenes 4 12 and 5 (Scheme 1). The synthesis of 5 conꢀ
sists of the successive metallation of both Н(9) protons
in 3 with butyllithium followed by formaldehyde addition.
Starting bisphthalodinitriles 7 and 8 for the synthesis
of phthalocyanines were obtained by the reactions of
3ꢀnitrophthalodinitrile (6) 13 with compounds 4 and 5.
9,9ꢀBis(2,3ꢀdicyanophenoxymethyl)fluorene (7) was synꢀ
thesized in the presence of К2СО3 14 in 54% yield. Under
these conditions, tertꢀbutylated analog 5 reacts incomꢀ
pletely to give only monosubstituted product 8. The target
bisphthalodinitrile 9 was synthesized in a high yield (69%)
using NaH as a base (see Scheme 1).
Resulting bisphthalodinitriles
7
and
9
with
Со(ОАс)2•4 Н2О were refluxed in an oꢀdichlorobenzene
(DCB)—isoamyl alcohol (AmiOH) (4 : 1) mixture in the
presence of DBU for 3 h to form cobalt 1,25:11,15ꢀbis(2,7ꢀ
R = H (1), But (2)
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 332—336, February, 2004.
1066ꢀ5285/04/5302ꢀ0346 © 2004 Plenum Publishing Corporation

New phthalocyanine complexes
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 2, February, 2004
347
assumed15 that a mixture of several isomers is produced
by the tetramerization of compounds of the type of 11.
Isolated phthalocyanines 1, 2, 10, and 12 are dark
blue powders noticeably soluble in organic solvents:
0.005 g mL–1 for 1, 0.035 g mL–1 for 2, 0.008 g mL–1
for 10, and 0.075 g mL–1 for 12 (in toluene as the solꢀ
vent). The presence of tertꢀbutyl groups in complex 2
decreases considerably its tendency to aggregation, which
is indicated by its higher solubility compared to the soluꢀ
bility of complex 1.
Scheme 1
1
The structures of all intermediates were proved by Н
and 13С NMR spectroscopy and elemental analysis. The
resulting phthalocyanines were characterized by electronic
absorption spectroscopy (EAS), MALDIꢀTOF mass specꢀ
trometry, and elemental analysis. The IR spectrum of
derivative 10 contains a signal at 2233 cm–1, indicating
the presence of nitrile groups in the structure, and conꢀ
firms the structure proposed.
The mass spectra of the synthesized phthalocyanines
contain intense signals of molecular ions, m/z: 1015 (1),
1241 (2), 1494 (10), and 747 (12) with the characteristic
ratio of isotopomers.
The electronic absorption spectra of phthalocyanines
are characterized by the intense Q band at 680—686 nm
inherent in Рс2– and corresponding to the electron tranꢀ
sition between the πꢀ and π*ꢀorbitals. The spectrum of
derivative 10 exhibits the longꢀwave bathochromic shift
of the Q band by 13 nm.
The EAS study of the behavior of complexes 1 and 2 in
solutions revealed a linear concentration dependence of
the absorbance of the solution in a wide concentration
interval (10–4—10–6 mol L–1) for both complexes (Fig. 1),
indicating the absence of aggregation in solutions of these
complexes.
The catalytic properties of the phthalocyanines synꢀ
thesized were studied. The homogeneous oxidation of
styrene by air oxygen in the presence of NaBH4 catalyzed
by the synthesized complexes was chosen for the study,
using an analogy with the available data.16
A
2.5
1
2
di(R)fluoreneꢀ9,9ꢀdiyldimethoxy)phthalocyaninates
(R = Н (1), But (2)). The synthesis of the unsubstituted
analog also afforded the product of trimerization of
bisphthalodinitrile with one cobalt atom (10), and its yield
was threefold higher than that of the target complex
(Scheme 2).
2.0
1.5
1.0
0.5
2
1
The tetramerization of 3ꢀethoxyphthalodinitrile (11)
gave cobalt 1,8(11),15(18),22(25)ꢀtetraethoxyphthaloꢀ
cyaninate (12) (Scheme 3) to be used in subsequent cataꢀ
lytic studies. Compound 11 was obtained from 6 by the
method analogous to that described previously.15 It is
0
20
40
60
C•10–6/mol L–1
Fig. 1. Plots of the absorbance of solutions of complexes 1 and 2
vs. concentration.

348
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 2, February, 2004
Lyubimtsev and Nifant´ev
Scheme 2
i. DCB : AmiOH = 4 : 1, DBU, Co(OAc)2
Scheme 3
The obtained kinetic curves (Fig. 2) demonstrate both
the rate and completeness of the reaction. As can be seen,
n/mmol
1.2
a
1
0.8
2
0.4
3
0
5
10
15
20
t/h
n/mmol
b
1.2
1
2
0.8
0.4
i. K2CO3, DMF. ii. DCB : AmiOH = 4 : 1, DBU, Co(OAc)2.
3
0
5
10
15
20
t/h
n/mmol
1.2
c
1
2
i. EtOH, NaBH4, Pc(Co), O2.
0.8
0.4
0
Under these conditions, a byꢀproduct, viz., ethylꢀ
benzene, is formed along with the main reaction product
(2ꢀphenylethanol). The mechanism of formation of both
products is discussed in detail.16,17
3
5
10
15
20
t/h
To compare the activity and to reveal common reguꢀ
larities, we studied tetraethoxyꢀsubstituted cobalt phthaloꢀ
cyanine 12 with the similar electron environment.
Fig. 2. Kinetic curves obtained using complexes 1 (a), 2 (b), and
12 (с) as catalysts: 1, styrene; 2, phenylethanol; and 3, ethylꢀ
benzene.

New phthalocyanine complexes
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 2, February, 2004
349
3ꢀNitrophthalodinitrile (6) was synthesized by a known proꢀ
cedure.13
the activity of the complexes decreases in the series
12 > 2 > 1, which is indicated by a higher rate of formaꢀ
tion of 2ꢀphenylethanol and ethylbenzene at the initial
step of the reaction. This dependence can be explained by
the open character of the coordination sphere of the metal
in the complex. The catalytic activity of all complexes
decreases in the reaction course. This is explained, first,
by the instability of the phthalocyanine complexes under
homogeneous catalytic conditions.16 The stability of the
complexes increases in the series 12 << 1 < 2. This is
clearly seen from the slope of the kinetic curve at the final
reaction step (see Fig. 2). This fact demonstrates a higher
stability of new complexes 1 and 2 compared to that of
tetraethoxy derivative 12.
9,9ꢀBis(2,3ꢀdicyanophenoxymethyl)fluorene (7). A mixture of
compound 4 (2 g, 8.85 mmol), compound 6 (3.5 g, 20.23 mmol),
anhydrous DMF (20 mL), and anhydrous K2CO3 (6.0 g,
43.47 mmol) was stirred for 120 h in an argon atmosphere at
∼20 °C. Then the mixture was poured into water. The precipiꢀ
tate formed was filtered off, washed with water, and dried at
70 °C. The resulting product was purified by column chromaꢀ
tography on silica gel (toluene—AcOEt (8 : 1) mixture as the
1
eluant, Rf 0.69). The yield was 54%. M.p. 265 °C. Н NMR
(СDСl3), δ: 4.55 (s, 4 Н, 2 СН2); 7.32, 7.40 (both d, 2 Н each,
2 СН, J = 8.2 Hz); 7.46, 7.54 (both t, 2 Н each, 2 СНflu, J =
7.5 Hz); 7.69 (t, 2 Н, 2 СН, J = 8.2 Hz); 7.86, 8.11 (both d,
2 Н each, 2 СНflu, J = 7.5 Hz). 13С NMR, δ: 53.25 (Сflu(9));
70.36 (СН2); 104.61, 113.32 (2 С—CN); 114.99, 116.66 (2 CN);
116.88, 120.34, 125.61, 127.94 (4 СНflu); 126.00, 129.25, 134.95
(3 СН); 140.60, 142.96 (4 Сflu quatern.); 160.79 (С—О). Calcuꢀ
lated (%): С, 77.83; Н, 3.76; N, 11.71. C31H18N4O2. Found (%):
С, 77.79; Н, 3.91; N, 11.40.
Experimental
1
Н and 13С NMR spectra were recorded on a Varian
VXRꢀ400 instrument (400 MHz) in CDCl3 or (СD3)2SO. The
chemical shifts are presented in the δ scale relatively to Me4Si.
Thinꢀlayer chromatography was carried out on Silufol UVꢀ254
plates. MALDIꢀTOF mass spectra (method of matrixꢀassisted
laser desorption and ionization with timeꢀofꢀflight mass anaꢀ
lyzer) were detected on VISIONꢀ2000 instruments. Elemental
analysis was carried out on a CHN analyzer (CarloꢀErba). Elecꢀ
tronic absorption spectra were recorded in the 190—1100 nm
region on a Heliosꢀα spectrophotometer.
All solvents were purified and dried prior to use according to
standard procedures.18 A standard 15% solution of BuLi in hexꢀ
ane (Merck) was used for the synthesis of compound 5. Solid
paraform (highꢀpurity grade) was preliminarily dried in vacuo at
room temperature. A 60% suspension of NaH in paraffinic oil
(Merck) was used for the synthesis of compound 9.
2,7ꢀDiꢀtertꢀbutylfluorene 3 was synthesized by a described
procedure.11
The formation of product 8 was monitored by NMR. The
spectrum of the reaction mixture contained two characteristic
singlets of nonequivalent methylene protons: δ 4.19 and
Н
4.38 (СDCl3).
2,7ꢀDiꢀtertꢀbutylꢀ9,9ꢀbis(2,3ꢀdicyanophenoxymethyl)fluorene
(9). A saturated solution of compound 5 (2 g, 5.9 mmol) in
DMF was added dropwise to a suspension of NaH (0.6 g,
25 mmol) and anhydrous DMF (30 mL) with vigorous stirring
and cooling to –78 °C. After 10 min, a solution of compound 6
(2.15 g, 12.4 mmol) was added dropwise to the reaction mixture
under the same conditions. After 0.5 h, cooling was stopped.
The reaction mixture was stirred for 12 h and then poured into
water. The precipitate formed was filtered off, washed with waꢀ
ter, and dried on a filter and then at 70 °C to a constant weight.
Then the product was purified by chromatography using a toluꢀ
ene—AcOEt (8 : 1) mixture as the eluant (Rf 0.63). The yield
69%. M.p. 317 °C. 1Н NMR (СDСl3), δ: 1.43 (s, 18 Н, 6 СН3);
4.56 (s, 4 Н, 2 СН2); 7.34, 7.39 (both d, 2 Н each, 2 СН, J =
7.9 Hz); 7.55 (d, 2 Н, 2 СНflu, J = 8.1 Hz); 7.68 (t, 2 Н, 2 СН,
J = 7.9 Hz); 7.73 (d, 2 Н, 2 СНflu, J = 8.1 Hz); 8.08 (s, 2 Н,
2 СНflu). 13С NMR, δ: 31.51 (С(Me)3); 35.12 (С(Me)3); 53.33
(Сflu(9)); 70.68 (СН2); 104.41, 113.23 (2 С—CN); 115.04,
116.62 (2 CN); 116.88, 119.54, 125.48 (3 СНflu); 122.76,
126.29, 134.95 (3 СН); 137.97, 143.12 (4 Сflu quatern.); 151.21
(С—С(Me)3); 160.85 (С—О). Calculated (%): С, 79.33; Н, 5.76;
N, 9.49. C39H34N4O2. Found (%): С, 79.31; Н, 5.89; N, 9.32.
3ꢀEthoxyphthalodinitrile (11). A mixture of anhydrous EtOH
(0.33 mL, 6.50 mmol), compound 4 (1.0 g, 5.78 mmol), DMF
(10 mL), and anhydrous К2СО3 (2.0 g, 14.49 mmol) was stirred
for 120 h in an argon atmosphere at ∼20 °C. Then the reaction
mixture was poured into water. The precipitate formed was filꢀ
tered off and dried at 70 °C. The yield was 78%. M.p. 134 °C.
1Н NMR (СDСl3), δ: 1.53 (t, 3 Н, СН3, J = 7.8 Hz); 4.23 (q,
2 Н, СН2, J = 7.8 Hz); 7.24 (d, 1 Н, Н(6), J = 8.1 Hz); 7.35 (d,
1 Н, Н(4), J = 8.1 Hz); 7.65 (t, 1 Н, Н(5), J = 8.1 Hz).
13С NMR, δ: 14.27 (СН3); 65.52 (СН2); 104.85, 112.95
(2 С—CN); 115.26, 116.98 (2 CN); 116.51, 124.81, 134.37 (С(4),
С(5), С(6)); 161.21 (С—NO2). Calculated (%): С, 69.76;
Н, 4.65; N, 16.28. C10H8N2O. Found (%): С, 70.11; Н, 4.83;
N, 16.13.
9,9ꢀBis(hydroxymethyl)fluorene (4) was synthesized by a
known procedure.12
2,7ꢀDiꢀtertꢀbutylꢀ9,9ꢀbis(hydroxymethyl)fluorene
(5).
A 1.6 М solution of BuLi (22.5 mL, 36 mmol) was added dropwise
in an argon flow to an iceꢀcooled solution of compound 1 (10 g,
36 mmol) in anhydrous THF (150 mL). After 5 min, dry
paraform (1.11 g, 36 mmol) was introduced into the reaction
mixture. Cooling was stopped, and the mixture was stirred for 3 h.
Then a 1.6 М solution of BuLi (22.5 mL, 36 mmol) was added
dropwise with cooling. After 5 min, the second portion of
paraform of (1.11 g, 36 mmol) was added. After 12 h, the reacꢀ
tion mixture was poured into a solution of NaHCO3 (120 mL),
and the resulting mixture was extracted with Et2O (3×50 mL).
The joint organic fraction was washed with a solution of NaCl
and dried over MgSO4. A viscous liquid obtained after solvent
evaporation was recrystallized from hexane. The yield was 75%.
M.p. 219—221 °C. 1Н NMR (СDСl3), δ: 1.39 (s, 18 Н, 6 СН3);
1.98 (s, 2 Н, 2 ОН); 4.03 (s, 4 Н, 2 СН2); 7.46 (d, 2 Н, Н(3),
H(6), J = 8.1 Hz); 7.62 (s, 2 Н, Н(1), H(8)); 7.67 (d, 2 Н, Н(4),
H(5), J = 8.1 Hz). 13С NMR, δ: 31.52 (С(Me)3); 34.84
(С(Me)3); 57.45 (С(9)flu); 66.91 (СН2); 119.37, 120.93, 125.15
(3 СН); 138.33, 145.64, 150.13 (6 Сflu quatern.). Calculated (%):
С, 81.67; Н, 8.87. C23H30O2. Found (%): С, 81.37; Н, 8.86.

350
Russ.Chem.Bull., Int.Ed., Vol. 53, No. 2, February, 2004
Lyubimtsev and Nifant´ev
Synthesis of cobalt phthalocyaninates 1, 2, and 12 (general
(15 m×0.53 mm×0.5 µm) with a polydimethylsiloxane coating
and a flameꢀionization detector. The quantitative calculation
was performed using known concentrations of the internal stanꢀ
dard 2ꢀfluoroaniline (0.46 mg mL–1).
procedure). A mixture of dinitriles 7 and 9 (2.10 mmol) or dinitrile
11 (4.20 mmol), Со(OAc)2•4 H2O (0.26 g, 1.05 mmol), and
DBU (1 mL) was refluxed in a mixture of DCB (40 mL) and
isoamyl alcohol (10 mL) to the end of the reaction (2.5—3 h).
The reaction course was monitored by TLC. Then the dark blue
reaction mixture was concentrated by distilling off the solvent
and chromatographed on neutral Al2O3 using a toluene—Py
(15 : 1) mixture as the eluant. The primary blue fraction was
collected. The eluate was concentrated to a volume of 2 mL, and
hexane was added. The dark blue precipitate formed was filtered
off, washed with hexane, and dried in vacuo.
Cobalt 1,25:11,15ꢀbis(fluoreneꢀ9,9ꢀdiyldimethoxy)phthaloꢀ
cyaninate (1). Rf 0.44 (toluene—Py, (15 : 1) as the eluant).
The yield 3%. UV (toluene), λmax/nm (ε): 680 (17700). MS,
m/z: 1015.0 [M]+. Found (%): С, 73.51; Н, 3.78; N, 10.87.
C62H36CoN8O4. Calculated (%): С, 73.30; Н, 3.57; N, 11.03.
Cobalt 1,25:11,15ꢀbis(2,7ꢀdiꢀtertꢀbutylfluoreneꢀ9,9ꢀdiyldiꢀ
methoxy)phthalocyaninate (2). Rf 0.54 (toluene—Py (15 : 1) as
the eluant). The yield was 14%. UV (toluene), λmax/nm (ε):
686 (45600). MS, m/z: 1241 [M]+. Found (%): С, 75.75;
Н, 5.98; N, 8.91. C78H68CoN8O4. Calculated (%): С, 75.48;
Н, 5.48; N, 9.03.
References
1. H. S. Nalwa and A. Kakuta, Thin Solid Films., 1995, 254, 218.
2. C. C. Leznoff and A. B. P. Lever, Phthalocyanine Properties,
VCH, New York, 1989, p. 1—3, 87—92.
3. M. N. Nicholson, Phthalocyanines — Properties and Applicaꢀ
tions, VCH, New York, 1993, 3, 71.
4. A. J. Appleby, J. Electroanal. Chem., 1993, 357, 117.
5. P. Salazar, in Handbook of Petr. Proc., Ed. R. A. Myers,
McGrawꢀHill, New York, 1986, 9.
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Complex 10 was obtained along with the chromatographic
isolation of compound 1 (Rf 0.65) using a toluene —Py mixꢀ
ture (15 : 1) as the eluant. The yield was 9%. UV (toluene),
max/nm: 693. MS, m/z: 1493 [M]+.
λ
11. K. D. Stigers, M. R. Koutroulis, Chung De M., and J. S.
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Cobalt 1,8(11),15(18),22(25)ꢀtetraethoxyphthalocyaninate
(12). Rf 0.37 (toluene—Py (15 : 1) as the eluant). The yield
was 34%. UV (toluene), λmax/nm: 686. MS, m/z: 747 [M]+.
Found (%): С, 64.75; Н, 4.56; N, 14.81. C40H32CoN8O4. Calꢀ
culated (%): С, 64.17; Н, 4.28; N, 14.97.
14. S. Marcuzzio, P. Svirskaya, and S. Greenberg, Can. J. Chem.,
1985, 63, 3057.
Procedure of catalytic experiments. A mixture of anhydrous
EtOH (4 mL), NaBH4 (0.10 g, 3 mmol), styrene (0.173 mL,
1.5 mmol), and a solution of the complex (0.015 mmol) in
anhydrous THF (0.2 mL) was vigorously stirred in an oxygen
atmosphere with periodical sampling for analysis. A taken sample
(150 µL) was diluted with pentane (specialꢀpurity grade, 2.5 mL).
The resulting turbid solution was filtered through a cotton wool
layer, which then was washed with pentane (1 mL). A standard
15. С. С. Leznoff and D. M. Drew, Can. J. Chem., 1996, 74, 307.
16. Т. Sugimori, S. Horike, S. Tsumura, M. Handa, and
К. Kasuga, Inorg. Chim. Acta, 1998, 283, 275.
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18. H. Becker, W. Berger, G. Domschke, Organikum. Organischꢀ
chemisches Grundpraktikum, VEB Deutscher Verlag der
Wissenschaften, Berlin, 1976, Bd. II.
solution (1 mL) of 2ꢀfluoroaniline in pentane (2.3 mg mL–1
)
and Et3N (0.5 mL) were added to the combined solution. The
resulting mixture (5 mL) was shaken, and a sample of 0.2 µL
was analyzed by gas chromatography on a Kristall 2000 M
chromatograph equipped with a ZBꢀ1 capillary column
Received July 11, 2003;
in revised form December 3, 2003