2,3,9,10,16,17,23,24-Octakis(hexylsulfonyl)phthalocyanines with good n-type semiconducting properties. Synthesis, spectroscopic, and electrochemical characteristics

Article abstract of DOI:10.1039/c1jm10295h

The synthesis of peripherally octa-substituted phthalocyanine compounds with eight strong electron-withdrawing hexylsulfonyl groups was systematically studied. Three new phthalocyanines M[Pc(SO₂C₆H ₁₃)₈] [Pc(SO<

Full text of DOI:10.1039/c1jm10295h

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PAPER
2,3,9,10,16,17,23,24-Octakis(hexylsulfonyl)phthalocyanines with good n-type
semiconducting properties. Synthesis, spectroscopic, and electrochemical
characteristics†
a
a
Yi Zhang,a Pan Ma,ab Peihua Zhu,c Xianyao Zhang,ab Yingning Gao,ab Dongdong Qi, Yongzhong Bian,
*
d
Nagao Kobayashi and Jianzhuang Jiang
a
*
Received 20th January 2011, Accepted 23rd February 2011
DOI: 10.1039/c1jm10295h
The synthesis of peripherally octa-substituted phthalocyanine compounds with eight strong electron-
withdrawing hexylsulfonyl groups was systematically studied. Three new phthalocyanines M[Pc
(SO2C6H13)8] [Pc(SO2C6H13)8 ¼ 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocyaninate; M ¼ 2H
(1), Cu (2), Zn (3)] were synthesized via direct cyclic tetramerization of 4,5-di(hexylsulfonyl)
phthalonitrile or through a diiminoisoindoline intermediate. Compounds 1–3 could alternatively be
prepared by oxidation of the hexylthio substituents in corresponding 2,3,9,10,16,17,23,24-octakis
(hexylthio)phthalocyanine compounds M[Pc(SC6H13)8] (M ¼ 2H, Cu, Zn) with m-chloroperbenzoic
acid. They were fully characterized by elemental analysis and a series of spectroscopic methods. Their
electrochemistry was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV).
Density function theory (DFT) calculations were conducted to study the effect of the strong electron-
withdrawing groups on the electronic structure of the phthalocyanine molecules. Particularly, the first
reduction potentials in the range ꢀ0.30ꢁꢀ0.04 V vs. the saturated calomel electrode (SCE) for 1–3
reveal their n-type semiconducting nature. The current–voltage characteristics of their aggregates
demonstrate the good semiconducting properties especially for 1 and 2 with the conductivity value of
5.24 ꢂ 10ꢀ4 and 2.73 ꢂ 10ꢀ4 S mꢀ1, respectively.
extraordinary chemical, thermal, and photostabilities,2–4 these
macrocyclic molecular materials have found important applica-
tions in medicine,5 optical storage,6 and photocatalysis.7 In
particular, the worldwide scientific interests in molecular-based
nano-electronic/optoelectronic devices led to extensive studies of
the semiconducting properties of phthalocyanine compounds in
recent years.8,9
Introduction
As the most important synthetic analogues of the naturally
occurring porphyrins, phthalocyanines have been an important
class of dyes and pigments since their early synthesis at the
beginning of last century.1 In close association with their unique
spectroscopic and electrochemical properties as well as
Intensive investigations clearly revealed the p-type semi-
conducting nature of a series of commercially available unsub-
stituted phthalocyanine derivatives8,10,11 and the n-type nature of
few phthalocyanine compounds with strong electron-with-
drawing groups at peripheral and/or non-peripheral positions
including Cu[Pc(F)16],12–15 Fe[Pc(Cl)16],12 and Cu[Pc(CN)8].12
For the purpose of fabricating complementary p–n circuits
compatible with low cost high throughput solution-based
manufacturing methods, novel phthalocyanine compounds
having peripheral and/or non-peripheral electron-withdrawing
groups with good solubility in common organic solvents should
therefore be developed in the first step.
aDepartment of Chemistry, University of Science and Technology Beijing,
Beijing, 100083, China. E-mail: jianzhuang@ustb.edu.cn; yzbian@ustb.
edu.cn
bDepartment of Chemistry, Shandong University, Jinan, 250100, China
cDepartment of Chemistry, University of Jinan, Jinan, 250022, China
dDepartment of Chemistry, Graduate School of Science, Tohoku
University, Sendai, 980-8578, Japan
† Electronic supplementary information (ESI) available: Synthesis
procedures for 4,5-di(hexylthio)phthalonitrile, H2Pc(SC6H13)8, Cu[Pc
(SC6H13)8], and Zn[Pc(SC6H13)8]; Experimental and simulated isotopic
pattern for the molecular ion of Cu[Pc(SO2C6H13)8] (2) shown in the
1
MALDI-TOF mass spectrum; H NMR spectra for H2Pc(SC6H13)8, Zn
[Pc(SC6H13)8], and H2Pc(SO2C6H13)8 (1) in CDCl3; Molecular orbital
maps of HOMO and LUMO for MPc and M[Pc(SO2CH3)8] (M ¼ 2H,
Zn); the electronic absorption spectra of the aggregates fabricated from
1–3 dispersed in methanol; SEM images of the two-electrode device
fabricated from the aggregates of 1–3; SEM images and I–V curves of
the two-electrode devices fabricated from the aggregates of H2Pc
(SC6H13)8, Zn[Pc(SC6H13)8], and H2Pc(SO2C6H13)8. See DOI:
10.1039/c1jm10295h
Actually, it is well known that incorporating substituents onto
the phthalocyanine ring is able to tune the physi-chemical,
electrochemical,
and
spectroscopic
properties
of
phthalocyanine derivatives. As a consequence, various kinds of
different substituents, which appear to be mainly limited to the
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electron-donating groups such as alkyl, alkoxyl, and alkylthio
have been introduced onto the peripheral and/or non-peripheral
positions of phthalocyanine ligand.16,17 However, well charac-
terized phthalocyanine derivatives with electron-withdrawing
substituents other than F, Cl, and CN still remain extremely rare
thus far, to the best of our knowledge. This is exemplified by
such a fact that detailed reports even on the most easily accessible
2(3),9(10),16(17),23(24)-tetrakis(alkoxycarbonyl)phthalocyanine
derivatives with four peripheral electron-withdrawing alkox-
ycarbonyl substituents seem to still be limited to the work
from a few research groups among the large number of
related publications.18,19 This is also true for 2,3,9,10,16,17,
23,24-octakis(alkoxycarbonyl)phthalocyanine derivatives with
eight peripheral electron-withdrawing alkoxycarbonyl substit-
uents. At the very beginning, 2,3,9,10,16,17,23,24-octakis
(alkoxycarbonyl)phthalocyanines were reported to be synthe-
sized by acyl chlorination of corresponding octakis(carboxyl)
phthalocyanine with UV-vis and IR spectra as the sole
spectroscopic evidence.20 Until 2007, the synthesis of these
compounds via the acyl chlorination route of octakis
Scheme
1
Synthesis of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyanine compounds M[Pc(SO2C6H13)8] (M ¼ 2H, Cu, Zn) (1–3).
(i) m-Chloroperbenzoic acid, CH2Cl2, rt; (ii) DBU, n-C5H11OH, 145 ꢃC;
(iii) M(OAc)2ꢄH2O, DMF, reflux; (iv) M(OAc)2ꢄH2O, DBU,
n-C5H11OH, 145 ꢃC; (v) first NH3, MeONa, MeOH, 0 ꢃC; then DMF/o-
dichlorobenzene (1:1), 150 ꢃC; (vi) first NH3, MeONa, MeOH, 0 ꢃC; then
1
(carboxyl)phthalocyanine was unambiguously confirmed by H
NMR and mass spectroscopy in addition to elemental anal-
ysis.21 In the same year, a new pathway to 2,3,9,10,16,17,
23,24-octakis(octyloxycarbonyl)phthalocyanine compounds M
[Pc(COOC8H17)8] (M ¼ 2H, Cu, Zn) was reported by this
group through cyclic tetramerization of 4,5-di(octyloxy-
M(OAc)2ꢄH2O, DMF/o-dichlorobenzene (1:1), 150 ꢃC; (vii)
M
(OAc)2ꢄH2O, 2-ethoxyethanol/o-dichlorobenzene (3:1), 145 ꢃC.
in the presence of M(OAc)2$H2O (M ¼ Cu, Zn) in a mixed solvent
of2-ethoxyethanolando-dichlorobenzene(3 : 1)withoutnecessity
via the formation of a diiminoisoindoline intermediate. These
compounds could be alternatively prepared via oxidation of the
hexylthio substituents in corresponding 2,3,9,10,16,17,23,24-
octakis(hexylthio)phthalocyanine derivatives M[Pc(SC6H13)8] (M
¼ 2H, Cu, Zn) using a relatively strong oxidation agent like m-
chloroperbenzoic acid, Scheme 1. The electrochemical and
current–voltage studies reveal their n-type nature and good semi-
conducting properties, respectively.
carbonyl)phthalonitrile, which was obtained by
a newly
developed procedure with o-xylene as the starting material.22a
This was supported by the following work of Opris et al.23
and Tylleman et al.24 with o-xylene and 4,5-dichlorophthalic
acid as the starting material, respectively.
On the other hand, incorporating another highly electron-
withdrawing group, an alkylsulfonyl substituent, onto the
periphery of phthalocyanine ring should be of interest to develop
solution-processable
phthalocyanine-based
n-type
semi-
conductors. However, despite the synthesis and photophysical
investigations of several alkylsulfonyl-containing asymmetrical
phthalocyaninederivatives,25 lessattentionhasbeendevotedtothe
octakis-substituted phthalocyanine derivatives with eight alkyl-
sulfonyl groups at the peripheral positions. Only two examples in
this regard can be found thus far.26 Torres and coworkers
reported an octakis(propylsulfonyl)phthalocyaninate palladium
(II) complex, which was synthesized by cyclic tetramerization of
a corresponding diiminoisoindoline precursor in the presence of
Pd(OAc)2.26a Recently, Geerts and coworkers synthesized metal
free octakis(alkylsulfonyl)phthalocyanines from the oxidation of
corresponding metal free 2,3,9,10,16,17,24,25-octakis(alkylthio)
phthalocyanines and studied their liquid crystal properties.26b
In the present paper, we describe the systematic studies on the
synthesis of 2,3,9,10,16,17,23,24-octakis(alkylsulfonyl)phthalo-
cyanines. Cyclic tetramerization of 4,5-di(hexylsulfonyl)phthalo-
nitrile (via diiminoisoindoline intermediate) in the absence and
presenceof a metalsaltM(OAc)2$H2O (M ¼ Cu, Zn), respectively,
in a mixed solvent of DMF and o-dichlorobenzene (1 : 1) provided
metal free 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocya-
nine (1) and 2,3,9,10,16,17,23,24-octakis(alkylsulfonyl)phthalo-
cyaninato metal compounds (2, 3), Scheme 1. Actually the latter
two phthalocyaninato metal complexes were also obtained by
direct cyclic tetramerization of 4,5-di(hexylsulfonyl)phthalonitrile
Results and discussion
Synthesis of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyanine compounds M[Pc(SO2C6H13)8] (M ¼ 2H, Cu,
Zn) (1–3)
There are generally two synthetic pathways for metal free
phthalocyanines H2Pc0 (Pc0 ¼ general phthalocyaninate). The
first pathway involves a cyclic tetramerization of the corre-
sponding phthalonitrile precursor using lithium as a template in
a high boiling point alcoholic solvent like n-pentanol followed by
treatment with acid. This method however failed to give the
corresponding metal free 2,3,9,10,16,17,23,24-octakis(alkylsul-
fonyl)phthalocyanine due to the nucleophilic substitution of
hexylsulfonyl groups by corresponding alkoxyl groups, which
actually led to a mixture of inseparable phthalocyanine deriva-
tives.26 The second pathway also involves a cyclic tetramerization
of the corresponding phthalonitrile precursor in high boiling
point organic alcoholic solvent but promoted by organic base
such as DBU. This still failed in leading to the isolation of
2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocyanine in the
present case due to the nucleophilic substitution on sulfonyl
groups in the electron-deficient aromatic ring of 4,5-di(hexyl-
sulfonyl)phthlonitrile. However, after being converted into the
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corresponding diiminoisoindoline intermediate upon the treat-
ment with NH3 and MeONa in MeOH at 0 ꢃC, cyclic tetra-
merization in a mixed solvent of DMF and o-dichlorobenzene
(1 : 1) at 150 ꢃC provided metal free 2,3,9,10,16,17,23,24-octa-
kis(hexylsulfonyl)phthalocyanine H2Pc(SO2C6H13)8 (1) in rela-
tively good yield, Scheme 1. This is also true for the synthesis
Spectroscopic characterization
All the three 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)-
phthalocyanine compounds 1–3 as well as their
2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine counter-
parts were characterized by a series of spectroscopic methods
1
including MALDI-TOF mass, H NMR, UV-vis, and IR spec-
of
2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocyaninato
troscopy. The MALDI-TOF mass spectra of these compounds
clearly showed intense signals for the molecular ion (M)+, Table
1. The isotopic pattern closely resembled the simulated one as
exemplified by the spectrum of 2 given in Fig. S1 (see the ESI†).
The electronic absorption spectra of 1–3 were recorded in
CHCl3 and the data are summarized in Table 2. Fig. 1 shows the
electronic absorption spectra of 1–3. Both the metal free
compound 1 and the metal complexes 2 and 3 display typical
features of the monomeric phthalocyanine counterparts.1 As
shown in Fig. 1, H2Pc(SO2C6H13)8 (1) shows a typical non-
aggregated molecular electronic absorption spectrum of metal
free phthalocyanines with the Soret band at 351 nm and split Q
bands at 668 and 705 nm with two shoulders at 604 and 650 nm,
respectively. The absorption spectra of M[Pc(SO2C6H13)8] (M ¼
Cu, Zn) (2, 3) display a typical Soret band at 342–376 nm. Their
Q band is observed at 684–686 nm with a very weak vibronic
band at 615–618 nm. It is worth noting that the weak band in the
range 417–448 nm, observed for M[Pc(SC6H13)8] (M ¼ 2H, Cu,
Zn), Fig. 1 and Table 2, due to the n / p* transitions arising
from the sulfur lone pairs of electrons, is absent in the spectra of
1–3,27,28 indicating the lack of a C–S bond in 1–3 in terms of the
electronic absorption spectroscopy. It is conceivable, by the
change of energy levels of molecular orbitals due to introduction
of strong electron-withdrawing alkylsulfonyl groups, that it
becomes more difficult for the n–p* transition to borrow inten-
sity from the p–p* transitions lying at higher energy. Further-
more, in comparison with M[Pc(SC6H13)8] (M ¼ 2H, Cu, Zn),
the Q absorption band for 1–3 takes a significant blue shift
(25–28 nm in the Q band region), revealing the relatively larger
HOMO–LUMO gap of 2,3,9,10,16,17,23,24-octakis(hexy-
metal complexes M[Pc(SO2C6H13)8] (M ¼ Cu, Zn) (2, 3) in the
presence of metal salt like M(OAc)2$H2O (M ¼ Cu, Zn).
Actually, direct cyclic tetramerization of 4,5-di(hexylsulfonyl)
phthlonitrile, without the necessity to convert it into diiminoi-
soindoline intermediate, in a mixed solvent of 2-ethoxyethanol
and o-dichlorobenzene (3 : 1) at 145 ꢃC in the presence of M
(OAc)2$H2O (M ¼ Cu, Zn) also led to the formation of M[Pc
(SO2C6H13)8] (M ¼ Cu, Zn) (2, 3). It is worth noting that despite
the synthesis of alkylsulfonyl-containing phthalocyanine deriva-
tives starting from 4,5-di(alkylsulfonyl)phthlonitrile and another
species of phthalonitrile in the presence of metal salt in a mixed
solvent of DMF and o-dichlorobenzene according to Torres and
co-wokrker,25,25a the reaction between 4,5-di(heptylsulfonyl)
phthlonitrile and
M(OAc)2$H2O (M ¼ Cu, Zn) in the mixed solvent of DMF and
o-dichlorobenzene at 145 ꢃC did not give the target phthalo-
cyaninato metal complexes as revealed by MALDI-TOF mass
spectroscopy in the present case. These three compounds in
particular the latter two phthalocyaninato metal complexes could
be alternatively prepared by oxidation of the eight hexylthio
substituents in the phthalocyanine ring of corresponding
2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine derivatives
M[Pc(SC6H13)8] (M ¼ 2H, Cu, Zn) (obtained by different
synthesis pathways as described also in Scheme 1 and ESI†)
using m-chloroperbenzoic acid, Scheme 1, verifying the high
stability of 2,3,9,10,16,17,23,24-octakis(alkylsulfonyl)phthalocya-
nine compounds towards the relatively strong oxidation agent.
Certainly, treatment of the metal free phthalocyanine H2Pc
(SO2C6H13)8 (1) with the metal salt M(OAc)2$H2O (M ¼ Cu,
Zn) in refluxing DMF also provided the two phthalocyaninato
metal complexes 2 and 3, Scheme 1.
lsulfonyl)phthalocyanine
compounds
than
that
of
2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine counter-
parts, Table 2. This result is in line with the electrochemical
studies and is reasonably explained by considering the energy
levels of the frontier molecular orbitals of the corresponding
compounds, which were obtained by calculations using a density
functional theory (DFT) method, vide infra.
Satisfactory elemental analysis results have been obtained for
all the three newly prepared alkylsulfonyl-substituted phthalo-
cyanine compounds after repeated column chromatography and
recrystallization, Table 1. This is also true for their
2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine counter-
parts M[Pc(SC6H13)8] (M ¼ 2H, Cu, Zn), Table 1.
Table 1 Analytical and mass spectroscopic data for the 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)phthalocyanine compounds 1–3 and the corre-
sponding hexylthio derivatives MPc(SC6H13)8 (M ¼ 2H, Cu, Zn)a
Analysis(%)
Compound
Molecular formula
M+ (m/z)
C
H
N
H2Pc(SO2C6H13)8 (1)
CuPc(SO2C6H13)8 (2)
ZnPc(SO2C6H13)8 (3)
H2C80H112N8S8 O16
CuC80H112N8S8 O16
ZnC80H112N8S8 O16
H2C30H112N8S8
CuC30H112N8S8
ZnC30H112N8S8
1698.9 (1698.6)b
1759.8 (1759.5)b
1760.5 (1760.5)b
1442.4 (1442.7)b
1503.9 (1503.6)b
1504.9 (1504.6)b
55.64 (56.16)c
52.70 (52.94)d
51.22 (51.66)e
66.37 (66.52)
63.92 (63.81)
61.61 (61.68)f
6.86 (6.87)c
6.87 (6.28)d
6.35 (6.05)e
7.94 (7.96)
7.53 (7.50)
7.55 (7.23)f
6.38 (6.47)c
5.64 (6.10)d
6.12 (5.95)e
7.45 (7.76)
6.84 (7.44)
6.64 (7.14)f
H2Pc(SC6H13 8
CuPc(SC6H13 8
ZnPc(SC6H13 8
)
)
)
Calculated values given in parentheses. b The value corresponds to the most abundant isotopic peak of the molecular ion (M+). c Contain 1.0 equiv.
a
solvated CH3OH. d Contain 0.5 equiv. solvated CHCl3 and 0.5 equiv. solvated CH3OH. e Contain 1.0 equiv. of solvated CHCl3. f Contain 0.5 equiv.
solvated CH3OH.
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Table 2 Electronic absorption data for the compounds 1–3 and the corresponding hexylthio derivatives MPc(SC6H13)8 (M ¼ 2H, Cu, Zn) in CHCl3
Compound
lmax/nm (log 3)
H2Pc(SO2C6H13)8 (1)
CuPc(SO2C6H13)8 (2)
ZnPc(SO2C6H13)8 (3)
351 (4.89)
356 (4.86)
376 (4.85)
361 (4.82)
360 (4.85)
365 (4.85)
604 (4.54)
637 (4.56)
650 (4.73)
615 (4.60)
618 (4.72)
672 (4.74)
641 (4.63)
638 (4.63)
668 (5.26)
701 (5.09)
705 (5.33)
684 (5.46)
686 (5.54)
732 (5.12)
711 (5.27)
710 (5.34)
342 (4.76)
343 (4.78)
329 (4.86)
328 (4.85)
329 (4.72)
H2Pc(SC6H13 8
CuPc(SC6H13 8
ZnPc(SC6H13 8
)
448 (4.57)
439 (4.41
417 (4.48)
)
)
Vibrational spectroscopy has been proven to be a versatile
technique for studying the intrinsic properties of phthalocyanine
compounds. In the IR spectra of 1–3, in addition to the
absorption bands contributed from the central aromatic Pc
macrocycle including the wagging and torsion vibrations of C–H
groups, isoindole ring stretching vibrations, and the C]N aza
group stretching vibrations,29 the newly observed absorptions
around 2960, 2930, and 2870 cmꢀ1 for all these three compounds
are attributed to the asymmetric and symmetric C–H stretching
vibrations of the hexylsulfonyl groups, respectively. In the IR
spectrum of metal free phthalocyanine compound 1, a weak
absorption at 3290 cmꢀ1 is obviously due to the asymmetrical
N–H stretching vibration.30 This is also true for H2Pc(SC6H13)8.
This assignment is supported by the lack of such a band in the IR
spectra of the copper and zinc complexes 2 and 3 as well as M[Pc
(SC6H13)8] (M ¼ Cu, Zn).
Due to the paramagnetic nature of the divalent copper ion
in Cu[Pc(SO2C6H13)8] (2), 1H NMR spectra only for
H2Pc(Pc(SO2C6H13)8 (1) and Zn[Pc(Pc(SO2C6H13)8] (3) were
recorded in CDCl3. This is also true for their
2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine counter-
parts, Fig. S2 and S3 (ESI†). Fig. 2 shows the 1H NMR spectrum
of 3 in CDCl3. The signal at d 10.46 is due to the a ring protons of
Pc(SO2C6H13)8, while the hexylsulfonyl group resonates at d 4.02
(SO2CH2), 2.12 (CH2), 1.23–1.34 (CH2CH2CH2), and 0.86
(CH3). The spectrum for the metal free analogue 1 is very much
similar to that of 3 except the signal due to the central protons are
located at d ꢀ0.32, Fig. S4 (ESI†). This is in a much lower field in
comparison with that for H2Pc(SC6H13)8 at d ꢀ3.15 (Fig. S2,
ESI†), suggesting that the ring current of the phthalocyanine
ligand decreases markedly on going from H2Pc(SC6H13)8 to
H2Pc(SO2C6H13)8.
Fig. 1 Electronic absorption spectra of H2Pc(SO2C6H13)8 (1) (a), Cu[Pc
(SO2C6H13)8] (2) (b), and Zn[Pc(SO2C6H13)8] (3) (c) in CHCl3 (solid lines)
and the corresponding hexylthio derivatives M[Pc(SC6H13)8] (M ¼ 2H,
Cu, Zn) (broken lines). There is no intensity relationship between the
spectra of M[Pc(SO2C6H13)8] and M[Pc(SC6H13)8].
Fig. 2 1H NMR spectrum for Zn[Pc(SO2C6H13)8] (3) in CDCl3. The
signals due to residue CHCl3 and H2O are denoted as * and #,
respectively.
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Electrochemical properties
The redox behavior of the octakis(hexylsulfonyl)phthalocyanines
1–3 was studied by cyclic voltammetry (CV) and differential pulse
voltammetry (DPV) in CH2Cl2. These compounds exhibited one
quasi-reversible or irreversible one-electron oxidation and up to
four quasi-reversible or irreversible one-electron reductions, all of
which can be attributed to ligand-based redox processes. The half-
wave potentials are summarized in Table 3. Representative
cyclic voltammogram and differential pulse voltammogram for
Zn[Pc(SO2C6H13)8] (3) are displayed in Fig. 3.
The effect of peripheral hexylsulfonyl substitution at the
phthalcoyanine ring is clearly reflected by the shift in the half-wave
potentials of all the redox processes of metal-free phthalocyanine 1.
Ascanbeseen in Table 3, substitution of eight hexylsulfonyl groups
at the peripheral positions of the phthalocyanine ring induces
significant shift to the positive direction for both the first oxidation
and first reduction but without considerably changing the differ-
ence between these two redox processes, relative to H2Pc, revealing
the electron-withdrawing nature of hexylsulfonyl groups attached
onto the peripheral positions of phthalocyanine ring. In line with
a previous result,22,31 the substitution of the stronger Lewis acid
Cu2+ in compound 2 by weaker Lewis acid Zn2+ in 3 induces an
obvious shift to the negative direction for both the first
oxidation and first reduction, Table 3. The fact that the half-
wave potentials for all the oxidation and reduction processes
of octakis(hexylsulfonyl)phthalocyanines 1–3 are systemati-
cally shifted to the positive direction by ca. 0.2–0.4 V in
comparison with those of corresponding octakis(octylox-
counterparts22a
indicates
the
Fig. 3 Cyclic voltammogram and differential pulse voltammogram of
Zn[Pc(SO2C6H13)8] (3) in CH2Cl2 containing 0.1 M [NBu4][ClO4] at scan
rates of 20 and 10 mV sꢀ1, respectively.
ycarbonyl)phthalocyanine
stronger electron-withdrawing nature of the hexylsulfonyl
group than that of octyloxycarbonyl group. Especially, the
first reduction potential of 1–3 in the range ꢀ0.30ꢁꢀ0.04 V,
relative to SCE, just falls within the empirically established
air-stability window (between ꢀ0.4 and 0 V vs. SCE) for n-
type organic semiconductors,32 revealing the n-type semi-
conducting nature of these octakis(hexylsulfonyl)phthalocya-
nine derivatives.
phthalocyanine skeleton induces a significant stabilization of the
energy level of both the HOMO and LUMO according to the
calculations. The calculated HOMO and LUMO energies are
ꢀ6.51, ꢀ6.49 and ꢀ4.38, ꢀ4.31 eV for M[Pc(SO2CH3)8] (M ¼
2H, Zn), while ꢀ4.98, ꢀ4.94 and ꢀ2.93, ꢀ2.75 eV for MPc (M ¼
2H, Zn),33 respectively, with the HOMO–LUMO gap remaining
almost unchanged with values of 2.13, 2.18 and 2.05, 2.19 eV for
the former two and latter two compounds. These results are in
line with the electrochemical experimental findings as detailed
above. At the end of this paragraph it is worth noting that the
To understand the effect of hexylsulfonyl substituents on the
electrochemistry of phthalocyanine derivatives 1–3, molecular
orbital (MO) calculations on M[Pc(SO2CH3)8] (M ¼ 2H, Zn)
were carried out using the DFT method, Table 4. Introduction of
eight methylsulfonyl groups onto the peripheral positions of the
Table 3 Half-wave redox potentials of the compounds 1–3, the corresponding hexylthio derivatives MPc(SC6H13)8, and octyloxylcarbonyl derivatives
MPc(COOC8H17)8 (M ¼ 2H, Cu, Zn) (V vs. SCE) in CH2Cl2 containing 0.1 M TBAP
a
1/2
Compound
Oxd3
Oxd2
Oxd1
Red1
Red2
Red3
Red4
DEꢃ
Ref.
H2Pc
+1.14
+0.93
+1.51
+1.41
+1.30
+0.58
+0.59
+0.62
+1.27
+1.14
+0.98
ꢀ0.78
ꢀ0.04
ꢀ0.13
ꢀ0.30
ꢀ0.90
ꢀ0.86
ꢀ0.75
ꢀ0.38
ꢀ0.49
ꢀ0.60
ꢀ1.30
ꢀ0.42
ꢀ0.61
ꢀ0.59
ꢀ1.15
ꢀ1.09
ꢀ0.98
ꢀ0.68
ꢀ0.81
ꢀ0.86
ꢀ1.90
ꢀ1.04
ꢀ1.18
ꢀ1.10
1.71
1.55
1.54
1.60
1.48
1.45
1.37
1.65
1.63
1.58
22b
H2Pc(SO2C6H13)8 (1)
CuPc(SO2C6H13)8 (2)
ZnPc(SO2C6H13)8 (3)
H2Pc(SC6H13 8
CuPc(SC6H13 8
ZnPc(SC6H13 8
H2Pc(COOC8H17 8
CuPc(COOC8H17 8
ZnPc(COOC8H17 8
ꢀ1.35b
ꢀ1.35b
this work
this work
this work
this work
this work
this work
22ac
)
)
)
+1.36
+1.30
+0.86
+1.02
+1.54
+1.60
+1.60
)
)
)
ꢀ1.42b
ꢀ1.50b
ꢀ1.46b
22ac
22ac
a
b
DEꢃ1/2 is the potential difference between the first oxidation and first reduction processes. Recorded by DPV. c Values in ref. 22a are V vs. Fc/Fc+
couple, so that in this table the values are changed to V vs. SCE by adding +0.50 V to the values in ref. 22a.
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Table 4 Calculated orbital energies (in eV) of M[Pc(SO2CH3)8] and M[Pc(SCH3)8] (M ¼ 2H, Zn) on the basis of DFT calculations
Compound
H2Pca
ZnPcb
H2Pc(SO2CH3)8
Zn[Pc(SO2CH3)8]
H2Pc(SCH3)8
Zn[Pc(SCH3)8]
LUMO + 1
LUMO
HOMO
HOMO-1
HOMO–LUMO gap
ꢀ2.79
ꢀ2.93
ꢀ4.98
ꢀ6.52
2.05
ꢀ2.75
ꢀ2.75
ꢀ4.94
ꢀ6.63
2.19
ꢀ4.33
ꢀ4.38
ꢀ6.51
ꢀ8.03
2.13
ꢀ4.31
ꢀ4.31
ꢀ6.49
ꢀ8.21
2.18
ꢀ2.76
ꢀ2.80
ꢀ4.85
ꢀ5.53
2.05
ꢀ2.74
ꢀ2.74
ꢀ4.82
ꢀ5.62
2.08
a
Cited from ref. 33a. b Cited from ref. 33b.
calculated HOMO–LUMO gap for M[Pc(SO2CH3)8] (M ¼ 2H,
Zn) is a bit (0.08ꢁ0.10 V) larger than that for M[Pc(SCH3)8]
(M ¼ 2H, Zn), Table 4. This corresponds well with the blue-
shift of the Q band observed in the electronic absorption
spectra of M[Pc(SO2C6H13)8] (M ¼ 2H, Zn) (1, 3) in comparison
with M[Pc(SC6H13)8] (M ¼ 2H, Zn).
with a final chloroform/methanol ratio of 1 : 3 (v/v), which was
kept in air for 24 h. Fig. S6 (ESI†) shows the electronic
absorption spectra of the aggregates fabricated from 1–3
dispersed in methanol. In comparison with their electronic
absorption spectra in homogeneous chloroform solution, both
the Soret and Q bands for 1–3 lose some intensity in the aggre-
gate phase and shift to the lower energy direction. According to
Kasha’s exciton theory,34a red shift in the main absorption bands
of these phthalocyanine compounds upon aggregation is typi-
cally a sign of the effective p–p interaction between phthalocy-
anine molecules in the direction parallel to the phthalocyanine
ring, indicating the J-type aggregate nature with a head-to-tail
molecular arrangement of the microstructures.34
The HOMO and LUMO maps of M[Pc(SO2CH3)8] (M ¼ 2H,
Zn) and MPc (M ¼ 2H, Zn) are shown in Fig. S5 (ESI†). As can
be seen, introduction of the electron-withdrawing -SO2- groups
onto the peripheral positions of the phthalocyanine ring induces
a decrease in the electron density of phthalocyanine ring,
resulting in a lower energy level of HOMO contributed from the
p orbitals of carbon and nitrogen atoms of the central Pc ring for
M[Pc(SO2CH3)8] (M ¼ 2H, Zn) than that of MPc (M ¼ 2H, Zn).
This is also true for the LUMO of M[Pc(SO2CH3)8] (M ¼ 2H,
Zn). However, as described above, the simultaneous decrease in
the energy level of both HOMO and LUMO does not consid-
erably change the HOMO–LUMO gap of M[Pc(SO2CH3)8]
(M ¼ 2H, Zn), relative to MPc (M ¼ 2H, Zn). This is also in good
agreement with the experimental observations, Table 3.
The morphology of the aggregates was examined by scanning
electron microscopy (SEM). Samples were prepared by casting
a drop of sample solution onto a carbon-coated grid. Fig. 4
displays the large-area SEM images of microstructures fabri-
cated from 1–3. As can be found, all these three phthalocyanine
compounds self-assemble into micro-wire aggregates with
0.5–1.5 mm widths and lengths of hundreds of micrometres.
The microstructures fabricated from 1–3 would be promising
candidates for applications in electronic devices in particular as
n-type semiconducting components for the fabrication of
complementary p–n circuits and organic bulk heterojunction
photovoltaic cells. To demonstrate the potentials of these
compounds, the microstructures were carefully pressed onto two
55 mm spaced Au electrodes to measure their current–voltage
characteristics, Fig. S7 (ESI†). Fig. 5 shows the current–voltage
(I–V) characteristics of micro-wires of 1–3. For the devices
measured, the conductivities for H2Pc(SO2C6H13)8 (1), Cu[Pc
(SO2C6H13)8] (2), and Zn[Pc(SO2C6H13)8] (3) micro-wires
extracted from the quasilinear region at low bias (up to ꢀ100 V)
were 5.24 ꢂ 10ꢀ4, 2.73 ꢂ 10ꢀ4, and 1.17 ꢂ 10ꢀ7 S mꢀ1, respec-
tively, demonstrating their good semi-conducting properties. In
particular, the conductivity for the former two compounds is as
The redox behavior of the octakis(hexylthio)phthalocyanines
M[Pc(SC6H13)8] (M ¼ 2H, Cu, Zn) was also studied by cyclic
voltammetry (CV) and differential pulse voltammetry (DPV) in
CH2Cl2. The half-wave potentials are summarized in Table 3.
Obviously, the slightly smaller potential difference (1.37ꢁ1.48 V)
between the first oxidation and first reduction of M[Pc(SC6H13)8]
(M ¼ 2H, Cu, Zn) in comparison with that (1.54ꢁ1.60 V) of M
[Pc(SO2CH3)8] (M ¼ 2H, Cu, Zn) (1–3) is in good agreement with
the blue-shift (25ꢁ28 nm) of the Q absorption band of the latter
species relative to the former ones.
I–V properties
The microstructures were fabricated by covering methanol over
a solution of the phthalocyanine compounds 1–3 in chloroform
Fig. 4 Low-magnification field-emission scanning electron microscopy (FESEM) images of H2Pc(SO2C6H13)8 (1) micro-wires (A), CuPc(SO2C6H13)8
(2) micro-wires (B), and ZnPc(SO2C6H13)8 (3) micro-wires (C) on SiO2.
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[ClO4] was recrystallized twice from tetrahydrofuran. All other
reagents and solvents were used as received. 4,5-Di(hexylthio)
phthalonitrile26b and 4,5-di(hexylsulfonyl)phthalonitrile25c were
prepared according to the published procedure with slight
modification.
1H NMR spectra were recorded on a Bruker DPX 400 spec-
trometer in CDCl3. Spectra were referenced internally using the
residual solvent resonance (d ¼ 7.26 ppm for 1H NMR) relative
to SiMe4. Electronic absorption spectra were recorded on
a Hitachi U-4100 spectrophotometer. IR spectra were recorded
in KBr pellets using a Bruker Tensor 37 spectrometer with 2 cmꢀ1
resolution. MALDI-TOF mass spectra were taken on a Bruker
Microflexꢀ LRF spectrometer with dithranol as the matrix.
Elemental analyses were performed on an Elementar Vavio El III
elemental analyzer. SEM images were obtained using a JEOL
JSM-6700F field-emission scanning electron microscope. The
current–voltage characteristics were obtained with a Keithley
4200 semiconductor characterization system at room tempera-
ture in air.
Fig. 5 I–V curves measured on H2Pc(SO2C6H13)8 (1) micro-wires
(dash line), Cu[Pc(SO2C6H13)8] (2) micro-wires (solid line), and
Zn[Pc(SO2C6H13)8] (3) micro-wires (dot line).
high as that for some chemical doping organic nano-
structures,34b,35 rendering them a wide range of electronic device
applications.
Electrochemical measurements were carried out with a BAS
CV-50W voltammetric analyzer. The cell comprised inlets for
a glassy carbon disk working electrode of 2.0 mm in diameter and
a silverwire counter electrode. The reference electrode was Ag/
Ag+ (a solution of 0.01M AgNO3 and 0.1M TBAP in acetoni-
trile), which was connected to the solution by a Luggin capillary
whose tip was placed close to the working electrode. It was
corrected for junction potentials by being referenced internally to
As can be seen from Fig. S8 (ESI†), the
three
2,3,9,10,16,17,23,24-octakis(hexylthio)phthalocyanine
counterparts H2Pc(b-SC6H13)8, Cu[Pc(b-SC6H13)8], and Zn[Pc-
(b-SC6H13)8] have also been fabricated into microstructures with
micro-sphere, micro-flowers, and three-dimensional network
morphology. The current–voltage (I–V) measurement reveals
the ferrocenium/ferrocene (Fc+/Fc) couple [E1/2(Fc+/Fc)
¼
their low conductivity with the value of 1.04 ꢂ 10ꢀ7, 5.28 ꢂ 10ꢀ7
,
+0.50 V vs. SCE]. Typically, a 0.1 M solution of [NBu4][ClO4] in
CH2Cl2 containing 0.5 mM of sample was purged with nitrogen
for 10 min, and then the voltammograms were recorded at
ambient temperature. The scan rate was 20 and 10 mV sꢀ1 for CV
and DPV, respectively.
and 8.16 ꢂ 10ꢀ7 S mꢀ1, Fig S9 (ESI†).
Conclusions
In summary, the synthesis of 2,3,9,10,16,17,23,24-octakis(hexy-
lsulfonyl)phthalocyanine derivatives in particular the copper and
zinc complexes have been described in detail. The effect of the
eight strong electron-withdrawing hexylsulfonyl groups on the
spectroscopic and electrochemical properties of the phthalocya-
nines has been demonstrated by experimental and DFT calcu-
lation methods. Electrochemical and current–voltage
measurements reveal their n-type nature and good semi-
conducting properties. This, in combination with their good
solubility in common organic solvents and high chemical
stability, gives great potential in applications as a necessary
component for fabricating both complementary p–n circuits and
organic bulk heterojunction photovoltaic cells, in particular via
solution-based processes.
Computational details
The primal input structures of M[Pc(SO2CH3)8] [M ¼ 2H (10),
and Zn (30)], which were obtained by putting eight methyl-
sulfonyl groups onto the peripheral positions of MPc, were
subjected to DFT calculation instead of M[Pc(SO2C6H13)8] [M ¼
2H (1), and Zn (3)] to simplify the calculations. The hybrid
density functional B3LYP (Becke-Lee-Young-Parr composite of
exchange–correlation functional) method was used for both
geometry optimizations and property calculations.36 In all cases,
the LanL2DZ, 6-31G(d), and 6-31+G(d) basis sets37 were
employed for Cu/Zn, C/N/H, and S/O, respectively. The Berny
algorithm using redundant internal coordinates was employed in
energy minimization and the default cutoffs were used
throughout.38 Using the energy-minimized structures generated
in the previous step, normal coordinate analyses were carried
out. All calculations were carried out using the Gaussian 03
program39 in the IBM P690 system in Shandong Province High
Performance Computing Centre.
Experimental section
General remarks
4,5-Dichlorophthalonitrile was purchased from TCI. n-Pentanol
was distilled from sodium. DMF and o-dichlorobenzene were
distilled from anhydrous MgSO4, while 2-ethoxyethanol from
anhydrous K2CO3. Dichloromethane was freshly distilled from
CaH2 under nitrogen. m-Chloroperbenzoic acid was purchased
from Tianjin Chemical Reagent Co. Column chromatography
was carried out on silica gel columns (Merck, Kieselgel 60, 70–
230 mesh) with the indicated eluents. The electrolyte [Bu4N]
Preparation of 4,5-di(hexylsulfonyl)phthalonitrile
m-Chloroperbenzoic acid (200 mg, 1.01 mmol) was slowly added
to
a solution of 4,5-di(hexylthio)phthalonitrile (100 mg,
0.27 mmol) in CH2Cl2 (3 mL) and stirred at room temperature
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for 16 h. The white precipitate was collected by filtration and
washed with water. The following crystallization from
ethanol gave the target compound as a white powder (90 mg,
to dryness under reduced pressure and the residue was chroma-
tographed on a silica gel column using CHCl3 as the eluent. The
blue band containing the target compound was collected.
Repeated chromatography followed by recrystallization from
CHCl3 and MeOH gave pure Cu[Pc(SO2C6H13)8] (2) as blue
powder (12 mg, 42%).
ꢃ
1
76%). Mp: 77 C. H NMR (CDCl3, 400 MHz): d 7.42 (s, 2H,
arom H), 3.64–3.68 (t, 4H, SO2CH2CH2CH2CH2CH2CH3),
1.72–1.76 (m, 4H, SO2CH2CH2CH2CH2CH2CH3), 1.41
(m, 4H, SO2CH2CH2CH2CH2CH2CH3), 1.28 (m, 8H,
SO2CH2CH2CH2CH2CH2CH3), 0.87 (t, 6H, SO2CH2-
CH2CH2CH2CH2CH3). MALDI-TOF MS: an isotopic cluster
peaking at m/z 424.2, Calcd. for C20H28N2O4S2: [M]+ 424.1.
Anal. Calcd. For C20H28N2O4S2$0.5H2O: C, 55.40; H, 6.74; N,
6.46; found: C, 54.98; H, 6.96; N, 6.08.
Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyaninato zinc complex Zn[Pc(SO2C6H13)8] (3) by cyclic
tetramerization of di(hexylsulfonyl)phthalonitrile via
diiminoisoindoline intermediate
By using the procedure described above with Zn(OAc)2$2H2O
(5 mg, 0.022 mmol) instead of Cu(OAc)2$H2O as the starting
material, compound Zn[Pc(SO2C6H13)8] (3) was obtained after
repeated chromatography with CHCl3 as eluent followed by
recrystallization from CHCl3 and MeOH as blue powder (13 mg,
43%).
Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyanine H2Pc(SO2C6H13)8 (1) by cyclic tetramerization
of di(hexylsulfonyl)phthalonitrile via diiminoisoindoline
intermediate
A solution of sodium (20 mg, 0.87 mmol) in methanol (20 mL)
was cooled to 0 ꢃC under stirring. Then 4,5-di(hexylsulfonyl)
phthalonitrile (472 mg, 1.1 mmol) was added and ammonia gas
was bubbled through the reaction mixture. After 20 min, the
solution became yellow and TLC revealed that no starting
material remained. The mixture was evaporated to dryness under
reduced pressure and the residue was chromatographed on
a silica gel column using CHCl3/methanol (9 : 1) as the eluent,
leading to corresponding diiminoisoindoline compound as
a yellow solid (160 mg, 33%). A solution of this compound
(36 mg, 0.08 mmol) in DMF/o-dichlorobenzene (1 : 1) (2 mL)
was heated at 150 ꢃC for 12 h under nitrogen. After being cooled
to room temperature, the mixture was evaporated to dryness
under reduced pressure and the residue was chromatographed on
a silica gel column using CHCl3 as the eluent. A blue band
containing the target compound was collected. Repeated chro-
matography followed by recrystallization from CHCl3 and
MeOH gave pure H2Pc(SO2C6H13)8 (1) as blue powder (14
mg, 40%).
Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyaninato copper complex Cu[Pc(SO2C6H13)8] (2) by
direct cyclic tetramerization of di(hexylsulfonyl)phthalonitrile
A mixture of di(hexylsulfonyl)phthalonitrile (30 mg, 0.07 mmol)
and Cu(OAc)2$H2O (5 mg, 0.025 mmol) in 2-ethoxyethanol/
ꢃ
o-dichlorobenzene (3 : 1) (2 mL) was heated at 145 C for 12 h
under nitrogen. After being cooled to room temperature, the
mixture was evaporated to dryness under reduced pressure and
the residue was chromatographed on a silica gel column using
CHCl3 as the eluent. The blue band containing the target
compound (2) was collected. Repeated chromatography fol-
lowed by recrystallization from CHCl3 and MeOH gave blue
powder (2.9 mg, 9.3%).
Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyaninato zinc complex Zn[Pc(SO2C6H13)8] (3) by direct
cyclic tetramerization of di(hexylsulfonyl)phthalonitrile
Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyanine H2Pc(SO2C6H13)8 (1) by oxidation of the
hexylthio subtituents of H2Pc(SC6H13)8
By using the procedure described above with Zn(OAc)2$2H2O
(5 mg, 0.022 mmol) instead of Cu(OAc)2$H2O as starting
material, compound Zn[Pc(SO2C6H13)8] (3) was obtained after
repeated chromatography with CHCl3 as eluent followed by
recrystallization from CHCl3 and MeOH as blue powder (3 mg,
9.6%).
m-Chloroperbenzoic acid (339.5 mg, 1.97 mmol) was slowly
added to a solution of H2Pc(SC6H13)8 (100.5 mg, 0.07 mmol) in
CH2Cl2 (10 mL) and stirred at room temperature for 16 h. The
resulting mixture was directly chromatographed on a silica gel
column using CHCl3 as the eluent. Repeated chromatography
followed by recrystallization gave pure H2Pc(SO2C6H13)8 (1) as
green powder (43.6 mg, 37%).
Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyaninato copper complex Cu[Pc(SO2C6H13)8] (2) by
oxidation of Cu[Pc(SC6H13)8]
Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyaninato copper complex Cu[Pc(SO2C6H13)8] (2) by
cyclic tetramerization of di(hexylsulfonyl)phthalonitrile via
diiminoisoindoline intermediate
m-Chloroperbenzoic acid (34.4 mg, 0.20 mmol) was slowly added
to a solution of Cu[Pc(SC6H13)8] (16.0 mg, 0.01 mmol) in CH2Cl2
(10 mL) and stirred at room temperature for 16 h. The resulting
mixture was directly chromatographed on a silica gel column
using CHCl3 as the eluent. A blue band containing the target
compound was collected. Repeated chromatography followed by
recrystallization from CHCl3 and MeOH gave pure Cu[Pc
(SO2C6H13)8] (2) as blue powder (9.9 mg, 56%).
A mixture of diiminoisoindoline compound (36 mg, 0.08 mmol)
derived from 4,5-di(hexylsulfonyl)phthalonitrile and Cu
(OAc)2$H2O (5 mg, 0.025 mmol) in DMF/o-dichlorobenzene
(1 : 1) (2 mL) was heated at 150 ꢃC for 12 h under nitrogen. After
being cooled to room temperature, the mixture was evaporated
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Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyaninato zinc complex Zn[Pc(SO2C6H13)8] (3) by
oxidation of Zn[Pc(SC6H13)8]
€
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starting material, compound Zn[Pc(SO2C6H13)8] (3) was
obtained after repeated chromatography with CHCl3 as the
eluent followed by recrystallization from CHCl3 and MeOH as
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Preparation of 2,3,9,10,16,17,23,24-octakis(hexylsulfonyl)
phthalocyaninato copper complex Cu[Pc(SO2C6H13)8] (2) by
insertion metal ion into H2Pc(SO2C6H13)8
A mixture of H2[Pc(SO2C6H13)8] (1) (43.6 mg,0.022 mmol) and
Cu(OAc)2$H2O (30.2 mg, 0.15 mmol) in DMF (5 mL) was
heated at 150ꢃ for 3 h under nitrogen. After being cooled to room
temperature, the mixture was evaporated to dryness under
reduced pressure and the residue was chromatographed on
a silica gel column using CHCl3 as the eluent. The blue band
containing the target compound (2) was collected. Repeated
chromatography followed by recrystallization from CHCl3 and
MeOH gave blue powder (40 mg, 88.6%).
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insertion metal ion into H2Pc(SO2C6H13)8
By means of the procedure described above using Zn
(OAC)2$2H2O (33 mg, 0.15 mmol) instead of Cu(OAc)2$H2O as
starting material, compound Zn[Pc(SO2C6H13)8] (3) was
obtained after repeated chromatography with CHCl3 as the
eluent followed by recrystallization from CHCl3 and MeOH as
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Acknowledgements
Financial support from the Natural Science Foundation of
China, Ministry of Education of China, Fundamental Research
Funds for the Central Universities, and Beijing Natural Science
Foundation is gratefully acknowledged. We are also grateful to
the Shandong Province High Performance Computing Centre
for a grant of computer time.
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