Synthesis of mesogenic phthalocyanine-C60 donor-acceptor dyads designed for molecular heterojunction photovoltaic devices

Article abstract of DOI:10.3762/bjoc.5.49

A series of phthalocyanine-C₆₀ dyads 2a-d was synthesized. Key steps in their synthesis are preparation of the low symmetry phthalocyanine intermediate by the statistical condensation of two phthalonitriles, and the final esterification of the

Full text of DOI:10.3762/bjoc.5.49

Synthesis of mesogenic phthalocyanine-C60
donor–acceptor dyads designed for molecular
heterojunction photovoltaic devices
Yves Henri Geerts*1, Olivier Debever1, Claire Amato1
and Sergey Sergeyev*1,2
Full Research Paper
Open Access
Address:
Beilstein Journal of Organic Chemistry 2009, 5, No. 49.
1Université Libre de Bruxelles (ULB), Laboratoire de Chimie des
Polymères, CP 206/01, Boulevard du Triomphe, 1050 Bruxelles,
Belgium and 2University of Antwerp, Department of Chemistry,
Groenenborgerlaan 171, 2020 Antwerp, Belgium
doi:10.3762/bjoc.5.49
Received: 25 June 2009
Accepted: 28 September 2009
Published: 07 October 2009
Email:
Yves Henri Geerts* - ygeerts@ulb.ac.be; Sergey Sergeyev* -
serguei.sergueev@ua.ac.be
Guest Editor: S. Laschat
© 2009 Geerts et al; licensee Beilstein-Institut.
License and terms: see end of document.
* Corresponding author
Keywords:
donor–acceptor dyad; fullerene; liquid crystals; phthalocyanine;
phthalonitrile
Abstract
A series of phthalocyanine-C60 dyads 2a–d was synthesized. Key steps in their synthesis are preparation of the low symmetry
phthalocyanine intermediate by the statistical condensation of two phthalonitriles, and the final esterification of the fullerene deriv-
ative bearing a free COOH group. Structural characterization of the molecules in solution was performed by NMR spectroscopy,
UV–vis spectroscopy and cyclic voltammetry. Preliminary studies suggest formation of liquid crystalline (LC) mesophases for
some of the prepared dyads. To the best of our knowledge, this is the first example of LC phthalocyanine-C60 dyads.
Introduction
Among sustainable energy technologies, photovoltaic (PV) an acceptor of electrons [4-7]. After absorption of a photon, an
conversion of solar energy is considered as a promising solu- initially formed exciton is dissociated at the donor/acceptor
tion. Although currently the market is dominated by inorganic interface into a positive charge (hole) and a negative charge
PV devices, development of organic PV materials is driven by (electron), which are transported to the electrodes. Hence, a crit-
their compatibility with solution processing and hence the ical issue in bulk heterojunction PV devices is the control of
potentially low cost of large-scale production by printing tech- morphology of materials, in order to provide both the efficient
nologies [1-3]. One of the most popular concepts in the design exciton generation and the rapid charge carrier transport. The
of organic PV devices is the “bulk heterojunction” architecture, logical step in the development of this architecture is
featuring blends of the two immiscible materials: a donor and “molecular heterojunction”, that is, creation of covalent link-
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Beilstein Journal of Organic Chemistry 2009, 5, No. 49.
ages between donor and acceptor components [6]. The main Within the concept of a “molecular heterojunction”, a number
idea is that in material well-organized on the molecular level, of phthalocyanine-fullerene dyads and triads were synthesized
donor and acceptor moieties will create the separate pathways [34-38] and long-lived photoinduced charge transfer was
for the transport of holes and electrons, respectively. One can demonstrated in these type of materials [39]. Although
intuitively expect that for such high order of self-organization, examples of mesogenic fullerene derivatives have been previ-
liquid crystalline (LC) materials will be beneficial, because they ously reported [40-44], mesogenic Pc-C60 dyads are unknown,
combine order and fluidity, which allows the self-healing of most probably due to the tedious purification of the unsymmet-
structural defects [8].
rically substituted phthalocyanines bearing long peripheral
substituents. A possible elegant solution to this problem was
One of the most widely used molecules in the bulk heterojunc- demonstrated by Torres and co-workers, who obtained LC
tion PV devices is fullerene C60, firstly in the pristine form and mesophases of several phthalocyanine-C60 dyads by blending
later as easily soluble derivatives such as phenylcycl- them with a mesogenic phthalocyanine derivative [45]. In this
opropa[6,6]C60-butanoic acid methyl ester (PCBM, 1, Figure 1) paper we report the synthesis of the first example, to the best of
[9-12]. It has been used in a combination with a plethora of our knowledge, of mesogenic phthalocyanine-fullerene dyads.
conjugated polymers [13-18] as well as small molecules [19-
21]. Furthermore, a number of C60-containing covalent Results and Discussion
ensembles were studied within the “molecular heterojunction” The structure of dyads 2a–d is depicted in Figure 1. We decided
concept [22-29].
to combine in one molecule the phenylcyclopropa[6,6]C60
moiety of PCBM as an acceptor and a phthalocyanine bearing
Phthalocyanines (Pc) have found a number of industrial applica- three swallow-tail alkoxy groups as a donor. The choice of the
tions as dyes and pigments due to their bright blue or green substituents on the phthalocyanine core was dictated by the
colors combined with extraordinary thermal and photochemical previous finding that the pseudosymmetrical phthalocyanine 3
stability [30]. Phthalocyanines bearing flexible peripheral bearing four such substituents is very soluble in many organic
substituents form columnar mesophases [8,31], which demon- solvents, forms columnar mesophases over a broad temperature
strate very efficient charge transport along the columns [32,33]. range and, at the same time, possesses a reasonably low clearing
A unique combination of properties makes phthalocyanines point (ca. 180 °C) [46]. Finally, a critical issue in obtaining a
excellent candidates as active materials for photovoltaic mesogenic phthalocyanine-C60 dyad can be a difficulty in
devices.
accommodating a bulky C60 molecule in the columnar LC
Figure 1: Phthalocyanine-C60 dyads 2a–d described in this paper, C60-derivative 1 (PCBM) and previously reported mesogenic phthalocyanine 3.
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Beilstein Journal of Organic Chemistry 2009, 5, No. 49.
mesophases [45]. To this end, we envisaged the variation of the cyanines or solid-phase synthesis on polymer supports [48].
linker between the fullerene and the phthalocyanine unit.
However, operationally simplest and shortest route is the statist-
ical condensation of the two different phthalonitriles. This
The synthesis of dyads 2a–d is summarized in Scheme 1 and method inevitably produces a mixture of the desired A3B
Scheme 2. The key step, which also represents a bottle-neck in phthalocyanines with the products of compositions A4, A2B2,
terms of yield (see below), is the preparation of the low- AB3 and B4. In theory, 3 : 1 molar ratio of the two dinitriles is
symmetry phthalocyanines 4a–d. To this end, we originally required to access A3B products. However, using larger excess
decided to explore the statistical condensation of phthalonitriles of one of dinitriles (often 9 : 1 stoichiometry is used) is more
5 and 6a–d (Scheme 1). Previously, synthesis of 4-alkoxy- practical. Although the amount of the A4 phthalocyanine in the
phthalonitriles such as 5 via aromatic nucleophilic substitution reaction mixture grows, the formation of cross-condensation
in 4-nitrophthalonitrile with the corresponding alcohols in the products other than A3B is essentially suppressed (see Figure
presence of LiOH in DMSO was reported [46]. However, the SI2 in the Supporting Information for the graphical presenta-
yields of phthalonitriles 5 were moderate (below 50%) and their tion of the product distribution). Hence, the isolation of the
separation from multiple side products was cumbersome. desired A3B is limited to the separation from the A4. Another
Hence, we preferred to prepare 5 (80% yield) by Williamson factor that facilitates the separation by chromatography is rather
reaction between phenol 7 and bromide 8. The latter was different polarity of the substituents on A and B units. In our
synthesized from the corresponding commercially available case, the oligomethylene linker with a terminal OH group is
alcohol by the well-known general method (CBr4/PPh3) [47]. A much more polar than the bulky swallow-tail alkyl group, and
similar procedure was then used to synthesize phthalonitriles we did not expect difficulties in the separation of condensation
6a–d (80–86% yield) starting from the corresponding commer- products.
cially available ω-bromoalcohols.
However, attempted condensation of 5 and 6a–d gave no
Several strategies for the synthesis of low-symmetry A3B desired phthalocyanine derivative. We reasoned that the unpro-
phthalocyanines (where A and B refer to the chemically tected OH group in one of the reaction components may affect
different isoindole units comprising the phthalocyanine core) the condensation, and converted alcohols 6a–d into acetals
were reported earlier, including expansion of subphthalo- 9a–d (84–93% yield) by treatment with an excess of meth-
Scheme 1: Synthesis of low-symmetry phthalocyanines 4a–d.
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Beilstein Journal of Organic Chemistry 2009, 5, No. 49.
substituent. However, although 2-decyltetradecyl substituents in
3 and 10a–d are formally chiral, they should actually be treated
as pseudo-achiral since the difference between the two of the
substituents at the asymmetric carbon (the two linear alkyl
groups of different length) is very small. As was shown previ-
ously, the complex diastereochemical composition does not
influence the behavior of phthalocyanines bearing similar
swallow-tail branched alkyl chains [46,54-57]. UV–vis absorp-
tion spectra of 4a–d (Figure 2) are characteristic for metal-free
phthalocyanine derivatives: they feature two intense long-wave
absorption bands (termed Q-bands).
Scheme 2: Synthesis of dyads 2a–d.
In the final synthetic step, reaction between 4a–d and the acid
oxyethoxymethyl chloride (MEMCl) in the presence of 11 (prepared by acid-catalyzed hydrolysis of the commercially
i-Pr2EtN as a base. The general choice of acetal as a protective available methyl ester 1, PCBM) [10,58] afforded the corres-
group was dictated by its excellent stability in the presence of ponding dyads 2a–d (Scheme 2). Although in general esterifica-
the strong bases, required for the cyclotetramerization of tion appears as a trivial synthetic transformation, esterification
phthalonitriles. Among various popular acetal protective of 11 is greatly complicated by its poor solubility in virtually all
groups, the relatively polar MEM moiety was chosen to facil- organic solvents. After some experimenting, we found that the
itate the chromatographic separation of the unsymmetrical classical dicyclohexylcarbodiimide/N,N-dimethylamino-
phthalocyanines 10a–d from the major side product 3: the latter pyridine (DCC/DMAP) protocol gives the best results, provided
bears only relatively apolar, bulky swallow-tail alkoxy groups. the acid 11 was first sonicated in o-dichlorobenzene for two
In addition, the signal of the terminal methyl group of the MEM hours prior to reaction, and then an alcohol 4a–d, DCC and
moiety serves as a convenient “marker” in rather complex 1H DMAP were added to the reaction mixture. After purification
NMR spectra of phthalocyanines 10a–d (see below). Condensa- by column chromatography, the dyads 2a–d were isolated in
tion of 5 and 9a–d in n-C5H11OH/n-C5H11OLi upon reflux yields up to 45%. Again, the relatively modest yields are
afforded the desired A3B phthalocyanines 10a–d (13–24% after comparable with or superior to those previously reported for the
column chromatography) together with pseudo-symmetrical A4 esterification of poorly soluble acid 11 with various alcohols
phthalocyanine 3 (35–51%). The seemingly modest yields of [22,50,59].
10a–d actually correspond to those reported earlier for other
A3B-type phthalocyanines: yields higher than 20% are rare in The structure of dyads 2a–d was confirmed by NMR, MALDI
such reactions [45,49-51]. The MEM protective group in 10a–d MS and UV–vis absorption spectroscopy. 1H NMR spectra of
was then quantitatively removed to give 4a–d upon treatment the dyads 2a–d essentially correspond to the superposition of
with pyridinium tosylate (PPTS) in t-BuOH according to previ- the spectra of the phthalocyanine 4a–d and PCBM (1), with the
ously reported general method [52].
exception of the signal of CH2OC=O in dyads 2a–d (ca. 4.10
ppm), which is shifted downfield vs. the signal of CH2OH in
The structure of the phthalocyanines 4a–d was confirmed by 1H phthalocyanines 4a–d (ca. 3.80 ppm). 13C NMR spectrum of
and 13C NMR, and HR-MALDI mass spectrometry. 1H NMR the dyad 2c also essentially represents a superposition of the
spectra of low-symmetry phthalocyanines 4a–d and 10a–d in spectra of phthalocyanine 4c and PCBM (1). However, its
CDCl3 closely resemble those of 3 and feature a series of three detailed interpretation is greatly complicated because of a large
unstructured multiplets from the protons of 1,2,4-substituted number of signals, broadening of the signals due to the complex
benzene rings. Inner-core protons in 4a–d and 10a–d are isomeric composition of phthalocyanine (see above), and over-
observed as a broad and concentration-sensitive high-field laps of signals (see Supporting Information for the original
signal. It should be noted that 3 (as well as any phthalocyanine NMR spectra). For this reason, only selected 13C chemical
derivative prepared from a 4-substituted phthalonitrile) repres- shifts are given in the Experimental Part. UV–vis absorption
ents a mixture of four regioisomers [48,53], while lower- spectra of the dyads 2a–d also appear as superposition of the
symmetry 4a–d and 10a–d are actual mixtures of as many as spectra of 4a–d and 1: next to the intense Q-band (maxima at
eight regioisomers each. This greatly complicates their NMR 670 and 707 nm) and B-band (between ca. 300 and ca. 450 nm)
spectra (see Supporting Information). Furthermore, each regi- of phthalocyanine moiety, very strong high energy absorption
oisomer is a mixture of different diastereoisomers due to the of the cyclopropanated C60 derivative with the maximum at ca.
presence of the asymmetric carbon atom in every peripheral 260 nm is observed (Figure 2).
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Beilstein Journal of Organic Chemistry 2009, 5, No. 49.
Table 1: Experimental values of reduction potentials Eired = (Epic +
Epia)/2 of 1, 2a,d and 3, vs. SCE, in CH2Cl2 (c = 10−4 M), scan rate
100 mV s−1.
E1red, V
E2red, V
E3red, V
E4red, V
E5red, V
1
2a
2d
3
−0.68
−0.73
−0.71
−1.06
−1.09
−1.09
−1.67
−1.60
−1.59
−0.94
−0.94
−0.96
−1.26
−1.25
−1.27
Figure 2: UV–vis absorption spectra of 2a (black), 4a (blue) and 1
(red) in CH2Cl2.
Cyclic voltammetry measurements of dyads 2a and 2d in
CH2Cl2 produced essentially identical results. Wave potentials
do not change upon elongation of the spacer between the donor
and the acceptor (Table 1). Furthermore, the voltammograms
effectively correspond to the superposition of those for PCBM
(1) and the phthalocyanine 3, and do not display supplementary
waves (Figure 3). The reduction part of the voltammograms of
2a,d displays five quasi-reversible reduction waves, three due to
the C60 moiety and two due to the phthalocyanine fragment. In
the oxidation part of the voltammograms of 2a,d, several poorly
resolved waves identical to those of phthalocyanine 3 are
Figure 3: Cyclic voltammograms of 1 (red), 2a (grey), 2d (blue) and 3
(black) in CH2Cl2 (c = 10−4 M), scan rate 100 mV s−1.
observed at potentials up to +1.6 V vs. saturated calomel elec- less that the length of the spacer in 2a–d between the C60 frag-
trode (SCE). These observations, together with UV–vis spectra, ment and the mesogenic phthalocyanine moiety decisively
suggest the absence of intramolecular charge transfer in the affects the supramolecular structure of the material.
ground state for dyads 2a–d.
Conclusion
Preliminary investigation of the dyads 2a–d by polarized optical We report the first example, to the best of our knowledge, of
microscopy (POM) showed that the length of the spacer mesogenic phthalocyanine-C60 dyads. The key step in their
between the phthalocyanine and the fullerene moieties signific- synthesis is the preparation of the low-symmetry phthalocy-
antly affects the thermotropic properties of the material. Dyads anines, bearing three mesogenic swallow-tail substituents and
2a,b are liquid at room temperature, while dyads 2c,d display at an OH-terminated polymethylene linker. These key intermedi-
room temperature fluidic birefringent textures confirming the ates were synthesized by experimentally simple statistical
occurrence of liquid crystalline (LC) mesophases. Upon condensation of two phthalonitriles, giving comparatively high
heating, transitions to isotropic liquid were observed at 120 °C yields (up to 24%) for this type of reaction. Upon the favorable
and 90 °C for 2c and 2d, respectively. For 2c this transition was combination of the length of the linker with the length of peri-
only detectable by POM and not by differential scanning calori- pheral substituents on the phthalocyanine, bulky C60 moiety can
metry (DSC), while for 2d DSC on heating revealed an endo- be accommodated in the LC mesophase. Detailed analysis of
thermic peak at 90 °C [enthalpy 2.7 kJ/mol] in perfect agree- this supramolecular organization, as well as deeper insight in
ment with POM observation. The small enthalpy value supports the structure-property relationships of dyads 2, will be the
the transition from LC mesophase to isotropic liquid. However, subject of a separate publication. Other objectives of our
assignment of the nature of LC mesophases for 1c,d from the ongoing research include: studies of macroscopic alignment in
available data was not obvious, since the textures observed by films of dyads 2, studies of charge carrier mobility in aligned
POM were not characteristic. The major conclusion is nonethe- films, and fabrication and evaluation of photovoltaic devices.
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Beilstein Journal of Organic Chemistry 2009, 5, No. 49.
Experimental
MgSO4 and concentrated in vacuum. Column chromatography
General details. All chemicals were purchased from Aldrich, (SiO2, CH2Cl2) afforded pure 5 as a light yellow solid (4.81
Acros or TCI and used without further purification. Acid 11 mg, 80%); Rf 0.7 (CH2Cl2). Analytical data identical to those
was prepared according to the published procedure [10]. TLC previously reported [46].
was performed on precoated plates with silica gel 60 F254
(Merck), visualization with UV (λ = 254 nm). Column chroma- 4-{10-[(2-Methoxyethoxy)methoxy]decyloxy}phthalonitrile
tography was performed on silica gel (0.040–0.063 mm, (9c). A solution of phthalonitrile 6c (570 mg, 1.47 mmol) and
Macherey–Nagel). 1H NMR and 13C NMR spectra were i-Pr2EtN (0.77 mL, 4.5 mmol) in CH2Cl2 (30 mL) was treated
recorded on Bruker Avance 300 or Varian VNMRS 400 spec- dropwise with MEMCl (0.33 mL, 2.94 mmol) and the resulting
trometers; chemical shifts are given in ppm relative to Me4Si mixture was stirred overnight at r.t. The mixture was then
(internal standard); coupling constants J are given in Hz. treated with aqueous saturated NaHCO3 (35 mL); the organic
MALDI mass spectra were recorded on a Waters MALDI- layer was separated, the aqueous layer was extracted with
QTOF Premier, using a 350 mW laser with dithranol (1,8- CH2Cl2 (2 × 40 mL), combined organic layers were dried over
dihydroxy-10H-anthracen-9-one) as matrix for phthalocyanines MgSO4 and evaporated. Column chromatography of the residue
and with DCB (trans-2-[3-(4-tert-butylphenyl)-2-methyl-2- (CH2Cl2/AcOEt 4 : 1, Rf 0.69) afforded 9c (479 mg, 84%) as a
propenylidene]malonitrile) as matrix for fullerene derivatives; light yellow solid; mp 43 °C; Rf 0.64 (CH2Cl2/AcOEt 9 : 1); 1H
EI and ESI mass spectra were recorded on a Waters AutoSpec NMR (300 MHz, CDCl3, 25 °C): δ = 7.68 (d, 3JH,H = 8.8 Hz,
6. UV–Visible absorption spectra were recorded on a HP 8453 1H), 7.24 (d, 4JH,H = 2.6 Hz, 1H), 7.14 (dd, 3JH,H = 8.8 Hz,
spectrophotometer in a quartz cell (optical path of 1 cm). For 4JH,H = 2.6 Hz, 1H), 4.69 (s, 2H, OCH2O), 4.03 (t, 3JH,H = 6.5
POM experiments, a NIKON Eclipse 80i microscope equipped Hz, 2H, CH2O), 3.68 (t, 3JH,H = 5.1 Hz, 2H, CH2O), 3.52–3.60
with a digital camera DS Camera Head D5-5M was used; (m, 4H, OCH2CH2O), 3.38 (s, 3H, MeO), 1.81 (quint, 3JH,H =
temperature was controlled by a Linkam Scientific Instruments 7.2 Hz, 2H), 1.26–1.64 (m, 14H); 13C NMR (100 MHz, CDCl3,
GS350 hot stage. For DSC, a Perkin Elmer Diamond DSC 25 °C): δ = 162.2, 135.1, 119.5, 119.3, 117.4, 115.7, 115.3,
calorimeter was used.
107.0, 95.5, 71.8, 69.3, 67.9, 66.7, 59.0, 29.7, 29.4, 29.4, 29.4,
29.2, 28.7, 26.2, 25.8; HR-MS (EI): m/z calcd. for C22H32N2O4
Electrochemistry. Cyclic voltammetry experiments were ([M]+): 388.2362, found 388.2374.
performed with a computer controlled Autolab potentiostat.
Measurements were carried out at room temperature in a three- 2 - { 1 0 - [ ( 2 - M e t h o x y e t h o x y ) m e t h o x y ] d e c y l o x y } -
electrode single-compartment cell (10 mL), in CH2Cl2 solu- 9(10),16(17),23(24)-tri(2-decyltetradecyloxy)-29H,31H-
tions (concentration 10−4 M), containing Bu4NPF6 (0.1 M) as phthalocyanine (10c). Li (125 mg, 17.7 mmol) was dissolved
supporting electrolyte, at a scan rate of 100 mV s−1. A glassy under Ar in n-pentanol (10 mL) and the mixture was heated to
carbon, polished by a slurry-suspension of alumina on micro- reflux until Li was completely dissolved. After cooling to r.t., a
cloth and washed by Milli-Q water before each experiment, was solution of phthalonitriles 5 (3.41 g, 7.1 mmol) and 9c (305 mg,
used as a working electrode. A spiral platinum wire was 0.79 mmol) in n-pentanol (15 mL) was added dropwise and the
employed as counter electrode and an Ag/AgCl/KCl(sat) used mixture was heated to reflux overnight. After cooling to r.t.,
as reference electrode was connected to the cell solution via a AcOH was added dropwise until pH 5–6 was reached. The
salt bridge containing a saturated aqueous KCl solution. The green solid was filtered and extensively washed with MeOH.
Ag/AgCl electrode was checked against the ferrocene/ Column chromatography of the residue afforded first 3 (eluted
ferrocinium (Fc/Fc+) couple (E°Fc/Fc+ = 0.425 V vs. Ag/AgCl) with CH2Cl2, 1.76 g, 50%) and then 10c (eluted with CH2Cl2/
before and after each experiment. All potentials are reported AcOEt 1 : 1, 347 mg, 24%). Green solid; Rf 0.75 (CH2Cl2/
versus saturated calomel electrode (SCE) (E°Fc/Fc+ = 0.405 V AcOEt 1:1). 1H NMR (300 MHz, CDCl3, 25 °C): δ = 8.50–8.90
vs. SCE). Before each measurement, solutions were deaerated (m, 4H), 8.10–8.50 (m, 4H), 7.30–7.60 (m, 4H), 4.71 (s, 2H,
by 20 min nitrogen bubbling.
OCH2O), 4.25–4.50 (m, 8H, ArOCH2), 3.65–3.80 (m, 4H,
CH2OCH2OCH2), 3.58–3.63 (m, 2H, OCH2CH2O), 3.36 (s,
4-(2-Decyltetradecyloxy)phthalonitrile (5). To a solution of 3H, MeO), 2.10–2.23 (m, 5H, ArOCH2CH2 + ArOCH2CH),
phenol 7 (1.80 g, 12.5 mmol) and bromide 8 (4.18 g, 10 mmol) 1.15–1.90 (m, 134H), 0.85 (t, 3JH,H = 6.8 Hz, 18H), −2.84 (s,
in dry DMF (60 mL) was added dry K2CO3 (1.72 g, 12.5 2H, NH); 13C NMR (100 MHz, CDCl3, 25 °C): δ = 160.2 (br),
mmol). The mixture was stirred at 90 °C under Ar for 7 h. After 147.0 (br), 136.6 (br), 127.8 (br), 122.2 (br), 117.0 (br), 104.0
cooling to r.t., the mixture was poured into water (60 mL) and (br), 94.6 (OCH2O), 70.9 (br, CH2O), 70.7 (br, CH2O), 67.4
extracted with AcOEt (3 × 200 mL). The combined organic (br, CH2O), 66.9 (CH2O), 65.7 (CH2O), 58.0 (MeO), 37.5 (br),
layers were washed with aqueous NaHCO3 (5%), dried with 30.5–31.0 (several CH2), 28.3–29.4 (several CH2), 26.3 (CH2),
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Beilstein Journal of Organic Chemistry 2009, 5, No. 49.
25.2–25.5 (several CH2), 21.5–21.8 (several CH2), 13.1 (Me);
HR-MS (MALDI): m/z calcd. for C118H190N8O7 ([M]+):
1831.4757, found 1831.4748.
Supporting Information
Experimental procedures and analytical data for derivatives
2a,b,d, 4a,b,d, 6a–d, 9a,b,d, 10a,b,d.
2-(10-Hydroxy-decyloxy)-9(10),16(17),23(24)-tri(2-decyl-
tetradecyloxy)-29H,31H-phthalocyanine (4c). A stirred solu-
tion of the phthalocyanine 10c (275 mg, 0.15 mmol) and PPTS
(188 mg, 0.75 mmol) in t-BuOH (20 mL) was heated to reflux
overnight. After cooling to r.t., the reaction mixture was
concentrated in vacuum. The resulting solid was suspended in
MeOH (50 mL), then filtered, extensively washed with MeOH
Supporting Information File 1
Experimental details
[http://www.beilstein-journals.org/bjoc/content/
supplementary/1860-5397-5-49-S1.doc]
and dried to give 4c (261 mg, 100%). Green solid; 1H NMR Acknowledgements
(300 MHz, CDCl3, 25 °C): δ = 8.90–9.20 (m, 4H), 8.45–8.80 This work has been financially supported by the European
(m, 4H), 7.50–7.75 (m, 4H), 4.35–4.55 (m, 8H, ArOCH2), 3.72 Union (integrated projects FP6-NAIMO NMP4-CT-2004-
(t, 3JH,H = 6.0 Hz, 2H, CH2OH), 2.03–2.20 (m, 5H, 500355 and FP7-ONE-P (grant agreement 212311)). S.S. is an
ArOCH2CH2 + ArOCH2CH), 1.10–1.95 (m, 134H), 0.80–0.93 FNRS researcher. O.D. is an FRIA research fellow.
(m, 18H), −3.07 (s, 2H, NH); 13C NMR (100 MHz, CDCl3, 25
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solid; Rf 0.67 (CH2Cl2/hexane 3 : 2); 1H NMR (300 MHz,
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(d, 3JH,H = 7.4 Hz, 2H), 7.30–7.60 (m, 7H), 4.20–4.50 (m, 8H,
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