Synthesis and mesomorphic properties of tetra- and octa-substituted phthalocyanines

Article abstract of DOI:10.1039/b314995a

Thia-bridged tetra- and octa-poly(oxyethylene)-substituted metal free- and Ni(II) phthalocyanines have been synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt (NiCl₂) or a strong organic base. The new compounds have been characterized by elemental analyses, UV/vis, IR, NMR and mass spectra. The mesogenic properties of these new materials were studied by differential scanning calorimetry, optical microscopy and X-ray investigations. Although octa-substituted phthalocyanine derivatives are liquid, all tetra-substituted compounds show a discotic mesophase over an extremely large temperature interval including room temperature. The relationship between the structure of the mesogenic units and the mesogenic behaviour is discussed and the influence of the different heteroatoms present in the side chains on the mesomorphic properties has been determined.

Full text of DOI:10.1039/b314995a

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P A P E R
Synthesis and mesomorphic properties of tetra- and octa-substituted
phthalocyaninesy
Ays¸e G. Gu¨rek,a Mahmut Durmus¸a and Vefa Ahsen*ab
a
Department of Chemistry, Gebze Institute of Technology, P. O. Box 141, 41400, Gebze,
Kocaeli, Turkey. E-mail: ahsen@gyte.edu.tr; Fax: +90 262 754 23 85; Tel: +90 262 754 23 60
Materials and Chemical Technologies Research Institute, TUBITAK-Marmara
Research Center, P. O. Box 21, 41470, Gebze, Kocaeli, Turkey
b
Received (in Montpellier, France) 19th November 2003, Accepted 29th January 2004
First published as an Advance Article on the web 7th May 2004
Thia-bridged tetra- and octa-poly(oxyethylene)-substituted metal free- and Ni(II) phthalocyanines have been
synthesized from the corresponding phthalonitrile derivatives in the presence of the anhydrous metal salt
(NiCl2) or a strong organic base. The new compounds have been characterized by elemental analyses, UV/vis,
IR, NMR and mass spectra. The mesogenic properties of these new materials were studied by differential
scanning calorimetry, optical microscopy and X-ray investigations. Although octa-substituted phthalocyanine
derivatives are liquid, all tetra-substituted compounds show a discotic mesophase over an extremely large
temperature interval including room temperature. The relationship between the structure of the mesogenic units
and the mesogenic behaviour is discussed and the influence of the different heteroatoms present in the side
chains on the mesomorphic properties has been determined.
derivatives have been synthesized with the aim of producing
more easily controllable macroscopic structures.14b These deri-
vatives have been predominantly alkyl,
Introduction
l5
alkoxy,16 alkoxy
Phthalocyanines (Pcs) constitute a long-established class of
commercially important dyes and pigments. The central cavity
of the molecule presents a complexing site for over 70 species
of metal atoms. Pcs and their symmetrically substituted deriva-
tives have received extensive attention over the last decades
due to their distinct properties and applications (e.g., electrical
conductivity,1 ionoelectronics,1b electrochromism,2 mesophase
formation3 and aggregation into monolayers of the Langmuir–
Blodgett type4), which make them unique substrates for new
materials.5 Pcs have usually constituted a group of crystalline
or polycrystalline compounds, whose insolubility in organic
solvents is very characteristic.6–8 A limiting factor for solution
studies on pcs is the solubility of the parent compound. Periph-
eral substitution with bulky substituents or the use of donor
solvents capable of binding to the axial position of the central
metal ion have been two practical ways to overcome this hin-
drance. In our previous works on macrocycle-substituted pcs
we have achieved the synthesis of very soluble examples in a
wide range of organic solvents.9 In addition to novel function-
alities such as alkali9a or transition metal9c,9d ion binding, ion
channel formation,10 enhanced conductivity,11 etc., the solubi-
lity of pc products has reached the 10ꢀ3 mol dmꢀ3 level.9a
Also, in the past few years the introduction of long-chain lipo-
philic substituents on the periphery of the pc ring has drasti-
cally improved their solubility in nonpolar solvents and in
some cases has provided these compounds with thermotropic
behaviour.12,13
methyl14 or oligo(ethyleneoxy)17 octa-substituted mesogens
with side chains substituted at the 2 and 3 positions on the
benzene ring or octa-alkyl18 or alkoxy methyl19 compounds
substituted at the 1 and 4 positions, but mesomorphic tetra-
substituted compounds have been rarely synthesized.20 In
addition, a number of unsymmetrically substituted pcs have
been shown to form thermotropic liquid crystals.21 The attach-
ment of polar side chains such as oligo(ethylene oxide) moi-
eties and crown ether rings to large aromatic macrocycles is
also of interest in the construction of supramolecular wires
and ion conducting channels.22 Several pcs of these types have
been designed in order to investigate complexation23 beha-
viour and their potential for electronic and ionoelectronic
applications.24
Adam et al. reported that a discotic liquid crystal of triphe-
nylene substituted by alkylthio groups exhibits considerably
higher charge carrier mobility in the discotic mesophase, com-
pared with conventional organic semiconductors.25a It can be
inferred from this example that sulfur atoms may significantly
influence the conductivity of the mesophase. Wo¨hrle and col-
leagues reported the first example of columnar mesomorphism
in octakis(octylthio)-substituted phthalocyanine zinc and
copper complexes.25b Ohta et al. reported the synthesis of a
series of octakis(alkylthio)phthalocyanines [abbreviated as
(CnS)8PcH2 , n ¼ 8, 10, 12, 16] and their copper complexes
[abbreviated as (CnS)8PcCu, n ¼ 8, 10, 12, 16] and thoroughly
investigated their mesomorphism; they discussed the influ-
ence of sulfur atoms and chain length on the mesomorphism
and the unique aggregated dimer structures in the columnar
mesophase.26
Pc is well-known as a disc-like molecule and it forms a one-
dimensional columnar structure in condensed phases. The first
mesomorphic phthalocyanines were reported in the early
1980s14a and since then numerous liquid crystalline pc
Although pcs with N- and O-donor substituents have been
frequently encountered, those with thioether moieties are
rather few.25b,27 The latter group essentially contains products
obtained by the cyclotetramerization of thioether-substituted
phthalonitriles, which themselves have been derived from
nucleophlic displacement reactions of dinitriles; a literature
y Electronic supplementary information (ESI) available: optical
texture of 6a, 8a and 8b observed at 25 ꢁC (Fig. S1, S2 and S3, respec-
tively). 1H-NMR and 13C-NMR spectral data for starting materials
and phthalocyanines in CDCl3 (Table S1 and S2, respectively). See
http://www.rsc.org/suppdata/nj/b3/b314995a/
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 9 3 – 6 9 9
693

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C 55.13, H 7.89%; C22H38O9S (478.60) requires C 55.21,
survey28 also shows that most of the recent work on thio-
ether-substituted phthalocyanines has been patented with
applications as IR absorbers.
H 8.00%. IR (KBr cell): nmax/cmꢀ1 2980–2880 (CH2), 1600,
1450, 1350 (SO2), 1190–1180 (SO2), 1120–1100 (C–O–C),
940, 820, 780, 680, 550; MS (EI): m/z (%) 479 (5) [M]þ,
328.1 (10), 346 (20) [M ꢀ (OCH2CH2)2OC2H5)]þ, 306.2 (30)
[M ꢀ OTos]þ, 214 (55) [M ꢀ 2(OCH2CH2)2OC2H5)]þ, 177
(100), 117 (60).
Phthalocyanine-based discotic liquid crystals can be expec-
ted to find application as conducting devices, because they have
self-assembling supramolecular structures.26 Also the meso-
morphic phthalocyanine derivatives show well-ordered films
thermally. The mass sensitivity results obtained by utilizing
quartz crystal microbalance (QCM) showed that the ordered
phthalocyanine films were more sensitive than the disordered
ones for the detection of different organic solvent vapours.29
In this paper, we describe the synthesis of new sterically hin-
dered thia-bridged tetra- and octa-poly(oxyethylene)-substi-
tuted pcs. The influence of the presence of the thia bridges in
the poly(oxyethylene) side chains on the mesomorphic proper-
ties has been determined. While tetra-substituted phthalocya-
nine derivatives demonstrate thermotropic phase behaviour
in an extremely large temperature interval including room tem-
perature, octa-substituted phthalocyanine derivatives do not
show liquid crystalline properties at room temperature,
because they are liquid at this temperature.
1,3-Di[2-2-(2-ethoxyethoxy)ethoxy)]-2-propanethiol (3). Com-
pound 2 (8.05 g, 16.8 mmol) was dissolved in anhydrous
ethanol (60 ml) and thiourea (1.60 g, 21 mmol) was added.
The mixture was refluxed for 48 h under stirring, after which
time the solvent was removed by distillation until the total
volume was 30 ml. To the resulting solution, a solution of
sodium hydroxide (1.35 g, 33.75 mmol) in 30 ml H2O
(degassed with argon) was added under argon atmosphere.
This mixture was refluxed and stirred for an additional 6 h,
under argon. The two-phase system that resulted was cooled
and separated; the upper aqueous phase was acidified with
dilute HCl and extracted with diethyl ether (50 ml ꢂ 3). The
ether layer was combined with the oily organic layer from
the reaction mixture and this solution was dried over Na2SO4 .
The dried ether solution was filtered and evaporated, giving
a thick liquid that was purified by column chromatography
on Al2O3 using dichloromethane–methanol (100:1) as eluent.
Experimental
General
Yield: 2.50
C15H32O6S (340.48) requires C 52.92, H 9.47%. IR (KBr cell):
max/cmꢀ1 2990–2850 (CH2), 2580 (SH), 1450, 1380, 1350,
g (44%). Anal. found C 52.88, H 9.03%;
All solvents were purified as described in Perrin and
Armarego.30 1,2-Dichloro-4,5-dicyanobenzene27b (4), 4-nitro-
phthalonitrile31 (5) and 1,3-di[2-(2-ethoxyethoxy)ethoxy]-2-
propanol32 (1) were prepared according to the reported
procedures. All other reagents and solvents were reagent
grade quality and were obtained from commercial suppliers.
Elemental analyses were obtained with a Carlo Erba 1106
instrument. Infrared spectra in sodium chloride cells for oily
compounds or KBr pellets were recorded on a Bio-Rad FTS
175C FT-IR spectrophotometer. Optical spectra in the UV-
visible region were recorded with a Schimadzu 2001 UV Pc
spectrophotometer using 1 cm path length cuvettes at room
temperature. Mass spectra were recorded on a VG Zab-Spec
spectrometer using the fast atomic bombardment (FAB) tech-
nique (35 kV) or electron impact technique. 1H and 13C NMR
spectra were recorded in CDCl3 solutions on a Bruker 500
MHz spectrometer using TMS as an internal reference. Transi-
tion temperatures were determined at scan rates of 10 ꢁC minꢀ1
using a Perkin Elmer DSC 6 differential scanning calorimeter.
The phase transition behaviour of these compounds was
observed with a Leitz Wetzler Orthoplan-pol polarizing micro-
scope equipped with a Linkam TMS 93 hot stage and a Lin-
kam LNP temperature controller. X-Ray measurements were
performed with Cu-Ka radiation using a Rigaku Kristalloflex
diffractometer (Dmax 2200) at room temperature.
n
1320, 1300, 1240, 1120–1100 (C–O–C), 940, 880, 840, 750. MS
(EI): m/z (%) 340.1 (5) [M]þ, 328.1 (10), 298 (5), 278.9
(10), 206.9 (80) [M ꢀ (OCH2CH2)2OC2H5)]þ, 172.9 (70), 147
(73), 135 (90), 115.9 (100), 99 (78), 91 (75), 74 (63)
[M ꢀ 2(OCH2CH2)2OC2H5)]þ, 61 (65).
4-Chloro-5{2-[2-(2-ethoxyethoxy)ethoxy]-1-[2-(2-ethoxyeth-
oxy)ethoxy)ethoxymethyl]ethylsulfanyl}phthalonitrile (6). 1,2-
Dichloro-4,5-dicyanobenzene (4; 0.99 g, 5 mmol) was dissolved
in anhydrous dimethyl sulfoxide (9 ml) under argon and 1,3-
di[2-(2-ethoxyethoy)ethoxy)]-2-propanethiol (3; 3.40 g, 10
mmol) was added. After stirring for 15 min at 50 ꢁC, dry and
finely powdered potassium carbonate (2.50 g, 18 mmol) was
added portion wise over 0.5 h with efficient stirring. The reac-
tion mixture was stirred under argon at 50 ꢁC for 48 h. After
cooling, the reddish-brown mixture was filtered off and solvent
was evaporated under reduced pressure. The product was puri-
fied by column chromatography on Al2O3 using dichloro-
methane–methanol (50:1) as the eluent. The product is oily
at room temperature. Yield: 1.50 g (60%). Anal. found C
54.94, H 6.75, N 5.34%; C23H33ClN2O6S (501.04) requires C
55.14, H 6.64, N 5.59%. IR (KBr cell): nmax/cmꢀ1 3040
=
=
(ArCH), 2990–2850 (CH ), 2220 (C N), 1570 (ArC C),
=
2
1460, 1350, 1220, 1120–1100 (C–O–C), 920, 750. MS (FAB,
m-NBA): m/z (%) 501.1 (20) [M]þ,400.1 (10), 367.0 (13)
[M ꢀ (OCH2CH2)2OC2H5)]þ, 235.1 (35) [M ꢀ 2(OCH2CH2)2-
OC2H5)]þ, 173.1 (95).
Synthesis of tosyl, thiol and phthalonitrile derivatives
2-[2-(2-Ethoxyethoxy)ethoxy]-1-[2-(2-ethoxyethoxy)ethoxy-
methyl] ethyl 4-methyl-1-benzene sulfonate (2). A solution of
1,3-di[2-(2-ethoxyethoxy)ethoxy]-2-propanol (1; 19.10 g, 58.88
mmol) in dry pyridine (65 ml) was cooled to 0 ꢁC and a solu-
tion of p-toluenesulfonyl chloride (12.35 g, 64.80 mmol) in
dry pyridine (25 ml) was added with stirring under argon at
a rate so that the temperature of the reaction mixture never
exceeded 5 ꢁC. After stirring for 48 h at room temperature,
the reaction mixture was poured over crushed ice and the
resulting aqueous solution was extracted with dichloro-
methane (100 ml ꢂ 3). The organic layer was washed at 0 ꢁC
with 6 N HCl solution, with H2O, dried with Na2SO4 and
evaporated to give a viscous oil that was chromatographed
on Al2O3(dichloromethane–methanol 100:1). This compound
is a colourless viscous oil. Yield: 22 g (81%). Anal. found
4,5-Di{2-[2-(2-ethoxyethoxy)ethoxy]-1-[2-((2-ethoxyethoxy)-
ethoxy)ethoxymethyl]ethylsulfanyl}phthalonitrile (7). Com-
pound 7 was prepared by the same procedure as described
for 6 by starting with 4 (0.74 g, 3.76 mmol), a large excess
of 3 (4.45 g, 13.07 mmol) and potassium carbonate (1.96 g,
14.20 mmol). The resulting light-brown oily product was pur-
ified by column chromatography on Al2O3 using dichloro-
methane–methanol (50:1) as the eluent. Yield: 1.90 g (63%).
This compound is a light yellow viscous oil. Anal. found C
56.55, H 7.95, N 3.36%; C38H64N2O12S2 (805.06) requires C
56.69, H 8.01, N 3.48%. IR (KBr cell): nmax/cmꢀ1 3040
=
=
(ArCH), 2980–2940 (CH ), 2220 (C N), 1560 (ArC C),
=
1450, 1350, 1240, 1200, 1120–1100 (C–O–C), 920, 880, 840. MS
2
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
694
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 9 3 – 6 9 9

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The crude product was purified by column chromatography
(EI): m/z (%) 805.3 (10) [M]þ, 670.2 (100) [M ꢀ (OCH2CH2)2-
OC2H5)]þ, 598.1 (10), 554.1 (11), 537.1 (4) [M ꢀ 2(OCH2CH2)2-
OC2H5)]þ, 360.2 (10), 272.4 (5) [M ꢀ 4(OCH2CH2)2OC2H5)]þ,
256 (5), 230 (25), 189.1 (34), 173.1 (46), 117.1 (100).
over Al2O3 with a mixture of dichloromethane–methanol
(30:1). Yield: 0.110 g (13%). Anal. found C 55.72, H 7.88, N
3.12%; C152H256N8NiO48S8 (3278.93) requires C 55.68, H
7.87, N 3.42%. IR (KBr cell): nmax/cmꢀ1 3040 (ArCH),
=
2980–2850 (CH2), 1600 (ArC C), 1520, 1450, 1410, 1380,
4-{2-[2-(2-Ethoxyethoxy)ethoxy]-1-[2-(2-ethoxyethoxy)eth-
oxy)methyl]ethylsulfanyl}phthalonitrile (8). 8 was prepared
according to the same procedure as described for 6 by starting
from with 4-nitrophthalonitrile (5; 0.866 g, 5 mmol), 3 (3.4 g,
10 mmol) and potassium carbonate (1.10 g, 7.97 mmol). The
light-brown waxy product was purified by column chromato-
graphy on Al2O3 using dichloromethane–methanol (50:1) as
the eluent Yield: 1.40 g (60%). The product is a light yellow
viscous oil at room temperature. Anal. found C 59.11, H 7.22,
N 5.95%; C23H34N2O6S2 (466.60) requires C 59.21, H 7.35,
N 6.00%. IR (KBr cell): nmax/cmꢀ1 3040 (ArCH), 2980–2940
1340, 1280, 1240, 1120–1080 (C–O–C), 960, 880, 780, 750,
710. MS (FAB): m/z (%) 3278 (98) [M þ 1]þ, 2971 (28)
[M ꢀ CH[CH2(OCH2CH2)2OC2H5]2)]þ, 2664 (20) [M ꢀ 2{CH
[CH2(OCH2CH2)2OC2H5]2}]þ, 2358 (15) [M ꢀ 3{CH[CH2-
(OCH2CH2)2OC2H5]2}]þ, 825 (19) [M ꢀ 4{CH[CH2(OCH2-
CH2)2OC2H5]2}]þ.
H2Pc (7b). A solution of 7 (0.85 g, 1.06 mmol) in dry
2-(dimethylamino)ethanol (1.8 ml) was refluxed under argon
atmosphere for 72 h and then the solvent was removed under
reduced pressure. The crude product was dissolved in dichloro-
methane and filtered. This mixture was passed through an
Al2O3 column using a mixture of 30:1 CH2Cl2–MeOH as elu-
ent. This product was further purified by preparative TLC
(silica gel) using a 20:1 CH2Cl2–MeOH solvent system. Yield:
0.100 g (12%). Anal. found C 56.16, H 8.07, N 3.12%;
=
=
(CH ), 2220 (C N), 1580 (ArC C), 1540, 1470, 1350, 1300,
=
2
1240, 1120–1100 (C–O–C), 940, 870, 840. MS (EI): m/z (%)
466.3 (10) [M]þ, 379.2 (35), 332.1 (20) [M ꢀ (OCH2CH2)2-
OC2H5)]þ, 306.2 (12), 233.1 (10), 218.1 (20), 205.1 (40), 200.1
(30) [M ꢀ 2(OCH2CH2)2OC2H5)]þ, 189.1 (35), 173.1 (40),
161.1 (38), 117.1 (100).
C
152H258N8O48S8(3222.26) requires C 56.66, H 8.07, N
3.48%. IR (KBr cell): nmax/cmꢀ1 3300 (NH), 3040 (ArCH),
Synthesis of phthalocyanines
=
2980–2850 (CH2), 1600 (ArC C), 1450, 1420, 1380, 1330,
NiPc (6a). 6 (0.64 g, 1.27 mmol), 1,8-diazabicyclo[5.4.0]-
undec-7-ene (DBU; 0.19 g, 1.27 mmol), anhydrous NiCl2 (0.21 g,
1.62 mmol) and dried 1-pentanol (4 ml) were refluxed with
stirring under argon atmosphere for 72 h. The 1-pentanol
was removed under reduced pressure and the crude green
product was purified by column chromatography (Al2O3 ,
CH2Cl2–methanol 30:1). The dark green waxy compound was
soluble in CH2Cl2 , CHCl3 , diethyl ether, methanol, etha-
nol, acetone, ethyl acetate. Yield: 0.140 g (21%). Anal. found
C 53.85, H 6.25, N 5.25%; C92Cl4H132N8NiO24S4 (2062.86)
requires C 53.57, H 6.45, N 5.43%. IR (KBr cell): nmax/cmꢀ1
1280, 1240, 1120–1080 (C–O–C), 950, 880, 750, 680. MS
(FAB): m/z (%) 3222 (100) [M þ 1]þ, 2884 (25) [M ꢀ
SCH[CH2(OCH2CH2)2OC2H5]2]þ, 2384 (15), 1714 (26), 1610
(90), 1381 (10) [M ꢀ 6{CH[CH2(OCH2CH2)2OC2H5]2}]þ,
1074 (12) [M ꢀ 7{CH[CH2(OCH2CH2)2OC2H5]2}]þ, 799 (20)
[M ꢀ 8{CH[CH2(OCH2CH2)2OC2H5]2}]þ.
NiPc (8a). A mixture of 8 (0.326, 0.7 mmol), DBU (0.16 ml,
1.1 mmol) and anhydrous NiCl2 (0.185 g, 1.14 mmol) in pen-
tanol (5 ml) was refluxed under argon atmosphere for 72 h.
The 1-pentanol was removed under reduced pressure and the
crude product was first purified by column chromatography
over Al2O3 with a mixture of CH2Cl2–MeOH (30:1). This pro-
duct was then purified with preparative TLC (silica gel) using
a 20:1 CH2Cl2–MeOH solvent system. Yield: 0.070 g (21%).
Anal found C 56.94, H 7.23, N 5.46%; C92H136N8NiO24S4
(1925.08) requires C 57.40, H 7.12, N 5.82%. IR (KBr cell):
=
=
3040 (ArCH), 2980–2850 (CH2), 1600 (ArC C), 1450,
1410, 1380, 1340, 1280, 1240, 1120–1080 (C–O–C), 960,
880, 780, 750, 700. MS (FAB): m/z (%) 2062.3 (75)
[M þ 1]þ, 1754.6 (20) [M ꢀ CH[CH2(OCH2CH2)2OC2H5]2]þ,
1447.4 (15) [M ꢀ 2{CH[CH2(OCH2CH2)2OC2H5]2}]þ, 1142.9
(17) [M ꢀ 3{CH[CH2(OCH2CH2)2OC2H5]2}]þ, 834.8 (78)
[M ꢀ 4{CH[CH2(OCH2CH2)2OC2H5]2}]þ.
n
max/cmꢀ1 3040 (ArCH), 2980–2850 (CH2), 1600 (ArC C),
1530, 1450, 1400, 1380, 1350, 1310, 1260, 1240, 1120–1080
(C–O–C), 930, 880, 810, 780, 750. MS (FAB): m/z (%)
1925 (100) [M þ 1]þ, 1618 (55) [M ꢀ CH[CH2(OCH2CH2)2-
OC2H5]2]þ, 1310 (17) [M ꢀ 2{CH[CH2(OCH2CH2)2OC2-
H5]2}]þ, 1003 (13) [M ꢀ 3{CH[CH2(OCH2CH2)2OC2H5]2}]þ,
695 (45) [M ꢀ 4{CH[CH2(OCH2CH2)2OC2H5]2}]þ.
H2Pc (6b). A mixture of 6 (1.2 g, 2.4 mmol) and DBU (0.186
g, 1.27 mmol) in dried 1-pentanol (8 ml) was refluxed under
argon atmosphere for 72 h. Evaporation of the solvent under
reduced pressure left a green product mixture. The crude pro-
duct was passed through an Al2O3 column using CH2Cl2–
methanol (20:1) as eluent. This product was further purified
by preparative thin layer chromatography (TLC) using a
30:1 CH2Cl2–MeOH solvent system. This compound has a
similar solubility as 6a. Yield: 0.120 g (10%). Anal. found C
55.18, H 6.81, N 5.36%; C92Cl4H134N8O24S4 (2006.18) requires
C 55,08, H 6.73, N 5.59%. IR (KBr cell): nmax/cmꢀ1 3300
H2Pc (8b). A solution of 8 (0.54 g, 1.16 mmol) in dry
2-(dimethylamino)ethanol (2 ml) was refluxed under argon
atmosphere for 48 h and then the solvent was removed under
reduced pressure. The crude product was dissolved in dichlor-
omethane and filtered. The mixture was passed through an
Al2O3 column using a CH2Cl2–MeOH (30:1) solvent system.
This product was further purified with preparative TLC (silica
gel) using a 20:1 CH2Cl2–MeOH solvent system. Yield: 0.155 g
(29%). Anal found C 59.21, H 7.26, N 6.04%; C92H138N8O24S4
(1868.40) requires C 59.14, H 7.45, N 6.00%. IR (KBr cell):
=
(NH), 3040 (ArCH), 2980–2850 (CH2), 1600 (ArC C), 1450,
1420, 1380, 1350, 1280, 1240, 1120–1080 (C–O–C), 1020,
930, 880, 800, 750, 680. MS (FAB): m/z (%) 2006.2 (55)
[M þ 1]þ, 1698.3 (17) [M ꢀ CH[CH2(OCH2CH2)2OC2H5]2]þ,
1391 (6) [M ꢀ 2{CH[CH2(OCH2CH2)2OC2H5]2}]þ, 1085 (8)
[M ꢀ 3{CH[CH2(OCH2CH2)2OC2H5]2}]þ, 778.9 (35) [M ꢀ 4
{CH[CH2(OCH2CH2)2OC2H5]2}]þ, 329.2(70).
n
max/cmꢀ1 3300 (NH), 3040 (ArCH), 2980–2850 (CH2), 1600
=
(ArC C), 1450, 1420, 1400, 1350, 1320, 1280, 1260, 1120–
1080 (C–O–C), 1020, 930, 880, 800, 750. MS (FAB): m/z (%)
1868 (42) [M þ 1]þ, 1561 (13) [M ꢀ CH[CH2(OCH2CH2)2-
OC2H5]2)]þ, 1254 (10) [M ꢀ 2{CH[CH2(OCH2CH2)2OC2-
H5]2}]þ, 948 (13) [M ꢀ 3{CH[CH2(OCH2CH2)2OC2H5]2}]þ,
641 (35) [M ꢀ 4{CH[CH2(OCH2CH2)2OC2H5]2}]þ.
NiPc (7a). A mixture of 7 (0.80 g, 1 mmol), anhydrous NiCl2
(0.13 g, 1 mmol) and anhydrous quinoline (3 ml) was heated
and stirred at 180–185 ꢁC for 48 h under argon atmosphere.
After cooling to room temperature, the reaction mixture was
treated with n-hexane and a waxy precipitate was separated.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 9 3 – 6 9 9
695

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base-catalyzed nucleophilic aromatic displacement.27,33,34 The
Results and discussion
same route was applied to prepare the monosubstituted dini-
trile derivative 8 from 3 and 5. Similarly, under the same con-
ditions 4 resulted in the expected compounds 6 and 7 by using
an excess amount and a large excess of 3, respectively. The
reactions were carried out in dimethyl sulfoxide (DMSO) at
50 ꢁC with potassium carbonate, which was used as the base.
The preparation of pc derivatives from the aromatic nitriles
required different reaction conditions.6 For various substituted
dinitriles, the reaction in the presence of strong non-nucleophi-
lic bases such as 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) or
1,5-diazabicyclo[4.3.0]non-5-ene (DBN), either in 1-pentanol
or in bulk with yields of phthalocyanines up to 90%, is the
most efficient in comparison to other methods.27a,36 In addi-
tion, these reactions are easy to perform, work under relatively
mild conditions and yield pure pcs. Therefore, the tetra-substi-
tuted metal-free pc derivatives 6b and 8b were obtained
directly from the reaction of dicyano compounds 6 and 8 in
1-pentanol at reflux temperature in the presence of DBU
(Fig. 1). Also, cyclotetramerization of dinitrile derivatives
Synthesis
Phthalocyanines (6a,b, 7a,b, 8a,b) were prepared by the route
shown in Scheme 1. This route is based on the thiol compound
3
and 1,2-dichloro-4,5-dicyanobenzene (4). Commercially
available 4,5-dichlorophthalic acid was converted into 4 as
described previously.27b Attempts to prepare the thiol com-
pound 3 from 1,3-di[2-(2-ethoxyethoxy)ethoxy]-2-propanol
(1) according to the usual methods were unsuccessful. Instead,
this conversion was achieved through the tosyl derivative 2 in
two steps according to the reported procedure.34a,35 Tosylation
of the hydroxy group was carried out in dry pyridine at room
temperature with p-toluenesulfonyl chloride. Conversion of
the tosyl compound 2 into the thiol derivative 3 was accom-
plished by boiling dry ethanol in the presence of thiourea for
48 h. In these reactions, the long reaction times were necessary
for good yields.
4-Nitro-1,2-dicyanobenzene (5) was also used recently to
prepare 4-monosubstituted phthalonitrile derivatives, through
Scheme 1 (i) p-MeC6H4SO2Cl, pyridine, room temperature; (ii) a: thiourea, EtOH, reflux, 48 h; b: NaOH/H2O, 3 h reflux in Ar atmosphere; (iii)
DMSO, K2CO3 , 50 ꢁC, 48 h.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 9 3 – 6 9 9
696
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4

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Table 1 Electronic spectra detail of phthalocyanines in chloroform
max/nm (e/104 dm3 molꢀ1 cmꢀ1
6 and 8 in the presence of anhydrous NiCl2 and DBU in 1-pen-
tanol gave the octa-substituted nickel(II) pcs 6a and 8a, respec-
tively. The reaction of disubstituted dinitrile derivative 7 in
2-(dimethylamino)ethanol yields the octa-substituted metal-
free pc 7b. In the case of octa-substituted Nipc 7a, cyclomeri-
zation was carried out in quinoline in the presence of anhy-
drous NiCl2 salt. We expect that 6a,b, and 8a,b were
prepared as a statistical mixture of four regioisomers owing
to the various possible positions of the oligo(ethyleneoxy)
side-chains relative to one another. From their molecular sym-
metry of D4h , C4h , C2v and Cs each isomer would be prepared
with a relative distribution of 1:1:2:4, respectively.37 No
attempt was made to separate the isomers of 6a, 6b, 8a and 8b.
The thia-bridged tetra- and octa-poly(oxyethylene)-substi-
tuted pcs (6a,b, 7a,b, 8a,b) were purified in each case by col-
umn chromatography (Al2O3) and preparative thin-layer
chromatography (TLC) using a mixed solvent system of
dichloromethane–methanol as eluent. The intense green waxy
products are very soluble in polar and apolar solvents such
as chloroform, benzene, diethyl ether, carbon tetrachloride,
N,N-dimethylformamide, ethanol and acetone. They could
thus be thoroughly investigated by 1H and 13C NMR. In addi-
tion to elemental analysis results, mass spectra (see Experimen-
tal ) of the new organic intermediate compounds and pcs
obtained by the EI and FAB techniques show relatively intense
molecular ion peaks. Another common point in all pcs deriva-
tive mass spectra is the clear appearance of the fragmentation
ion peaks corresponding to the stepwise loss of poly(oxyethy-
lene) {CH[CH2(OCH2CH2)2OC2H5]2} side chains. NMR
investigation of all compounds have provide the characteristic
chemical shifts for the structures as expected (Tables S1 and
S2, Electronic supplementary information).
l
)
Compound
Soret band region
Q band region
6a
6b
261.5 (5.22), 312.5 (9.46),
402.5 (2.56)
619.5 (4.16), 657.5,a
688.5 (21.70)
620.5 (3.28), 651.5,a
682.5 (13.58),
715.5(15.94)
630.5 (0.92), 669.5,a
702.0 (20.68)
635.5 (2.68), 673.5,a
700.5 (11.16),
730 (12.60)
615.0 (4.10), 650.0,a
682.0 (22.54)
616.0 (3.24), 651.0,a
678.0 (13.84),
711.5 (16.42)
238.5 (3.80), 308.0 (5.28),
351.5 (7.84)
7a
7b
272.0 (6.12), 322.5 (10.06),
422.0 (3.22)
266.0 (3.68), 359.5 (5.64),
432.0 (2.78)
8a
8b
260.0 (4.94), 303.0 (8.26),
392.0 (2.60)
297.0 (5.66), 345.5 (7.68),
411.5 (2.96)
a
Shoulder.
compared with unsubstituted, alkyl- or alkoxy-substituted
derivatives.
For phthalocyanines, the aggregation behaviour in solution
is a good indication of interaction between the aromatic
macrocycles. Aggregation is easily detected from optical
absorption studies. Any increase in concentration results in
aggregation of phthalocyanine molecules, which is accompa-
nied by a blue shift of the Q band with some decrease in inten-
sity.3 It has been concluded that aggregation is enhanced by
solvent polarity and the presence of aliphatic side chains.9,24
This has been indeed observed with octa-substituted derivatives
[Fig. 2(A)].
The optical absorption spectra of compounds 6a,b, 7a,b,
8a,b are dependent on the solvent used. Aggregation is not
detectable in tetrahydrofuran or chloroform. The tendency
to form aggregates increases in the order: tetrahydrofuran
< chloroform < dimethylformamide < carbon tetrachloride <
ethanol < methanol for octa-substituted Ni(II) pc (7a).
Interestingly, in methanol, the peak corresponding to mono-
mer is still present in the absorption spectrum [Fig. 2(B)]
whereas it disappeared for the octa-substituted metal-free pc
derivative (7b). Similar spectra have been obtained in the case
of both tetra-substituted phthalocyanine derivatives 6a,b
and 8a,b.
For substances 6a,b, 7a,b, 8a,b the typical absorption spec-
tra of phthalocyanines were observed,5 showing absorption
bands in the Soret band region of 300–400 nm and Q band
transitions at 600–700 nm (Table 1). The metal-free phthalo-
cyanines 6b, 7b and 8b give doublet Q band as a result of
the D2h symmetry. The nickel(II) phthalocyanines 6a, 7a and
8a exhibit intense Q bands around 700 nm with a relatively
sharp absorption peak and almost no shoulder on the higher
energy side, which would correspond to aggregated species.
For all the phthalocyanines the effect of thia-substitution was
a shift of these intense Q bands to higher wavelengths when
Fig. 2 (A) Visible absorption spectra of the octa-substituted metal-
free pc derivative 7b in (a) benzene, (b) MeOH. (B) Visible absorption
spectra of the octa-substituted Ni(II) pc derivative 7a in (a) tetrahydro-
furan, (b) chloroform, (c) carbon tetrachloride, (d) MeOH.
Fig. 1 Chemical structure of the tetra- and octa-substituted phthalo-
cyanine derivatives.
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 9 3 – 6 9 9
697

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textures of samples, preferentially fan- or flower-like textures
Characterization of the mesophase
(Fig. 3, Figures S1–S3, Electronic supplementary information)
of the mesophases were obtained by slow cooling from the
isotropic melt.
Table 2 lists the phase transition temperatures established by
DSC and polarizing microscopic observations for the tetra-
substituted pc derivatives (6,b, 8a,b). All mesophases were
found to be very viscous at lower temperatures. As a conse-
quence, not all DSC peaks could be confirmed optically. As
can be seen from Table 3, all tetra-substituted pc derivatives
show only one mesophase, Colh . However, the octa-substi-
tuted pc derivatives (7a,b) exhibit no mesomorphism and are
viscous oils at room temperature. The textures observed by
polarizing optical microscopy for the compounds studied are
very similar to those described in refs. 17 and 34 Excellent
The mesophases were identified by microscopic observation
and X-ray diffraction measurements at 30 ꢁC. The X-ray data
are summarized in Table 3. Powder diffraction patterns of
6a,b, 8a and 8b contain the typical reflections of a columnar
mesophase of substituted pcs.12 Tetra-substituted pcs gave five
p
sharp peaks whose spacings are in a ratio of 1 : 1/ 3 : 1/2 : 1/
p
7 : 1/3 : 1 in the low angle region, so that each of the meso-
phases could be established as a discotic hexagonal columnar
(Colh) mesophase. In the wide angle region the compounds
6a,b, 8a and 8b show a diffuse halo at 4.2, 4.3, 4.35 and 4.26
A respectively, which is compatible with the disorder of paraf-
˚
finic tails in the side chains. An additional reflection at 3.4 A is
˚
Table
2
Phase transition temperatures and enthalpies for the
tetra-substituted phthalocyanine derivatives as determined by DSCa
also observed, which may be assigned to the packing of macro-
cylic subunits in the columns. 6a,b, 8a and 8b show a diffuse
reflection, indicating that there is no long-range translational
order of the molecules along the axis of stacks, which is asso-
ciated with the discotic hexagonal disordered Colhd mesophase.34
T
Col h ! I/ꢁC (DH/kJ molꢀ1
)
Compound R2
M
Heating Cooling
6a
6b
7a
Cl
Cl
Ni 222.2 (1.330)
2H 160.0 (1.223)
216.6 (1.048)
156.7 (1.130)
–
–SCH[CH2O(CH2 Ni Liquid
CH2O)2C2H5]2
Conclusion
7b
–SCH[CH2O(CH2 2H Liquid
CH2O)2C2H5]2
–
Phthalocyanines showing mesogenic properties that contain
both sulfur and oxygen donors are rather rare. In the present
work, the synthesis of new tetra- and octa-thia(polyoxyethy-
lene)-substituted Ni(II) and metal-free phthalocyanines and
their characterization by standard methods (1H and 13C-
NMR, elemental analysis, IR, UV/vis and mass spectrometry)
was described. The compounds prepared are soluble in most
solvents ranging from carbon tetrachloride to methanol.
Tetra-substituted Ni(II) and metal-free phthalocyanine deriva-
tives are stable over a wide temperature range and exhibit
a disordered hexagonal columnar (Colhd) structure. However,
8a
8b
H
H
Ni 230.5 (0.906)
2H 198.0 (0.957)
220.0 (0.614)
183.3 (0.579)
a
Heating and cooling rates: 10 ꢁC minꢀ1, heating range: 10–300 ꢁC.
Table 3 X-Ray diffraction data of the tetra-substituted phthalo-
cyanine derivatives
Observed
Theoretical Lattice
˚
Miller
Compound spacing/A spacing/A constant/A Ratio indices
˚
˚
6a
24.44
13.97
12.19
9.19
24.44
14.10
12.21
9.23
8.14
6.70
–
1
3
4
7
9
(100)
(110)
(200)
(210)
(300)
(311)
p
p
p
p
a ¼ 27.94
a
Colhd
8.02
6.69
p
12
4.19
3.59
–
6b
24.35
13.62
11.93
9.41
24.35
14.06
12.17
9.20
8.11
7.03
–
1
(100)
(110)
(200)
(210)
(300)
(311)
p
3
4
7
9
p
a ¼ 28.12
p
p
a
Colhd
8.01
7.11
p
12
4.30
3.57
–
8a
8b
22.76
13.02
11.40
8.71
22.76
13.14
11.38
8.60
–
1
(100)
(110)
(200)
(210)
p
a ¼ 26.28
3
4
7
p
a
Colhd
p
4.35
3.61
–
25.57
14.18
12.85
9.71
25.57
14.76
12.80
9.66
8.52
7.38
7.03
–
1
3
4
7
9
(100)
(110)
(200)
(210)
(300)
(311)
p
p
p
p
a ¼ 29.53
a
8.54
7.49
Colhd
p
12
7.06
4.26
3.41
–
a
At 25 ꢁC.
Fig. 3 Optical texture of 6b observed at 25 ꢁC (magnification ꢂ 16).
T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
698
N e w . J . C h e m . , 2 0 0 4 , 2 8 , 6 9 3 – 6 9 9

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1995, 1817; (c) J. M. Kroon, R. B. M. Koehorst, M. von Dijk,
G. M. Sanders and E. J. R. Sudho¨lter, J. Mater. Chem., 1997,
7, 615.
octa-substituted pc derivatives (7a,b) exhibit no mesomorph-
ism and are viscous oils at room temperature. Comparing
the mesophases of the branched thioether pc derivatives and
their analogous oxoether derivatives, a Colh mesophase could
be seen over a wide temperature region for the thioether pc
derivatives. Future investigations will focus on the chemical
sensor properties of these mesogenic compounds.
18 M. J. Cook, M. F. Daniel, K. J. Harrison, N. B. McKeown and
A. J. Thompson, J. Chem. Soc., Chem. Commun., 1987, 1086.
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McKeown, J. Chem. Soc., Perkin Trans. 1, 1991, 3053.
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22 C. F. von Nostrum, S. J. Picken, A. J. Schouten and R. J. M.
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Acknowledgements
The authors thank Prof. Jacques Simon for his fruitful
discussions.
24 (a) O. E. Sielcken, M. M. von Tilborg, M. F. M. Roks, R.
Hendriks, W. Drenth and R. J. M. Nolte, J. Am Chem. Soc.,
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T h i s j o u r n a l i s Q T h e R o y a l S o c i e t y o f C h e m i s t r y a n d t h e
C e n t r e N a t i o n a l d e l a R e c h e r c h e S c i e n t i f i q u e 2 0 0 4
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699