Fluorous molecules for dye-sensitized solar cells: Synthesis and properties of di-branched, di-anchoring organic sensitizers containing fluorene subunits

Article abstract of DOI:10.1039/c7nj01516j

Four organic sensitizers having a di-branched molecular structure D-(π-A)₂ (D = para-substituted arylamine, π = 9,9-dibutylfluorene, A = cyanoacrylic acid) were synthesized, characterized, and applied in the development of dye-sensitized solar cells (DSSCs). It was found that the nature of the para-substituent affects the behavior of these sensitizers. In particular, the introduction of a C11 linear fluorous alkoxy group led to an improvement in the power conversion efficiency with respect to the commonly employed nonfluorous alkoxy substituents.

Full text of DOI:10.1039/c7nj01516j

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ISSN 1144-0546
PAPER
Jason B. Benedict et al.
The role of atropisomers on the photo-reactivity and fatigue of
diarylethene-based metal–organic frameworks
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ARTICLE
Fluorous molecules for dye-senzitized solar cells: synthesis and
properties of di-branched, di-anchoring organic sensitizers
containing fluorene subunits
Received 00th January 20xx,
Accepted 00th January 20xx
Ilir Pecnikaj,a Daniela Minudri,b Luis Otero,b Fernando Fungo,*b Marco Cavazzini,c Simonetta
Orlandic and Gianluca Pozzi*c
DOI: 10.1039/x0xx00000x
www.rsc.org/
Four organic sensitizers having a di-branched molecular structure D-(π-A)2 (D = para-substituted arylamine, π = 9,9-
dibutylfluorene, A = cyanoacrylic acid) were synthesized, characterized, and applied in the development of dye-sensitized
solar cells (DSSCs). It was found that the nature of the para-substituent affects the behavior of these sensitizers. In particular,
the introduction of a C11 linear fluorous alkoxy group led to an improvement in the power conversion efficiency with respect
to the commonly employed nonfluorous alkoxy substituents.
.
triarylamine derivatives and cyanoacrylic acid, which also works
as the anchoring group to the metal oxide electrode, have been
the most commonly used D and A components, respectively,
Introduction
A great deal of research is currently being conducted in the field
of dye-sensitized solar cells (DSSCs) based on the sensitization
of a nanostructured metal oxide semiconductor interface by a
photoexcited dye.1,2 Many different issues are addressed,
ranging from the comprehension and modeling of the
underlying fundamental phenomena to the assessment of the
life cycle and economic effectiveness of the final devices.3-8
However, the development of new photosensitizers that could
ensure optimal photovoltaic parameters and acceptable
lifetime service to DSSCs remains a major goal in this field,
despite the impressive number of light-absorbing compounds
with different molecular structures already proposed and
tested.2,9-12 Encouraging results have been obtain in the case of
structurally simple dipolar organic dyes comprising an electron-
rich donor component (D) and an electron-withdrawing
acceptor counterpart (A) bridged by a π-conjugated linkage.
Such a flexible D-π-A modular blueprint allows for a great
diversity of conceivable molecular structures. Organic
sensitizers with tailored optical and energetic properties, high
molar extinction coefficients and long term chemical stability
have been thus synthesized through the judicious combination
of the three basic D, π and A elements.13 In practice,
while the nature of the π-conjugated unit has been more
systematically modified. This last parameter has a deep
influence on the final performance of the dye, as it modulates
the absorption of solar light and the ability to inject electrons to
the metal oxide conduction band from photoinduced
intramolecular charge transfer states produced upon irradiation
of the dipolar molecule. Therefore, the inclusion of different π-
conjugated cores such as simple C-C double or triple bonds, aryl
or heteroaromatic rings, or combinations of all these elements
has been widely investigated.14 The adoption of this strategy
proved to be instrumental in providing highly efficient organic
dyes that contributed to fabricate DSSCs with photovoltaic
performances close to those obtained using well-established
Ru-based sensitizers.15-17
The basic D-π-A molecular design has some drawbacks, too.
Besides the inherent aggregation tendency shown by many rod-
like shaped D-π-A dyes,13,14 the presence of
a single
accepting/anchoring A group results in a reduced interfacial
electron transfer ability and higher propensity to detach from
the semiconductor surface under operating conditions. The
incorporation of the most successful dipolar structural motifs
into multi-branched, multi-anchoring molecular architectures
(Figure 1a) can help to relieve these problems, as early
demonstrated by Abbotto et al. who first designed di-anchoring
dyes of the form D-(π-A)2, where two branches stem from the
same D unit.18 Following this line of reasoning, several research
groups devised other D-(π-A)2 dyes containing variously
substituted arylamines, carbazoles, phenothiazines or
phenoxazines as D units,19,20 as well as more exotic X- and Y-
shaped dyes, such as spiro-configured molecules where two
identical D-π-A branches are interconnected by a common sp3-
a.Department of Chemical, Toxicological and Pharmacological Evaluation of Drugs,
Faculty of Pharmacy, Catholic University Our Lady of Good Counsel, Rr. D. Hoxha,
Tirana, Albania
b.Departamento de Química, Universidad Nacional de Río Cuarto. CONICET,
Agencia Postal No 3, X5804BYA, Río Cuarto, Argentina. E-mail:
ffungo@exa.unrc.edu.ar
c. Istituto di Scienze e Tecnologie Molecolari del Consiglio Nazionale delle Ricerche,
ISTM-CNR, Via Golgi 19, 20133 Milano, Italy. E-mail: gianluca.pozzi@istm.cnr.it
Electronic Supplementary Information (ESI) available: Additional synthesis and
characterization details; UV-Vis absorption spectra of dyes on TiO2; cyclic
voltammograms. See DOI: 10.1039/x0xx00000x
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carbon atom.21-23 Nevertheless, the design of multi-branched, functionalization of a versatile bis(fluorenyl)amineVinietweArrmticleedOinalitnee
multi-anchoring dyes remains a relatively underdeveloped field has been developed and applied to the syDnOthI:e1s0i.s10o3f9/C7NJ01516J
FBA1 FBA4
-
and there is much room for further research on the optimization (Scheme 1).
of the D, π and A components and their integration into new In brief, the Cu-catalyzed C-N coupling reaction between tert-
molecular architectures through the application of suitable butyl carbamate and a fourfold molar excess of the starting
synthetic schemes.
In preceding works, we demonstrated the use of fluorene as the available 2,7-dibromofluorene, afforded the Boc-protected
π-conjugated central core of multi-branched spiro-configured secondary amine in 56% yield, while the unreacted dibromo
(D-π-A)2-sensitizers.21,22 Here, it is shown that fluorene can play fluorene was recovered and reused. Bis-lithiation/electrophilic
a similar role in D-(π-A)2 molecules (Figure 1b), and that the quench of gave the bis-aldehyde (82% yield) from which
photovoltaic performance of di-branched, di-anchoring amine was readily released by acid cleavage in 89% yield. Pd-
material 1, readily obtained by alkylation of commercially
2
2
3
4
sensitizers can be improved through the introduction of linear catalyzed cross-coupling of this bis(fluorenyl)amine
perfluorinated (fluorous) alkoxy substituents in the para- intermediate with suitable aryl halides, followed by
position of the central D unit.
Knoevenagel condensation with cyanoacetic acid, led to the
desired D-(π-A)2 dyes. This synthetic pathway enables the
introduction of a great variety of substituents on their
arylamine D unit and therefore the possible fine-tuning of their
ultimate behaviour as sensitizers in DSSCs, as it appears from a
thorough analysis of literature data.19 In this regard, the
presence of electron-donating para-alkoxy substituents is a
common feature of many effective multi-branched, multi-
anchoring dyes based on arylamines. We thus decided to
investigate the effect of similar substituents on the behaviour
of the D-(π-A)2 dyes derived from 4. Dyes FBA1 and FBA2
bearing standard short (p-OMe) and long (p-OC11H23) chain
substituents, respectively, where obtained using known aryl
halides. The unusual fluorous substituents present in dyes FBA3
and FBA4 were introduced thanks to the use of two purposely
synthesized aryl halides (see ESI).
Photophysical and electrochemical characterization
The photophysical properties of the branched dyes were
evaluated in solvent media with different polarity, namely
toluene (TOL), 1,2-dichloroethane (DCE) and acetonitrile
(MeCN). As shown in Figure 2 and summarized in Table 1, all
dyes display three main absorption bands in DCE solution, two
of which are in the near UV region (λmax at ≈320 and ≈350 nm)
and may be attributed to π-π* transitions in the fluorene
system. The third and more intense band, corresponding to an
intramolecular charge transfer (ICT) transition, is observed at
lower energy (λmax at ≈480-500 nm). The ICT character of this
band was confirmed by the fluorescence solvatochromism
observed when solvents with different polarity were
investigated. The four dyes under study showed a marked
batochromic displacement when the polarity of the solvent was
increased (see Figure 2 and Table 1). For example, the maximum
emission of FBA3 was shifted 134 nm to lower energy when TOL
was changed for MeCN. On the other hand, comparison of the
absorption spectra of the four dyes in the same solvent (e.g.
DCE, Table 1) revealed that the ICT light absorption band
maximum for FAB4 has higher energy values (blue shift ≈15 nm)
with respect to the other dyes, which share most of the
structural features with FBA4, except for the nature of the para-
substituent of the central D unit (Figure 2).
Figure 1. (a) General structure of D-(π-A)2 and X-shaped, spiro-configured dyes for DSSCs;
(b) D-(π-A)2 fluorene-based dyes synthesized in this work.
Results and discussion
Synthesis of dyes
Arylamine donors and cyanoacrylic acid acceptors are the most
widely used structural units in D-(π-A)2 sensitizers,19 similarly to
conventional dipolar D-π-A dyes. This feature was maintained in
the design of the fluorene-based FBA1-FBA4 (Figure 1). On the
other hand, fluorene is a useful building-block for the
construction of dipolar sensitizers,24-26 but its incorporation as
π-conjugated unit in D-(π-A)2 dyes for DSSCs has never been
described. A convenient general approach based on the N-
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Scheme 1. Synthesis of fluorene-based D-(π-A)2 dyes.
Figure 2. Normalized UV-Vis absorption spectra (black solid line) and excitation spectra (black dashed line) of the dyes in DCE solution. Normalized emission spectra of the dyes in
DCE (light-blue solid line), TOL (red solid line) and MeCN (green solid line) solution. Emission spectra were measured by excitation at the maximum of the respective ICT bands.
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The observed trend can be thus related to the presence of para- conduction band of TiO2 revealed that in all cases the expected
alkoxy substituents in FAB1, FAB2 and FAB3, which increases electron flow (injection into TiO2 from dye excited state and dye
the electron density on the amino group stabilizing the regeneration by the I–/I3 couple) is exothermic, thus making
photogenerated positive charge. It can be also noted that the DSSC operation viable.
insertion of a propylene spacer between the oxygen atom and
the linear perfluoroalkylated C8-chain offers an effective
insulation against the electron-withdrawing effect of the latter.
Indeed, the ICT band maxima of FAB3 and FBA2 are fully
comparable.
–
Table 1. Optical and electrochemical characteristics of the studied dyes
λmax Absorption (nm)
DCE
λmax Emission (nm)a
E1/2 (V)b
TOL
559
561
552
525
DCE
669
596
655
633
MeCN
c
FBA1
FBA2
FBA3
FBA4
320/349/500
322/348/494
318/345/495
323/351/482
-
0.33
0.35
0.34
0.51
c
-
686
662
a Emission spectra were measured by excitation at the maximum of the respective
ICT bands. b Potential values relative to Fc/Fc+ redox couple (0.40 V vs SCE). c Low
solubility hampers light emission measurements.
The dyes excitation spectra in DCE solution are also shown as
black dashed lines in Figure 2. The observed similarity between
the excitation and absorption spectra indicates that all the
excited states contribute to the formation the ICT processes.
Finally, the UV-Vis absorption spectra of the adsorbed
sensitizers on TiO2 porous electrodes fit well with the
corresponding spectra in solution (see ESI, Figure S1). As
expected, the ICT band looks broader and shows a small
maximum wavelength displacement with respect to the
spectrum in solution due to the interaction of the dye molecules
with the TiO2 surface and among themselves. All these optical
characteristics are in agreement with related structures and
highly desirable from the DSSC point of view.21,26
Figure 3. Energy level diagram of the studied dyes. Oxidation potentials in the ground
and excited states are reported. The redox potential of the iodide/triiodide couple and
the lower edge of the conduction band of TiO2 are introduced for comparison.
Computational analysis
The optimized spatial configuration of the di-branched FBA dyes
and the frontier molecular orbitals were determined by
semiempirical AM1 calculations (HyperChem package).
Representative results relative to the fluorous dyes FBA3 and
FBA4 are shown in Figures 4a-f. In both cases the two fluorene
branches connected to the central aryl amino group are
extended apart from each other due to sp3 hybridization of the
nitrogen atom (Figures 4a-b). Accordingly, both branches are
capable of interaction with the TiO2 surface through the
cyanoacrylic end groups. This conclusion was further
corroborated by comparison of FT-IR spectroscopy data
obtained from FBA3 dispersed in KBr pellets or adsorbed on
TiO2. In this last case the spectra revealed that the characteristic
band at 1691 cm-1 assigned to the free carboxylic acid groups of
the KBr dispersed dye entirely vanishes, thus providing clear
indication of the double-anchoring behaviour (see ESI, Figure
S3).21,22,27
Cyclic voltammetric measurements were performed to study
the electrochemical behaviour of the new sensitizers. All four
compounds exhibit a typical quasi-reversible oxidation wave,
which is related to the oxidation of the arylamine group (see ESI,
Figure S2). The calculated oxidation half wave potentials (E1/2
)
are summarized in Table 1. As in the case of optical properties,
the observed differences in oxidation potentials are directly
related to the molecular structures of the compounds under
study and can be similarly analyzed. FBA4 shows the highest E1/2
value (0.51 V), while FBA1, FBA2 and FBA3 are ≈0.15 V easier to
oxidize, with similar E1/2 values among them, because of the
presence of para-alkoxy substituents that are able to stabilize
the generated positive charge.26 The electron-withdrawing
fluorous chain attached to FBA3 do not affect the oxidation
process thanks to the efficient electronic shielding provided by
the propylene spacer.
Figures 4c-d show that the HOMOs of FBA3 and FBA4 are
localized mostly around the central aryl amino groups, whereas
the LUMOs (Figures 4e-f) are localized on the cyanoacrylic
residues, regardless of the kind of fluorous substituent.
Therefore, it is expected that upon photoexcitation the electron
distributions are moved from the donor units (ground state) to
the acceptor units, close to the anchoring groups, which favour
the electron injection from the dye molecules to the TiO2
conduction band edge.
Starting from the experimental optical and electrochemical
parameters discussed above, the energy level diagram shown in
Figure 3 was built, from which the energetic feasibility of the
DSSC process could be evaluated. The comparison of the energy
levels of the ground and excited states of the dyes with the
redox potential of the iodine couple and the lower edge of the
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Figure 4. Geometric optimization (AM1 semiempirical calculations at HyperChem software) of the dyes FBA4 (upper panels) and FBA3 (lower panels): a-b spatial configuration, c-d
HOMO and e-f LUMO molecular orbitals.
It must be also noted that the bulky fluorous domain (nine CF3 Typical photocurrent–voltage (J/V) curves J curves are shown in
groups) present in FBA4 forms a sort of hydrophobic/lipophobic Figure 5 while averaged values of the key photovoltaic
umbrella over the donor group, which is oxidized upon the parameters calculated from all devices are collected in Table 2.
photoinduced charge transfer process (Figure 4a). This feature The measurement procedure of the J-V curves can affect the
is not present in the other members of the dye series and can obtained DSSC parameters (short circuit photocurrent density,
possibly hamper the regeneration of the reduced form of the JSC; open circuit photovoltage, VOC; fill factor, FF; energy
dye during DSSC operation (see later).
conversion efficiency, η), as discussed in recent literature
examples.28,29 Thus, in order to carry out a comparative analysis
Photovoltaic properties of DSSC devices
of the performance of the FAB# dyes series used in DSSC
DSSC devices based on the donor-acceptor di-branched di- construction, and for avoid measurements procedure effects,
anchoring sensitizers were constructed in order to evaluate the we applied a voltage sweep from JSC to VOC at 5 mV/s scan rate,
photovoltaic performance of the FBA dyes. A common to ensure a steady state cell operation regime. This procedure
fabrication methodology, described in the experimental minimize any hysteresis effect originated from chemical
section, was employed, in order to fairly compare the fluorous capacitance and series resistances in the DSSC.28,29
and non-fluorous sensitizers. Additionally, all the fabricated Both Jsc and Voc values of DSSCs based on FBA2 and FBA3 dyes
cells exhibited similar light absorption in the visible range bearing long linear para-alkoxy substituents are clearly higher
(electrode absorbance ∼2 at λ = 470 nm), suggesting similar dye than those of DSSCs built with the para-alkoxy free FBA4 dye,
loading over TiO2 surface. Fifteen batches of four cells were but also than those obtained in the case of FBA1 that contains
tested for each dye.
a simple –OMe substituent. Moreover, in all the analyzed
batches of samples the cells constructed with the fluorous
compound FBA3 exhibited a short circuit photocurrent about
35% higher than those fabricated with the otherwise identical
FBA2 dye holding a linear hydrocarbon chain.
Table 2. DSSC performance data of di-anchoring D-(π-A)2 photosensitizers.
Jsc (mA/cm2)
3.76
VOC (V)
0.55
FF
η (%)
1.4
FBA1
FBA2
FBA3
FBA4
0.68
0.68
0.66
0.70
5.05
0.61
2.1
5.95
0.64
2.5
3.07
0.58
1.2
We already reported that the presence of perfluoroalkyl
substituents in fluorene centered D-π-A photosensitizers has a
strong influence in the generation of photoelectric effects.26 In
particular, the introduction of branched fluorous groups in the
tail D end of the molecular structure allowed to obtain higher
Figure 5. Photocurrent-voltage curves for di-anchoring D-(π-A)2 photosensitizers.
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energy conversion efficiencies, due to the generation of larger reduced ability of the fluorene π-bridges to ensure electron
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31
photocurrent densities. This fact was ascribed to the anti- delocalization between the donor and acceDpOtI:o1r0u.1n03it9s/.C7NTJh0is15h1a6Js
aggregation behaviour offered by the fluorous substituents, and a negative effect on the overall energy conversion efficiencies,
to their efficient shielding effect on the TiO2 surface that avoids but it is crucial for the fabrication of semitransparent, coloured
deleterious back electron transfer to the iodine electrolyte. The solar cells of high interest from an architectural point of view
present results confirm the beneficial effect of the presence of and for the design and construction of smart windows in energy
fluorous substituents on the donor moiety of D-(π-A)2 efficient modern buildings.32,33
sensitizers. However,
a correct choice of the fluorous
substituents is extremely important. Indeed, the fluorous dye
FBA4 was found to generate the lowest photocurrent and
energy conversion efficiency values among the investigated
dyes. Two major factors contribute to this behaviour, namely
the absence of a direct ether bond between the aryl amino D
unit and the fluorinated fragment, and the above mentioned
stereochemical constraints. As can be seen in Figure 4a the
phenyl amine donor group in FBA4 is roofed over by the
umbrella-like fluorous substituent. To ensure efficient DSSC
operation, the donor group photo-oxidized upon light
absorption and electron injection must be quickly reduced by
the triiodide present in the electrolyte solution. The steric
hindrance and the solvophobic environment produced by nine
CF3 groups can hamper the efficient redox reaction, with a
consequent negative effect on the photocurrent generation,
which is about one half of that obtained with the other fluorous
Conclusions
A set of di-branched, di-anchoring organic photosensitizers D-
(π-A)2 comprising of two identical fluorene subunits attached to
a pivotal aryl amino donor group has been synthesized. The
photovoltaic performances of these new Y-shaped compounds
in DSSCs are deeply influenced by the nature of the substituents
present on the donor unit. In particular the introduction of the
linear fluorous alkoxy substituent –O(CH2)3C8F17 ensures
improved power conversion efficiency with respect to standard
short- and long-chain electron-donating para-alkoxy
substituents previously used in many effective multi-branched,
multi-anchoring dyes based on arylamines.19 The beneficial
influence of fluorous groups was already observed in fluorene-
based D-π-A photosensitizers and it was ascribed to a
combination of reduced aggregation of the dye and efficient
shielding of the titania surface, that avoids deleterious back
electron transfer to the iodine electrolyte.26 The same effects
are likely to play a major role in the present case, since
photophysical and electrochemical studies and frontier
molecular orbitals calculations evidence the inherently similar
electronic properties of the fluorous and non-fluorous para-
alkoxy-substituted dyes. This is a useful clue for future
improvements in dye molecular design. At the same time, the
introduction of a spherical-shaped, bulky fluorous substituent
connected to the donor unit through a C-C bond has
detrimental consequences that are possibly related to both
electronic factors and to an excessive steric hindrance. Such a
behaviour was not observed in the case of linear D-π-A
photosensitizer based on fluorene and should be also taken into
account in the future development of multi-branched, multi-
anchoring molecular architectures containing fluorous
components.
dye FBA3
.
Figure 6. IPCE spectrum of the DSSC fabricated with the fluorous dye FBA 3.
The use of organic D-(π-A)2 dyes based on fluorene subunits in
DSSCs afforded photovoltaic performance inferior to those
obtained with one of the most efficient and widely used
photosensitizers, namely the Ru-based N719 dye.30 For cells
fabricated under the same experimental conditions, the latter
ensured 5.2% energy conversion efficiency against the highest
2.5% value obtained using FBA3. Indeed, contrary to the black-
coloured N719, the present D-(π-A)2 photosensitizers are not
panchromatic and absorb only a part of the solar, as exemplified
in Figure 6 where a picture of the red photoelectrode containing
FBA3 and the corresponding incident photon to current
efficiency (IPCE) spectrum are reported. The complete set of
IPCE spectra for dyes FAB1-4 is reported in Figure S4, ESI. In all
cases the IPCE curves closely follow the absorption spectra of
the corresponding dyes. Also, the IPCE maxima and device
performance trends are in good agreement. The selective light
harvesting behaviour of these dyes is likely resultant from the
Experimental
Materials and methods
Chemicals. All commercially available products were used as
received without further purification. 2,7-Dibromo-9,9-dibutyl-
9H-fluorene
1
was prepared as described in the literature.34
Synthesis details for 1-Iodo-4-(undecyloxy)benzene, 1-iodo-4-
(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-
heptadecafluoroundecyloxy)benzene
and
1-(1,3-
bis(1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)propan-2-yloxy)-
2-((1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)propan-2-
yloxy)methyl)propan-2-yl)-4-bromobenzene are provided in the
Electronic Supporting Information. Solvents were purified by
standard methods and dried if necessary. Reactions were
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monitored by thin layer chromatography (TLC) that was radiometer. The photocurrent and voltage were measured
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DOI: 10.1039/C7NJ01516J
conducted on plates precoated with silica gel Si 60-F254 (Merck, using a solar simulator (Sciencetech 150) equipped with an AM
Germany). Column chromatography was carried out on silica gel 1.5 G filter. The reported data are average values of a series of
SI 60 (Merck, Germany), mesh size 0.063 – 0.200 mm (normal) at least fifteen cells for each dye.
or 0.040 – 0.063 mm (flash). 1H NMR and 13C NMR were Synthetic procedures
recorded on a Bruker Avance 400 spectrometer (400 and 100.6
MHz, respectively); 19F NMR spectra were recorded on a Bruker
Synthesis of tert-butyl bis(7-bromo-9,9-dibutyl-9H-fluoren-2-
yl)carbamate (2). A flame-dried Schlenk tube was charged with
AC 300 spectrometer (282 MHz). ESI mass spectra were
2,7-dibromo-9,9-dibutyl-9H-fluorene
1 (1.74 g, 4.0 mmol), CuI
obtained with an ICR-FTMS APEX II (Bruker Daltonics) mass
spectrometer. Elemental analyses were carried out by the
Departmental Service of Microanalysis (University of Milano).
Photophysical and electrochemical characterization of dyes.
Absorption and fluorescence spectra were recorded on a
Shimadzu UV-2401PC spectrometer and on a Spex FluoroMax
fluorometer, respectively Spectra were acquired using quartz
cells (path length: 1 cm) at room temperature in 1,2-
dichloroethane (DCE), acetonitrile (MeCN) and toluene (TOL)
solutions. To obtain the absorption spectra of the dyes
(38 mg, 0.2 mmol), tert-butyl carbamate (117 mg, 1.0 mmol)
and K3PO4 (0.85 g, 4.0 mmol), evacuated, and backfilled with
nitrogen. N,N-Dimethylethylenediamine (90 µL, 0.8 mmol) and
dry toluene (8 mL) were added under nitrogen. The Schlenk
tube was sealed and the reaction mixture was stirred at 110 °C
for 24 h. The resulting suspension was allowed to reach room
temperature and filtered through a short pad of Celite. The
filtrate was evaporated under reduced pressure and the residue
was purified by flash column chromatography (silica gel,
hexane/AcOEt 95/5) affording compound
Yield: 466 mg (56%). Mp = 212 °C. 1H NMR (400 MHz, CDCl3): δ
spectrometer. Electrochemical properties of the dyes were [ppm] = 7.55 (d, J = 8.1 Hz, 2H), 7.52 – 7.47 (m, 2H), 7.46 – 7.41
2 as a white solid.
adsorbed on titanium oxide,
a diffuse reflectance cell
(integrating sphere) was added to the Shimadzu UV-2401PC
determined using an Autolab Electrochemical Workstation
PGSTAT 30 provided with a conventional three electrodes cell
with a Pt disk, silver wire and Pt coil as working reference and
counter electrodes, respectively. A deoxygenated 0.10 M
solution of tetra-n-butylammonium hexafluorophosphate
(TBAPF6) in DCE containing 1 mmol of salt was used as the
supporting electrolyte for all dyes. The Pt working electrode was
polished between experiments with 0.3 mL of alumina paste
and sequentially sonicated in water and absolute ethanol.
Ferrocene was used as an internal standard. Therefore, all the
potential values are reported relative to Fc/Fc+ redox couple
(0.40 V vs SCE).35
(m, 4H), 7.20 – 7.12 (m, 4H), 1.88 (m, 8H), 1.47 (s, 4H), 1.13 –
0.99 (m, 4H), 0.66 (t, J = 7.3 Hz, 6H), 0.59 (m, 4H). 13C NMR
(100.6 MHz, CDCl3): δ [ppm] = 153.8, 153.2, 151.0, 143.0, 139.7,
137.5, 130.2, 126.2, 125.6, 121.9, 121.1, 121.0, 120.0, 81.2,
55.4, 40.1, 28.5, 26.0, 23.1, 14.0. Anal. Calcd. for C47H57Br2NO2:
C 68.20, H 6.94, N 1.69. Found: C 68.18, H 6.97, N 1.65.
Synthesis of tert-butyl bis(9,9-dibutyl-7-formyl-9H-fluoren-2-
yl)carbamate (3). A solution of n-butyl lithium in hexane (1.6 M,
2.0 mL, 3.2 mmol) was added dropwise over 10 min to a stirred
solution of compound 2 (0.83 g, 1.0 mmol) in dry THF (9 mL) at
-78 °C under nitrogen. The resulting mixture was stirred for an
additional hour at this temperature, then dry DMF (0.24 mL, 3.0
mmol) was added dropwise. The final reaction mixture was
allowed to attain room temperature and stirred 2 h, followed
by quenching with 5% aq. HCl (3 mL) and extraction of the
aqueous phase with Et2O (3 × 10 mL). The combined organic
layers were washed with H2O, brine and dried over MgSO4. The
solvent was evaporated under reduced pressure and the
DSSC preparation and characterization. The assembly of the
dye-sensitized solar cells was performed using a commercial
Solaronix test cell kit, with the purpose of standardizing the
operations and performing comparative studies based on
multiple samples. The kit was composed by a fluorine-doped tin
oxide (FTO) glass covered by screen printing with Solaronix
Titanium Oxide pastes (active layer of Ti-Nanoxide T/SP covered
by a reflective layer of Ti-Nanoxide R/SP, active area: 6 x 6 mm), residue was purified by flash column chromatography (silica gel,
platinized electrodes (FTO glass with a homogeneous surface of
the precursor Platisol T/SP), a sealing film made of Meltonix
1170-60, a slim glass and Iodolyte Z-50 Solaronix as redox
electrolyte. Dye-coating of the TiO2 films was carried out by
soaking the films in 10−3 M solution of dye in absolute ethanol,
hexane/AcOEt 85/15) affording compound
3 as a pale yellow
1
solid. Yield: 595 mg (82%). Mp = 205 °C. H NMR (400 MHz,
CDCl3): δ [ppm] = 10.05 (s, 2H), 7.86 – 7.84 (m, 4H), 7.78 (d, J =
8.2 Hz, 2H), 7.69 (d, J = 8.2 Hz, 2H), 7.26 (d, J = 2.7 Hz, 2H), 7.21
(dd, J = 8.2, 1.9 Hz, 2H), 2.09 – 1.87 (m, 8H), 1.48 (s, 9H), 1.12 –
0.99 (m, 8H), 0.65 (t, J = 7.3 Hz, 12H), 0.62 – 0.47 (m, 8H). 13C
NMR (100.6 MHz, CDCl3): δ [ppm] = 192. 5, 153.6, 152.9, 151.8,
147.0, 144.0, 137.1, 135.3, 130.9, 125.8, 123.1, 122.0, 121.3,
120.0, 81.6, 55.4, 40.0, 28.4, 26.1, 23.1, 14.0. Anal. Calcd. for
C49H59NO4: C 81.06, H 8.19, N 1.93. Found: C 81.00, H 8.25, N
1.91.
0
after heating the electrode to 60 C. The two electrodes were
laminated together using Meltonix 1170-60 and the solar cell
was filled with Iodolyte Z-50 through a hole in the cathode. The
filling hole was then sealed with Meltonix 1170-60 and a thin
circle glass of 6 mm diameter.
Photocurrent spectra were obtained by illumination of the solar
cell with monochromatic light obtained from a 75-W high-
pressure Xe lamp (Photon Technology Instrument, PTI) and a
monochromator equipped with a stepper motor controlled by a
personal computer. The incident light intensities at different
wavelengths were measured with a Coherent Laser-Mate Q
Synthesis of bis(9,9-dibutyl-7-formyl-9H-fluoren-2-yl)amine (4). To
a stirred solution of carbamate 3 (0.73 g, 1.0 mmol) in dry DCM
(6 mL) cooled to 10 °C trifluoroacetic acid (6 mL) was added
dropwise under nitrogen. The solution was stirred 3 h at room
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 7
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Journal Name
temperature after which the volatiles were eliminated under 7.84 – 7.80 (m, 4H), 7.72 (d, J = 8.2 Hz, 2H), 7.60 (d, JV=iew8.A3rtiHclez,O2nHlin)e,
DOI: 10.1039/C7NJ01516J
reduced pressure. The residue was dissolved in DCM and the 7.14 – 7.10 (m, 4H), 7.06 (dd, J = 8.3, 2.0 Hz, 2H), 6.87 (d, J = 8.3 Hz,
solution was washed with H2O, 5% aq. NaOH, H2O, brine and 2H), 3.97 (t, J = 6.5 Hz, 2H), 2.01 – 1.94 (m, 4H), 1.89 – 1.77 (m, 6H),
dried over MgSO4. The solvent was evaporated under reduced 1.52 – 1.42 (m, 2H), 1.39 – 1.28 (m, 14H), 1.17 – 1.02 (m, 8H), 0.88 (t,
pressure and the residue was purified by flash column J = 6.8 Hz, 3H), 0.71 (t, J = 7.3 Hz, 12H), 0.69 – 0.53 (m, 8H). 13C NMR
chromatography (silica gel, petroleum ether/AcOEt 4/1) (100.6 MHz, CDCl3): δ [ppm] = 192.3, 156.3, 153.7, 151.1, 148.7,
affording compound 4 as a yellow solid. Yield: 557 mg (89%). Mp 147.5, 140.2, 134.5, 133.8, 130.9, 127.4, 122.8, 122.0, 121.6, 119.1,
= 163 °C (dec.). 1H NMR (400 MHz, CD2Cl2): δ [ppm] = 10.03 (s, 117.1, 115.4, 68.3, 55.1, 39.9, 31.9, 29.6, 29.5, 29.4, 26.1, 23.0, 22.7,
2H), 7.86 – 7.84 (m, 4H), 7.77 (d, J = 8.2 Hz, 2H), 7.74 (d, J = 8.2 14.1, 13.9. Anal. Calcd. for C61H77NO3: C 8
Hz, 2H), 7.26 (d, J = 1.9 Hz, 2H), 7.12 (dd, J = 8.2, 2.0 Hz, 2H), Found: C 83.80, H 8.96, N 1.57.
3.99, H 8.90, N 1.61.
6.35 (s, 1H), 2.11 – 1.92 (m, 8H), 1.17 – 1.08 (m, 8H), 0.71 (t, J = Synthesis of N,N-bis(9,9-dibutyl-7-formyl-9H-fluoren-2-yl)-N-
7.5 Hz, 12H), 0.70 – 0.58 (m, 8H). 13C NMR (100.6 MHz, CD2Cl2): (4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-
δ [ppm] = 192.5, 154.7, 151.4, 148.2, 144.2, 135.1, 133.6, 131.1, heptadecafluoroundecyloxy)amine (7). A flame-dried Schlenk
123.5, 122.7, 119.4, 117.7, 112.2, 55.7, 40.77, 26.6, 23.6, 14.2. tube was charged with compound
4 (94 mg, 0.15 mmol), 1-iodo-
Anal. Calcd. for C44H51NO2: C 84.44, H 8.21, N 2.24. Found: C 4-(4,4,5,5,6,6,7,7,8,8,9,9,10,10,11,11,11-
84.41, H 8.22, N 2.15.
heptadecafluoroundecyloxy)benzene (170 mg, 0.25 mmol),
Synthesis of N,N-bis(9,9-dibutyl-7-formyl-9H-fluoren-2-yl)-N-(4- Cs2CO3 (407 mg, 1.25 mmol) and Pd(OAc)2 (5.6 mg, 0.025
methoxyphenyl)amine (5). A flame-dried Schlenk tube was mmol), evacuated, and backfilled with nitrogen. Dry, degassed
charged with compound 4
(188 mg, 0.3 mmol), 4-bromoanisole toluene (4 mL) and PtBu3 (1 M in toluene, 50 µL, 0.05 mmol)
(22 µL, 0.5 mmol), Cs2CO3 (652 mg, 2.0 mmol) and Pd(OAc)2 (12 were subsequently added under nitrogen. The Schlenk tube was
mg, 0.05 mmol), evacuated, and backfilled with nitrogen. Dry, sealed and the reaction mixture was stirred at 110 °C for 8 h.
degassed toluene (7 mL) and PtBu3 (1 M in toluene, 100 µL, 0.1 After cooling to room temperature the reaction mixture was
mmol) were subsequently added under nitrogen. The Schlenk diluted with DCM and filtered through a short pad of Celite. The
tube was sealed and the reaction mixture was stirred at 110 °C filtrate was evaporated under reduced pressure and the residue
for 24 h. After cooling to room temperature the reaction was purified by column chromatography (silica gel, DCM)
mixture was diluted with DCM and filtered through a short pad affording compound 7
as a yellow foam. Yield: 117 mg (66%).1H
of Celite. The filtrate was evaporated under reduced pressure NMR (400 MHz, CDCl3): δ [ppm] = 10.03 (s, 2H), 7.84-7.82 (m, 4H),
and the residue was purified by flash column chromatography 7.73 (d, J = 8.3 Hz, 2H), 7.61 (d, J = 8.3 Hz, 2H), 7.16 – 7.11 (m, 4H),
(silica gel, petroleum ether/DCM 1/1) affording compound
a yellow foam. Yield: 158 mg (72%).1H NMR (400 MHz, CDCl3): δ Hz, 2H), 2.46 – 2.26 (m, 2H), 2.19 – 2.08 (m, 2H), 2.05 – 1.92 (m, 4H),
[ppm] = 10.03 (s, 2H), 7.8 – 7.8 (m, 4H), 7.73 (d, J = 8.2 Hz, 2H), 1.91 – 1.79 (m, 4H), 1.17 – 1.01 (m, 8H), 0.70 (t, J = 7.3 Hz, 12H), 0.62
5 as 7.05 (dd, J = 8.3, 2.0 Hz, 2H), 6.87 (d, J = 8.9 Hz, 2H), 4.06 (t, J = 5.8
4
2
7.61 (d, J = 8.3 Hz, 2H), 7.17 – 7.12 (m, 4H), 7.06 (dd, J = 8.3, 2.0 Hz, (m, 8H). 13C NMR (100.6 MHz, CDCl3): δ [ppm] = 192.3, 155.5,
2H), 6.88 (d, J = 9.0 Hz, 2H), 3.84 (s, 3H), 2.06 – 1.80 (m, 8H), 1.15 – 153.7, 151.1, 148.6, 147.5, 140.8, 134.5, 133.9, 130.9, 127.3, 122.8,
1.04 (m, 8H), 0.71 (t, J = 7.3 Hz, 12H), 0.68 – 0.54 (m, 8H). 13C NMR 122.1, 121.7, 119.1, 117.2, 115.4, 66.6, 55.1, 39.9, 28.0 (t, JCF = 22
(100.6 MHz, CDCl3): δ [ppm] = 192.4, 156.8, 153.
147.6, 140. , 134.7, 134.0, 131.0, 127.5, 12
119.2, 117.3, 115.0, 55.7, 55.3, 40.0, 26.2, 23.1, 14.
9
, 151.
, 122.1, 121.
. Anal. (br s, 2F), -123.8 (br s, 2F), -126.5 (br s, 2F). Anal. Calcd. for
3
, 148.8, Hz), 26.1, 23.0, 20.6, 13.9. 19F NMR (282 MHz, CDCl3): δ [ppm] =
81.2 (t, J = 9.6 Hz, 3F), -114.7 (br s, 2F), -122.0 – -122.3 (m, 6F), -123.1
-
6
3
.
0
8,
1
Calcd. for C51H57NO3: C 8
7.89, N 1.89.
3
.68, H
7
.85, N
1
.
91. Found: C 83.70, H C61H60F17NO3: C 62.19, H
5
.13, N
1
.19. Found: C 62.31, H 5.27, N
1.12.
Synthesis of N,N-bis(9,9-dibutyl-7-formyl-9H-fluoren-2-yl)-N-(4-
undecyloxyphenyl)amine (6). A flame-dried Schlenk tube was
Synthesis of N,N-bis(9,9-dibutyl-7-formyl-9H-fluoren-2-yl)-N
-
(4-
(1,3-bis(1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)propan-2-yloxy)-
2-((1,1,1,3,3,3-hexafluoro-2-(trifluoromethyl)propan-2-
charged with compound
4 (94 mg, 0.15 mmol), 1-iodo-4-
yloxy)methyl)propan-2-yl)phenyl)amine (8).
A
flame-dried
(undecyloxy)benzene (93 mg, 0.25 mmol), Cs2CO3 (407 mg, 1.25
mmol) and Pd(OAc)2 (5.6 mg, 0.025 mmol), evacuated, and
backfilled with nitrogen. Dry, degassed toluene (4 mL) and PtBu3
(1 M in toluene, 50 µL, 0.05 mmol) were subsequently added
under nitrogen. The Schlenk tube was sealed and the reaction
mixture was stirred at 110 °C for 20 h. After cooling to room
temperature the reaction mixture was diluted with DCM and
filtered through a short pad of Celite. The filtrate was
evaporated under reduced pressure and the residue was
purified by flash column chromatography (silica gel,
Schlenk tube was charged with compound
4
(94 mg, 0.15
mmol),
1-(1,3-bis(1,1,1,3,3,3-hexafluoro-2-
(trifluoromethyl)propan-2-yloxy)-2-((1,1,1,3,3,3-hexafluoro-2-
(trifluoromethyl)propan-2-yloxy)methyl)propan-2-yl)-4-
bromobenzene (229 mg, 0.25 mmol), Cs2CO3 (407 mg, 1.25
mmol) and Pd(OAc)2 (5.6 mg, 0.025 mmol), evacuated, and
backfilled with nitrogen. Dry, degassed toluene (4 mL) and PtBu3
(1 M in toluene, 50 µL, 0.05 mmol) were subsequently added
under nitrogen. The Schlenk tube was sealed and the reaction
mixture was stirred at 110 °C for 24 h. After cooling to room
temperature the reaction mixture was diluted with Et2O and
filtered through a short pad of Celite. The filtrate was
hexane/Et2O 4/1) affording compound 6 as a yellow foam. Yield:
115 mg (89%).1H NMR (400 MHz, CDCl3): δ [ppm] = 10.03 (s, 2H),
8 | J. Name., 2012, 00, 1-3
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ARTICLE
evaporated under reduced pressure and the residue was H 7.93, N 4.13. MS (ESI+): m/z calcd. for C67H79N3O5: 1005.6.
View Article Online
DOI: 10.1039/C7NJ01516J
purified by flash column chromatography (silica gel, Found 1006.2 [M+H]＋.
Synthesis of FBA3. A solution of dialdehyde
7 (117 mg, 0.1
hexane/Et2O 4/1) affording compound 8 as a yellow foam. Yield:
140 mg (64%).1H NMR (400 MHz, CDCl3): δ [ppm] = 10.04 (s, 2H),
7.87 – 7.83 (m, 4H), 7.75 (d, J = 8.4 Hz, 2H), 7.65 (d, J = 8.3 Hz,
2H), 7.21 – 7.12 (m, 6H), 7.07 (dd, J = 8.2, 2.0 Hz, 2H), 4.40 (s,
6H), 2.05 – 1.93 (m, 4H), 1.91 – 1.76 (m, 4H), 1.15 – 1.00 (m, 8H),
0.70 (t, J = 7.3 Hz, 12H), 0.67 – 0.55 (m, 8H). 13C NMR (100.6
MHz, CDCl3): δ [ppm] = δ 192.3, 153.8, 151.2, 148.0, 147.2,
147.1, 134.9, 134.8, 130.8, 130.6, 126.9, 124.2, 123.2, 122.9,
121.8, 120.1 (q, JCF = 293 Hz), 119.3, 118.4, 79.4 (m), 68.1, 55.2,
48.0, 39.7, 26.1, 22.9, 13.8. 19F NMR (282 MHz, CDCl3): δ [ppm]
= -68.7 (s). Anal. Calcd. for C66H60F27NO3: C 54.29, H 4.14, N 0.96.
Found: C 54.12, H 4.30, N 0.95.
mmol), cyanoacetic acid (85 mg, 1 mmol), and ammonium
acetate (15 mg, 0.2 mmol) in AcOH (10 mL) was stirred under
reflux for 5 h. The solvent was evaporated under reduced
pressure, and the residue was taken up in DCM, washed
extensively with H2O, and dried over MgSO4. After removal of
the solvent at reduced pressure, the crude product was further
purified by column chromatography (silica gel, DCM, and then
DCM/AcOH 95/1). The dark paste thus obtained was washed
with cold petroleum ether affording the title compound as a
dark-red foam. Yield: 108 mg (82%). 1H NMR (400 MHz, CDCl3):
δ [ppm] = 8.37 (s, 2H), 8.08 – 7.98 (m, 4H), 7.72 (d, J = 8.4 Hz,
2H), 7.62 (d, J = 8.3 Hz, 2H), 7.19 – 7.12 (m, 4H), 7.06 (dd, J = 8.4,
1.9 Hz, 2H), 6.89 (d, J = 8.9 Hz, 2H), 4.07 (t, J = 5.6 Hz, 2H), 2.48 –
2.24 (m, 2H), 2.20 – 2.09 (m, 2H), 2.06 – 1.77 (m, 8H), 1.19 –
1.05 (m, 8H), 0.73 (t, J = 7.3 Hz, 12H), 0.70 – 0.51 (m, 8H).13C
NMR (100.6 MHz, CDCl3): δ [ppm] = 167.6, 157.0, 155.8, 154.0,
151.4, 148.8, 147.4, 140.5, 133.8, 132.0, 129.0, 127.6, 125.5,
122.1, 121.9, 119.6, 117.0, 115.9, 115.5, 99.0, 66.6, 55.3, 39.8,
27.98 (t, JCF = 22 Hz), 26.1, 23.0, 20.7, 13.9. 19F NMR (282 MHz,
CDCl3): δ [ppm] = -81.7 (t, J = 10.1 Hz, 3F), -114.3 (br s, 2F), -121.9 –
-123.2 (m, 6F), -123.6 (br s, 2F), -124.3 (br s, 2F), -127.0 (br s, 2F).
λmax(DCE)/nm 318 (ε/dm3 mol-1 cm-1 45877), 345 (45406) and 495
(82850). Anal. Calcd. for C67H62F17N3O4: C 61.33, H 4.76, N 3.20.
Found: C 61.42, H 4.59, N 3.09. MS (ESI+): m/z calcd. for
C67H62F17N3O4: 1311.4. Found 1312.2 [M+H]＋.
Synthesis of FBA1. A solution of dialdehyde
5 (146 mg, 0.2
mmol), cyanoacetic acid (85 mg, 1 mmol), and ammonium
acetate (15 mg, 0.2 mmol) in AcOH (10 mL) was stirred under
reflux for 6 h. The solvent was evaporated under reduced
pressure, and the residue was taken up in DCM, washed
extensively with H2O, and dried over MgSO4. After removal of
the solvent at reduced pressure, the crude product was further
purified by column chromatography (silica gel, DCM, and then
DCM/AcOH 100/3) affording the title compound as a dark-red
1
foam. Yield: 158 mg (91%). H NMR (400 MHz, CDCl3): δ [ppm]
= 8.37 (s, 2H), 8.07 – 7.99 (m, 4H), 7.72 (d, J = 8.5 Hz, 2H), 7.62
(d, J = 8.3 Hz, 2H), 7.19 – 7.12 (m, 4H), 7.07 (dd, J = 8.4, 1.6 Hz,
2H), 6.90 (d, J = 9.0 Hz, 2H), 3.85 (s, 3H), 2.06 – 1.94 (m, 4H),
1.94 – 1.79 (m, 4H), 1.11 (m, 8H), 0.73 (t, J = 7.3 Hz, 12H), 0.69
– 0.57 (m, 8H). 13C NMR (100.6 MHz, CDCl3): δ [ppm] = 167.7,
157.0, 151.4, 147.4, 131.9, 129.1, 127.6, 125.9, 125.5, 121.8,
121.7, 119.6, 115.9, 116.6, 114.8, 99.0, 55.5, 55.3, 39.8, 26.1,
23.0, 13.9. λmax(DCE)/nm 320 (ε/dm3 mol-1 cm-1 30817), 349
(27471) and 500 (50472). Anal. Calcd. for C57H59N3O5: C 79.05,
H 6.87, N 4.85. Found: C 79.00, H 6.90, N 4.87. MS (ESI–): m/z
calcd. for C57H59N3O5: 865.4. Found 864.4 [M–H]-..
Synthesis of FBA4. A solution of dialdehyde
8 (146 mg, 0.1
mmol), cyanoacetic acid (85 mg, 1 mmol), and ammonium
acetate (15 mg, 0.2 mmol) in AcOH (10 mL) was stirred under
reflux for 5 h. The solvent was evaporated under reduced
pressure, and the residue was taken up in Et2O, washed
extensively with H2O, and dried over MgSO4. After removal of
the solvent at reduced pressure, the crude product was further
purified by column chromatography (silica gel, gradient DCM to
DCM/AcOH 25/1) affording the title compound as a dark-red
Synthesis of FBA2. A solution of dialdehyde
6 (174 mg, 0.2
mmol), cyanoacetic acid (85 mg, 1 mmol), and ammonium
acetate (15 mg, 0.2 mmol) in AcOH (10 mL) was stirred under
reflux for 5 h. The solvent was evaporated under reduced
pressure, and the residue was taken up in DCM, washed
extensively with H2O, and dried over MgSO4. After removal of
the solvent at reduced pressure, the crude product was further
1
foam. Yield: 112 mg (70%). H NMR (400 MHz, CDCl3): δ [ppm]
= 8.39 (s, 2H), 8.07 – 8.01 (m, 4H), 7.75 (d, J = 8.2 Hz, 2H), 7.66
(d, J = 8.3 Hz, 2H), 7.23 – 7.14 (m, 6H), 7.08 (dd, J = 8.2, 2.0 Hz,
purified by column chromatography (silica gel, DCM, and then 2H), 4.41 (s, 6H), 2.07 – 1.93 (m, 4H), 1.92 – 1.76 (m, 4H), 1.17 –
1.04 (m, 8H), 0.72 (t, J = 7.3 Hz, 12H), 0.69 – 0.58 (m, 8H).13C
NMR (100.6 MHz, CDCl3): δ [ppm] = 167.6, 157.0, 154.2, 151.5,
148.3, 147.1, 147.0, 134.8, 131.9, 131.1, 129.3, 127.2, 125.6,
124.7, 123.2, 122.0, 120.1 (q, JCF = 293 Hz), 119.8, 118.6, 115.8,
99.4, 79.4 (m), 68.0, 55.3, 48.0, 39.6, 26.1, 22.9, 13.8. 19F NMR
(282 MHz, CDCl3): δ [ppm] = -68.7 (s). λmax(DCE)/nm 323 (ε/dm3
mol-1 cm-1 47781), 351 (36187) and 482 (78920). Anal. Calcd. for
C72H62F27N3O7: C 54.24, H 3.92, N 2.64. Found: C 54.22, H 3.96,
N 2.65. MS (ESI+): m/z calcd. for C72H62F27N3O7: 1593.4. Found
1593.3 [M]＋.
DCM/AcOH 95/1). The dark paste thus obtained was washed
with cold petroleum ether affording the title compound as a
dark-red foam. Yield: 177 mg (88%). 1H NMR (400 MHz, CDCl3):
δ [ppm] = 8.37 (s, 2H), 8.09 – 7.95 (m, 4H), 7.72 (d, J = 8.4 Hz,
2H), 7.62 (d, J = 8.3 Hz, 2H), 7.22 – 7.00 (m, 6H), 6.89 (d, J = 8.9
Hz, 2H), 3.98 (t, J = 6.2 Hz, 2H), 2.07 – 1.77 (m, 10H), 1.58 – 1.45
(m, 2H), 1.41 – 1.25 (m, 14H), 1.19 – 1.03 (m, 8H), 0.89 (t, J = 6.7
Hz, 3H), 0.73 (t, J = 7.3 Hz, 12H), 0.70 – 0.54 (m, 8H). 13C NMR
(100.6 MHz, CDCl3): δ [ppm] = 167.6, 157.1, 156.6, 154.0, 151.4,
148.9, 147.5, 139.9, 133.7, 132.1, 129.0, 127.7, 125.5, 121.9,
119.6, 116.9, 115.9, 115.5, 98.9, 68.4, 55.3, 39.8, 31.9, 29.7,
29.6, 29.5, 29.4, 26.1, 23.0, 22.7, 14.1, 13.9. λmax(DCE)/nm 322
(ε/dm3 mol-1 cm-1 29933), 348 (29624) and 494 (53582). Anal.
Calcd. for C67H79N3O5: C 79.96, H 7.91, N 4.18. Found: C 79.89,
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27 F. Zhang, W. Ma, Y. Jiao, J. Wang, X. Shan, H. Li, X. Lu and S
Meng, ACS Appl. Mater. Interfaces, 201D4O, I: 10.1039/C7NJ01516J
, 223V5ie9w. Article Online
Acknowledgements
6
28 S. Sarker, H. W. Seo, Y.-K. Jina, K.-S. Lee, M. Lee and D. M. Kim,
Electrochim. Acta, 2015, 182, 493.
29 F. Wu, X. Li, Y. Tong and T. Zhang, J. Power Sources, 2017, 342
704.
30 Z.-S. Wang, H. Kawauchi, T. Kashima and H. Arakawa, Coord.
Chem. Rev., 2004, 248, 1381.
31 W. Li, Y. Wu, X. Li, Y. Xie and W. Zhu, Energy Environ. Sci., 2011,
The authors gratefully acknowledge the financial support
provided by the CNR/Regione Lombardia project “Integrated
Zero Emission Buildings”, the Consejo Nacional de
Investigaciones Científicas y Técnicas (CONICET), Agencia
Nacional Científica
y Tecnológica (ANPCyT-FONCyT) and
Universidad Nacional de Río Cuarto (UNRC). LO and FF are
permanent research fellows of CONICET.
4
, 1830.
32 F. Bella, G. Leftheriotis, G. Griffini, G. Syrrokostas, S. Turri, M.
Grätzel and C. Gerbaldi, Adv. Funct. Mat., 2016, 26, 1127.
33 A.-L. Anderson, S. Chen, L. Romero, I. Top and R. Binions,
Buildings, 2016, 6, 37.
34 M. J. Xiong, H. L. Zhong and M. S. Wong, Aust. J. Chem., 2007,
60, 608.
Notes and references
1
2
B. O'Regan and M. Grätzel, Nature, 1991, 353, 737
A. Hagfeldt, G. Boschloo, L. C. Sun, L. Kloo and H. Pettersson,
Chem. Rev., 2010, 110, 6595.
35 C. M. Cardona, W. Li, A. E. Kaifer, D. Stockdale and G. C. Bazan,
Adv. Mater., 2011, 23, 2367.
3
4
5
6
7
8
9
N. Martsinovich and A. Troisi, Energy Environ. Sci., 2011, 4,
4473.
E. M. J. Johansson, R. Lindblad, H. Siegbahn, A. Hagfeldt and
H. Rensmo, ChemPhysChem, 2014, 15, 1006.
B. Roose, S. Pathak and U. Steiner, Chem. Soc. Rev., 2015, 44
8326.
V. S. Manthou, E. K. Pefkianakis, P. Falaras and G. C.
Vougioukalakis, ChemSusChem, 2015, , 588.
J. Wu, Z. Lan, J. Lin, M. Huang, F. Yunfang, L. Leqing and G. Luo,
Chem. Rev., 2015, 115, 2136.
M. L. Parisi, S. Maranghi and R. Basosi, Renew. Sust. Energ.
Rev., 2014, 39, 124.
A. Mishra, M. K. R. Fischer and P. Bäuerle, Angew. Chem. Int.
Ed., 2009, 48, 2474.
,
8
10 J. N. Clifford, E. Martínez-Ferrero, A. Viterisi and E. Palomares,
Chem. Soc. Rev., 2011, 40, 1635.
11 S. Ahmad, E. Guillen, L. Kavan, M. Grätzel and M. K.
Nazeeruddin, Energy Environ. Sci., 2013, 6, 3439.
12 M. Urbani, M. Grätzel, M. K. Nazeeruddin and T. Torres, Chem.
Rev., 2014, 114, 12330.
13 C.-P. Lee, R. Y.-Y. Lin, L.-Y. Lin, C.-T. Li, T.-C. Chu, S.-S. Sun, J. T.
Lin and K.-C. Ho, RSC Adv., 2015, 5, 23810.
14 M. Asif, Solar Energy, 2016, 123, 127.
15 W. Zeng, Y. Cao, Y. Bai, Y. Wang, Y. Shi, M. Zhang, F. Wang, C.
Pan and P. Wang, Chem. Mater., 2010, 22, 1915.
16 Y. Xie, Y. Tang, W. Wu, Y. Wang, J. Liu, X. Li, H. Tian and W.-H.
Zhu, J. Am. Chem. Soc., 2015, 137, 14055.
17 Z.-S. Huang, H. Meier and D. Cao, J. Mater. Chem. C, 2016, 4,
2404.
18 A. Abbotto, N. Manfredi, C. Marinzi, F. De Angelis, E. Mosconi,
J.-H. Yum, Z. Xianxi, M. K. Nazeeruddin and M. Grätzel, Energy
Environ. Sci., 2009, 2, 1094.
19 N. Manfredi, B. Cecconi and A. Abbotto, Eur. J. Org. Chem.,
2014, 32, 7069.
20 X.-X. Dai, H.-L. Feng, Z.-S. Huang, M.-J. Wang, L. Wang, D.-B.
Kuang, H. Meier and D. Cao, Dyes Pigments, 2015, 114, 47.
21 D. Heredia, J. Natera, M. Gervaldo, L. Otero, F. Fungo, C.-Y. Lin
and K.-T. Wong, Org. Lett., 2010, 12, 12.
22 L. Macor, M. Gervaldo, F. Fungo, L. Otero, T. Dittrich, C.-Y. Lin,
L.-C. Chi, F.-C. Fang, S.-W. Lii, K.-T. Wong, C.-H. Tsai and C.-C.
Wu, RSC Adv., 2012, 2, 4869.
23 G. Pozzi, S. Orlandi, M. Cavazzini, D. Minudri, L. Macor, L.
Otero and F. Fungo, Org. Lett., 2013, 15, 4642.
24 A. Baheti, P. Tyagi, K. R. Justin Thomas, Y.-C. Hsu and J. T. Lin,
J. Phys. Chem. C, 2009, 113, 8541.
25 L.-Y. Lin, C.-H. Tsai, K.-T. Wong, T.-W. Huang, C.-C. Wu, S.-H.
Chou, F. Lin, S.-H. Chen and A.-I. Tsai, J. Mater. Chem., 2011,
21, 5950.
26 G. Marzari, J. Durantini, D. Minudri, M. Gervaldo, L. Otero, F.
Fungo, G. Pozzi, M. Cavazzini, S. Orlandi and S. Quici, J. Phys.
Chem. C, 2012, 116, 21190.
10 | J. Name., 2012, 00, 1-3
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