Opp-dibenzoporphyrins as a light-harvester for dye-sensitized solar cells

Article abstract of DOI:10.1002/asia.201200507

New opp-dibenzoporphyrins were prepared in a concise method that was based on a Pd⁰-catalyzed cascade reaction. These porphyrins, which contained carboxylic-acid linker groups on benzene rings that were fused to the porphyrin at their β,β'-posi

Full text of DOI:10.1002/asia.201200507

DOI: 10.1002/asia.201200507
Opp-Dibenzoporphyrins as a Light-Harvester for Dye-Sensitized Solar Cells
Rohit Deshpande,[a] Bo Wang,[a] Lin Dai,[a] Lin Jiang,[a] C. Scott Hartley,[a]
Shouzhong Zou,[a] Hong Wang,*[a] and Lei Kerr*[b]
Abstract: New opp-dibenzoporphyrins
were prepared in a concise method
that was based on a Pd0-catalyzed cas-
cade reaction. These porphyrins, which
contained carboxylic-acid linker groups
on benzene rings that were fused to the
porphyrin at their b,b’-positions, were
examined as sensitizers for dye-sensi-
tized solar cells for the first time.
Whereas all of the porphyrins showed
solar-energy-to-electricity conversion,
an opp-dibenzoporphyrin with conju-
gated carboxylic-acid linkers displayed
the highest conversion efficiency and
an exceptionally high Jsc value. Cyclic
voltammetry of these porphyrins sug-
gested that the fusion of two aromatic
benzene rings onto the periphery of
the porphyrin lowered the HOMO–
LUMO energy gap; the incorporation
of a conjugated carboxylic-acid linker
group decreased the HOMO–LUMO
gap even further. These CV data are
consistent with DFT calculations for
these porphyrins and agree well with
the UV/Vis absorption- and fluores-
cence spectra of these porphyrins.
Keywords: benzoporphyrins · cyclic
voltammetry
· density functional
calculations · dyes/pigments · dye-
sensitized solar cells
Introduction
the b-position of the porphyrin, the solar-energy-to-electrici-
ty conversion efficiency (h) was significantly increased.[4] An
efficiency of 7.1% was reported by the Officer and Grꢀtzel
groups in 2007. Very recently, a new class of porphyrins has
been introduced that contained donor–acceptor features at
the meso-positions of the porphyrin through a p-conjugated
bridge.[5] By co-sensitizing with a metal-free dye that had
a complementary spectroscopic response, an unprecedented
high efficiency of 11% was achieved in 2010. By replacing
the tert-butyl groups with octyloxy groups, a record high effi-
ciency (h=12.3%) was obtained,[5k] the highest efficiency so
far for DSSCs.
Dye-sensitized solar cells (DSSCs) have emerged as a prom-
ising photovoltaic technology because they offer the possi-
bility of efficient and inexpensive solar-energy-to-electricity
conversion.[1] In recent years, extensive efforts have been de-
voted to improving the photovoltaic performance and stabil-
ity of DSSCs. Porphyrins are attractive candidates as light
harvesters for DSSCs because of their primary light-harvest-
ing role in nature. Consequently, they have been investigat-
ed for applications in DSSCs over the last twenty years.[1a,d,2]
However, until recently, the overall performance of porphyr-
ins has been significantly inferior to that of ruthenium–poly-
pyridyl dyes. Early work focused on porphyrins with the
linker group (a functional group that is used to connect the
dye to the semiconductor electrode, usually a carboxylic
acid) attached at the meso aryl ring and the resulting DSSCs
generally exhibited low solar-energy-to-electricity conver-
sion efficiencies (<4%).[2c,3] Recently, through attachment
of the linker group through a conjugated spacer moiety at
Although a number of porphyrins have been investigated
in DSSCs, only a handful of b-functionalized porphyrins
have been reported owing to their synthetic complexity.[6]
Porphyrins that are fused with aromatic rings at their b-posi-
tions (p-extended porphyrins) are even more rare owing to
the limited number of available synthetic approaches; in
particular, the marked lack of methods for the functionaliza-
tion of their periphery severely limits their applications.[7]
Only examples of quinoxaline-fused porphyrins are known
in the literature, thus leading to a maximum efficiency of
6.3%.[8] Nevertheless, extended porphyrins appear to be
ideal candidates to further explore porphyrins as light-har-
vesters for solar-energy conversion. Because of the exten-
sion of their p-conjugation, the Soret band of those mole-
cules is bathochromically shifted up to 450–550 nm[9] and an
enhancement of their Q bands is often observed[9a,4e–h] These
features make this class of porphyrin molecules extremely
attractive as dye-sensitizers for DSSCs.
[a] R. Deshpande, B. Wang, L. Dai, L. Jiang, Prof. C. S. Hartley,
Prof. S. Zou, Prof. H. Wang
Department of Chemistry and Biochemistry
Miami University, 701 East High Street
Oxford, OH 45056 (USA)
Fax : (+1)513-529-5715
E-mail: wangh3@muohio.edu
[b] Prof. L. Kerr
Department of Paper and Chemical Engineering
Miami University, 701 East High Street
Oxford, OH 45056 (USA)
Despite recent progress,[9a,b,10] most of the syntheses of p-
extended porphyrins that have been reported require harsh
conditions and/or lengthy procedures. In particular, the lack
Fax : (+1)513-529-0768
E-mail: kerrll@muohio.edu
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of functional groups in these
methods makes the design and
synthesis of functionalized ex-
tended porphyrins challenging.
For example, to be used in
DSSCs, a carboxylic acid group
(that serves to anchor the dye
onto the semiconductor (TiO2)
surface) must be attached onto
the porphyrins. Very recently,
we developed a concise method
to prepare functionalized ben-
zoporphyrins.[11] In this method,
an alkene reacts with a b,b’-di-
bromoporphyrin
through
a three-step cascade reaction
that involves a vicinal two-fold
Heck reaction, 6p-electrocycli-
zation, and subsequent aromati-
zation. The wide variety of
commercially available alkenes
and the easy access to bromo-
porphyrins make it possible to
access a relatively large number
of functionalized benzoporphyr-
ins. Herein, we report the syn-
thesis and characterization of
a series of new opp-dibenzopor-
phyrins and their evaluation as
light harvesters in DSSCs.
Results and Discussion
Synthesis
Scheme 1. Synthesis of opp-dibenzoporphyrins.
The synthesis of opp-dibenzo-
porphyrin dyes is illustrated in
Optical and Electrochemical Properties
Scheme 1. It is widely accepted that porphyrin-aggregation
affects solar-cell efficiency. Thus, porphyrins were prepared
with increasingly bulky substituents, such as para-methyl,
para-isopropyl, and para-tert-butyl, on their meso-phenyl
rings. Tetrabromoporphyrins 2a–2d were readily obtained in
high yield (85–95%) through the treatment of correspond-
ing free-base porphyrin 1 with N-bromosuccinimide (NBS)
in refluxing CHCl3. Tetrabromoporphyrins 2a–2d reacted
with methyl acrylate or (E)-ethyl-penta-2,4-dienoate
through the a Pd0-catalyzed cascade reaction to afford opp-
dibenzoporphyrins 3a–3e in 45–60% yield. Metal insertion
Figure 1 shows the UV/Vis absorption spectra of compounds
5a–5e. Upon fusion of two benzene rings onto the porphy-
rin framework, the Soret band of compounds 5a–5d was
centered at 458 nm, which was about 20–30 nm red-shifted
relative to that of their respective parent porphyrins (1).
The Soret band of compound 5e was further red-shifted by
with ZnACHTUNGTRENNUNG(OAc)2 converted free-base porphyrins 3a–3e into
ZnII–porphyrins 4a–4e in high yields (85–95%). Hydrolysis
of compounds 4a–4e with KOH in refluxing iPrOH afford-
ed ZnII–opp-dibenzoporphyrins 5a–5e in 65–78% yields,
which were suitable for applications in DSSC. The structures
1
of all of these new compounds were verified by H NMR,
13C NMR, and UV/Vis spectroscopy, and by MS (MALDI-
TOF).
Figure 1. UV/Vis absorption spectra of compounds 5a–5e in MeOH.
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Opp-Dibenzoporphyrins as a Light-Harvester for DSSCs
11 nm relative to that of compound 5a–5d, owing to the in-
corporation of conjugated carboxylic-acid linkers onto the
porphyrin. The Q bands of compound 5e were also red-
shifted and broadened. The absorption of compound 5e is
expected to have better overlap with the solar spectrum and
should be more beneficial for harnessing solar energy.
The steady-state fluorescence spectra of compounds 5a–
5e were measured in MeOH by exciting at the position of
the strongest Soret absorption (Figure 2). Two emission
bands were observed (centered at 638 nm and 703 nm) for
compounds 5a–5d. Corresponding to the red-shifting and
broadening of the absorption bands, the two emission bands
of compound 5e were also broadened and red-shifted to
643 nm and 708 nm, respectively.
rin are two p orbitals (a1u and a2u) and two degenerate p* or-
bitals (egx and egy) in the Gouterman four-orbital model.[12]
Analogous MOs are predicted for these less-symmetrical
(effectively C2v) structures (Figure 4). The calculated energy
levels (Table 1) suggest that the LUMO and LUMO+1
remain very nearly degenerate for all of the porphyrins (5a–
5e), owing to the symmetric structure of these porphyrins.
The energy levels of the frontier orbitals of compounds 5a,
5b, and 5c are almost identical, which can be explained by
the presence of similar alkyl substituents (methyl, iPr, and
tBu, respectively) at the para positions of the meso-phenyl
groups. When the substituents at the para position of the
meso-phenyl ring are replaced by methoxy groups (5d),
both the HOMO and the LUMO energy levels move up
slightly (by about 0.06 eV relative to those of compound
5a), whilst the HOMO–LUMO energy gap (about 2.67 eV)
remains unchanged. The LUMO and LUMO+1 of com-
pound 5e are essentially degenerate, but the HOMOÀ1 and
HOMO are further apart than those of compounds 5a–5c.
Comparison of compound 5e with compound 5a suggests
that the incorporation of conjugated carboxylic-acid linkers
leads to a smaller HOMO–LUMO energy gap (by 0.13 eV),
which can be ascribed to a much-lower-energy LUMO be-
cause the HOMO is almost unchanged. These effects are
Figure 2. Steady-state fluorescence spectra of compounds 5a–5e in
MeOH.
DFT Calculations
To gain insight into the optical- and electrochemical proper-
ties of the DSSC-suitable porphyrins (5a–5e), DFT calcula-
tions were performed. From the optimized geometries
(Figure 3), all of the porphyrins (5a–5e) were found to
adopt slightly saddled conformations. The electronic absorp-
tion of the porphyrins, including both Soret bands and
À
Q bands, is due to p p* transitions. The frontier orbitals
that are responsible for the transitions in the parent porphy-
Figure 4. Molecular orbitals of compounds 5a–5e, calculated at the
B3LYP/6-31G(d) level of theory.
Table 1. Calculated molecular-orbital energy levels in compounds 5a–5e.
Compound
HOMOÀ1
HOMO
LUMO
LUMO+1
5a
5b
5c
5d
5e
À5.25
À5.27
À5.26
À5.12
À5.34
À5.13
À5.14
À5.13
À5.07
À5.11
À2.46
À2.47
À2.46
À2.40
À2.57
À2.43
À2.44
À2.43
À2.38
À2.53
Figure 3. Molecular geometries of compounds 5a–5e, calculated at the
B3LYP/6-31G(d) level of theory.
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Hong Wang, Lei Kerr et al.
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Table 2. Oxidation/reduction potentials [V] of porphyrins 4a, 4d, and 4e.
consistent with the observed red-shifting- and broadening in
the absorption and emission spectra of compound 5e upon
the introduction of conjugated linker groups onto the fused
benzene rings of the porphyrin. The HOMOs of compounds
5a–5e involve heavy participation of the fused benzene
rings. Whereas the LUMO of compounds 5a–5d mainly re-
mains on the porphyrin core, the LUMO of compound 5e
engages both the fused benzene rings and the conjugated
linker groups.
Cyclic voltammetry (CV) was used to determine the
redox potentials of these porphyrins (Figure 5). The first ox-
idation potentials of both dibenzoporphyrins 5a and 5b
were negatively shifted by 100 mV compared with their re-
spective parent porphyrins, thus indicating an increase in the
HOMO energy level by 0.1 eV upon fusion of two benzene
rings on the porphyrin periphery. The LUMO energy level
remained almost unchanged (only decreased by about
0.03 eV; Figure 5a,b). The smaller HOMO–LUMO energy
gap corresponded to their red-shifted electronic absorption.
Owing to the low solubility of compounds 5d and 5e in
N,N-dimethylformamide (DMF), the CVs of compounds 4d
and 4e were measured instead, assuming that there was no
significant difference between the electronic properties of
the carboxylic-acid group and the methyl-ester group. For
comparison, the CV of compound 4a was also measured;
the potentials are collected in Table 2. The peak potential
for the first reduction (about À1.0 V) was almost unchanged
for compounds 4a, 4d, and 4e. However, the difference
Compound
V (versus SCE)
0 to À1
À1 to À2
0 to +1
4a
4d
4e
À1.40
À1.40
À1.30
À1.00
À1.00
À1.00
+1.06
+1.04
+1.01
comes on the addition of a second electron: Compound 4e
is more readily reduced than compounds 4a and 4d. For the
first oxidation (the peak is at around +1.0 V), compound 4e
is about 50 mV more easily oxidized than both compounds
4a and 4d. These data suggest that compound 4e has the
smallest HOMO–LUMO energy gap, whilst compounds 4a
and 4d have similar HOMO–LUMO energy gaps. The in-
corporation of conjugated linker groups decreases the
HOMO–LUMO energy gap, which is consistent with the
red shifts in both the Soret- and Q bands in the electronic
absorption spectra. These data also agree well with the DFT
calculations.
Photovoltaic Properties of Porphyrin-Sensitized TiO2 Solar
Cells
The amount of dye that is adsorbed onto a TiO2 surface in-
fluences the efficiency of the cell. To obtain an optimized
solar-energy-to-electricity conversion, a concentration study
was performed with compound 5b. The TiO2 electrode was
immersed in solutions of the
porphyrin (2b) in EtOH for
12 h. The efficiency (h) of solar-
energy-to-electricity conversion
was calculated according to h=
Jsc ꢂVoc ꢂFF (Jsc =short-circuit
current density, Voc =open-cir-
cuit voltage, FF=fill factor). As
listed in Table 3, the highest ef-
ficiency of solar-energy-to-elec-
tricity conversion was obtained
at 0.2 mm. At lower concentra-
tion, the conversion efficiency
was also lower, which may be
due to the insufficient adsorp-
tion of the dye; when higher
concentrations were used, a de-
creasing trend of conversion ef-
ficiency was clearly observed.
This decreasing efficiency was
likely due to more serious ag-
gregation of the porphyrin at
higher concentrations. On the
other hand, the excess dye mol-
ecules blocked the subsequent
layers of the dye next to the
TiO2 surface from being ex-
Figure 5. Cyclic voltammograms of porphyrins in DMF that contained 0.1m TBAP; scan rate: 0.1 VsÀ1. a) 1b
and 5b; b) 1a and 5a; c) 4a, 4d, and 4e.
posed to the redox species and
impeded the dye regeneration,
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Opp-Dibenzoporphyrins as a Light-Harvester for DSSCs
Table 3. Concentration study of porphyrin 5b.
Concentration [mM] Jsc [mAcmÀ2
]
Voc [V] FF
Efficiency [%]
0.45 0.82
0.47 1.59
0.1
0.2
0.3
0.4
0.5
3.61
6.26
4.27
3.41
1.28
0.5
0.54
0.54
0.53
1.05
0.46 1.06
À0.46 0.82
0.41 0.54
thereby resulting in a lower efficiency of solar-energy-to-
electricity conversion in the DSSCs.
Then, the optimized concentration (0.2 mm in EtOH) was
used for modifying the TiO2 electrode with other porphyrins
(5a, 5c–5e); the data for the solar-cell performance of com-
pounds 5a–5e are listed in Table 4. N719 dye ([RuL2
Figure 6. UV/Vis absorption spectra of compounds 5a and 5c. Before:
before adsorption on the TiO2 surface; after: after adsorption on the
TiO2 surface.
The efficiency of solar-energy-to-electricity conversion of
compound 5d was 2.22%, which was smaller than that of
compound 5a. This result can be explained by a slight in-
crease in the HOMO–LUMO gap of compound 5a, owing
to the introduction of strongly electron-donating methoxy
groups at the para positions of the meso-phenyl rings. The
highest solar-conversion efficiency was obtained with com-
pound 5e, which possessed a more extended p system than
compounds 5a–5d. The UV/Vis spectra of compound 5e
showed much more broadened and red-shifted absorption
bands. This feature is expected to bring broader overlap
with the solar spectrum and, thus, enhanced solar-energy
conversion. Notably, the Jsc value of compound 5e (12.87) is
exceptionally high and comparable to that of the best-per-
forming porphyrin dye in a DSSC.[5a–h] This result suggests
that attaching conjugated linkers can considerably change
the electronic profile of the porphyrin dye and, thus, signifi-
cantly enhance the light-harvesting capability of the porphy-
rin dye.
Table 4. Photovoltaic performance of DSSCs that were based on opp-di-
benzoporphyrins 5a–5e.
Dye
Jsc [mAcmÀ2
]
Voc [V]
FF
Efficiency [%]
N719
5a
5b
5c
5d
19.6
8.86
5.05
5.52
7.48
12.87
0.72
0.57
0.54
0.58
0.57
0.53
0.57
0.58
0.56
0.57
0.53
0.46
7.98
2.93
1.54
1.81
2.22
3.14
5e
ACHTUNGTRENNUNG(NCS)2]:2TBA, L=2,2’-bipyridyl-4,4’-dicarboxylic acid,
TBA=tetra-n-butylammonium) on TiO2 was used as a refer-
ence material. Compounds 5a, 5b, and 5c were prepared to
understand how porphyrin-aggregation affected the efficien-
cy of solar-energy-to-electricity conversion of the DSSC.
Compound 5c contains the most bulky group on the meso-
phenyl rings of the porphyrin and are expected to have the
smallest aggregation effect compared with compounds 5a
and 5b. It is generally understood that the lower the aggre-
gation effect, the higher the solar-energy conversion. Owing
to similar alkyl substitutions on the meso-phenyl rings of the
porphyrins, the optical- and electrochemical properties of
compounds 5a, 5b, and 5c are almost identical. Contrary to
this generally accepted view, compound 5a, which is expect-
ed to have the highest aggregation effect, displayed the
highest efficiency for solar-energy-to-electricity conversion
(h=2.93%). The lower efficiency of compound 5c is attrib-
uted to its much lower Jsc value. The UV/Vis absorption
spectra of the dye solutions before and after immersion of
the TiO2 electrode are shown in Figure 6. Compound 5a dis-
plays a much bigger difference between the absorptions
before and after adsorption of the dye relative to that of
compound 5c, thus implying that a larger amount of com-
pound 5a was adsorbed onto the TiO2 surface than that of
compound 5c under similar conditions (0.2 mm, 12 h). It is
likely that the lower Jsc values of compounds 5b and 5c re-
sulted from the smaller amounts of porphyrin dyes that
were present on the TiO2 surface and the aggregation effect
did not play a role in determining the solar-conversion effi-
ciencies of these porphyrins under the above-mentioned
conditions.
Conclusions
New opp-dibenzoporphyrins have been synthesized through
a Pd0-catalyzed cascade reaction. These opp-dibenzopor-
phyrins were evaluated for the first time as a light harvester
for dye-sensitized solar cells. These porphyrins displayed
moderate solar-energy-to-electricity conversion efficiencies
of 1.54–3.14%. Our study shows that the installation of
a more bulky group on the meso-phenyl rings of the porphy-
rin did not help enhance the solar-energy conversion, pre-
sumably owing to lower adsorption of the porphyrin dye on
the TiO2 surface. The incorporation of conjugated carboxyl-
ic-acid linkers onto the porphyrin considerably broadened
and red-shifted the absorption bands of the porphyrin,
thereby leading to a very high Jsc value (12.89), which is
comparable to the highest reported values of porphyrin dyes
for DSSC. The electronic and optical properties of these
compounds were measured by using UV/Vis spectroscopy,
steady-state fluorescence spectrometry, and cyclic voltam-
metry, and these data correlated well with DFT calculations.
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Hong Wang, Lei Kerr et al.
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Synthesis of Free-Base opp-Dibenzoporphyrins 3a–3e
Tetrabromoporphyrin (0.045 mmol), palladium acetate (5.12 mg,
Experimental Section
2
General
0.023 mmol), triphenylphosphine (15.54 mg, 0.059 mmol), and K2CO3
(26.16 mg, 0.19 mmol) were added to a Schlenk flask and dried under
vacuum. The vacuum was released under an argon atmosphere to allow
for the addition of DMF (7 mL), dry toluene (9 mL), and methyl acrylate
or (E)-methyl-penta-2,4-dienoate (1.35 mmol). Then, the mixture was de-
gassed by four freeze–pump–thaw cycles and the flask was purged with
argon again. The Schlenk flask was sealed and heated at reflux for 72 h.
The solvent was removed and the residue was subjected to preparative
column chromatography on silica gel (CH2Cl2). The band that contained
the desired porphyrin was collected and recrystallized from CHCl3/
MeOH.
All solvents were of analytical grade unless otherwise stated and were
either obtained from Sigma–Aldrich or from ACROS. TLC was per-
formed on Silicycle UltraPure Silica Gel 60 F254 TLC plates. Preparative
column chromatography was performed on silica gel (40–60 mm) that was
purchased from Silicycle. 1H NMR and 13C NMR spectroscopy was per-
formed on a Bruker Avance 500 NMR spectrometer. All samples were
1
prepared in either CDCl3 or CD3OD. The chemical shifts in the H NMR
spectra were referenced to CDCl3 at d=7.24 ppm or to CD3OD at d=
4.78 and 3.35 ppm. The chemical shifts in the 13C NMR spectra were ref-
erenced to CDCl3 at d=77 ppm or to CD3OD at d=49.3 ppm. UV/Vis
spectra were recorded on an Agilent 8453 UV/Vis spectrometer in
CH2Cl2 or MeOH. MS was performed on a Bruker MALDI-TOF mass
spectrometer. Melting points were measured on an Electrothermal MEL-
TEMP apparatus and were uncorrected.
3a: Reddish-brown crystals (60%); m.p.>3308C; 1H NMR (500 MHz,
3
CDCl3, 258C, TMS): d=8.85 (s, 4H; b-H), 8.05 (d, J
N
3
o-Ph-H), 7.65 (d, JACTHNUTRGNEU(GN H,H)=7.5 Hz, 8H; m-Ph-H), 7.37 (s, 4H; fused-ben-
zene-H), 3.90 (s, 12H; OCH3), 2.76 (s, 12H; CH3), À2.66 ppm (s, 2H;
inner H); 13C NMR (125 MHz, 258C, TMS): d=21.62, 29.71, 52.48,
118.19, 125.76, 127.90, 128.60, 129.06, 138.63, 138.73, 139.16, 142.70,
148.73, 168.43 ppm; IR: n˜ =3001, 2962, 2919, 2850, 1712, 1419, 1358,
DFT Calculations
Gaussian 03 (Rev. D.02) calculations were performed on the Redhawk
computer cluster at Miami University. Following geometry-optimizations,
vibrational-frequency analysis was used to ensure that all of the station-
ary points were energy minima. Geometry-optimization and electronic-
structure calculations of the porphyrins were performed by using the
B3LYP functional and the 6–31G(d) basis set. Molecular orbitals were vi-
sualized by using Molekel 5.4.0.8.[13]
1259, 1219, 1091, 1009, 901, 791, 701 cmÀ1
; UV/Vis (CH2Cl2): lmax
(log e)=443 (6.02), 534 (5.21), 568 (5.19), 610 (5.16), 628 nm (5.15); MS
(MALDI-TOF): m/z calcd for C64H50N4O8: 1002.363; found: 1002.253.
3b: Reddish-brown crystals (55%); m.p.>3208C; 1H NMR (500 MHz,
3
CDCl3, 258C, TMS): d=8.82 (s, 4H; b-H), 8.10 (d, J
N
3
o-Ph-H), 7.68 (d, J
ACHTUNGTREN(NUNG H,H)=7.5 Hz, 8H; m-Ph-H), 7.39 (s, 4H; fused-ben-
zene-H), 3.85 (s, 12H; OCH3), 3.30 (m, 4H, isopropyl CH), 1.58 (d, 3J-
Electrochemistry
(H,H)=7.0 Hz, 24H; isopropyl CH3), À2.60 ppm (s, 2H; inner H);
13C NMR (125 MHz, CDCl3, 258C, TMS): d=24.43, 34.35, 52.46, 119.03,
125.35,125.96, 127.93, 129.10, 133.89, 138.95, 139.24, 142.55, 148.72 149.85,
168.57 ppm; IR: n˜ =2961, 2919, 2850, 1735, 1459, 1375, 1259, 1089, 864,
691 cmÀ1; UV/Vis (CH2Cl2): lmax (log e)=444 (6.43), 534 (5.43), 568
(5.32), 611 nm (5.29); MS (MALDI-TOF): m/z calcd for C72H66N4O8:
1114.488; found: 1114.455.
Cyclic voltammograms were recorded with a three-electrode cell and
a CHI 750 electrochemical analyzer. A Au coil was used as the working
electrode, a Pt coil was used as the counter electrode, and a Pt disk
served and the quasi-reference electrode.
Photovoltaic Measurements
3c: Reddish-brown crystals (48%); m.p.>3308C; 1H NMR (500 MHz,
The porphyrin molecules were sensitized on TiO2 to test the solar-cell ef-
ficiency. The TiO2-film method used herein was based on that reported
by Nazeeruddin et al. in 1993.[14] Commercial TiO2 (P25, Degussa AG,
Germany), acetylacetone, and Triton X-100 were used to make TiO2
paste. A doctor-blade method was used to spread the paste onto SnO2:F
(FTO) glass. Samples were then annealed at 4508C for 30 min.
3
CDCl3, 258C, TMS): d=8.83 (s, 4H; b-H), 8.11 (d, J
o-Ph-H), 7.83 (d, JACTHNUTRGNEU(GN H,H)=8.0 Hz, 8H; m-Ph-H), 7.39 (s, 4H; fused-ben-
(H,H)=8.0 Hz, 8H;
3
zene-H), 3.84 (s, 12H; OCH3), 1.64 (s, 36H; tert-butyl-H), À2.57 ppm (s,
2H; inner H); 13C NMR (125 MHz, CDCl3, 258C, TMS): d=31.74, 35.07,
52.48, 118.97, 124.80, 125.26, 127.93, 129.10, 133.68, 138.53, 139.22, 142.49,
148.53, 152.21, 168.43 ppm; IR: n˜ =3001, 2962, 2919, 2850, 1712, 1419,
1358, 1259, 1219, 1091, 1009, 901, 791, 701 cmÀ1; UV/Vis (CH2Cl2): lmax
(log e)=440 (5.64), 530 (5.21), 566 nm (5.20); MS (MALDI-TOF): m/z
calcd for C76H74N4O8: 1170.551; found: 1170.455.
Synthesis
Compounds 1 were prepared according to literature procedures.[15]
Synthesis of Tetrabromoporphyrins 2
1
3d: Brown solid (52%); m.p.>3308C; H NMR (500 MHz, CDCl3, 258C,
3
TMS): d=8.87 (s, 4H; b-H), 8.06 (d, J
G
A mixture of porphyrin 1 (0.4 g, 0.5 mmol) and NBS (0.6 g, 3.3 mmol) in
dry CHCl3 (120 mL) was heated at reflux in a 250 mL round-bottomed
flask overnight. The progress of the reaction was monitored by TLC
(CHCl3/cyclohexane, 1:1). The reaction mixture was then cooled to RT
and filtered through a short plug of silica gel (CH2Cl2). The filtrate was
evaporated to dryness and recrystallized from CH2Cl2/MeOH to give
compound 2.
(s, 4H; fused-benzene-H), 7.35 (d, 3J
ACTHNUTRGNE(NUG H,H)=8.0 Hz, 8H; m-Ph-H), 4.13
(s, 12H; OCH3), 3.90 (s, 12H; OCH3), À2.64 ppm (s, 2H; inner H);
13C NMR (125 MHz, CDCl3, 258C, TMS): d=52.48, 55.74, 113.48, 118.63,
125.74, 127.89, 129.05, 134.03, 134.81, 139.41, 142.61, 149.05, 160.43,
168.43 ppm; IR: n˜ =3001, 2962, 2919, 2850, 1712, 1419, 1358, 1259, 1219,
1091, 1009, 901, 791, 701 cmÀ1; UV/Vis (CH2Cl2): lmax (log e)=444 (6.02),
534 (5.00), 610 (4.71), 634 nm (4.53); MS (MALDI-TOF): m/z calcd for
C64H50N4O12: 1066.343; found: 1066.293.
2b: Dark-brown powder (93%); m.p.>3108C; 1H NMR (500 MHz,
3
CDCl3, 258C, TMS): d=8.71 (s, 4H; b-H), 8.08 (d, J
N
1
3e: Brown solid (45%); m.p.>3308C; H NMR (500 MHz, CDCl3, 258C,
3
o-Ph-H), 7.62 (d, J
ACHTUNGTRENNUNG(H,H)=8.0 Hz, 8H; m-Ph-H), 3.23 (m, 4H; isopropyl
3
TMS): d=8.84 (s, 4H; b-H), 8.13 (d, J
A
CH), 1.51 (d, 3J
(H,H)=7.0 Hz, 24H; isopropyl CH3), À2.76 ppm (s, 2H;
tons), 8.05 (d, 3J
(H,H)=7.5 Hz, 8H; o-Ph-H), 7.68 (d, 3J
ACHUTGTNRENNUG CAHTUNGTRENNUNG
inner H); 13C NMR (125 MHz, 258C, TMS): d=24.37, 34.19, 120.41,
124.69, 125.65, 135.68, 138.10, 140.39, 148.42, 149.62 ppm; UV/Vis
(CH2Cl2): lmax (log e)=442 (5.66), 542 (4.89), 692 (4.85), 628 (4.83),
634 nm (4.80); HRMS (MALDI-TOF): m/z calcd for C56H50Br4N4:
1098.640; found: 1098.542.
8H; m-Ph-H), 7.29 (s, 4H; fused-benzene-H), 6.05 (d, 3J
AHCTUNGTRENNUNG
4H; alkenyl protons), 3.89 (s, 12H; OCH3), 2.81 (s, 12H; CH3),
À2.61 ppm (s, 2H; inner H); UV/Vis (CH2Cl2): lmax (log e)=461 (6.08),
488 (5.99), 580 (4.31) 618 (4.16), 675 nm (3.83); MS (MALDI-TOF): m/z
calcd for C72H58N4O8: 1107.250; found: 1108.002.
2c: Dark-brown powder (85%); m.p.>3108C; 1H NMR (500 MHz,
3
CDCl3, 258C, TMS): d=8.72 (s, 4H; b-H), 8.08 (d, J
N
Synthesis of ZnII–opp-Dibenzoporphyrins 4a–4e
3
o-Ph-H), 7.65 (d, JACHTUNGTRENNUNG(H,H)=8.0 Hz 4H; m-Ph-H), 1.57 (s, 36H; tert-butyl-
H), À2.76 ppm (s, 2H; inner H); UV/Vis (CH2Cl2): lmax (log e)=432
(5.66), 533 (4.56), 673 (4.35), 604 (4.19), 625 nm (4.15); these spectroscop-
ic data are in agreement with the literature values.[11]
A mixture of porphyrin 3 (0.042 mmol) and ZnACTHNGUETRNNU(G OAc)2 (6.0 equiv) in
CHCl3/MeOH (18 mL:6 mL) was heated at reflux for 1 h. Upon comple-
tion of the reaction (monitored by TLC), the solvent was evaporated and
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Opp-Dibenzoporphyrins as a Light-Harvester for DSSCs
the residue was subjected to column chromatography on silica gel
(CH2Cl2). The fraction that contained the desired compound was collect-
ed and recrystallized from CH2Cl2/MeOH.
UV/Vis (CH2Cl2): lmax (log e)=457 (5.71), 589 (4.91), 627 nm (4.80); MS
(MALDI-TOF): m/z calcd for C60H40N4O8Zn: 1010.392; found: 1011.0.
5b: Greenish-brown solid (78%); m.p.>3308C; 1H NMR (500 MHz,
4a: Greenish-brown solid (90%); m.p.>3308C; 1H NMR (500 MHz,
CDCl3, 258C, TMS): d=8.60 (s, 4H; b-H), 7.92 (d, J
N
3
3
3
CDCl3, 258C, TMS): d=8.85 (s, 4H; b-H), 7.95 (d, J
N
o-Ph-H), 7.54 (d, JACTHNGUTERN(UNG H,H)=7.5 Hz, 8H; m-Ph-H), 7.96 (s, 4H; fused-ben-
3
o-Ph-H), 7.62 (d, J
N
zene-H), 3.18 (m, 4H; isopropyl CH), 1.48 ppm (d, 3J
ACHTNGUTERN(UNG H,H)=6.5 Hz,
zene-H), 3.72 (s, 12H; OCH3), 2.76 ppm (s, 12H; CH3); 13C NMR
(125 MHz, CDCl3, 258C, TMS): d=22.60, 53.46, 119.98, 126.75, 128.90,
129.73, 130.05, 134.58, 139.62, 139.72, 140.15, 143.63, 149.71, 169.42 ppm;
IR: n˜ =3001, 2956, 2921, 2850, 1710, 1427, 1336, 1253, 998, 791, 764,
670 cmÀ1; UV/Vis (CH2Cl2): lmax (log e)=450 (5.88), 581 (5.30), 627 nm
(5.26); MS (MALDI-TOF): m/z calcd for C64H48N4O8Zn: 1064.402;
found: 1064.139.
24H; isopropyl CH3); 13C NMR (125 MHz, CDCl3, 258C, TMS): d=
24.92, 35.66, 120.66, 126.69, 129.12, 132.01, 132.24, 134.40, 142.05, 145.55,
150.46, 151.95, 174.13 ppm; IR: n˜ =3300–2800 (broad), 3119, 3033, 2809,
1698, 1544, 1440, 1396, 1367, 1290, 1119, 1054, 990, 790, 759, 693 cmÀ1
;
UV/Vis (CH2Cl2): lmax (log e)=457 (5.91), 590 (4.96), 634 nm (4.76); MS
(MALDI-TOF): m/z calcd for C68H56N4O8Zn: 1120.339; found: 1120.366.
5c: Greenish-brown solid (75%); m.p.>3308C; 1H NMR (500 MHz,
4b: Greenish-brown solid (93%); m.p.>3308C; 1H NMR (500 MHz,
CDCl3, 258C, TMS): d=8.59 (s, 4H; b-H), 7.95 (d, J
N
3
3
3
CDCl3, 258C, TMS): d=8.81 (s, 4H; b-H), 8.02 (d, J
N
o-Ph-H), 7.74 (d, JACTHNGUTERN(UNG H,H)=8.0 Hz, 8H; m-Ph-H), 7.52 (s, 4H; fused-ben-
3
o-Ph-H), 7.63 (d, J
zene-H), 3.59 (s, 12H; OCH3), 3.28 (m, 4H; isopropyl CH), 1.56 ppm (d,
3J(H,H)=7.0 Hz, 24H; isopropyl CH3); 13C NMR (125 MHz, CDCl3,
G
zene-H), 1.60 ppm (s, 36H; tert-butyl-H); IR: n˜ =3001, 2962, 2919, 2850,
1712, 1419, 1358, 1259, 1219, 1091, 1009, 901, 791, 701 cmÀ1; UV/Vis
(CH2Cl2): lmax (log e)=458 (6.04), 590 (5.39), 562 nm (5.35); MS
(MALDI-TOF): m/z calcd for C72H64N4O8Zn: 1178.681; found: 1179.1.
ACHTUNGTRENNUNG
258C, TMS): d=24.44, 34.29, 52.28, 119.74, 125.60, 127.99, 131.56, 133.35,
139.96, 140.37, 143.89, 149.32, 150.62, 168.32 ppm; IR: n˜ =3001, 2956,
2919, 2850, 1719, 1429, 1350, 1250, 1105, 1018, 972, 837, 791, 764,
693 cmÀ1; UV/Vis (CH2Cl2): lmax (log e)=451 (6.25), 582 (5.36), 622 nm
(5.22); MS (MALDI-TOF): m/z calcd for C72H64N4O8Zn: 1176.402;
found: 1176.366.
5d: Greenish solid (70%); m.p.>3308C; 1H NMR (500 MHz, CDCl3,
258C, TMS): d=8.59 (S, 4H; b-H), 7.94 (d, 3J
ACHTUNGTRENNUNG
H), 7.90 (s, 4H; fused-benzene-H), 7.27 (d, 3J
ACHTUNGTRENNUNG
H), 4.05 ppm (s, 12H; OCH3); IR: n˜ =3001, 2962, 2919, 2850, 1712, 1419,
1358, 1259, 1219, 1091, 1009, 901, 791, 701 cmÀ1; UV/Vis (CH2Cl2): lmax
(log e)=459 (6.05), 590 (5.38), 626 nm (5.30); MS (MALDI-TOF): m/z
calcd for C60H40N4O12Zn: 1074.359; found: 1075.075.
4c: Greenish-brown solid (95%); m.p.>3308C; 1H NMR (500 MHz,
3
CDCl3, 258C, TMS): d=8.80 (s, 4H; b-H), 8.02 (d, J
N
3
5e: Greenish solid (60%); m.p.>3308C; 1H NMR (500 MHz, CDCl3,
o-Ph-H), 7.76 (d, JACHTUNGTRENNUNG(H,H)=8.0 Hz, 8H; m-Ph-H), 7.26 (s, 4H; fused-ben-
zene-H), 3.49 (s, 12H; OCH3), 1.60 ppm (s, 36H; tert-butyl-H); 13C NMR
(125 MHz, CDCl3, 258C, TMS): d=31.77, 34.99, 52.28, 119.58, 124.38,
125.39, 127.71, 131.54, 133.18, 139.61, 140.30, 143.75, 150.63, 151.57,
168.26 ppm; IR: n˜ =3001, 2962, 2919, 2850, 1712, 1419, 1358, 1259, 1219,
1091, 1009, 901, 791, 701 cmÀ1; UV/Vis (CH2Cl2): lmax (log e)=451 (6.02),
581 (4.71), 556 nm (4.60); MS (MALDI-TOF): m/z calcd for
C76H72N4O8Zn: 1232.464; found: 1232.479.
3
258C, TMS): d=8.72 (s, 4H; b-H), 8.47 (d, J
A
yl protons), 7.93 (d, 3J
(H,H)=7.5 Hz, 8H; o-Ph-H), 7.65 (d, 3J
ACHUTGTNRENNUG ACHTUNGTRENNUNG
7.5 Hz, 8H; m-Ph-H), 7.39 (s, 4H; fused-benzene-H), 6.09 (d, 3J
ACHTUNGTRENNUNG
15.5 Hz, 4H; alkenyl protons), 2.76 ppm (s, 12H; CH3); UV/Vis
(CH2Cl2): lmax (log e)=471 (5.95), 596 (5.13), 638 (4.86); MS (MALDI-
TOF): m/z calcd for C68H48N4O8Zn: 1114.510; found: 1115.018.
4d: Greenish solid (85%); m.p.>3308C; 1H NMR (500 MHz, CDCl3,
258C, TMS): d=8.83 (s, 4H; b-H), 7.96 (d, 3J
ACHTUNGTRENNUNG
H), 7.45 (s, 4H; fused-benzene-H), 7.29 (d, 3J
ACHTUNGTRENNUNG
Acknowledgements
H), 4.09 (s, 12H; OCH3), 3.77 ppm (s, 12H; OCH3); 13C NMR (125 MHz,
CDCl3, 258C, TMS): d=52.91, 56.24, 113.98, 119.14, 126.24, 128.40,
129.55, 134.54, 135.32, 139.92, 143.11, 149.55, 160.94, 168.88 ppm; IR: n˜ =
3001, 2962, 2919, 2850, 1712, 1419, 1358, 1259, 1219, 1091, 1009, 901, 791,
701 cmÀ1; UV/Vis (CH2Cl2): lmax (log e)=452 (6.20), 580 (5.50), 625 nm
(5.42); MS (MALDI-TOF): m/z calcd for C64H48N4O12Zn: 1128.256;
found: 1128.075.
H.W. thanks Miami University and the Ohio Board of Reagents (Re-
search Incentive Grant) for financial support. C.S.H. acknowledges sup-
port from the U.S Air Force Office of Scientific Research (Award no.
FA9550-10-1-0377). The National Science Foundation (CHE0839233) is
acknowledged for providing funds to purchase the MALDI TOF mass
spectrometer that was used in this work.
4e: Greenish-brown solid (84%); m.p.>3308C; 1H NMR (500 MHz,
3
CDCl3, 258C, TMS): d=8.85 (s, 4H; b-H), 7.97 (d, J
(H,H)=7.5 Hz, 8H;
o-Ph-H), 7.82 (d, 3J
(H,H)=7.5 Hz, 8H; m-Ph-H) 7.29 (s, 4H; fused-benzene-H), 5.91 (d, 3J-
(H,H)=15.5 Hz, 4H; alkenyl protons), 3.76 (s, 12H; OCH3), 2.78 ppm (s,
ACHTUNGTRENNUNG
(H,H)=15.5 Hz, 8H; alkenyl protons), 7.63 (d, 3J-
[1] a) R. A. J. Thomas W. Hamann, A. B. F. Martinson, H. Van Ryswyk,
J. T. Hupp, Energy Environ. Sci. 2008, 1, 66–78; b) N. Robertson,
Photonics Spectra 2008, 42, 48; c) N. Robertson, Angew. Chem.
2008, 120, 1028–1030; Angew. Chem. Int. Ed. 2008, 47, 1012–1014;
d) N. Robertson, Angew. Chem. 2006, 118, 2398–2405; Angew.
Chem. Int. Ed. 2006, 45, 2338–2345; e) B. O’Regan, M. Grꢀtzel,
Nature 1991, 353, 737–740; f) A. B. F. Martinson, T. W. Hamann,
M. J. Pellin, J. T. Hupp, Chem. Eur. J. 2008, 14, 4458–4467.
ACHTUNGTRENNUNG
ACHTUNGTRENNUNG
12H; CH3); UV/Vis (CH2Cl2): lmax (log e)=471 (6.03), 596 (4.51), 631
(5.25) 636 nm (4.24); MS (MALDI-TOF): m/z calcd for C72H56N4O8Zn:
1170.620; found: 1170.230.
Synthesis of Porphyrins 5a–5e
[2] a) Y. Xie, P. Joshi, M. Ropp, D. Galipeau, L. F. Zhang, H. Fong, Y. J.
You, Q. Q. Qiao, J. Porphyrins Phthalocyanines 2009, 13, 903–909;
b) S. Ito, S. M. Zakeeruddin, R. Humphry-Baker, P. Liska, R. Char-
vet, P. Comte, M. K. Nazeeruddin, P. Pechy, M. Takata, H. Miura, S.
Uchida, M. Grꢀtzel, Adv. Mater. 2006, 18, 1202; c) W. M. Campbell,
A. K. Burrell, D. L. Officer, K. W. Jolley, Coord. Chem. Rev. 2004,
248, 1363–1379; d) L. Schmidt-Mende, U. Bach, R. Humphry-
Baker, T. Horiuchi, H. Miura, S. Ito, S. Uchida, M. Grꢀtzel, Adv.
Mater. 2005, 17, 813; e) L. Schmidt-Mende, W. M. Campbell, Q.
Wang, K. W. Jolley, D. L. Officer, M. K. Nazeeruddin, M. Grꢀtzel,
ChemPhysChem 2005, 6, 1253–1258; f) J. R. Durrant, S. A. Haque,
E. Palomares, Chem. Commun. 2006, 3279–3289; g) J. Rochford, D.
Chu, A. Hagfeldt, E. Galoppini, J. Am. Chem. Soc. 2007, 129, 4655–
4665; h) J. T. Dy, K. Tamaki, Y. Sanehira, J. Nakazaki, S. Uchida, T.
A mixture of porphyrin 4 (0.033 mmol) and KOH (1.05 mmol) in isopro-
panol/H2O (15 mL:7 mL) was under reflux overnight. Upon completion
of the reaction (monitored by TLC), the solvent was removed and the
residue was purified by column chromatography on silica gel. The
column was first eluted with CH2Cl2/MeOH (50:1) to separate the incom-
pletely hydrolyzed products and then with MeOH to collect the desired
product. The solvent was removed under reduced pressure and the resi-
due was recrystallized from MeOH/CH2Cl2.
5a: Greenish-brown solid (78%); m.p.>3308C; 1H NMR (500 MHz,
3
CDCl3, 258C, TMS): d=8.65 (s, 4H; b-H), 7.95 (d, J
N
3
o-Ph-H), 7.58 (d, J
zene-H), 2.70 ppm (s, 12H; CH3); IR: n˜ =3300–2800
2809, 1706, 1540, 1440, 1401, 1337, 1284, 1121, 992, 793, 759, 693 cmÀ1
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
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Hong Wang, Lei Kerr et al.
FULL PAPER
Kubo, H. Segawa, Electrochemistry 2009, 77, 206–209; i) H. Imahori,
S. Hayashi, H. Hayashi, A. Oguro, S. Eu, T. Umeyama, Y. Matano,
J. Phys. Chem. C 2009, 113, 18406–18413; j) A. J. Mozer, M. J. Grif-
fith, G. Tsekouras, P. Wagner, G. G. Wallace, S. Mori, K. Sunahara,
M. Miyashita, J. C. Earles, K. C. Gordon, L. C. Du, R. Katoh, A.
Furube, D. L. Officer, J. Am. Chem. Soc. 2009, 131, 15621; k) M.
Linke-Schaetzel, C. E. Anson, A. K. Powell, G. Buth, E. Palomares,
J. D. Durrant, T. S. Balaban, J. M. Lehn, Chem. Eur. J. 2006, 12,
1931–1940.
Hayashi, Y. Toude, T. Umeyama, Y. Matano, S. Ito, ChemSusChem
2011, 4, 797–805.
[9] a) O. Finikova, A. Cheprakov, I. Beletskaya, S. Vinogradov, Chem.
Commun. 2001, 261–262; b) O. S. Finikova, S. E. Aleshchenkov,
R. P. Brinas, A. V. Cheprakov, P. J. Carroll, S. A. Vinogradov, J. Org.
Chem. 2005, 70, 4617–4628; c) O. S. Finikova, A. V. Cheprakov,
S. A. Vinogradov, J. Org. Chem. 2005, 70, 9562–9572; d) K. Kuroto-
bi, K. S. Kim, S. B. Noh, D. Kim, A. Osuka, Angew. Chem. 2006,
118, 4048–4051; Angew. Chem. Int. Ed. 2006, 45, 3944–3947; e) S.
Baluschev, V. Yakutkin, T. Miteva, Y. Avlasevich, S. Chernov, S.
Aleshchenkov, G. Nelles, A. Cheprakov, A. Yasuda, K. Mullen, G.
Wegner, Angew. Chem. 2007, 119, 7837–7840; Angew. Chem. Int.
Ed. 2007, 46, 7693–7696; f) C. Borek, K. Hanson, P. I. Djurovich,
M. E. Thompson, K. Aznavour, R. Bau, Y. R. Sun, S. R. Forrest, J.
Brooks, L. Michalski, J. Brown, Angew. Chem. 2007, 119, 1127–
1130; Angew. Chem. Int. Ed. 2007, 46, 1109–1112; g) Y. Sun, C.
Borek, K. Hanson, P. I. Djurovich, M. E. Thompson, J. Brooks, J. J.
Brown, S. R. Forrest, Appl. Phys. Lett. 2007, 90, 213503; h) H.
Yamada, D. Kuzuhara, T. Takahashi, Y. Shirnizu, K. Uota, T. Okuji-
ma, H. Uno, N. Ono, Org. Lett. 2008, 10, 2947–2950.
[10] a) S. Ito, T. Murashima, H. Uno, N. Ono, Chem. Commun. 1998,
1661–1662; b) O. Ongayi, V. Gottumukkala, F. R. Fronczek,
M. G. H. Vicente, Bioorg. Med. Chem. Lett. 2005, 15, 1665–1668;
c) L. J. Jiao, E. H. Hao, F. R. Fronczek, M. G. H. Vicente, K. M.
Smith, Chem. Commun. 2006, 3900–3902; d) M. G. H. Vicente, L.
Jaquinod, R. G. Khoury, A. Y. Madrona, K. M. Smith, Tetrahedron
Lett. 1999, 40, 8763–8766; e) M. G. H. Vicente, A. C. Tome, A.
Walter, J. A. S. Cavaleiro, Tetrahedron Lett. 1997, 38, 3639–3642;
f) W. Liu, F. R. Fronczek, M. G. H. Vicente, K. M. Smith, Tetrahe-
dron Lett. 2005, 46, 7321–7324; g) M. A. Filatov, A. Y. Lebedev,
S. A. Vinogradov, A. V. Cheprakov, J. Org. Chem. 2008, 73, 4175–
4185; h) O. S. Finikova, A. V. Cheprakov, I. P. Beletskaya, P. J. Car-
roll, S. A. Vinogradov, J. Org. Chem. 2004, 69, 522–535; i) O. S. Fini-
kova, A. V. Cheprakov, P. J. Carroll, S. A. Vinogradov, J. Org. Chem.
2003, 68, 7517–7520; j) A. M. G. Silva, K. T. de Oliveira, M. A. F.
Faustino, M. Neves, A. C. Tome, A. M. S. Silva, J. A. S. Cavaleiro, P.
Brandao, V. Felix, Eur. J. Org. Chem. 2008, 704–712; k) A. Pereira,
C. M. A. Alonso, M. Neves, A. C. Tome, A. M. S. Silva, F. A. A. Paz,
J. A. S. Cavaleiro, J. Org. Chem. 2008, 73, 7353–7356; l) A. C. Tomꢃ,
P. S. S. Lacerda, M. Neves, J. A. S. Cavaleiro, Chem. Commun. 1997,
1199–1200.
[3] M. K. Nazeeruddin, R. Humphry-Baker, D. L. Officer, W. M. Camp-
bell, A. K. Burrell, M. Grꢀtzel, Langmuir 2004, 20, 6514–6517.
[4] a) W. M. Campbell, K. W. Jolley, P. Wagner, K. Wagner, P. J. Walsh,
K. C. Gordon, L. Schmidt-Mende, M. K. Nazeeruddin, Q. Wang, M.
Grꢀtzel, D. L. Officer, J. Phys. Chem. C 2007, 111, 11760–11762;
b) Q. Wang, W. M. Carnpbell, E. E. Bonfantani, K. W. Jolley, D. L.
Officer, P. J. Walsh, K. Gordon, R. Humphry-Baker, M. K. Nazeer-
uddin, M. Grꢀtzel, J. Phys. Chem. B 2005, 109, 15397–15409.
[5] a) C. W. Lee, H. P. Lu, C. M. Lan, Y. L. Huang, Y. R. Liang, W. N.
Yen, Y. C. Liu, Y. S. Lin, E. W. G. Diau, C. Y. Yeh, Chem. Eur. J.
2009, 15, 1403–1412; b) C. F. Lo, S. J. Hsu, C. L. Wang, Y. H. Cheng,
H. P. Lu, E. W. G. Diau, C. Y. Lin, J. Phys. Chem. C 2010, 114,
12018–12023; c) C. Y. Lin, C. F. Lo, L. Luo, H. P. Lu, C. S. Hung,
E. W. G. Diau, J. Phys. Chem. C 2009, 113, 755–764; d) H. P. Lu,
C. L. Mai, C. Y. Tsia, S. J. Hsu, C. P. Hsieh, C. L. Chiu, C. Y. Yeh,
E. W. G. Diau, Phys. Chem. Chem. Phys. 2009, 11, 10270–10274;
e) C. Y. Lee, C. X. She, N. C. Jeong, J. T. Hupp, Chem. Commun.
2010, 46, 6090–6092; f) C. P. Hsieh, H. P. Lu, C. L. Chiu, C. W. Lee,
S. H. Chuang, C. L. Mai, W. N. Yen, S. J. Hsu, E. W. G. Diau, C. Y.
Yeh, J. Mater. Chem. 2010, 20, 1127–1134; g) C. L. Wang, Y. C.
Chang, C. M. Lan, C. F. Lo, E. W. G. Diau, C. Y. Lin, Energy Envi-
ron. Sci. 2011, 4, 1788–1795; h) Y. C. Chang, C. L. Wang, T. Y. Pan,
S. H. Hong, C. M. Lan, H. H. Kuo, C. F. Lo, H. Y. Hsu, C. Y. Lin,
E. W. G. Diau, Chem. Commun. 2011, 47, 8910–8912; i) T. Bessho,
S. M. Zakeeruddin, C. Y. Yeh, E. W. G. Diau, M. Grꢀtzel, Angew.
Chem. 2010, 122, 6796–6799; Angew. Chem. Int. Ed. 2010, 49, 6646–
6649; j) S. L. Wu, H. P. Lu, H. T. Yu, S. H. Chuang, C. L. Chiu, C. W.
Lee, E. W. G. Diau, C. Y. Yeh, Energy Environ. Sci. 2010, 3, 949–
955; k) A. Yella, H. W. Lee, H. N. Tsao, C. Y. Yi, A. K. Chandiran,
M. K. Nazeeruddin, E. W. G. Diau, C. Y. Yeh, S. M. Zakeeruddin,
M. Grꢀtzel, Science 2011, 334, 629–634.
[6] a) M. S. Kang, J. B. Oh, K. D. Seo, H. K. Kim, J. Park, K. Kim, N. G.
Park, J. Porphyrins Phthalocyanines 2009, 13, 798–804; b) S. Haya-
shi, Y. Matsubara, S. Eu, H. Hayashi, T. Umeyama, Y. Matano, H.
Imahori, Chem. Lett. 2008, 37, 846–847; c) S. Hayashi, M. Tanaka,
H. Hayashi, S. Eu, T. Umeyama, Y. Matano, Y. Araki, H. Imahori,
J. Phys. Chem. C 2008, 112, 15576–15585.
[11] R. Deshpande, L. Jiang, G. Schmidt, J. Rakovan, X. P. Wang, K.
Wheeler, H. Wang, Org. Lett. 2009, 11, 4251–4253.
[12] a) H. L. Anderson, Chem. Commun. 1999, 2323–2330; b) A. Ceule-
mans, W. Oldenhof, C. Gorllerwalrand, L. G. Vanquickenborne, J.
Am. Chem. Soc. 1986, 108, 1155–1163.
[7] H. Imahori, T. Umeyama, S. Ito, Acc. Chem. Res. 2009, 42, 1809–
1818.
[13] U. Varetto, Molekel 5.4.0.8; Swiss National Supercomputing Centre,
Manno, Switzerland.
[8] a) S. Eu, S. Hayashi, T. Urneyama, Y. Matano, Y. Araki, H. Imahori,
J. Phys. Chem. C 2008, 112, 4396–4405; b) A. Kira, Y. Matsubara,
H. Iijima, T. Umeyama, Y. Matano, S. Ito, M. Niemi, N. V. Tkachen-
ko, H. Lemmetyinen, H. Imahori, J. Phys. Chem. C 2010, 114,
11293–11304; c) S. Mathew, H. Iijima, Y. Toude, T. Umeyama, Y.
Matano, S. Ito, N. V. Tkachenko, H. Lemmetyinen, H. Imahori, J.
Phys. Chem. C 2011, 115, 14415–14424; d) H. Imahori, H. Iijima, H.
[14] M. K. Nazeeruddin, A. Kay, I. Rodicio, R. Humphry-Baker, E.
Mꢄller, P. Liska, N. Vlachopoulos, M. Grꢀtzel, J. Am. Chem. Soc.
1993, 115, 6382-6390.
[15] P. Rothemund, J. Am. Chem. Soc. 1936, 58, 625-627..
Received: June 7, 2012
Published online: && &&, 0000
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www.chemasianj.org
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Chem. Asian J. 0000, 00, 0 – 0
ÝÝ These are not the final page numbers!

FULL PAPER
opp-ortunity knocks: Symmetrical
opp-dibenzoporphyrins with various
linkers and substituents were used as
sensitizers for dye-sensitized solar
cells. These porphyrins displayed mod-
erate efficiency for the conversion of
solar energy into electricity.
Dye-Sensitized Solar Cells
Rohit Deshpande, Bo Wang, Lin Dai,
Lin Jiang, C. Scott Hartley,
Shouzhong Zou, Hong Wang,*
Lei Kerr*
&&&& — &&&&
Opp-Dibenzoporphyrins as a Light-
Harvester for Dye-Sensitized Solar
Cells
Chem. Asian J. 2012, 00, 0 – 0
ꢁ 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemasianj.org
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These are not the final page numbers! ÞÞ