Peripherally and axially carboxylic acid substituted subphthalocyanines for dye-sensitized solar cells

Article abstract of DOI:10.1002/chem.201303639

A series of subphthalocyanines (SubPcs) bearing a carboxylic acid group either at the peripheral or axial position have been designed and synthesized to investigate the influence of the COOH group positions on the dye-sensitized solar cell (DSSC) performance. The DSSC devices based on SubPcs with axially substituted carboxylic acid groups showed low photovoltaic performance, whereas peripherally substituted one exhibited higher power conversion efficiency owing to improved injection from LUMO of SubPcs to the TiO₂ conduction band.

Full text of DOI:10.1002/chem.201303639

DOI: 10.1002/chem.201303639
Full Paper
&
Photosensitizers
Peripherally and Axially Carboxylic Acid Substituted
Subphthalocyanines for Dye-Sensitized Solar Cells
[a]
[a]
[b]
[b]
[a]
¨
Mine Ince, Anaıs Medina, Jun-Ho Yum, Aswani Yella, Christian G. Claessens,
M. Victoria Martꢀnez-Dꢀaz,[a] Michael Grꢁtzel,[b] Mohammad K. Nazeeruddin,*[b] and
Tomꢂs Torres*[a, c]
Abstract: A series of subphthalocyanines (SubPcs) bearing
a carboxylic acid group either at the peripheral or axial posi-
tion have been designed and synthesized to investigate the
influence of the COOH group positions on the dye-sensitized
solar cell (DSSC) performance. The DSSC devices based on
SubPcs with axially substituted carboxylic acid groups
showed low photovoltaic performance, whereas peripherally
substituted one exhibited higher power conversion efficien-
cy owing to improved injection from LUMO of SubPcs to the
TiO2 conduction band.
Introduction
which are synthetic analogues of porphyrin, have been widely
used as sensitizers because of their improved light-harvesting
properties in the far red- and near-IR spectral regions and their
extraordinary robustness.[3] However, efficiency values of Pc-
based DSSCs are in general below those made of their porphy-
rin relatives owing to a lack of absorption in the visible region.
Nevertheless, the performance of Pc-based solar cells has been
recently improved up to 5.9% by careful modifications of Pc
structures.[4]
Porphyrinoid dyes have a high molar extinction coefficient in
the red/near-infrared region and therefore they have recently
received much attention as the alternative to Ru-based dyes
for their application in the field of dye-sensitized solar cells
(DSSCs). Among them, a very high efficiency of up to 11% has
been achieved by rational design of a push–pull porphyrin dye
bearing an electron-donating diarylamino group at one meso
position opposite to the binding 4-ethynylbenzoic acid
moiety.[1] A record power conversion efficiency in this family of
porphyrin sensitizers has been recently reported by the same
authors using a related porphyrin dye (YD2-o-C8) and an or-
ganic dye as co-sensitizer.[2] These results demonstrate that
a careful choice of the appropriate substituted porphyrinoids
may yet offer a feasible alternative the most commonly used
ruthenium dyes. Unfortunately, the photophysical stability of
these porphyrin dyes is not very high, but these results are the
most important proof of concept for future applications of por-
phyrinoids in DSSCs. On the other hand, phthalocyanines (Pc),
The chemical flexibility of Pcs from the structural point of
view allows the formal replacement of one or more isoindol
units by other hetero- or carbocycles. This fact has been ex-
ploited in the preparation of novel Pc derivatives with different
absorption properties to match the terrestrial solar emission
spectrum. For instance, the formal removal of one isoindol unit
from the Pc skeleton leads to the SubPc analogues. Subphtha-
locyanines (SubPcs)[5] are Pc analogues comprising a 14-p elec-
tron nonplanar aromatic macrocycle consisting of three diimi-
noisoindole units N-fused around a central boron atom. In con-
trast with their related congeners, namely the planar Pcs,
SubPcs possess a peculiar conical structure, which provides
them with relatively high solubility and low tendency to aggre-
gate. The important photophysical advantage of this class of
compounds is based on their strong light absorption proper-
ties in the visible region (500–700 nm), which makes them an
effective light harvesting material for artificial photosynthetic
systems.[6] Additionally, their electronically rich p-conjugated
system and lower oxidation potential render them an excellent
material for the production of solution-processed small-mole-
cule OPVs.[7] For instance, Verreet et al. have reported efficient
organic photovoltaic cells with a power conversion efficiency
of 4% by using a fluorinated fused subphthalocyanine dimer
as a deep-red absorbing acceptor.[8] In this regard, SubPcs have
appeared as an alternative active-layer component in photo-
voltaic devices owing to the high open-circuit voltage (Voc)
values obtained by their introduction. Even though SubPcs
[a] Dr. M. Ince, Dr. A. Medina, Dr. C. G. Claessens, Dr. M. V. Martꢀnez-Dꢀaz,
Prof. T. Torres
Departamento de Quꢀmica Orgꢁnica
Universidad Autꢂnoma de Madrid, Cantoblanco, 28049 Madrid (Spain)
Fax: (+34)914973966
E-mail: tomas.torres@uam.es
[b] Dr. J.-H. Yum, Dr. A. Yella, Prof. M. Grꢃtzel, Dr. M. K. Nazeeruddin
Laboratory for Photonics and Interfaces
Institute of Chemical Sciences and Engineering
School of Basic Sciences, Swiss Federal Institute of Technology
1015 Lausanne (Switzerland)
Fax: (+41)21693-4111
E-mail: mdkhaja.nazeeruddin@epfl.ch
[c] Prof. T. Torres
IMDEA Nanociencia
C/Faraday, 9, Cantoblanco, 28049 Madrid (Spain)
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201303639.
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have proven to be promising candidates as donor material for
small-molecule organic solar cells, there has been no report on
the immobilization of SubPcs on nanocrystalline TiO2 to date.
The characteristic features of SubPcs, therefore, encouraged us
to investigate dye-sensitized solar cells using SubPcs as a light
harvesting material.
benzoic acid. SubPc 6 was prepared by a statistical condensa-
tion reaction of 4-iodophthalonitrile[9] and 4-tert-butylphthalo-
nitrile (1:2 molar ratio) in the presence of BCl3, followed by
substitution of the axial chlorine atom with 4-tert-butylphenol
in toluene. After purification by column chromatography, com-
pound 6 was obtained in 12% yield, (Scheme 1). SubPcs 1 and
In this context, the work presented herein is focused on the
synthesis of new SubPc sensitizers (Figure 1) bearing a carbox-
Scheme 1. Synthesis of subphthalocyanines (SubPcs) 6, 1, and 2.
Figure 1. Molecular structure of subphthalocyanines designed for DSSCs.
2 were prepared by Sonagashira coupling reaction between io-
doSubPc 6 and the corresponding carboxylic acid derivative.
Both reactions were carried out in DMF in the presence of
[PdCl2(PPh3)2] as a catalyst, triethylamine as the base, and a cat-
alytic amount of copper iodide. The purification of the crude
material by column chromatography allowed the isolation of
carboxySubPcs from the remaining iodoSubPc. SubPc 1 and 2
were obtained in 43% and 48% yields, respectively, based on
the recovered SubPc 6. SubPcs 1, 2, and 6 are each mixture of
two constitutional isomers, which could not be separated by
column chromatography.
ylic acid group located either at the peripheral or axial posi-
tions. The photovoltaic performance of SubPcs in DSSCs was
tested for the first time and the results provide a comparison
of photovoltaic properties of SubPcs with carboxylic acid
groups appended axially and peripherally.
Results and Discussion
Synthesis
Subphthalocyanines are formed by cyclotrimerization of phtha-
lonitriles in the presence of boron reagents in a high-boiling-
point solvent, such as p-xylene.[5] Among the different boron
reagents, BCl3 has been the more widely used. In general, the
axial functionalization of SubPcs with nucleophiles such as
phenol derivatives not only facilitates their purification by
column chromatography separation, but also prevents hydroly-
sis during the chromatographic work up in silica gel, as is
sometimes the case of bromo- or chloro-substituted SubPcs.
On the other hand, functionalization of the peripheral benzene
ring of the SubPc is somewhat difficult owing to its chemical
instability. Indeed, the SubPc ring is frequently destroyed in
the presence of a nucleophile at high temperatures or in basic
media. Nevertheless, several metal-catalyzed reactions have
been reported by our group on the coupling of peripherally
iodine-substituted SubPcs with terminal alkynes.[6b–d]
Figure 2 displays the UV/Vis spectra of SubPc 1 and 2, which
are very similar, showing the Q band at 580 nm, together with
a shoulder of vibronic origin.
The precursor 8 of the axially substituted SubPc 3 was pre-
pared in an overall yield of 76% by a cyclotrimerization reac-
tion of tetrafluorophthalonitrile in the presence of boron tri-
choride, followed by in situ substitution reaction of the chloro-
SubPc intermediate with m-hydroxybenzaldehyde in toluene
(Scheme 2). SubPc 8 was converted to SubPc 3 in 90% yield
by oxidation with sodium chlorite in the presence of sulfamic
acid as hypochlorite scavenger.
The synthesis of thioether-substituted SubPcs 4 and 5 was
carried out as outlined in Scheme 3. Butyl and tert-butyl
phenyl (alkyl and a bulky non-aggregating group, respectively)
were chosen as radicals on the sulfur atoms. Dicyano com-
pounds 9 and 10 were obtained in 72% and 80% yields, re-
spectively, by nucleophilic aromatic substitution of 4,5-dichlor-
ophthalonitrile[10] with butanothiol and tert-butylthiophenol.
Cylotrimerization of the corresponding phthalonitrile in pres-
ence of BCl3, followed by in situ substitution of axial chlorine
with 3-hydroybenzoic acid directly afforded SubPcs 4 and 5 in
42 and 27% yield, respectively.
The synthesis of SubPcs 1 and 2, peripherally substituted
with a terminal carboxylic acid group was, thus, carried out in
two steps. First, di(tert-butyl)iodoSubPc 6 was synthesized and
then the corresponding acid derivatives were obtained by
means of a Sonogashira catalytic cross-coupling reaction with
the appropriate alkyne, namely propargylic acid and 4-ethynyl-
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Figure 3. UV/Vis spectra of SubPc 3, 4, and 5 in CHCl3 (ca. 1.10À5 m).
Figure 2. UV/Vis spectra of SubPc 1 and 2 in CHCl3 (ca. 1.10À5 m).
SubPcs gave rise to well-resolved spectra in CDCl3. All aromatic
protons appear between 9.5–7.0 ppm, with the exception of
the axial phenoxy ligand, the signals of which are shifted up-
field, which is due to the strong ring current produced by the
aromatic core.
Photovoltaic studies
Tables 1 and 2 summarize the I–V (short-circuit currents Jsc,
open-circuit voltages Voc, fill factors FF, and conversion efficien-
cies h) of the peripherally and axially substituted carboxy-
SubPcs in DSSCs, respectively. Owing to the cone-shaped ge-
ometry of SubPcs, which contrasts with the flat structure of
Pcs, SubPcs have a remarkably lower aggregation tendency;
therefore, the addition of coadsorbant does not influence the
photovoltaic performance. All of the SubPcs dye solutions
Scheme 2. Synthesis of SubPcs 8 and 3.
Table 1. Photovoltaic performance of SubPc 1 and 2 in the presence of
different electrolytes.
Dye
Electrolyte
Jsc [mA/cm2]
Voc [mV]
FF
h [%]
1
959
960
AY2
AY3
959
960
AY2
AY3
0.32
0.94
5.36
6.17
0.19
0.55
5.5
542
532
347
357
547
519
343
347
0.647
0.715
0.550
0.599
0.639
0.727
0.585
0.622
0.11
0.36
1.03
1.32
0.07
0.21
1.12
1.08
2
4.9
Scheme 3. Synthesis of SubPcs 4 and 5.
Table 2. Photovoltaic performance of SubPc 3, 4, and 5.
The UV/Vis absorption spectra for axially carboxySubPcs are
shown in Figure 3. SubPcs 4 and 5 bearing electron-donating
group revealed a strong bathochromic shift of their Q band
(ca. 30 nm) with respect to acceptor SubPc 3.
All of the compounds were characterized by MALDI-TOF,
1H NMR, UV/Vis, and IR spectroscopy. Unlike typical broadened
peaks observed in the 1H NMR spectra of phthalocyanines that
are due to the tendency of their p-system to form aggregates,
Dye
Electrolyte
Jsc [mA/cm2]
Voc [mV]
FF
h [%]
3
A6986
AY3
A6986
AY3
A6986
AY3
0.193
0.308
0.536
2.243
0.325
0.963
338
253
372
275
400
292
0.700
0.582
0.718
0.611
0.729
0.616
0.05
0.05
0.14
0.38
0.09
0.17
4
5
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were prepared in THF at a concentration of 0.1 mm. The film
thickness of transparent TiO2 and light-scattering layer were
7 mm and 4 mm, respectively. Table 1 shows the photovoltaic
performance of dyes 1 and 2 in DSSC using different electro-
lytes (see the Supporting Information for the composition of
the liquid electrolytes).
Conclusion
A series of new axially and peripherally carboxylic acid substi-
tuted SubPcs was prepared and incorporated into DSSC devi-
ces. Power conversion efficiencies were found to be very low
with axially carboxySubPcs. The possible reason for low effi-
ciency could be a mismatch between the TiO2 conduction
band and the LUMO of SubPc and the lack of electronic com-
munication between the p-conjugated chromophore and the
anchoring group owing to the presence of the boron atom.
On the other hand, SubPc derivatives bearing carboxyl groups
at peripheral positions 1 and 2 exhibited a power conversion
efficiency of ca. 1.32% and 1.08%, respectively. These results
are promising and instructive considering that it is the first
report on SubPc-based DSSCs. Further modification of SubPcs
by peripherally substituting them with other donor groups/
and peripherally anchoring groups patterns could be useful to
improve these molecules as photosensitizers for DSSC applica-
tions. The research directed on these lines are undergoing in
our group.
The devices using electrolyte 959 gave a Voc of around
540 mV for both dyes. However, very low short-circuit photo-
current densities (Jsc) were obtained, and as a consequence re-
sulted in lower power conversion efficiencies. Addition of
0.05m LiI to the electrolyte 959 (coded as 960), the efficiencies
obtained were three times higher than in the previous cells for
both SubPcs owing to the increased Jsc. This can be attributed
to the presence of Li+ in electrolyte 960, which caused a drop
in the photovoltage as a result of the downward shift of the
conduction band of the titania and hence an increase in the
Jsc. As addition of LiI increased the Jsc value, an electrolyte em-
ploying 1m LiI and 0.05m I2 (coded as AY2) was used, and this
resulted in higher short-circuit photocurrent density of 5.3 and
5.5 mA/cm2 for SubPc 1 and 2, respectively, which are more
than 10 times higher than that obtained with 959 electrolyte,
whereas the Voc was lower for both dyes and this could be at-
tributed to the downward shift of the conduction band of the
titania owing to the lithium ions, as observed previously.[11] Fi-
nally, by using AY3 electrolyte, which is a mixture of 0.5m LiI
and 0.5m NaI, the power conversion efficiency of cells sensi-
tized with SubPc 1 and 2 reached 1.32 and 1.08%, respectively.
Figure 4 shows the I–V curves obtained with the electrolyte
AY3.
Experimental Section
4’-tert-Butylphenoxy[2(3),16(17)-di(tert-butyl)-9-
iodosubphthalocyaninato]boron(III) (mixture of regioisom-
ers; 6)
BCl3 (7.5 mL, 1m solution in p-xylene) was added to a mixture of 4-
tert-butylphthalonitrile (578 mg, 3.14 mmol) and 4-iodophthaloni-
trile (400 mg, 1.57 mmol) under an argon atmosphere. The reaction
mixture was refluxed at 1508C for 2 h. After cooling down to room
temperature, the unreacted BCl3 and solvent were quickly removed
in vacuo. 4-tert-butylphenol (943 mg, 6.28 mmol), dry toluene
(4 mL), and then TEA (0.2 mL, 1.6 mmol) were added to the crude
mixture and stirring was continued at 1108C for 3 h. The solvent
was removed by vacuum distillation and the solid was washed
with a mixture of methanol/water (4:1). The compound was puri-
fied by column chromatography on silica gel (hexane/dioxane 8:1)
as eluent to yield 6 (186 mg, 0.18 mmol) as a reddish solid. Yield:
1
12%. H NMR (CDCl3, 300 MHz): d=9.2 (d, J=6 Hz, 1H), 8.87 (d, J=
9 Hz, 2H), 8.78–8.72 (m, 2H), 8.6–8.4 (m, 1H), 8.1 (d, J=9 Hz, 1H),
7.9 (d, J=9, 2H) 6.7 (d, J=9 Hz, 2H), 5.2 (d, J=9 Hz, 2H), 1.5 (s,
18H), 1.07 ppm (s, 9H); FTIR (film): n˜ =2961, 2866, 1618, 1605,
1510, 1456, 1177, 1068, 885, 762 cmÀ1; UV/Vis (CHCI3): lmax (loge) =
571 (4.64), 513 (4.08), 315 (4.34), 268 nm (4.46); HRMS (MALDI-TOF,
DCTB): m/z: calcd for C42H40BIN6O [M+]: 781.2432; found: 781.2472.
4’-tert-Butylphenoxy [2(3),16(17)-di(tert-butyl)-9-carboxye-
thynyl subphthalocyaninato)]boron(III) (1) and 4’-tert-butyl-
phenoxy [2(3),16(17)-di(tert-butyl)-9-(4’’-ethynylbenzoic acid)
subphthalocyaninato]boron(III) (2)
Figure 4. I–V curves obtained with the Subpcs 1 (c) and 2 (a) with the
electrolyte AY3 containing 0.5m LiI, 0.5m NaI, and 0.05m I2 in acetonitrile.
General procedure: A mixture of SubPc 6 (50 mg, 0.064 mmol),
[PdCl2(PPh3)2] (4.5 mg, 0.006 mmol) and CuI (0.6 mg, 0.003 mmol)
was stirred in the mixture of DMF/TEA (6:1) (3.5 mL) under argon.
The corresponding alkynyl carboxylic acid derivative (0.2 mmol)
was added while the temperature was kept at 08C. The reaction
was then stirred at room temperature for 2 h. Water was then
added and the mixture was extracted with EtOAc. The combined
organic layers were dried over MgSO4 and evaporated in vacuo.
The power conversion efficiencies (h) of DSSCs based on
SubPcs 3, 4,and 5 were found to be very low owing to mainly
lower photocurrents (see Table 2). The use of AY3 electrolyte
improved the Jsc, which are however still lower than those of
SubPc 1 and 2.
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The solid residue was purified by column chromatography on silica
gel (CH2Cl2/MeOH 10:1).
3’-Carboxyphenoxy-[2,3,9,10,16,17-
thiobutylsubphthalocyaninato]boron(III) (4) and 3’-carboxy-
phenoxy-[2,3,9,10,16,17-tert-
SubPc 1 (12 mg, 0.016 mmol) was obtained as a reddish solid.
Yield: 43% (based on the recovered starting iodoSubPc). 1H NMR
(300 MHz, CDCl3): d =9.3 (s, 1H), 9.2 (s, 2H), 9.1–8.9 (m, 3H), 8.4–
8.2 (m, 3H), 6.9 (d, J=9 Hz, 2H), 5.6 (d, J=9 Hz, 2H), 1.7 (s, 18H),
1.3 ppm (s, 9H); FTIR (film): n˜ =3298, 2961, 2921, 2853, 2218, 1730,
1609, 1474, 1366, 1258, 1177, 1055, 812, 798, 758cmÀ1; UV/Vis
(CHCl3): lmax (loge) = 580 (4.57), 570 (4.49), 542 (4.26), 515 (4.11),
316 (4.40), 268 nm (4.58); HRMS (MALDI-TOF, DCTB): m/z: calcd for
C45H41BN6O3 [M+]: 723.3364; found: 723.3401.
butylthiophenylsubphthalocyaninato]boron(III) (5)
General procedure: A solution of corresponding phthalonitrile
(5 mmol) in the presence of BCl3 (5 mL, 1m solution in p-xylene)
was heated under reflux for 30 min. After cooling down to room
temperature, the unreacted BCl3 and solvent were quickly removed
in vacuo. 3-hydroybenzoic acid (2.5 mmol) and dry toluene (2 mL)
were added to crude mixture and stirring was continued at 1108C
for 12 h. The reaction mixture was cooled down to room tempera-
ture, the solvent was removed under vacuum. The solid residue
was directly subjected to column chromatography on silica gel
using a 3:1 mixture of hexane/EtOAc as eluent.
SubPc 4 was obtained as a deep blue solid. Yield: 42%. 1H NMR
(400 MHz, CDCl3): d=8.6 (s, 6H), 7.4 (d, J=8, 1H), 6.9 (t, J=8, 1H),
6.2 (s, 1H), 5.7 (d, J=8, 1H), 3.2–3.3 (m, 12H), 1.8–1.7 (m, 12H),
1.6–1.4 (m, 12H), 1.0–0.8 ppm (m, 18H); FTIR (KBr): n˜ =2934, 2760,
1481, 1221, 1097, 1056, 904 cmÀ1; UV/Vis (CHCl3): lmax (loge) = 600
(4.9), 582 (4.7), 414 (4.4), 388 (4.5), 295 nm (4.8); HRMS (MALDI-
TOF): m/z: calcd for C55H65N6S6O3B [M+]:1059.3565; found:
1059.3783.
SubPc 2 (17 mg, 0.021 mmol) was obtained as a reddish solid.
Yield: 48% (based on the recovered starting iodoSubPc). 1H NMR
(300 MHz, CDCl3): d=9.4 (s, 1H), 9.2–9.0 (m, 5H), 8.4 (d, J=9 Hz,
2H), 8.3–8.2 (m, 3H), 7.9 (d, J=9 Hz, 2H), 6.9 (d, J=9 Hz, 2H), 5.5
(d, J=9 Hz, 2H), 1.4 (s, 18H), 1.08 ppm (s, 9H); FTIR (film) n˜ =3379,
2961, 2934, 2893, 1726, 1699, 1618, 1510, 1470, 1267, 1254, 1124,
1097, 806, 760 cmÀ1; UV/Vis (CHCl3): lmax (loge) = 583 (4.68), 568
(4.61), 543 (4.35), 523 (4.22), 310 (4,57), 271 nm (4.58); HRMS
(MALDI-TOF, DCTB): m/z: calcd for C51H45BN6O3 [M+]: 799.3677;
found: 799.3744.
SubPc 5 was obtained as a deep blue solid. Yield: 27%. 1H NMR
(400 MHz, CDCl3): d=8.4 (s, 6H), 7.4 (brs, 24H), 7.3 (m, 1H), 6.8 (t,
J=8, 1H), 6.1 (s, 1H), 5.3 (d, J=8, 1H), 1.3 ppm (m, 54H). FTIR
(KBr); n˜ =3437, 2912, 1702, 1625, 1497, 1376, 1098, 877 cmÀ1; UV/
Vis (CHCl3): lmax (loge) = 607 (5.0), 554 (4.5), 423 (4.4), 387 (4.5),
290 nm (4.9); HRMS (MALDI-TOF): m/z: calcd for C91H89N6S6O3B [M+
]: 1515.5441; found: 1515.5560.
3’-Formylphenoxy-[1,2,3,4,8,9,10,11,15,16,17,18-dodeca-
fluoro subphthalocyaninato]boron(III) (8)
BCl3 (5 mL, 1m solution in p-xylene) was added to tetrafluoroph-
thalonitrile (5 mmol) under argon atmosphere. The reaction mix-
ture was refluxed for 30 min. After cooling down to room tempera-
ture, the unreacted BCl3 and solvent were quickly removed in
vacuo. 3-Hydroxybenzaldehyde (2.5 mmol) and dry toluene (2 mL)
were added to crude mixture and stirring was continued at 1108C
for 2 h. The reaction mixture was cooled down to room tempera-
ture, the solvent was evaporated and the solid residue was washed
with a mixture of methanol/water (4:1). The compound was then
purified by column chromatography on silica gel using a 20:1 mix-
ture of toluene/THF as eluent. Compound 8 was further purified by
washing with hexane, giving a dark magenta solid. Yield: 76%.
1H NMR (300 MHz, CDCl3): d=9.63 (s, 1H), 7.2 (dd, Jo =7.6 Hz, Jm =
1.6 Hz, 1H), 7.0 (dd, Jo =7.6 Hz, Jo’ =8.2 Hz, 1H), 5.9 (brs, 1H),
5.57 ppm (dd, Jo’ =8.2 Hz, Jm =1.6 Hz, 1H). FTIR (KBr): n˜ =1682,
1533, 1483, 1266, 1112, 1091, 1054 cmÀ1; UV/Vis (CHCl3): lmax (loge)
= 571 (4.6), 554 (sh), 527 (sh), 307 (4.0), 269 nm (4.1); MS (LSI-MS,
m-NBA): m/z: 748 [M]+. HRLSI-MS (C31H5N6O3F12B): m/z: calcd for
[M+]: 748.0012; found: 748.0006.
Acknowledgements
Financial support is acknowledged from the European Union
within the FP7-ENERGY-2012–1 framework, GLOBALSOL pro-
ject, proposal no. 309194–2, ENERGY.2012.10.2.1, NANOMAT-
CELL, Grant agreement no. 308997, and the Spanish MEC and
MICINN (CTQ2011–24187/BQU and CONSOLIDER INGENIO
2010, CSD2007–00010 on Molecular Nanoscience, PRI-PIBUS-
2011–1128) and the Comunidad de Madrid (MADRISOLAR-2,
S2009/PPQ/1533). M.K.N. thanks World Class University pro-
grams (Photovoltaic Materials, Department of Material Chemis-
try, Korea University) funded by the Ministry of Education, Sci-
ence and Technology through the National Research Founda-
tion of Korea (no. R31-2008-000-10035-0) and the Center for
Advanced Molecular Photovoltaics.
3’-Carboxyphenoxy-[1,2,3,4,8,9,10,11,15,16,17,18-
dodecafluorosubphthalocyaninato]boron(III) (3)
NaClO2 (26 mg, 0.25 mmol) was added slowly to a solution of alde-
hyde 8 (520 mg, 0.71 mmol) in acetone (400 mL). A sulfamic acid
solution (22 mg, 0.25 mmol) in deionized water (50 mL) was then
added in one portion. The reaction mixture was stirred at 08C for
30 min. Once the oxidation was completed (checked by TLC), the
solution was poured into cold water (400 mL). The precipitate was
centrifuged and washed with water/methanol (2:1). Compound 3
was obtained as a dark magenta solid. Yield: 90%. 1H NMR
(400 MHz, CDCl3): d=7.5–7.4 (m, 1H), 6.9–6.8 (m, 1H), 6.1 (brs,
1H), 5.6–5.4 ppm (m, 1H). FTIR (KBr): n˜ =1682, 1533, 1483, 1266,
1112, 1091, 1054 cmÀ1; UV/Vis (CHCl3): lmax (loge) = 571 (4.9), 554
(4.6), 527 (4.3), 307 (4.5), 269 nm (4.4); HRMS (MALDI-TOF): m/z:
calcd for C31H5N6O3F12B [M+]: 747.0354; found: 746.8889.
Keywords: dye-sensitized solar cells
porphyrinoids · subphthalocyanines
· photosensitizers ·
[1] T. Bessho, S. M. Zakeeruddin, C. Y. Yeh, E. W. G. Diau, M. Grꢁtzel, Angew.
Chem. 2010, 122, 6796; Angew. Chem. Int. Ed. 2010, 49, 6646.
[2] A. Yella, H.-W. Lee, H. N. Tsao, C. Yi, A. K. Chandiran, M. K. Nazeeruddin,
E. W.-G. Diau, C.-Y. Yeh, S. M. Zakeeruddin, M. Grꢁtzel, Science 2011, 334,
629.
[3] a) M. V. Martꢀnez-Diaz, G. de La Torre, T. Torres, Chem. Commun. 2010,
46, 7090; b) M. V. Martꢀnez-Diaz, M. Ince, T. Torres, Monatsh. Chem. 2011,
142, 699; c) M. G. Walter, A. B. Rudine, C. C. Wamser, J. Porphyrins Phtha-
locyanines 2010, 14, 759; d) M. Garcꢀa-Iglesias, J.-H. Yum, R. Humphry-
Baker, S. M. Zakeeruddin, P. Pechy, P. Vazquez, E. Palomares, M. Grꢁtzel,
M. K. Nazeeruddin, T. Torres, Chem. Sci. 2011, 2, 1145; e) I. Lopez-Duarte,
Chem. Eur. J. 2014, 20, 2016 – 2021
www.chemeurj.org
2020
ꢃ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
M. Wang, R. Humphry-Baker, M. Ince, M. V. Martꢀnez-Diaz, M. K. Nazeer-
uddin, T. Torres, M. Grꢁtzel, Angew. Chem. 2012, 124, 1931; Angew.
Chem. Int. Ed. 2012, 51, 1895.
f) A. Medina, C. G. Claessens, G. M. A. Rahman, A. M. Lamsabhi, O. Mꢄ,
M. YꢂÇez, D. M. Guldi, T. Torres, Chem. Commun. 2008, 1759; g) D. Gon-
zꢂlez-Rodrꢀguez, E. Carbonell, G. De Miguel Rojas, C. Atienza Castellanos,
D. M. Guldi, T. Torres, J. Am. Chem. Soc. 2010, 132, 16488.
[4] a) S. Mori, M. Nagata, Y. Nagahata, K. Yasuta, R. Goto, M. Kimura, M.
Taya, J. Am. Chem. Soc. 2010, 132, 4054; b) M. E. Ragoussi, J. J. Cid, J. H.
Yum, G. de La Torre, D. Di Censo, M. Grꢁtzel, M. K. Nazeeruddin, T.
Torres, Angew. Chem. 2012, 124, 4451; Angew. Chem. Int. Ed. 2012, 51,
4375; c) M. Kimura, H. Nomoto, H. Suzuki, T. Ikeuchi, H. Matsuzaki, T. N.
Murakami, A. Furube, N. Masaki, M. J. Griffith, S. Mori, Chem. Eur. J.
2013, 19, 7496; d) M. E. Ragoussi, M. Ince, T. Torres, Eur. J. Org. Chem.
2013, 6475.
[5] a) A. Meller, A. Ossko, Monatsh. Chem. 1972, 103, 150; b) B. del Rey, U.
Keller, T. Torres, G. Rojo, F. Agullo-Lopez, S. Nonell, C. Marti, S. Brasselet,
I. Ledoux, J. Zyss, J. Am. Chem. Soc. 1998, 120, 12808; c) C. G. Claessens,
T. Torres, Chem. Eur. J. 2000, 6, 2168; d) C. G. Claessens, D. Gonzꢂlez-Ro-
drꢀguez, T. Torres, Chem. Rev. 2002, 102, 835; e) T. Torres, Angew. Chem.
2006, 118, 2900; Angew. Chem. Int. Ed. 2006, 45, 2834.
[7] a) K. L. Mutolo, E. I. Mayo, B. P. Rand, S. R. Forrest, M. E. Thompson, J.
Am. Chem. Soc. 2006, 128, 8108; b) C. E. Mauldin, C. Piliego, D. Poulsen,
D. A. Unruh, C. Woo, B. Ma, J. L. Mynar, J. M. J. Frꢅchet, ACS Appl. Mater.
Interfaces 2010, 2, 2833; c) E. B. Isaacs, S. Sharifzadeh, B. Ma, J. B.
Neaton, J. Phys. Chem. Lett. 2011, 2, 2531; d) H. Gommans, D. Cheyns, T.
Aernouts, C. Girotto, J. Poortmans, P. Heremans, Adv. Funct. Mater. 2007,
17, 2653; e) R. Pandey, A. A. Gunawan, K. A. Mkhoyan, R. J. Holmes, Adv.
Funct. Mater. 2012, 22, 617.
[8] B. Verreet, B. P. Rand, D. Cheyns, A. Hadipour, T. Aernouts, P. Heremans,
A. Medina, C. G. Claessens, T. Torres, Adv. Energy Mater. 2011, 1, 565.
[9] a) H. Lam, S. M. Marcuccio, P. I. Svirskaya, S. Greenberg, A. B. P. Lever,
C. C. Leznoff, R. L. Cerny, Can. J. Chem. 1989, 67, 1087; b) J. G. Young, W.
Onyebuagu, J. Org. Chem. 1990, 55, 2155.
[6] a) D. Gonzꢂlez-Rodrꢀguez, T. Torres, D. M. Guldi, J. Rivera, L. Echegoyen,
Org. Lett. 2002, 4, 335; b) C. G. Claessens, T. Torres, Chem. Commun.
2004, 1298; c) D. Gonzꢂlez-Rodrꢀguez, T. Torres, D. M. Guldi, J. Rivera,
M. A. Herranz, L. Echegoyen, J. Am. Chem. Soc. 2004, 126, 6301; d) D.
Gonzꢂlez-Rodrꢀguez, C. G. Claessens, T. Torres, S. Liu, L. Echegoyen, N.
Vila, S. Nonell, Chem. Eur. J. 2005, 11, 3881; e) R. S. Iglesias, C. G. Claes-
sens, T. Torres, G. M. Rahman, D. M. Guldi, Chem. Commun. 2005, 2113;
[10] D. Wçhrle, M. Eskes, K. Shigehara, A. Yamada, Synthesis 1993, 194.
[11] D. F. Watson, G. J. Meyer, Coord. Chem. Rev. 2004, 248, 1391.
Received: September 15, 2013
Published online on January 17, 2014
Chem. Eur. J. 2014, 20, 2016 – 2021
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2021
ꢃ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim