Phthalocyanine synthesis in ionic liquids: Preparation of differently substituted phthalocyanines in tetrabutylammonium bromide

Article abstract of DOI:10.1055/s-2005-861855

A series of alkylthio, alkoxy, and phenoxy phthalonitriles have been prepared by nucleophilic substitution reactions on suitable phthalonitrile precursors in molten tetrabutylammonium bromide. This readily available and inexpensive ionic liquid can also b

Full text of DOI:10.1055/s-2005-861855

PAPER
1141
Phthalocyanine Synthesis in Ionic Liquids: Preparation of Differently
Substituted Phthalocyanines in Tetrabutylammonium Bromide
Phthalocyanin
u
e
S
ynthesis
i
i
Ionic
-
L
iquidsChi Lo, Diana Y. Y. Cheng, Dennis K. P. Ng*
Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong, P. R. China
Fax +85226035057; E-mail: dkpn@cuhk.edu.hk
Received 24 November 2004; revised 4 January 2005
For nucleophilic substitution reactions, they can enhance
the reactivity of the nucleophiles, reducing the yield of the
side products formed.11 On this basis, we extended the
present studies using the inexpensive ionic liquid tetrabu-
Abstract: A series of alkylthio, alkoxy, and phenoxy phthaloni-
triles have been prepared by nucleophilic substitution reactions on
suitable phthalonitrile precursors in molten tetrabutylammonium
bromide. This readily available and inexpensive ionic liquid can
also be used as a medium for the cyclization of these dinitriles giv- tylammonium bromide as a reaction medium to prepare a
ing the corresponding substituted phthalocyanines.
series of substituted phthalonitriles. The preparation was
mainly based on nucleophilic aromatic substitution reac-
tions of common nitro-, chloro-, and fluoro-phthalonitrile
precursors. We first examined the reactions with thiols,
which have a high nucleophilicity. As shown in Table 1,
treatment of 4-nitrophthalonitrile (1a) with one equivalent
of 1-octanethiol or 1-dodecanethiol in one equivalent of
tetrabutylammonium bromide at 90 °C gives the corre-
sponding substituted products 2a and 2b in ca. 30% yield
(Table 1, entries 1 and 3). Addition of two equivalents of
thiols and increasing the temperature to 100 °C increase
the yield up to 79% (Table 1, entries 2, 4, and 5). 3-Nitro-
phthalonitrile (1b) reacts with these thiols in a similar
manner giving the corresponding 3-alkylthiophthaloni-
triles 2c and 2d in excellent yields (Table 1, entries 6 and
7). These reactions can be performed in gram scale with
comparable yields and, as expected, the ionic liquid can
be recycled (see Experimental Section). Another remark-
able feature of these reactions is that base such as K2CO3
is not needed. This is in contrast to the analogous reac-
tions performed in organic solvents.12 It seems that the
ionic liquid medium has an additional function to enhance
the nucleophilicity of the thiols.13 Interestingly, when four
equivalents of these thiols was used, the reactions with 1a
gave a substantial amount of the metal-free tetrakis(al-
kylthio)phthalocyanines 3a (11%) and 3b (23%)
(Scheme 1). Similar reactions with 1b, however, only led
to trace amounts of metal-free phthalocyanines with a
substantial amount of substituted phthalonitriles 2c and
2d as detected by TLC analysis. Although the role of the
excess amounts of thiols in promoting the cyclization of
2a and 2b is not clear at this stage, this one-pot synthesis
of tetrakis(alkylthio)phthalocyanines from the commer-
cially available 4-nitrophthalonitrile (1a) is worth noting.
Key words: phthalonitriles, phthalocyanines, ionic liquids, nucleo-
philic substitution reactions
Phthalocyanines represent an important class of function-
al materials.1 Owing to the many desirable physical and
chemical characteristics, these highly conjugated com-
pounds have found practical applications in various dis-
ciplines such as molecular opto-electronics,2 catalysis,3
and photodynamic therapy,4 in addition to their traditional
use as industrial dyes and pigments.5 In view of these im-
portant applications, there is a need to develop efficient
synthetic methods for differently substituted phthalo-
cyanines, in particular those methods which are easy to
operate and environmentally benign if one considers the
large-scale preparation of these materials. Substituents on
the peripheral positions are usually introduced through
nucleophilic substitution of common phthalonitrile pre-
cursors such as 3- (or 4)-nitrophthalonitrile, 4,5-dichlo-
rophthalonitrile, and 2,3-dicyanohydroquinone.6 These
reactions together with the subsequent cyclization are
usually performed in organic solvents. Solid-state synthe-
ses, which can be promoted by microwave irradiation,7
are not common for substituted phthalocyanines.8 Recent-
ly, ionic liquids have emerged as superior reaction media
in organic synthesis because of their low vapor pressure,
high thermal stability, high ionic conductivity, and ease of
recovery.9 Although a vast number of reactions can now
be performed in these media, to our knowledge, prepara-
tion of phthalocyanines in ionic liquids has not been re-
ported so far.10 We describe herein the use of
tetrabutylammonium bromide as a low-cost ionic liquid
medium for the preparation of differently substituted ph-
thalonitriles and their corresponding metal-free and met-
allophthalocyanines.
Apart from the monosubstitution, di- and tetrasubstitution
reactions were also performed using 4,5-dichlorophtha-
lonitrile (1c) and tetrafluorophthalonitrile (1d) as the
starting materials. The reactions of these dinitriles with 1-
octanethiol gave the desired di- and tetrathiolated dini-
triles in moderate yields (Table 1, entries 8 and 9). The re-
action of 1c, however, required the addition of two
equivalents of K2CO3.
Owing to the ionic nature, ionic liquids are particularly
useful for reactions involving charged reactive species.9
SYNTHESIS 2005, No. 7, pp 1141–1147
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x
.
x
x
.2
0
0
5
Advanced online publication: 10.03.2005
DOI: 10.1055/s-2005-861855; Art ID: F17104SS
© Georg Thieme Verlag Stuttgart · New York

1142
P.-C. Lo et al.
PAPER
phthalonitrile 2g or 2h, respectively. The yield increased
upon addition of a larger amount of 1-octanol and K2CO3
(Table 2, entries 1–4). Similarly, treatment of 4,5-dichlo-
rophthalonitrile (1c) with phenol and K2CO3 in tetrabutyl-
ammonium bromide also gave the disubstituted product 2i
in satisfactory yield (Table 2, entry 5). 2,3-Dicyanohydro-
quinone (1e) is a very common precursor for 3,6-dialk-
oxyphthalonitriles, which can be prepared by typical
nucleophilic substitution reactions. As demonstrated by
the reaction of 1e and 1-bromoheptane (Table 2, entry 6),
these reactions could also be performed in this ionic liquid
effectively.
Scheme 1
The results summarized in Tables 1 and 2 show that a
wide range of substituted phthalonitriles can be prepared
in molten tetrabutylammonium bromide. It is worth not-
ing that these nucleophilic substitution reactions are usu-
ally performed in dipolar aprotic solvents such as N,N-
dimethylformamide and dimethyl sulfoxide.12,14 The use
The nucleophilic aromatic substitution reactions of these
phthalonitrile precursors with alcohols could also be per-
formed in tetrabutylammonium bromide in the presence
of K2CO3. Treatment of 3- or 4-nitrophthalonitrile (1a or
1b) with 1-octanol gave the corresponding octyloxy-
Table 1 Preparation of Alkylthio Phthalonitriles in Tetrabutylammonium Bromidea
Entry
1
Precursor
Thiol
Thiol (equiv)
1
Temp (°C)
90
Product
Yield (%)
29
C8H17SH
1a
1a
2a
2a
2
3
C8H17SH
C12H25SH
2
1
100
90
77
30
1a
2b
2b
4
5
6
1a
1a
C12H25SH
C12H25SH
C8H17SH
1
2
2
100
100
100
51
79
91
2b
1b
1b
2c
7
C12H25SH
2
100
93
2d
2e
8b
C8H17SH
C8H17SH
5
8
100
100
50
55
1c
9
1d
2f
a All reactions were performed in 1 equiv of Bu4NBr in the absence of K2CO3 for 16 h unless otherwise stated.
b In the presence of 2 equiv of K2CO3.
Synthesis 2005, No. 7, 1141–1147 © Thieme Stuttgart · New York

PAPER
Phthalocyanine Synthesis in Ionic Liquids
1143
Table 2 Preparation of Alkoxy and Phenoxy Phthalonitriles in Tetrabutylammonium Bromidea
Entry
1
Precursor
Alcohol/Alkyl Halide Equiv of Alcohol/ Equiv of K2CO3
Alkyl Halide
Product
Yield (%)
1a
C8H17OH
1.5
6
19
2g
2g
2
3
1a
1b
C8H17OH
C8H17OH
4
8
6
39
20
1.5
2h
2h
4
1b
1c
C8H17OH
C6H5OH
4
3
8
72
39
5b
15
2i
2j
6c
C7H15Br
3
8
86
1e
a All reactions were performed in 1 equiv of Bu4NBr at 100 °C for 24 h unless otherwise stated.
b Using 10 equiv of Bu4NBr.
c Using 2 equiv of Bu4NBr at 120 °C.
of this commercially available ionic liquid, which can be tuted phthalonitriles from Table 1 were chosen arbitrarily
used as received, can greatly simplify the procedure in- to react with DBU and various metal salts including
cluding a prior solvent treatment and subsequent removal Zn(OAc)2·2H2O, CoCl2, and Ni(OAc)2·4H2O in molten
of the high-boiling solvents. The solvent-free condition tetrabutylammonium bromide. The reactions gave the
and the recyclable property of the medium make these re- corresponding metallophthalocyanines in moderate
actions attractive as an environmentally benign method to yields. The results are summarized in Table 4.
prepare these useful phthalocyanine precursors.
In summary, we have described a convenient and general
With a range of substituted dinitriles, we then examined procedure for the preparation of differently substituted
the feasibility of using this medium to perform their cy- phthalonitriles and the corresponding phthalocyanines.
clization reactions. As shown in Table 3, treatment of var- The method employs the inexpensive tetrabutylammoni-
ious mono- and disubstituted phthalonitriles with 1,8- um bromide as the reaction medium instead of the tradi-
diazabicyclo[5.4.0]undec-7-ene (DBU) in molten tetrabu- tional organic solvents.
tylammonium bromide (130 °C) gives the corresponding
metal-free phthalocyanines. The yields are comparable
with those obtained in classical organic solvent me-
dia.14b,15 Again, both the set-up and work-up procedures
are simplified because of the unique nature of this ionic
liquid medium. These reaction conditions, however, could
not lead to the formation of desired phthalocyanines from
the dinitriles 2i and 2j. Some unidentified products were
formed in these reactions.
All reactions were carried out under N2. Phthalonitriles 1c,14b 2k,16
and 2m14d were prepared by literature procedures. Bu4NBr (98%,
Acros) and other reagents were used as received. Virtually all the
phthalonitriles 2 and phthalocyanines 3 and 4 reported herein have
been described previously either in literature or in patent.17
1H NMR spectra were recorded on a Bruker DPX 300 spectrometer
(300 MHz) in CDCl3 unless otherwise stated. Spectra were refer-
enced internally by using the residual solvent resonance (d = 7.26)
relative to SiMe4. EI and FAB mass spectra were measured on a
Thermo Finnigan MAT 95 XL mass spectrometer. Matrix-assisted
laser desorption/ionization time-of-flight (MALDI-TOF) spectra
were obtained on a Bruker bench TOF mass spectrometer equipped
with a standard UV-laser desorption source, using a-cyano-4-hy-
Apart from the metal-free phthalocyanines, metallated de-
rivatives could also be prepared in this medium with the
addition of the corresponding metal salts. Several substi-
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1144
P.-C. Lo et al.
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Table 3 Preparation of Metal-Free Phthalocyanines in Tetrabutylammonium Bromide
Entry
Phthalonitrile
R1
R2
R3
R4
H
H
H
H
H
H
H
Phthalocyanine Yield (%)
1
2
3
4
5
6
7
2a
2b
2c
H
SC8H17
SC12H25
H
H
3a
3b
3c
3d
3e
3f
20
20
13
50
50
20
40
H
H
SC8H17
H
2k
2e
H
H
H
SC4H9
SC8H17
OC8H17
H
SC4H9
SC8H17
H
2g
2m
H
3g
Table 4 Preparation of Metallophthalocyanines in Tetrabutylammonium Bromide
Entry
Phthalonitrile
R1
R2
M
Phthalocyanine
Yield (%)
1
2
3
4
5
2b
2k
2k
2e
2e
SC12H25
SC4H9
SC4H9
SC8H17
SC8H17
H
Zn
Zn
Co
Zn
Ni
4a
4b
4c
4d
4e
31
67
33
20
50
SC4H9
SC4H9
SC8H17
SC8H17
droxycinnamic acid as matrix. UV-Vis spectra were taken on a Cary
5G UV-Vis-NIR spectrophotometer.
were extracted with Et2O (3 × 25 mL) and the ionic liquid could be
recovered by filtration and re-used after washing extensively with
Et2O. The combined Et2O extracts were rotary-evaporated and the
crude products were purified either by column chromatography or
recrystallization. A larger quantity of 1b (1 g) reacted with 1-oc-
tanethiol giving 2c in 82% yield, while 1c (1 g) reacted with phenol
affording 2i in 37% yield.
Phthalonitriles 2; General Procedure
According to the conditions described in Tables 1 and 2, phthaloni-
triles 1a–e (500 mg) were treated with thiols, alcohols, or 1-bromo-
heptane (and K2CO3) in molten Bu4NBr. After cooling, the mixtures
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Phthalocyanine Synthesis in Ionic Liquids
1145
4-Octylthiophthalonitrile (2a)12b
MS (EI): m/z (%) = 331 (100), 312 (16, [M+]), 195 (41), 77 (39).
1H NMR: d = 7.63 (d, J = 8.4 Hz, 1 H, ArH), 7.54 (d, J = 1.8 Hz, 1
H, ArH), 7.48 (dd, J = 1.8, 8.4 Hz, 1 H, ArH), 3.00 (t, J = 7.2 Hz, 2
H, SCH2), 1.72 (quintet, J = 7.2 Hz, 2 H, CH2), 1.40–1.52 (m, 2 H,
CH2), 1.26–1.38 (m, 8 H, CH2), 0.89 (t, J = 6.9 Hz, 3 H, CH3).
3,6-Bis(heptyloxy)phthalonitrile (2j)17h
1H NMR: d = 7.14 (s, 2 H, ArH), 4.04 (t, J = 6.3 Hz, 4 H, OCH2),
1.82 (quintet, J = 6.3 Hz, 4 H, CH2), 1.40–1.50 (m, 4 H, CH2), 1.26–
1.36 (m, 12 H, CH2), 0.89 (t, J = 6.9 Hz, 6 H, CH3).
MS (EI): m/z (%) = 272 (21, [M+]), 178 (44), 145 (39), 91 (51), 71
(86), 57 (100).
MS (EI): m/z (%) = 356 (8, [M+]), 160 (92), 98 (83), 57 (100).
HRMS (EI): m/z calcd for C16H20N2S: 272.1342; found: 272.1341.
HRMS (EI): m/z calcd for C22H32N2O2: 356.2458; found: 356.2451.
4-Dodecylthiophthalonitrile (2b)12a
Phthalocyanines 3 and 4; General Procedure
1H NMR: d = 7.63 (d, J = 8.4 Hz, 1 H, ArH), 7.54 (d, J = 2.1 Hz, 1
H, ArH), 7.48 (dd, J = 2.1, 8.4 Hz, 1 H, ArH), 3.00 (t, J = 7.5 Hz, 2
H, SCH2), 1.71 (quintet, J = 7.5 Hz, 2 H, CH2), 1.40–1.48 (m, 2 H,
CH2), 1.21–1.35 (m, 16 H, CH2), 0.88 (t, J = 6.9 Hz, 3 H, CH3).
A mixture of phthalonitrile 2 (100 mg) [and MXn (0.4 equiv) (for
the preparation of 4)] in Bu4NBr (2 equiv) was heated to 90 °C, then
a few drops of DBU (2–4 equiv) were added. The mixture was heat-
ed overnight at 130 °C to give a deep green solution. After a brief
cooling, the mixture was mixed with EtOH–H2O (1:1, 20 mL) and
filtered. The crude product was then purified by column chromatog-
raphy. The nickel phthalocyanine 4e was unstable in EtOH–H2O.
The reaction mixture was loaded directly onto a silica gel column
for purification (Tables 3 and 4).
MS (EI): m/z (%) = 328 (91, [M+]), 149 (71), 69 (82), 57 (100).
HRMS (EI): m/z calcd for C20H28N2S: 328.1968; found: 328.1961.
3-Octylthiophthalonitrile (2c)17c
1H NMR: d = 7.52–7.63 (m, 3 H, ArH), 3.05 (t, J = 7.5 Hz, 2 H,
SCH2), 1.71 (quintet, J = 7.5 Hz, 2 H, CH2), 1.41–1.50 (m, 2 H,
CH2), 1.22–1.32 (m, 8 H, CH2), 0.88 (t, J = 6.9 Hz, 3 H, CH3).
2(3),9(10),16(17),23(24)-Tetrakis(octylthio)phthalocyanine
(3a)17i
1H NMR: d = 6.93–7.57 (m, 12 H, PcH), 3.04–3.23 (m, 8 H, SCH2),
1.89–1.98 (m, 8 H, CH2), 1.60–1.72 (m, 8 H, CH2), 1.35–1.52 (m,
32 H, CH2), 0.98–1.02 (m, 12 H, CH3), –6.37 (br s, 2 H, NH).
MS (EI): m/z = 272 (33, [M+]), 160 (79), 71 (83), 57 (100).
HRMS (EI): m/z calcd for C16H20N2S: 272.1342; found: 272.1337.
3-Dodecylthiophthalonitrile (2d)17d
MS (MALDI-TOF): an isotopic cluster peaking at m/z = 1090.17
(calcd for M+: 1090.55).
1H NMR: d = 7.52–7.60 (m, 3 H, ArH), 3.05 (t, J = 7.2 Hz, 2 H,
SCH2), 1.71 (quintet, J = 7.2 Hz, 2 H, CH2), 1.41–1.50 (m, 2 H,
CH2), 1.20–1.32 (m, 16 H, CH2), 0.88 (t, J = 6.9 Hz, 3 H, CH3).
UV-Vis (CHCl3): lmax = 337, 602, 633, 663, 699 nm.
MS (EI): m/z (%) = 328 (31, [M+]), 149 (79), 69 (77), 57 (100).
2(3),9(10),16(17),23(24)-Tetrakis(dodecylthio)phthalocyanine
(3b)12a
HRMS (EI): m/z calcd for C20H28N2S: 328.1968; found: 328.1970.
1H NMR: d = 7.21–7.90 (m, 12 H, PcH), 3.18–3.34 (m, 8 H, SCH2),
1.92–2.10 (m, 8 H, CH2), 1.68–1.86 (m, 8 H, CH2), 1.20–1.54 (m,
64 H, CH2), 0.82–0.96 (m, 12 H, CH3).
4,5-Bis(octylthio)phthalonitrile (2e)12b
1H NMR: d = 7.40 (s, 2 H, ArH), 3.00 (t, J = 7.5 Hz, 4 H, SCH2),
1.74 (quintet, J = 7.5 Hz, 4 H, CH2), 1.41–1.52 (m, 4 H, CH2), 1.23–
1.34 (m, 16 H, CH2), 0.88 (t, J = 7.2 Hz, 6 H, CH3).
MS (MALDI-TOF): an isotopic cluster peaking at m/z = 1314.42
(calcd for M+: 1314.80).
MS (EI): m/z (%) = 416 (22, [M+]), 304 (37), 149 (62), 69 (100).
UV-Vis (CHCl3): lmax = 344, 425, 617, 648, 683, 715 nm.
HRMS (EI): m/z calcd for C24H36N2S2: 416.2314; found: 416.2311.
1(4),8(11),15(18),22(25)-Tetrakis(octylthio)phthalocyanine
(3c)17c
Tetrakis(octylthio)phthalonitrile (2f)17e
1H NMR: d = 3.07 (t, J = 7.5 Hz, 4 H, SCH2), 3.02 (t, J = 7.5 Hz, 4
H, SCH2), 1.20–1.60 (m, 48 H, CH2), 0.86 (t, J = 6.6 Hz, 12 H,
CH3).
1H NMR: d = 8.10–8.55 (m, 4 H, PcH), 6.98–7.58 (m, 8 H, PcH),
2.66–3.36 (m, 8 H, SCH2), 1.22–2.18 (m, 48 H, CH2), 0.82–1.02 (m,
12 H, CH3), –2.47 to –2.35 (m, 2 H, NH).
MS (MALDI-TOF): an isotopic cluster peaking at m/z = 1090.22
(calcd for M+: 1090.55).
4-Octyloxyphthalonitrile (2g)17f
1H NMR: d = 7.70 (d, J = 8.7 Hz, 1 H, ArH), 7.25 (d, J = 2.4 Hz, 1
H, ArH), 7.17 (dd, J = 2.4, 8.7 Hz, 1 H, ArH), 4.04 (t, J = 6.6 Hz, 2
H, OCH2), 1.82 (quintet, J = 6.6 Hz, 2 H, CH2), 1.38–1.48 (m, 2 H,
CH2), 1.24–1.36 (m, 8 H, CH2), 0.90 (t, J = 6.9 Hz, 3 H, CH3).
UV-Vis (CHCl3): lmax = 334, 420 (sh), 638, 665, 702, 732 nm.
2,3,9,10,16,17,23,24-Octakis(butylthio)phthalocyanine (3d)17j
1H NMR: d = 8.48 (s, 8 H, PcH), 3.42 (t, J = 7.5 Hz, 16 H, SCH2),
2.06 (quintet, J = 7.5 Hz, 16 H, CH2), 1.79 (sextet, J = 7.5 Hz, 16 H,
CH2), 1.20 (t, J = 7.5 Hz, 24 H, CH3).
MS (EI): m/z (%) = 256 (23, [M+]), 71 (88), 57 (100).
HRMS (EI): m/z calcd for C16H20N2O: 256.1570; found: 256.1572.
MS (MALDI-TOF): an isotopic cluster peaking at m/z = 1218.24
(calcd for M+: 1218.44).
3-Octyloxyphthalonitrile (2h)
1H NMR: d = 7.65 (t, J = 8.1 Hz, 1 H, ArH), 7.33 (d, J = 8.1 Hz, 1
H, ArH), 7.25 (d, J = 8.1 Hz, 1 H, ArH), 4.14 (t, J = 6.6 Hz, 2 H,
OCH2), 1.87 (quintet, J = 6.6 Hz, 2 H, CH2), 1.43–1.54 (m, 2 H,
CH2), 1.24–1.38 (m, 8 H, CH2), 0.89 (t, J = 6.9 Hz, 3 H, CH3).
UV-Vis (CHCl3): lmax = 323, 360, 447, 635, 668, 700, 733 nm.
2,3,9,10,16,17,23,24-Octakis(octylthio)phthalocyanine (3e)17k
1H NMR: d = 8.46 (br s, 8 H, PcH), 3.43 (br s, 16 H, SCH2), 2.08
(br s, 16 H, CH2), 1.78 (br s, 16 H, CH2), 1.28–1.56 (m, 64 H, CH2),
0.91 (br s, 24 H, CH3).
MS (EI): m/z (%) = 256 (18, [M+]), 227 (32), 71 (90), 57 (100).
HRMS (EI): m/z calcd for C16H20N2O: 256.1570; found: 256.1573.
MS (MALDI-TOF): an isotopic cluster peaking at m/z = 1667.63
(calcd for M+: 1666.94).
4,5-Bis(phenyloxy)phthalonitrile (2i)14b
1H NMR: d = 7.35 (t, J = 7.5 Hz, 4 H, ArH), 7.19 (s, 2 H, ArH), 7.16
(t, J = 7.5 Hz, 2 H, ArH), 7.02 (d, J = 7.5 Hz, 4 H, ArH).
UV-Vis (CHCl3): lmax = 323, 430 (sh), 635, 668, 700, 732 nm.
Synthesis 2005, No. 7, 1141–1147 © Thieme Stuttgart · New York

1146
P.-C. Lo et al.
PAPER
2(3),9(10),16(17),23(24)-Tetrakis(octyloxy)phthalocyanine
(3f)17l
Acknowledgment
1H NMR: d = 6.73–8.90 (m, 12 H, PcH), 3.78–4.10 (m, 8 H, OCH2),
1.88–2.08 (m, 8 H, CH2), 0.88–1.77 (m, 52 H, CH2 and CH3), –5.24
(br s, 2 H, NH).
We thank Prof. T.-W. Dominic Chan and Pui-Kwan Chan for recor-
ding some of the mass spectra.
MS (FAB): m/z = 1026 (7, [M+]), 970 (8), 914 (7), 307 (46), 154
(100), 137 (64).
References
(1) (a) Phthalocyanines – Properties and Applications, Vol. 1-
4; Leznoff, C. C.; Lever, A. B. P., Eds.; VCH: New York,
1989–1996. (b)McKeown, N. B. Phthalocyanine Materials:
Synthesis, Structure and Function; Cambridge University
Press: Cambridge, 1998.
HRMS (FAB): m/z calcd for C64H82N8O4: 1026.6454; found:
1026.6419.
UV-Vis (CHCl3): lmax = 341, 390, 610, 646, 669, 706 nm.
1(4),8(11),15(18),22(25)-Tetrakis(2,4-dimethyl-3-pentyl-
oxy)phthalocyanine (3g)15c
(2) See for example: (a) Perry, J. W.; Mansour, K.; Lee, I.-Y. S.;
Wu, X.-L.; Bedworth, P. V.; Chen, C.-T.; Ng, D.; Marder, S.
R.; Miles, P.; Wada, T.; Tian, M.; Sasabe, H. Science 1996,
273, 1533. (b) Bao, Z.; Lovinger, A. J.; Dodabalapur, A.
Adv. Mater. 1997, 9, 42. (c) Bao, Z.; Lovinger, A. J.;
Brown, J. J. Am. Chem. Soc. 1998, 120, 207. (d) de la
Torre, G.; Vázquez, P.; Agulló-López, F.; Torres, T. J.
Mater. Chem. 1998, 8, 1671. (e) Crone, B.; Dodabalapur,
A.; Lin, Y.-Y.; Filas, R. W.; Bao, Z.; LaDuca, A.;
Sarpeshkar, R.; Katz, H. E.; Li, W. Nature 2000, 403, 521.
(f) Schön, J. H.; Kloc, C.; Bao, Z.; Batlogg, B. Adv. Mater.
2000, 12, 1539. (g) Dini, D.; Barthel, M.; Hanack, M. Eur. J.
Inorg. Chem. 2001, 3759.
(3) See for example: (a) Meunier, B.; Sorokin, A. Acc. Chem.
Res. 1997, 30, 470. (b) Ito, N.; Etoh, T.; Hagiwara, H.; Kato,
M. Synthesis 1997, 153. (c) Ravikanth, M.; Achim, C.;
Tyhonas, J. S.; Münck, E.; Lindsey, J. S. J. Porphyrins
Phthalocyanines 1997, 1, 385. (d) Oyaizu, K.; Haryono, A.;
Natori, J.; Tsuchida, E. J. Chem. Soc., Faraday Trans. 1998,
94, 3737. (e) Bench, B. A.; Brennessel, W. W.; Lee, H.-J.;
Gorun, S. M. Angew. Chem. Int. Ed. 2002, 41, 750. (f) Tao,
X.; Ma, W.; Zhang, T.; Zhao, J. Chem. Eur. J. 2002, 8, 1321.
(4) Ali, H.; van Lier, J. E. Chem. Rev. 1999, 99, 2379.
(5) Erk, P.; Hengelsberg, H. In The Porphyrin Handbook, Vol.
19; Kadish, K. M.; Smith, K. M.; Guilard, R., Eds.;
Academic Press: San Diego, 2003, Chap. 119.
1H NMR: d = 9.04–9.12 (m, 4 H, PcH), 8.03–8.10 (m, 4 H, PcH),
7.66–7.74 (m, 4 H, PcH), 4.31–4.72 (m, 4 H, OCH), 2.30–2.66 (m,
8 H, CH), 1.49–1.54 (m, 24 H, CH3), 1.21–1.26 (m, 24 H, CH3),
–0.06 to 0.09 (m, 2 H, NH).
MS (MALDI-TOF): an isotopic cluster peaking at m/z = 970.61
(calcd for M+: 970.58).
UV-Vis (CHCl3): lmax = 318, 632, 667, 700, 731 nm.
[2(3),9(10),16(17),23(24)-Tetrakis(dodecylthio)phthalocyani-
nato]zinc(II) (4a)
1H NMR: d = 6.70–7.75 (m, 12 H, PcH), 2.40–2.90 (m, 8 H, SCH2),
1.20–1.60 (m, 80 H, CH2), 0.88–0.92 (m, 12 H, CH3).
MS (MALDI-TOF): an isotopic cluster starting at m/z = 1376.35
(calcd for M+: 1376.72).
UV-Vis (CHCl3): lmax = 357, 625, 662, 693 nm.
[2,3,9,10,16,17,23,24-Octakis(butylthio)phthalocyani-
nato]zinc(II) (4b)16
1H NMR (pyridine-d5): d = 9.35 (s, 8 H, PcH), 3.60 (t, J = 7.2 Hz,
16 H, SCH2), 2.06 (quintet, J = 7.2 Hz, 16 H, CH2), 1.77 (sextet,
J = 7.2 Hz, 16 H, CH2), 1.10 (t, J = 7.2 Hz, 24 H, CH3).
MS (MALDI-TOF): an isotopic cluster starting at m/z = 1280.29
(calcd for M+: 1280.36).
(6) Sharman, W. M.; van Lier, J. E. In The Porphyrin
Handbook, Vol. 15; Kadish, K. M.; Smith, K. M.; Guilard,
R., Eds.; Academic Press: San Diego, 2003, Chap. 97.
(7) (a) Maree, M. D.; Nyokong, T. J. Chem. Res., Synop. 2001,
68. (b) Tolbin, A. Y.; Ivanov, A. V.; Tomilova, L. G.;
Zefirov, N. S. J. Porphyrins Phthalocyanines 2003, 7, 162.
(c) Liu, L.-C.; Hu, A. T. J. Porphyrins Phthalocyanines
2003, 7, 565.
UV-Vis (THF): lmax = 366, 626, 695 nm.
[2,3,9,10,16,17,23,24-Octakis(butylthio)phthalocyaninato]co-
balt(II) (4c)17o
MS (FAB): m/z (%) = 1276 (3, [M+]), 154 (66), 69 (74), 55 (100).
UV-Vis (THF): lmax = 334, 616, 680 nm.
(8) (a) Wöhrle, D.; Schmidt, V. J. Chem. Soc., Dalton Trans.
1988, 549. (b) Frick, K.; Ziener, U.; Hanack, M. Eur. J.
Inorg. Chem. 1999, 1309. (c) Walsh, C. J.; Mandal, B. K.
Chem. Mater. 2000, 12, 287.
(9) (a) Welton, T. Chem. Rev. 1999, 99, 2071. (b) Wasser-
scheid, P.; Keim, W. Angew. Chem. Int. Ed. 2000, 39, 3772.
(c) Sheldon, R. Chem. Commun. 2001, 2399. (d)Dupont, J.;
de Souza, R. F.; Suarez, P. A. Z. Chem. Rev. 2002, 102,
3667. (e) Wasserscheid, P.; Welton, T. Ionic Liquids in
Synthesis; Wiley-VCH: Weinheim, 2003.
(10) (a) A room temperature phthalocyanine-based molten salt,
however, has been reported: Dickinson, E.; Williams, M. E.;
Hendrickson, S. M.; Masui, H.; Murray, R. W. J. Am. Chem.
Soc. 1999, 121, 613. (b) Catalytic oxidation of thiols by
cobalt(II) phthalocyanines in ionic liquid has also been
reported recently: Chauhan, S. M. S.; Kumar, A.; Srinivas,
K. A. Chem. Commun. 2003, 2348.
[2,3,9,10,16,17,23,24-Octakis(octylthio)phthalocyani-
nato]zinc(II) (4d)17k
1H NMR: d = 8.12 (br s, 8 H, PcH), 3.04 (br s, 16 H, SCH2), 1.79
(br s, 16 H, CH2), 1.25–1.61 (m, 80 H, CH2), 0.91 (br s, 24 H, CH3).
MS (MALDI-TOF): an isotopic cluster starting at m/z = 1728.66
(calcd for M+: 1728.86).
UV-Vis (CHCl3): lmax = 368, 638, 702 nm.
[2,3,9,10,16,17,23,24-Octakis(octylthio)phthalocyaninato]nick-
el(II) (4e)17p
1H NMR: d = 8.30 (br s, 8 H, PcH), 3.38 (br s, 16 H, SCH2), 2.04
(br s, 16 H, CH2), 1.74 (br s, 16 H, CH2), 1.20–1.58 (m, 64 H, CH2),
0.90 (br s, 24 H, CH3).
MS (MALDI-TOF): an isotopic cluster starting at m/z = 1722.22
(calcd for M+: 1722.86).
(11) (a) Kim, D. W.; Song, C. E.; Chi, D. Y. J. Org. Chem. 2003,
68, 4281. (b) Liu, Z.; Chen, Z.-C.; Zheng, Q.-G. Synthesis
2004, 33.
UV-Vis (THF): lmax = 319, 432, 635, 670, 702 nm.
Synthesis 2005, No. 7, 1141–1147 © Thieme Stuttgart · New York

PAPER
Phthalocyanine Synthesis in Ionic Liquids
1147
(12) (a) Gürol, I.; Ahsen, V.; Bekaroglu, Ö. J. Chem. Soc., Dalton
Trans. 1994, 497. (b) Del Rey, B.; Keller, U.; Torres, T.;
Rojo, G.; Agulló-López, F.; Nonell, S.; Martí, C.; Brasselet,
S.; Ledoux, I.; Zyss, J. J. Am. Chem. Soc. 1998, 120, 12808.
(13) In a study of conjugate addition of thiols to electron deficient
alkenes in molten Bu4NBr, Ranu et al. have suggested that
the bromide ions form hydrogen bondings with the thiols,
leading to an increase in their nucleophilicity: Ranu, B. C.;
Dey, S. S.; Hajra, A. Tetrahedron 2003, 59, 2417.
(14) See for example: (a) Siegl, W. O. J. Heterocycl. Chem.
1981, 18, 1613. (b) Wöhrle, D.; Eskes, M.; Shigehara, K.;
Yamada, A. Synthesis 1993, 194. (c) Eberhardt, W.;
Hanack, M. Synthesis 1997, 95. (d) Liu, W.; Lee, C.-H.;
Chan, H.-S.; Mak, T. C. W.; Ng, D. K. P. Eur. J. Inorg.
Chem. 2004, 286.
(17) The following compounds have been described previously.
See: (a) For 2a and 2e: Ref. 12b. (b) For 2b and 3b: Ref.
12a. (c) For 2c and 3c: Torres Cebada, T.; Sastre Santos, A.;
Del Rey Alvarez, B. Spanish Patent ES 2116867, 1998;
Chem. Abstr. 1999, 130, 261059. (d) For 2d: Taniguchi, M.;
Narizuka, T.; Tomita, H. Jpn. Kokai Tokkyo Koho JP
08269004, 1996; Chem. Abstr. 1997, 126, 46981. (e) For
2f: Duggan, P. J.; Gordon, P. F. Eur. Pat. Appl. EP 155780,
1985; Chem. Abstr. 1986, 105, 70242. (f) For 2g: Yamada,
A.; Shigehara, J.; Kurata, R.; Hikosaka, M. Jpn. Kokai
Tokkyo Koho JP 61207365, 1986; Chem. Abstr. 1987, 106,
32617. (g) For 2i: Ref. 14b. (h) For 2j: Cook, M. J.; Dunn,
A. J.; Howe, S. D.; Thomson, A. J.; Harrison, K. J. J. Chem.
Soc., Perkin Trans. 1 1988, 2453. (i) For 3a: Suda, Y.;
Shigehara, K.; Yamada, A.; Matsuda, H.; Okada, S.; Masaki,
A.; Nakanishi, H. Proc. SPIE-Int. Soc. Opt. Eng. 1991, 1560,
75. (j) For 3d: Shigehara, K.; Takizawa, M.; Takeda, K.
Synth. Met. 1995, 71, 2303. (k) For 3e and 4d: Eichhorn, H.;
Wöhrle, D.; Pressner, D. Liq. Cryst. 1997, 22, 643. (l) For
3f: Ozawa, H.; Oshima, K. Jpn. Kokai Tokkyo Koho JP
62139157, 1987; Chem. Abstr. 1988, 108, 66063. (m) For
3g: Ref. 15c. (n) For 4b: Ref. 16. (o) For 4c: Ozoemena, K.;
Westbroek, P.; Nyokong, T. Electrochem. Commun. 2001,
3, 529. (p) For 4e: Nicolau, M.; del Rey, B.; Torres, T.;
Mingotaud, C.; Delhaes, P.; Cook, M. J.; Thorpe, S. C.
Synth. Met. 1999, 102, 1462.
(15) (a) Wöhrle, D.; Schnurpfeil, G.; Knothe, G. Dyes Pigments
1992, 18, 91. (b) Gürek, A. G.; Bekaroglu, Ö. J. Chem. Soc.,
Dalton Trans. 1994, 1419. (c) Lee, C.-H.; Ng, D. K. P.
Tetrahedron Lett. 2002, 43, 4211.
(16) Choi, M. T. M.; Li, P. P. S.; Ng, D. K. P. Tetrahedron 2000,
56, 3881.
Synthesis 2005, No. 7, 1141–1147 © Thieme Stuttgart · New York