Synthesis and properties of new binuclear nickel(II) phthalocyanines

Article abstract of DOI:10.1023/A:1022456601080

New binuclear nickel(II) phthalonitrile complexes, viz., Ni^II 2,2′,9(10),9′(10′),17(18),17′(18′),24(25), 24′(25′)-tetra(phenylene-1,2-dioxy)bisphthalocyanine and Ni ^II 2,2′,9(10),9′(10′),17(18),17′(18′), 24(25),24′(25′)-tetra(4-tert-butyl-phenylene-1,2-dioxy) bisphthalocyanine, were synthesized. The complexes were characterized by electronic spectroscopy and MALDI-TOF mass spectrometry and studied as active components for membranes of ion-selective electrodes in solutions of dicarboxylic acids.

Full text of DOI:10.1023/A:1022456601080

150
Russian Chemical Bulletin, International Edition, Vol. 52, No. 1, pp. 150—153, January, 2003
Synthesis and properties of new binuclear nickel(II) phthalocyanines
b
b
a
Yu. N. Blikova,a A. V. Ivanov, L. G. Tomilova, and N. V. Shvedene
ꢀ
aDepartment of Chemistry, M. V. Lomonosov Moscow State University,
Leninskie Gory, 119899 Moscow, Russian Federation.
Fax: +7 (095) 939 0290. Eꢀmail: blikova@analyt.chem.msu.ru
bInstitute of Physiologically Active Compounds, Russian Academy of Sciences,
142432 Chernogolovka, Moscow Region, Russian Federation
New
binuclear
nickel(II)
phthalonitrile
complexes,
viz.,
NiII
2,2´,9(10),9´(10´),17(18),17´(18´),24(25),24´(25´)ꢀtetra(phenyleneꢀ1,2ꢀdioxy)bisphthaloꢀ
cyanine and NiII 2,2´,9(10),9´(10´),17(18),17´(18´),24(25),24´(25´)ꢀtetra(4ꢀtertꢀbutylꢀ
phenyleneꢀ1,2ꢀdioxy)bisphthalocyanine, were synthesized. The complexes were characterized
by electronic spectroscopy and MALDI—TOF mass spectrometry and studied as active comꢀ
ponents for membranes of ionꢀselective electrodes in solutions of dicarboxylic acids.
Key words: bisphthalodinitriles, binuclear nickel(II) phthalocyanines, MALDI—TOF mass
spectrometry, electronic absorption spectra.
Porphyrins and their synthetic analogs, phthalocyaꢀ
17(18),17´(18´),24(25),24´(25´)ꢀtetra(4ꢀtertꢀbutylpheꢀ
nyleneꢀ1,2ꢀdioxy)bisphthalocyanines (4b) (Scheme 1).
It is known8 that nonꢀsubstituted phthalocyanine comꢀ
plexes are poorly soluble in organic solvents and can be
transferred in solution only on heating in αꢀchloroꢀ
naphthalene, DMSO, or DMF. To enhance the solubility
of the binuclear phthalocyanine, we synthesized complex
4b, which is coupled through four pyrocatechol bridges
with the But group in the benzene ring. However, the
solubility of phthalocyanine complex 4b turned out the
same as that of complex 4a.
Highꢀmolecular phthalocyanineꢀcontaining subꢀ
stances can be formed as byꢀproducts of the synthesis.
This is indicated by both the insoluble portion of the
reaction mixture and low yields of the target products.
Nevertheless, repeated refluxing of the solid residue of
the reaction mixture with CH2Cl2 makes it possible to
extract almost completely the binuclear NiII phthalocyaꢀ
nines. Thus obtained complexes are highly soluble in lowꢀ
boiling solvents, such as CH2Cl2, CHCl3, THF, and
Me2CO.
nines, are under intense study as semiconductors, cataꢀ
lysts, and materials for nonlinear optics and liquid crysꢀ
tals. The porphyrin and phthalocyanine systems themꢀ
selves have some useful properties. Nevertheless, much
effort is directed to searching for more complicated reꢀ
lated structures, i.e., dimers and oligomers with different
types of bridges, which possess unique spectral and elecꢀ
trochemical properties.1—3 Since the porphyrin ring is relaꢀ
tively unstable in catalysis of multielectron processes,4 an
important task is to synthesize and study thermally and
photochemically more stable binuclear phthalocyanine
complexes.
In this work, binuclear NiII phthanocyanines of the
"ball" type conjugated through four pyrocatechol or
4ꢀtertꢀbutylpyrocatechol bridges were synthesized for the
first time.
Results and Discussion
To synthesize the target products, we employed a proꢀ
cedure used earlier for the synthesis of some sandwichꢀ
type phthalocyanines and monophthalocyanines5,6 from
the corresponding nitriles in the presence of a metal salt.
This allows the stage of formation of isoindolines and
metalꢀfree phthalocyanines to be avoided.7
New binuclear NiII phthalocyanines of the "ball" type
were chromatographed in a CHCl3—EtOH system with
the optimal ratio CHCl3 : EtOH = 20 : 1. When only
CHCl3 or EtOH is used, the complexes are not eluted
and, hence, we used EtOH for chromatographic removal
of admixtures.
Based on 4ꢀnitrophthalodinitrile (1) and pyrocatechol
derivatives 2a,b, we synthesized 1,2ꢀbis(3,4ꢀdicyanophenꢀ
oxy)benzene (3a) and 1,2ꢀbis(3,4ꢀdicyanophenoxy)ꢀ4ꢀ
tertꢀbutylbenzene (3b), whose tetramerization resulted in
NiII 2,2´,9(10),9´(10´),17(18),17´(18´),24(25),24´(25´)ꢀ
tetra(phenyleneꢀ1,2ꢀdioxy)ꢀ (4a) and 2,2´,9(10),9´(10´),
The electronic absorption spectra (EAS) of complexes
4a,b contain bands at 600—800 nm (Fig. 1) characteristic
of phthalocyanines. The presence of the But group in the
pyrocatechol bridge of complex 4b results in an insignifiꢀ
cant bathochromic shift of the absorption maximum from
670 (4a) to 673 nm (4b).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 141—144, January, 2003.
1066ꢀ5285/03/5201ꢀ150 $25.00 © 2003 Plenum Publishing Corporation

New binuclear NiII phthalocyanines
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
151
Scheme 1
R = H (a), But (b)
It is known9—11 that the EAS of planar binuclear phꢀ
thalocyanines exhibit broadening or splitting of the Q
band, which corresponds to electronic transitions between
the π—π* orbitals of the phthalocyanine rings, into two
components. The total absorption intensity decreases
compared to that of the monophthalocyanine analog. Such
a behavior is explained9—11 by increased interaction beꢀ
tween two phthalocyanine rings due to the bridges and, as
a consequence, by a change in the πꢀconjugation mechaꢀ
nism. However, in our case, the general pattern of the
absorption spectra for complexes 4a,b is similar to the
spectral characteristic of metal monophthalocyanines.
Probably, this is determined by two interacting πꢀphthaloꢀ
cyanine systems rigidly fixed above each other due to four
bridges. This shifts the main maximum by 7 and 10 nm for
complexes 4a,b, respectively, compared to nonꢀsubstiꢀ
tuted NiII monophthalocyanines (λmax = 663 nm).
The composition of binuclear NiII phthalocyanines of
the "ball" type was confirmed by the MALDI—TOF* mass
spectrometry. The m/z values in the mass spectra of comꢀ
pounds 4a,b are 1574 and 1792, respectively, which corꢀ
responds (due to the isotopic splitting of the molecular
ion peak and within the experimental error) to the calcuꢀ
lated molecular weights of these complexes (1566.749 and
1791.174).
A
2
1
In our opinion, binuclear complexes 4a,b can be used
as receptors for selective binding of carboxylic dianions
and ditopic compounds. It is schematically presented
in Fig. 2.
1
Both reagents were studied as active components of
anionꢀselective electrodes. Polyvinyl chloride membranes
containing binuclear phthalocyanines plasticized with
оꢀnitrophenyl octyl ether manifest an anionic response in
2
400
500
600
700
λ/nm
Fig. 1. Electronic absorption spectra of components 4a (1) and
4b (2) in CH2Cl2.
* The method of matrixꢀactivated laser desorption and ionizaꢀ
tion with a timeꢀofꢀflight mass analyzer.

152
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Blikova et al.
reaction mixture was brought to ∼20 °C, and the mixture was
stirred for 2 h. The resulting suspension was poured into crushed
ice (100 g), and the fine precipitate formed was filtered off and
washed with iceꢀcold water to рН 7. The precipitate was dried
on the filter at ∼20 °C and then in a desiccator at 65 °C. After
chromatography of the obtained substance (Al2O3 5—40 mesh
(Lachema), CHCl3 as eluent) and evaporation of the solvent,
product 1 was obtained as white crystals in 70% yield (9.47 g),
m.p. 140—142 °C, Rf 0.33 (CHCl3 as eluent).
4ꢀtertꢀButylpyrocatechol (2b) was synthesized from pyrocatꢀ
echol and ButOH using 85% phosphoric acid according to a
previously described procedure12 in 26% yield (m.p. 53 °C, b.p.
160 °C (22 Torr)).
Fig. 2. Schematic structure of the complex formed between the
binuclear phthalocyanine and ditopic molecule with several coꢀ
ordinateꢀactive groups.
1,2ꢀBis(3,4ꢀdicyanophenoxy)benzene (3a). A mixture of
4ꢀnitrophthalodinitrile (1) (2.12 g, 12.2 mmol), pyrocatechol
(0.60 g, 5.4 mmol), and anhydrous K2CO3 (3.75 g, 27.0 mmol)
in anhydrous DMF (14 mL) was stirred for 36 h at ∼20 °C. After
the end of the reaction, the mixture was poured into water
(100 mL) and extracted with AcOEt (3×50 mL). The orꢀ
ganic layer was washed with a saturated solution of K2CO3
(3×50 mL), 4 М HCl (∼40 mL), water to the neutral reaction,
and a saturated solution NaCl (100 mL) and dried above calꢀ
cined Na2SO4. After chromatography on silica gel* (40/100
(Lachema), AcOEt—petroleum ether (3 : 5) as eluent) and
evaporation of the solvent, product 3a was obtained as white
needleꢀlike crystals in 75% yield (1.47 g), m.p. 186 °C, Rf 0.29
(AcOEt—petroleum ether (3 : 5) as eluent). Found (%): C, 72.50;
H, 2.26; N, 15.08. C22H10N4O2. Calculated (%): C, 72.92;
solutions of maleic and terephthalic acids against the backꢀ
ground of tris(hydroxymethyl)aminomethane (рН ∼7.8).
However, to form the incomplete anionic function, a senꢀ
sor needs prolonged conditioning in solutions of the poꢀ
tentialꢀdetermining ion. In addition, to enhance the reꢀ
producibility of potential measurements, one has to inꢀ
troduce a cationogenic additive. The main reason for such
a behavior of new reagents can be an insufficient strucꢀ
tural correspondence of the reagent and analyte.
Probably, similar phthalocyanine structures but conꢀ
jugated through different bridges from one side only can
be more appropriate receptors. Due to the rotation around
the bridge, binuclear phthalocyanine can exist in several
conformations to provide great challenges for strucꢀ
tural correspondence with the compound to be deterꢀ
mined.
1
H, 2.78; N, 15.46. Н NMR (CDCl3), δ: 7.13 (dd, 2 H, H(12),
JH(12),H(11) = 8.6 Hz, JH(12),H(8) = 2.5 Hz); 7.16 (d, 2 H, H(8),
JH(12),H(8) = 2.5 Hz); 7.41, 7.29 (both dd, 2 H each, H(3),
H(4), H(5), H(6), JH(3),H(4) = JH(6),H(5) = 6.1 Hz, JH(3),H(5)
=
Thus, we synthesized for the first time NiII
2,2´,9(10),9´(10´),17(18),17´(18´),24(25),24´(25´)ꢀtetꢀ
ra(phenyleneꢀ1,2ꢀdioxy)ꢀ and 2,2´,9(10),9´(10´),17(18),
17´(18´),24(25),24´(25´)ꢀtetra(4ꢀtertꢀbutylphenyleneꢀ
1,2ꢀdioxy)bisphthalocyanines by the tetramerization of
the corresponding bisphthalodinitriles. The results obꢀ
tained by the ionometric study indicate that the binuclear
phthalocyanines can be used for selective binding and
determination of carboxylic dianions and other ditopic
compounds.
JH(6),H(4) = 3.6 Hz); 7.74 (d, 2 Н, H(11), JH(11),H(12) = 8.6 Hz).
13С NMR, δ: 109.6 (C(10)); 114.8, 115.2 (2 CN); 117.6 (C(9));
120.7, 120.8 (C(4), C(5), C(3), C(6)); 123.6 (C(8)); 128.4
(C(12)); 135.5 (C(11)); 144.7 (C(1), C(2)); 160.4 (C(7)).
MS (EI, 70 eV), m/z (Irel (%)): 362 [M]+ (100).
1,2ꢀBis(3,4ꢀdicyanophenoxy)ꢀ4ꢀtertꢀbutylbenzene (3b). A
mixture of 4ꢀnitrophthalodinitrile (1) (2.02 g, 11.7 mmol), 4ꢀ
tertꢀbutylpyrocatechol (0.86 g, 5.2 mmol), and anhydrous K2CO3
(3.60 g, 26.0 mmol) in anhydrous DMF (13 mL) was stirred for
36 h at ∼20 °C. After the end of the reaction, the mixture was
poured into water (80 mL) and extracted with AcOEt (3×50
mL). The organic layer was washed with a saturated solution of
K2CO3 (3×50 mL), 4 М HCl (∼30 mL), water to the neutral
reaction, and a saturated solution of NaCl (60 mL) and dried
above calcined Na2SO4. After the solvent was evaporated, the
brown oil was recrystallized from an AcOEt—petroleum ether
mixture. Compound 3b was obtained as white needleꢀlike crysꢀ
tals in 58% yield (1.25 g), m.p. 170—171 °C. Synthesis at a
higher temperature (35—40 °C) did not shorten the reaction
duration, however, the yield of the product increased to 68%.
Found (%): C, 73.62; H, 4.15; N, 13.29. C26H18N4O2. Calcuꢀ
lated (%): C, 73.63; H, 4.34; N, 13.39. 1Н NMR (CDCl3), δ:
1.39 (s, 9 H, Me); 7.05—7.75 (m, 9 H, Ar). 13С NMR, δ: 31.3
Experimental
Absorption spectra were recorded on a Heliosꢀα spectroꢀ
photometer in the region from 190 to 1100 nm. 1Н NMR spectra
were recorded on Bruker AMꢀ300 and Bruker ACꢀ200 instruꢀ
ments. The MALDI—TOF mass spectra were obtained on a
Reflex III instrument in the reflection regime with a nitrogen
laser (337 nm). 2,5ꢀDihydrobenzoic acid was used as matrix.
Thin layer chromatography was carried out on Silufol UVꢀ254
plates. All solvents and initial materials were purified immediꢀ
ately before use according to standard procedures.
4ꢀNitrophthalodinitrile (1). A vigorously stirred mixture of
4ꢀnitrophthalodiamide (6.4 g, 78.4 mmol) and anhydrous Py
(126 mL, 1.6 mol) was added dropwise for 2 h at 0—5 °C by
РОС13 (14.58 mL, 156.8 mmol). Then the temperature of the
* The alternative method for purification is column chromatogꢀ
raphy on Al2O3 (5—40 mesh (Lachema)), CHCl3 as eluent,
column 50×5 cm. After the solvent was evaporated and the
product was washed with hot hexane, the yield was 60%.

New binuclear NiII phthalocyanines
Russ.Chem.Bull., Int.Ed., Vol. 52, No. 1, January, 2003
153
(C(Me3)3); 35.1 (C(Me)3); 109.6, 114.9 (C(9), C(10), C(15),
C(16)); 117.8 (C(6)); 120.5 (4 CN); 120.6, 120.7, 120.8 (C(5),
C(3), C(12), C(18)); 123.0 (C(8), C(14)); 125.6 (C(11), C(17));
135.5 (C(4)); 142.1 (C(2)); 144.1 (C(1)); 152.9 (C(7)); 150.7
(C(13)). MS (EI, 70 eV), m/z (Irel (%)): 418 [M]+ (35), 403
[M – Me]+ (100).
References
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Nickel(II)
2,2´,9(10),9´(10´),17(18),17´(18´),24(25),
24´(25´)ꢀtetra(phenyleneꢀ1,2ꢀdioxy)bisphthalocyanine (4a).
1,2ꢀBis(3,4ꢀdicyanophenoxy)benzene (3a) (0.95 g, 2.6 mmol)
was dissolved on heating in isoamyl alcohol (15 mL), and
Ni(AcO)2•4H2O (0.33 g, 1.3 mmol) and DBU (0.2 mL) were
added to the mixture. The resulting mixture was refluxed for 5 h
in an argon flow. Then the reaction mixture was cooled, and the
insoluble precipitate was filtered off, thoroughly washed with
petroleum ether, and dried in a desiccator for 3 h at 110 °C.
According to the EAS and TLC data, the filtrate of the reaction
mixture contained no phthalocyanine complexes. The target
product was extracted by multiple boiling of the precipitate in
CH2Cl2. The yield was 0.097 g (9.5%), Rf 0.25 (CHCl3—EtOH
(20 : 1) as eluent). EAS, λmax/nm: 670. MS MALDI—TOF,
found, m/z: 1574 [M]+. C88H40N16O8Ni2. Calculated:
Mr = 1566.749.
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Nickel(II)
2,2´,9(10),9´(10´),17(18),17´(18´),24(25),
24´(25´)ꢀtetra(4ꢀtertꢀbutylphenyleneꢀ1,2ꢀdioxy)bisphthaloꢀ
cyanine (4b) was synthesized similarly to compound 4a from
1,2ꢀbis(3,4ꢀdicyanophenoxy)ꢀ4ꢀtertꢀbutylbenzene (3b). The
yield was 0.086 g (11%), Rf 0.28 (CHCl3—EtOH (20 : 1) as
eluent). EAS, λmax/nm: 673. MS MALDI—TOF, found, m/z:
1792 [M]+, 1810 [M + H2O]+. C104H72N16O8Ni2. Calculated:
Mr = 1791.174.
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~
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This work was financially supported by the Russian
Foundation for Basic Research (Project No. 00ꢀ03ꢀ
32658).
Received February 21, 2002;
in revised form September 13, 2002