Phenothiazinyl rhodanylidene merocyanines for dye-sensitized solar cells

Article abstract of DOI:10.1021/jo202608w

Phenothiazinyl rhodanylidene acetic acid merocyanine dyes with variable substitution pattern on the peripheral benzene ring were synthesized in good to excellent yields by Knoevenagel condensation of the corresponding phenothiazinyl aldehydes and rhodanin

Full text of DOI:10.1021/jo202608w

Article
pubs.acs.org/joc
Phenothiazinyl Rhodanylidene Merocyanines for Dye-Sensitized
Solar Cells
Tim Meyer,† Daniel Ogermann,‡ Andrea Pankrath,† Karl Kleinermanns,*,‡ and Thomas J. J. Muller*,†
̈
†Institut fur Organische Chemie und Makromolekulare Chemie, Heinrich-Heine Universitat Dusseldorf, Universitatstrasse 1,
̈
̈
̈
̈
D-40225 Dusseldorf, Germany
̈
‡Institut fur Physikalische Chemie, Heinrich-Heine Universitat Dusseldorf, Universitatstrasse 1, D-40225 Dusseldorf, Germany
̈
̈
̈
̈
̈
S
* Supporting Information
ABSTRACT: Phenothiazinyl rhodanylidene acetic acid mer-
ocyanine dyes with variable substitution pattern on the
peripheral benzene ring were synthesized in good to excellent
yields by Knoevenagel condensation of the corresponding
phenothiazinyl aldehydes and rhodanine-N-acetic acid. The
electronic properties were investigated by cyclic voltammetry,
absorption, and fluorescence spectroscopy. Electron releasing
substitution leads to an appreciable lowering of the oxidation
potential, bathochromic shift of the absorption band, and
minimization of the emission quantum yield. Not least as a
consequence of these properties, the compounds are
interesting for use as chromophores in dye-sensitized solar
cells (DSSC). DSSCs were constructed and successfully tested
by determining the characteristic parameters such as incident-
photon-to-electron conversion efficiency (IPCE), fill factor
(FF), and overall efficiency.
electron-donor components in material scientific investigations
such as electrically conducting charge-transfer composites,12
polymers,13 Do−Acc arrangements,14 and also as chromo-
phores in dye-sensitized photovoltaic cells.15 As part of our
program to synthesize and study oligophenothiazines,8,16 we
have just recently disclosed are general and modular synthetic
access to phenothiazinyl merocyanine dyes with variable
substitution patterns on the peripheral benzene ring and N-
methyl rhodanylidene or 2,3-dioxoindanylidene as acceptor
units.17 All these merocyanines revealed a reversible redox
behavior that stems from the phenothiazinyl centered oxidation
to give stable radical cations. Based upon an excellent
correlation of the oxidation potentials with Hammett σp
parameters, it was not only possible to shift and predictably
fine-tune the first oxidation, but also to correlate a remote
substituent effect on the luminescence efficiency. Electro-
optical absorption, absorption and emission spectroscopy in
conjunction with time-dependent DFT computations on
selected synthetic model systems rationalize the peculiar highly
polar excited state behavior of phenothiazinyl merocyanines.
Besides a pronounced emissive solvochromism all merocya-
nines of the series reveal large Stokes shifts caused by large
dipole moment changes upon excitation from the ground to the
excited state. Based upon the improved spectral overlap with
INTRODUCTION
■
Merocyanines1 are unsymmetrical and highly dipolar and have
adopted a central role among Do−Acc dyes. In particular,
merocyanines are well-suited to self-organize in mesoscopic and
macroscopic morphologies,2 and therefore, they have become
increasingly important as absorbing chromophores in dye-
sensitized solar cells (DSSC)3 for photovoltaics with a wide
range of donor auxochromes. For several reasons, phenothia-
zines,4 a class of tricyclic nitrogen−sulfur heterocycles with a
broad pharmaceutical profile,5 are particularly intriguing as
redox active donor systems. They possess low and highly
reversible first-oxidation potentials4,6 with a pronounced
propensity to form stable radical cations,7 and their redox
and fluorescence properties can be tuned.8 Furthermore, the
inherent folded conformation of phenothiazine9 with a folding
angle of 158.5°, which can be transformed into a stable radical
cation with a planar conformation and excellent delocaliza-
tion,10 qualifies phenothiazine-based Do−Acc chromophores as
excellent models for redox-switchable merocyanines. In
addition, phenothiazine derivatives with extended π-conjugated
substituents often display intense luminescence upon UV/vis
excitation with remarkable Stokes shifts that might be due to
solvent relaxation and, in part, to geometry changes in the
excited state. As a consequence, the favorable electronic
properties of phenothiazines have led to applications as
electrophore probes in supramolecular assemblies11 for photo-
induced electron transfer (PET) and sensor studies, and as
Received: December 19, 2011
Published: February 24, 2012
© 2012 American Chemical Society
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a
Scheme 1. Synthesis of N-Alkyl 7-Substituted 3-Formyl Phenothiazines 1e−1j
a
Beller cyanation: Pd(OAc)2, dppf, K4[Fe(CN)6], Na2CO3, NMP, 120 °C, 18 h. bSuzuki coupling: Pd(PPh3)4, (hetero)aryl boronate, K2CO3, DME,
c
d
H2O, 95 °C, 10 h. Buchwald-Hartwig coupling: Pd(dba)2, HP(t-Bu)3BF4, sec. amine, NaOC(CH3)3, dry 1,4-dioxane, 110 °C, 26 h. Ullmann
coupling: CuI, L-proline, sec. amine, K2CO3, dry DMSO, 100 °C, 24 h.
the solar spectrum of rhodanylidene moiety,18 the possibility of
its favorable HOMO−LUMO tuning,19 and the detailed
information on the excited state properties of its phenothiazinyl
merocyanine derivatives, we set out to synthesize electron-rich
phenothiazinyl rhodanylidene acetic acid merocyanines, to
study their electronic properties, and to investigate their use
and performance in the organic solar cells as sensitizing dyes.
bromination of the corresponding alcohol with N-bromo
succinimide in the presence of triphenylphosphane.
With various N-alkyl 3-formyl phenothiazines 1 in hand,
Knoevenagel condensation with rhodanine acetic acid as the
methylene active condensation partner gave rise to the
formation of various electron-rich phenothiazinyl rhodanyli-
dene acetic acid merocyanines 2 in good to excellent yields as
red to violet solids (Scheme 3).
The structures of all merocyanines 2 were unambiguously
RESULTS AND DISCUSSION
■
1
assigned by H and 13C NMR, UV/vis and IR spectroscopy,
Synthesis. The key reaction for the synthesis of electron-
rich phenothiazinyl merocyanines is the Knoevenagel con-
densation of the corresponding phenothiazinyl carbaldehydes 1
and rhodanine N-acetic acid in acetic acid in the presence of
ammonium acetate as a catalyst.17 The 7-substituted
phenothiazinyl carbaldehydes 1e−1j are accessible via cross-
coupling methodologies, as previously exemplified with
phenothiazines for Suzuki-Miyaura coupling,16c Beller cyana-
tion,8b or Buchwald-Hartwig- and Ullmann-N-arylations,8c,d
from the N-alkyl 7-bromo-3-formyl phenothiazines 1c and 1d
as key intermediates (Scheme 1). The latter are synthesized in
three steps starting from phenothiazine by alkylation,
Vilsmeier−Haack formylation and bromination (Scheme 2).
For increasing the solubility a 2-decyltetradecyl substituent, the
so-called “dovetail” was chosen as side chain. The “dovetail
bromide” required for the alkylation can be obtained by
mass spectrometry, and combustion analysis. Interestingly,
although two geometrical isomers for the newly formed double
bonds can be expected, the appearance of single sets of the
signals in the NMR spectra indicates the stereoselective
formation of the Z-isomers in all cases. Previously, the
stereoselectivity was additionally corroborated by X-ray
structure analysis of two phenothiazinyl merocyanine deriva-
tives.17
Photophysical Properties. The phenothiazinyl rhodanyli-
dene acetic acid merocyanine dyes 2a−2f display four distinct
broad, unstructured absorption bands in the UV/vis region at
252−269, 294−307, 358−366, and 462−503 nm (Table 1,
Figure 1). In case of dye 2g an additional band appears at 343
nm instead of the first band, while dye 2h displays only three
absorption bands at 271, 374, and 536 nm. As shown before by
comparison of phenothiazinyl rhodanylidene merocyanines,
and N,N-diethyl- and N,N-diphenylaniline model systems, the
longest wavelength absorption arises from the aniline-
rhodanylidene merocyanine substructure, whereas the pheno-
thiazinyl specific bands are found at higher energies.17 A closer
look at the spectroscopic data shows a strong dependence of
the location of the low-energy absorption bands and their
corresponding molar extinction coefficients on the electronic
nature of the substituents at the peripheral benzene ring of the
phenothiazine. While derivatives with electron-withdrawing
groups absorb at higher energies and show their largest molar
extinction coefficients at the longest wavelength maxima,
electron-donating groups exhibit a deviant behavior. The
unsubstituted dye 2a reveals its longest wavelength absorption
at 478 nm, which shifts in the presence of a nitrile acceptor to
462 nm, and bathochromically in case of donor substituted
dyes. By choosing C-bonded phenothiazine or N-bonded
pyrrolidine as donor-fragments (2e, 2h), even a shift of 30 or
almost 60 to 536 nm is possible. At the same time the molar
extinction coefficients of the short wavelength maxima increase
strongly, while those of the longest wavelength band drop only
Scheme 2. Synthesis of N-Alkyl 7-Bromo-3-formyl
Phenothiazines 1c and 1d
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Scheme 3. Synthesis of Electron-rich Phenothiazinyl Rhodanylidene Acetic Acid Merocyanines 2
a
Table 1. Absorption and Emission Properties of the Dyes 2
noncommunicable π-systems. The appearance of a new broad
absorption band at 343 nm in the spectrum of dye 2g supports
this argumentation, because it is in accord with absorption
spectra of N-alkylated carbazoles.20 All dyes 2 reveal more or
b
c
emission λmax,em
d
absorption λmax,abs [nm]
Stokes shift Δv
̃
e
dye
(ε 103[M−1cm−1])
[nm] (Φf)
[cm−1
]
2a 252 (18), 305 (14),
651 (0.01)
643 (0.05)
630 (0.21)
655 (<0.01)
688 (<0.01)
636 (<0.01)
657 (<0.01)
659 (<0.01)
5600
5600
5800
6000
5300
5500
5700
3500
less intense fluorescence and show large Stokes shifts (Δv) in a
̃
366 (14), 478 (20)
range from 5300−6000 cm−1, which represents a peculiar and
characteristic behavior of many phenothiazine based chromo-
phores (Figure 2). Noticeably, dye 2f shows only a small shift
2b 256 (28), 297 (20),
361 (21), 473 (29)
2c 265 (18), 297 (21),
363 (16), 462 (22)
2d 269 (29), 303 (25),
358 (19), 471 (23)
2e 265 (36), 307 (16),
359 (24), 503 (18)
2f
258 (62), 300 (22),
359 (19), 472 (24)
2g 294 (33), 343 (17),
363 (17), 478 (22)
2h 271 (31), 374 (22), 536 (18)
a
Absorption and emission spectra were measured in CH2Cl2, T = 293
b
c
K. Recorded in CH2Cl2 at c(2) = 10−3 M. Recorded in CH2Cl2 at
d
c(2) = 10−6 M. Determined with 4-dicyanomethylene-2-methyl-6-[p-
(dimethylamino)styryl]-4H-pyran (DCM) as a standard in DMSO, Φf
e
= 0.78. Δv = 1/λ
− 1/λmax,em.
̃
max,abs
Figure 2. Absorption (solid line) and emission (dashed line) of
compound 2d (recorded in CH2Cl2, T = 293 K, excitation wavelength
λexc = 471 nm (a.u. = arbitrary units)).
slightly in comparison to the unsubstituted derivative. Sterically
demanding donor-fragments, such as N-bonded phenothiazine
or carbazole (2f, 2g), show no effect on the location of the
absorption bands, which can be explained by an out-of-plane
rotation of these substituents resulting in the generation of two
of 3500 cm−1, what can be ascribed to its low-energy
absorption. The broad, unstructured emission bands display
maxima at 630−688 nm, depending on the substitution pattern.
However the emission intensity as reflected by the fluorescence
quantum yields varies significantly with the peripheral benzo
substituent on the phenothiazine. The electron-deficient
substituted merocyanines 2b−2c exhibit the highest quantum
yields of 5 and 21% in this series. Increasing the electron
density significantly quenches the fluorescence. While the
derivative with the electronically neutral hydrogen (2a) shows a
fluorescence quantum yield of 1%, for donor-substituted
phenothiazinyl merocyanines, the yield decreases considerably.
Electrochemical Properties. The cyclic voltammograms
of the dyes 2 exhibit two, in the case of 2e three, reversible
oxidations, typical of phenothiazine derivatives (Table 2). Their
potential strongly depends on the electronic nature of the
substituent of the peripheral benzene ring. The nitrile
substituted derivative as the most electron-deficient dye
shows the first oxidation wave at 1116 mV, that is, anodically
shifted compared to the unsubstituted dye 2a. The second
oxidation presumably lies outside the measurement range of
Figure 1. Normalized absorption spectra of 2 (recorded in CH2Cl2 at
T = 293 K (a.u. = arbitrary units)).
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a
Table 2. Cyclovoltammetric Data and Electrochemical Properties of the Dyes 2
b
b
b
+2/+3
d
e
E(S+/S*) vs NHE
0/+1
+1/+2
E0
E0
E0
E0−0
c
c
c
dye
[mV]
[mV]
[mV]
E1/20/+1 vs NHE [V] E1/2+1/+2 vs NHE [V] E1/2+2/+3 vs NHE [V]
[eV]
[V]
2a
2b
2c
2d
2e
2f
898
970
1116
792
686
719
926
423
1563
1614
1.10
1.17
1.31
0.99
0.88
0.92
1.12
0.62
1.76
1.81
2.13
2.16
2.24
2.24
2.03
2.21
2.03
1.99
−1.03
−0.99
−0.93
−1.25
−1.15
−1.29
−0.91
−1.37
1443
873
1.64
1.07
1.29
1.60
1.24
1477
1.68
1095
1400
1044
2g
f
2h
a
Recorded in CH2Cl2, T = 293 K, ν = 100 mV s−1, electrolyte: [Bu4N][PF6], Pt working electrode, Pt counter electrode, Ag/AgCl reference
b
c
d
electrode. E0 = (Epa − Epc)/2 with Fc/Fc+. E1/2: E0 vs NHE (E0 (3M KCl/Ag/Ag+) = 0.198 V vs NHE). E0−0 was determined from the cross-
e
f
section of absorption and emission spectra. Excited state oxidation potential E(S+/S*) = E1/2
− E0−0. 1,1′-Dimethylferrocen was used as an
0/+1
internal standard.
dichloromethane. In contrast, electron-rich substituents reduce
the oxidation potentials significantly. In the case of
phenothiazine as donor fragment (2e) the decrease is 200
mV, or even the double by using pyrrolidine (2f). The linear
correlation of the oxidation potential of the phenothiazinyl
merocyanines with the Hammett substitution parameter σp, as
previously discussed,17 seems to proceed at strongly electron
pushing substituted dyes. The sterically loaded derivatives 2f
and 2g are out of ordinary because these compounds are
distinguished with comparable high first oxidation potentials of
719 and 926 mV, respectively. A closer look at the absorption
behavior and literature measurements gives the evident
explanation; the dyes exhibit in a twisted conformation. Both
π-systems subsist orthogonally to each other, wherefore there is
no communication in the electronic ground state within the
bonded fragments. The detected potentials accord with the
measurements of the corresponding N-alkylated donor frag-
ments (E0,phenothiazine0/+1 = 701 mV,21 E0,carbazole0/+1 = 930 mV22).
Figure 3. Cyclic voltammogram of dye 2h (red line) and 2a (black
line) (recorded in CH2Cl2, T = 293 K, ν = 100 mVs−1, electrolyte:
[Bu4N][PF6], Pt working electrode, Pt counter electrode, Ag/AgCl
reference electrode).
With the help of the photophysical and the electrochemical
measurement data, we are able to appreciate the HOMO and
LUMO energy levels of the synthesized dyes (Table 2). In
connection with the fixed energy potentials of a typical DSSC,
the standard potential for the conducting band (CB) of TiO2 to
is the broadening of the longest wavelength band. The
absorption extends from 370 to 800 nm compared to 400−
700 nm for the dyes in solution. Due to the adsorption on the
TiO2 surface the harvesting of solar light is thus increased. Two
reasons could be possible to explain the observed broadening.
At first the energy of the π* level is lowered due to the
interaction of the carboxylic acid with the Ti4+ ions on the TiO2
surface. The increased electron delocalization of the π* level
leads to a bathochromic shift of the absorption spectra.
Furthermore dye aggregation and excimer formation (J-
aggregates) can lead to a broadening of the absorption.23
Figure 6 shows the IPCE (incident photo-to-current
conversion efficiency) spectra of the DSSCs. Only moderate
IPCEs from 8% (2c) to 37% (2f) were achieved at the
absorption maximum of the dyes. One possible reason is a
rather low efficiency of electron injection in the conducting
band of TiO2. The photophysical and electrochemical analysis
is in line with the measured IPCEs. According to the absorption
spectra, the dyes 2e, 2g and 2h should show the best IPCE
values at long wavelengths up to 700 nm. In the case of 2e, we
measure efficiencies of 5% at 650 nm. The highest IPCE value
(at about 470 nm) shows the dye 2f. In this spectral range the
dye exhibits its absorption maximum with a relative high molar
extinction coefficient of 24000 M−1 cm−1. At first view the low
NHE: ECB = −0.5 V, and for the iodide/triiodide (I−/I3 ) redox
−
couple to NHE: E = 0.53 V (Figure 3), we can prepare a
schematic energy diagram (Figure 4). To ensure a satisfied
performance of the solar cell, a high energy HOMO level,
below the redox potential, and a low energy LUMO level,
above the Fermi energy of the semiconductor, are required to
ensure a low energy absorption, uninhibited charge transitions
and an easy oxidizability of the dye. These requirements are
given for all dyes. While the HOMO energy level, which
correlates directly with the measurements of the cyclo-
voltammetry, shows the prediscussed influence of the electronic
nature of the substituents, the LUMO level is less influenced. In
general, electron donating groups increase, whereas electron
withdrawing groups decrease the accordant value.
Photovoltaic Devices and Solar Cell Performance. To
test the dyes 2a−2h as sensitizers in DSSCs, solar cells with
nanocrystalline TiO2 were prepared. The exact preparation is
demonstrated in the experimental part and the results, together
with the standard N3 (cis-bis(isothiocyanato)bis(2,2′-bipyridyl-
4,4′-dicarboxylato)-ruthenium(II)), are summarized in Table 3.
The absorption spectra of the adsorbed dyes on the TiO2
surface are shown in Figure 5. They are similar to the
absorption spectra of the dyes in solution. The main difference
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Figure 4. Schematic energy level diagram (HOMO−LUMO) for the dyes 2a−2h.
Table 3. Photovoltaic Performance DSSCs Based on the
a
Dyes 2
dye
jSC [mA cm−2
]
UOC [mV]
FF
η [%]
2a
2b
2c
2d
2e
2f
2.00
1.77
1.07
3.33
4.46
3.87
3.64
1.28
11.73
607
627
613
638
683
698
615
575
690
0.58
0.59
0.53
0.57
0.60
0.65
0.57
0.58
0.51
0.7
0.6
0.4
1.2
1.9
1.8
1.3
0.5
4.1
2g
2h
N3
a
Measured under irradiation with AM 1.5 G simulated solar light (100
mW cm−2) at room temperature, 13 μm of film thickness, 0.78 cm2 of
working area. The concentrations of the dyes are 0.2 mM in CH2Cl2
and of the electrolyte 0.6 M tetrabutylammonium iodide (TBAI), 0.1
M lithium iodide, 0.05 M iodine and 0.5 M 4-tert-butylpyridine (TBP)
in 5 mL of acetonitrile.
Figure 6. Spectra of the incident photon-to-current conversion
efficiencies (IPCE) obtained for nanocrystalline TiO2 solar cells
sensitized by the dyes 2a−2h.
Figure 5. Absorption spectra of the dyes 2 on TiO2 surface measured
in reflection arrangement (the absorption of pure TiO2 nanoparticles
was subtracted).
Figure 7. Photocurrent density jSC vs voltage curves of DSSCs based
on the dyes 2 with iodine/triiodide electrolyte under irradiation at AM
1.5 simulated solar light (100 mW cm−2).
IPCE value of 2h surprises as it has the lowest oxidation
potential of all dyes and highest absorption in the visible
spectral range. Hence, electron detachment should be quite
easy and efficient. The explanation is given by the tendency of
this dye to form aggregates, resulting in low efficiencies.
The solar cells sensitized with the dyes 2a−2h show
moderate short circuit photocurrent densities jsc from 1.07
(2c) to 4.46 (2e) mA cm−2 and reasonable fill factors in the
range 0.51−0.65 (Figure 7). Figure 4 indicates that all energetic
positions of the excited state oxidation potential (LUMO) are
more negative than the edge of the TiO2 conduction band
(−0.5 V vs NHE24). An electron injection from the LUMO of
the dyes into the conducting band can take place. The oxidized
dyes can be regenerated by accepting electrons from the
iodide/triiodide electrolyte, because the ground state (HOMO)
of all used dyes are sufficiently more positive than the potential
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of the electrolyte (E0 = 0.53 V25). The dye 2e sensitized SC
achieves the best overall conversion efficiency (η) of 1.9%, see
Table 3. The energetic positions of HOMO (0.88 V) and
LUMO (−1.15 V) and the broad absorption up to 700 nm
(extended conjugated π-system) enhance the photovoltaic
performance. Keeping in mind that the efficiency of a DSSC
prepared from the standard N3 with the preparation technique
described in Section 4 was 4.1%, we achieved reasonable 46%
of this value using 2e as sensitizer. The SC sensitized with dye
2f shows a similar efficiency (1.8%). In this case, the absorption
extents only to 630 nm. However dye 2f has the highest IPCE-
values of all investigated dyes (37% at 470 nm). The dyes 2c
and 2h represent a group of sensitizers which are not suitable
for DSSCs. The overall efficiencies of 0.5% (2h) and 0.4% (2c)
are too low. Dye 2c features a strong electron withdrawing
substituent (cyano group) at the donor part of the molecule.
The decreased electron density in the phenothiazine moiety
hinders the oxidation of the dye and efficient charge transfer. As
stated before, aggregation of dye 2h is observed during
preparation of the DSSC as indicated by the opacity of the
solution and precipitation. The precipitated dye in the pores of
the TiO2 film decreases the yield of charge carrier injection so
that only low conversion efficiencies are obtained. The neutral
substitution (−H) of dye 2a results in a DSSC overall efficiency
of 0.7%. The photocurrent lies in the range between the values
of DCCSs based on sensitizers with strong electron push or
pull moieties. The bromide substituted dye 2b achieves similar
solar cell efficiencies (η = 0.6%) as dye 2a. Probably because of
the marginally larger bathochromic shift of 2a (λabs (max) =
478 nm (2a), 473 nm (2b)) and its lower fluorescence
quantum yield, the efficiencies of dye 2a sensitized SCs are
higher than those of dye 2b sensitized SCs.
energetic properties the tendency to form aggregates effects the
efficiencies of the DSSCs. Dye 2h has the lowest oxidation
0/+1
potential of all dyes (E0
= 423 mV). Hence, it should be
quite easy to oxidize, but its aggregation results in low
efficiencies (η = 0.4%). Furthermore, the steric constitution of
the substituent influences the characteristics of the dyes. In the
case of the dyes 2f and 2g the substituent is rotated out of the
plane of the chromophore and conjugation is thus prevented.
The use of phenothiazine based building blocks as sensitizers
has several distinct advantages over other sensitizers. At first,
the synthesis of phenothiazinyl rhodanylidene acetic acid
merocyanine dyes with various substituents is easier, more
efficiently compared, and less expensive than the commonly
used metal (e.g., ruthenium) complexes. The flexible
substitution of the donor or the acceptor moieties, whereby
the energetic positions of HOMO and LUMO can be adjusted
exactly, is a great advantage of these sensitizers.
Our results show impressively the systematic optical and
electrochemical behavior of these compounds. The develop-
ment of one-pot routes to synthesize other merocyanine dyes
with electron-rich substituents in favorable steric constitutions
as well as optimal energetic positions of HOMO and LUMO,
and their application as sensitizers in DSSCs will be subject of
further research.
EXPERIMENTAL SECTION
■
General Considerations. Reagents, catalysts, ligands, and solvents
were purchased reagent grade and used without further purification.
DMSO was dried and distilled from CaH2 under argon atmosphere. 1-
Bromo-2-decyl-tetradecane,26 10-hexyl-10H-phenothiazine,8a 10-hexyl-
10H-phenothiazine-3-carbaldehyde (1a),27 and 7-bromo-10-hexyl-
10H-phenothiazine-3-carbaldehyde (1c)28 were prepared according
to literature procedures. Column chromatography: silica gel 60, mesh
70−230. TLC: silica gel plates 60 F254
.
CONCLUSION
Instrumentation. Chemical shifts δ in the 1H NMR and 13C NMR
spectra are reported in ppm relative to deuterated solvents (CD2Cl2,
THF-d8, acetone-d6, or DMSO-d6). The assignments of quaternary C,
CH, CH2, and CH3 signals were made by using DEPT spectra. The
absorption spectra of the dyes 2 in solution were recorded on a diode
array UV−vis spectrometer. Cyclic voltammetry experiments were
performed under argon in dry and degassed CH2Cl2 at room
temperature and at scan rates of 100, 250, 500, and 1000 mV s−1 using
an electrochemical workstation. The electrolyte was Bu4NPF6 (0.025
M). The working electrode was a 1 mm platinum disk, the counter
electrode was a platinum wire, and the reference electrode was an Ag/
■
A series of new phenothiazinyl rhodanylidene acetic acid
merocyanine dyes were successfully synthesized and charac-
terized by photophysical and electrochemical analysis. The dyes
exhibit a distinct donor-π-acceptor behavior comprising
phenothiazine derivatives as an electron donor and rhodany-
lidene acetic acid as an electron acceptor. Electron-rich or
electron-deficient substituents in the phenothiazine moiety
modify the physical and chemical properties of the system. An
electron-rich substituent like a second phenothiazinyl group
(dye 2e) decreases the first oxidation potential (E0
mV (2e)) compared to the unsubstituted phenothiazine and an
efficient intramolecular charge transfer can take place. An
electron withdrawing group, for example, a cyanide group (dye
0/+1
= 686
AgCl electrode. The potentials were corrected to the internal standard
0/+1
of Fc/Fc+ in CH2Cl2 (E0
= 450 mV).
Preparation of the DSSCs. TiO2 nanopowder (5 g Aerosil TiO2
P25) was suspended in nitric acid (1 N) to prepare a suitable TiO2
paste. This suspension was heated at 80 °C for 24 h.29 Then, the nitric
acid was evaporated and the TiO2 solid was dried for 3 days at 100 °C.
Finally the TiO2 solid was treated with 25 mL of water, acetylacetone
(2.5 g, 24.97 mmol), Triton-X-100 (1.25 g, 1.92 mmol) and
polyethylene oxide (M.W. 100000).30
We used aluminoborosilicate glass coated with fluorine doped tin
oxide (SnO2:F) as conducting transparent substrate (resistivity ≈ 10 Ω
cm−2). The active area was masked with scotch tape and was coated
with TiO2 suspension by use of a glass scraper and dried at 80 °C for
10 min. After removal of the scotch tape, we measured ∼13 μm
deposit thickness. This primed photo electrode was sintered in a
muffle furnace for ∼45 min at 450 °C. The cooled TiO2 electrode was
immersed in dye solution (0.2 mM in CH2Cl2) for 24 h at room
temperature. A thin platinum layer was spread on the FTO coating of
the counter electrode. Few drops of the active redox couple iodine/
iodide (0.1 M lithium iodide, 0.05 M iodine, 0.6 M tetrabutylammo-
nium iodide, and 0.5 M 4-tert-butylpyridine in acetonitrile) were
added to the photoelectrode for reduction of the oxidized dyes.
2c), reduces the electron density in the phenothiazine donor,
which hinders oxidation of the dye (E0
0/+1
= 1116 mV (2c)).
The substituent also influences the absorption region of the
synthesized dyes. A pronounced conjugated π-system shifts the
absorption to the red. The electron deficient merocyanines 2b−
c exhibit the highest fluorescence quantum yields in this series
(5 and 21%). However, a higher electron density in the
phenothiazine part quenches the fluorescence significantly.
These properties are favorable for a possible application as
sensitizer in DSSCs. The obtained efficiencies (IPCE and
overall efficiencies) are in good agreement with the photo-
physical and electrochemical results. The best performance
sensitizer dye 2e (η = 1.9%) corresponds to 46% of the
performance of a DSSC prepared with the standard dye N3
under our experimental conditions. As expected the sensitizer
2c leads to a low DSSC efficiency (η = 0.5%). Beside the
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Finally, the counter electrode was clamped to the photoelectrode/
electrolyte system.15
compound 1b as a yellow oil. 1H NMR (500 MHz, CD2Cl2): δ 0.89 (t,
J = 7.0 Hz, 6 H), 1.16−1.44 (m, 40 H), 1.93−2.01 (m, 1 H), 3.80 (d, J
= 7.1 Hz, 2 H), 6.93 (dd, J = 0.7, 8.2 Hz, 1 H), 6.96 (d, J = 8.4 Hz, 1
H), 6.98 (dt, J = 1.1, 7.5 Hz, 1 H), 7.15 (dd, J = 1.5, 7.7 Hz, 1 H), 7.19
(dt, J = 1.5, 7.5 Hz, 1 H), 7.59 (d, J = 1.9 Hz, 1 H), 7.65 (dd, J = 1.9,
8.4 Hz, 1 H), 9.79 (s, 1 H). 13C NMR (125.5 MHz, CD2Cl2): δ 14.5
(two CH3), 23.3 (two CH2), 26.7 (two CH2), 29.93 (CH2), 29.95
(CH2), 30.0 (two CH2), 30.16 (two CH2), 30.19 (CH2), 30.23 (two
CH2), 30.27 (CH2), 30.5 (two CH2), 32.0 (two CH2), 32.50 (CH2),
32.51 (CH2), 35.2 (CH), 52.4 (CH2), 116.2 (CH), 117.3 (CH), 124.1
(CH), 125.5 (Cquat), 126.7 (Cquat), 128.0 (CH), 128.1 (CH), 128.8
(CH), 130.4 (CH), 131.8 (Cquat), 144.7 (Cquat), 152.0 (Cquat), 190.4
(CH). MALDI-TOF MS m/z = 563.31. UV/vis λmax (ε) [nm] = 276
Measurements of the DSSCs. Measurements of the wavelength
dependence of the short circuit current (jSC) were carried out in a
light-proof box with a 70 W xenon lamp and a grating monochromator
in the spectral range of 300−800 at 1 nm resolution. Data were
transmitted to a computer and processed there. The light intensity
incident on the electrode (Iinc) was measured with a power meter. The
IPCE is defined by the following expression:31
2
j (A/cm ) × 1240
sc
IPCE(%) =
× 100
2
λ(nm) × I (W/cm )
(1)
inc
(19000), 289 (20000), 383 (8000). IR (film): v [cm−1] = 2924 (s),
̃
The photocurrent−voltage (I−V) curves were measured using a
120 W xenon lamp and a special filter, which was focused to give 100
mW cm−2 (1 sun) at Air Mass (AM) 1.5 at the surface of the solar cell.
The fill factors ff and overall efficiencies η were calculated according to
eqs 2 and 3. Here MPP is the “maximum power point” and Uoc the
open-circuit voltage.3b
2854 (s), 2721 (w), 2170 (w), 1695 (s), 1587 (m), 1574 (m), 1557
(m), 1494 (m), 1463 (s), 1416 (m), 1376 (m), 1344 (m), 1309 (w),
1288 (w), 1198 (m), 1149 (w), 1102 (m), 898 (w), 816 (w), 747 (m),
690 (w). Anal. Calcd for C37H57NOS (563.9): C 78.80, H 10.19, N
2.48. Found: C 78.60, H 10.37, N 2.49.
7-Bromo-10-(2-decyltetradecyl)-10H-phenothiazine-3-car-
baldehyde (1d). Bromine (0.8 mL, 15.4 mmol) dissolved in 2 mL of
acetic acid was added quickly to a solution of 10-(2-decyltetradecyl)-
10H-phenothiazine-3-carbaldehyde (1b) (8.70 g, 15.4 mmol) in 30
mL of glacial acetic acid. The reaction mixture was stirred at room
temperature for 10 h. Then, an oversaturated aqueous solution of
Na2CO3 was added, and the mixture was stirred for another 2 h. The
resulting green reaction mixture was extracted several times with
diethylether. The combined organic layers were dried with anhydrous
sodium sulfate, and the solvents were removed in vacuo. The residue
was chromatographed on silica gel (n-hexane/diethylether 30:1) to
2
MPP(W/cm )
ff =
2
j (A/cm ) × U (V)
oc
(2)
sc
2
j (A/cm ) × U (V) × ff
oc
sc
η(%) =
× 100
2
I
(W/cm )
(3)
inc
Optical absorption spectra of the synthesis products were recorded
by using a UV−vis spectrophotometer operated at a resolution of 1
nm. The absorption spectra of the electrodes were measured in a
reflection arrangement.
1
give 8.69 g (88%) of compound 1d as a yellow viscous oil. H NMR
(500 MHz, CD2Cl2): δ 0.88 (t, J = 7.0 Hz, 6 H), 1.20−1.44 (m, 40 H),
1.89−1.98 (m, 1 H), 3.75 (d, J = 7.2 Hz, 2 H), 6.78 (d, J = 8.6 Hz, 1
H), 6.96 (d, J = 8.4 Hz, 1 H), 7.26 (d, J = 2.2 Hz, 1 H), 7.28 (dd, J =
2.3, 8.6 Hz, 1 H), 7.59 (d, J = 1.9 Hz, 1 H), 7.66 (dd, J = 1.9, 8.4 Hz, 1
H), 9.79 (s, 1 H). 13C NMR (125.5 MHz, CD2Cl2): δ 14.5 (two CH3),
23.3 (two CH2), 26.7 (two CH2), 29.93 (CH2), 29.95 (CH2), 30.0
(two CH2), 30.15 (two CH2), 30.19 (CH2), 30.23 (two CH2), 30.27
(CH2), 30.4 (two CH2), 31.9 (two CH2), 32.5 (two CH2), 35.1 (CH),
52.6 (CH2), 116.1 (Cquat), 116.4 (CH), 118.5 (CH), 126.0 (Cquat),
127.8 (Cquat), 128.9 (CH), 130.3 (CH), 130.6 (CH), 130.8 (CH),
132.1 (Cquat), 144.0 (Cquat), 151.6 (Cquat), 190.3 (CH). MALDI-TOF
MS m/z = 641.30. UV/vis λmax (ε) [nm] = 247 (19000), 276 (24000),
10-(2-Decyl-tetradecyl)-10H-phenothiazine. 10H-Phenothia-
zine (9.00 g, 45.2 mmol) and potassium tert-butoxide (5.73 g, 51.1
mmol) were dissolved in 100 mL of dry THF and stirred for 70 min at
room temperature. Then, 1-bromo-2-decyl-tetradecane (31.9 g, 76.4
mmol) was added to the resulting, dark brown solution and the
mixture was heated to reflux for 18 h. After cooling to room
temperature, the reaction mixture was filtered through a short pad of
silica gel, which was washed several times with THF. The solvents
were removed in vacuo and the crude product was chromatographed
on silica gel (n-hexane) to give 21.81 g (90%) of 10-(2-decyl-
tetradecyl)-10H-phenothiazine as a colorless oil. 1H NMR (500 MHz,
CD2Cl2): δ 0.89 (t, J = 6.9 Hz, 6 H), 1.17−1.43 (m, 40 H), 1.91−2.00
(m, 1 H), 3.73 (d, J = 6.8 Hz, 2 H), 6.88−6.94 (m, 4 H), 7.11−7.18
(m, 4 H). 13C NMR (125.5 MHz, CD2Cl2): δ 14.5 (two CH3), 23.3
(two CH2), 26.8 (two CH2), 29.93 (CH2), 29.95 (CH2), 30.0 (two
CH2), 30.18 (two CH2), 30.20 (CH2), 30.24 (two CH2), 30.27 (CH2),
30.5 (two CH2), 32.1 (two CH2), 32.5 (two CH2), 35.0 (CH), 52.0
(CH2), 116.5 (two CH), 122.8 (two CH), 126.3 (two Cquat), 127.7
(two CH), 127.9 (two CH), 146.4 (two Cquat). MALDI-TOF MS m/z
= 535.3. UV/vis λmax (ε) [nm] = 258 (3400), 311 (6000). IR (film): v
[cm−1] = 2925 (m), 2852 (m), 2345 (w), 1923 (w), 1594 (m), 1572
(m), 1485 (m), 1459 (s), 1339 (m), 1285 (m), 1250 (s), 1128 (w),
1106 (w), 1039 (m), 926 (w), 848 (w), 748 (s), 726 (m), 625 (w).
Anal. Calcd for C36H57NS (535.9): C 80.68, H 10.72, N 2.61. Found:
C 81.02, H 11.02, N 2.67.
10-(2-Decyltetradecyl)-10H-phenothiazine-3-carbaldehyde
(1b). 10-(2-Decyl-tetradecyl)-10H-phenothiazine (7.63 g, 14.3 mmol),
and N-methylformanilide (1.9 mL, 15.6 mmol) were dissolved in 14
mL of dry 1,2-dichloroethane and the reaction mixture was cooled to
0 °C. Phosphorus oxychloride (1.6 mL, 17.7 mmol) dissolved in 3 mL
of 1,2-dichloroethane was added dropwise within 4 h to the reaction
mixture. The reaction was heated to reflux temperature for 48 h. Then,
after cooling to room temperature, 90 mL of an aqueous solution of
sodium acetate (40 wt %) was added and the resulting biphasic
reaction mixture was stirred for 3 h. The aqueous layer was extracted
several times with small amounts of diethyl ether. The combined
organic fractions were dried with anhydrous sodium sulfate and the
solvents were removed in vacuo. The residue was chromatographed on
silica gel (n-hexane/diethyl ether 25:1) to give 4.67 g (58%) of
292 (16000), 329 (5000), 383 (7000). IR (film): v [cm−1] = 3368 (w),
̃
2925 (s), 2853 (s), 2725 (m), 1695 (s), 1595 (s), 1557 (m), 1456 (s),
1416 (m), 1393 (m), 1337 (m), 1306 (m), 1271 (m), 1198 (s), 1156
(m), 1104 (m), 868 (w), 814 (m), 741 (m), 656 (w), 636 (w), 554
(w). Anal. Calcd for C37H56BrNOS (642.8): C 69.13, H 8.78, N 2.18.
Found: C 69.52, H 9.08, N 2.06.
10-(2-Decyltetradecyl)-7-formyl-10H-phenothiazine-3-car-
bonitrile (1e). Anhydrous Na2CO3 (0.33 g, 3.11 mmol), K4[Fe-
(CN)6] (0.29 g, 0.79 mmol) (ground to a fine powder and dried under
vacuum), Pd(OAc)2 (7.00 mg, 0.03 mmol), 1,1′-bis-
(diphenylphosphanyl)ferrocene (35.0 mg, 0.06 mmol) and 7-bromo-
10-(2-decyltetradecyl)-10H-phenothiazine-3-carbaldehyde (1d) (2.00
g, 3.11 mmol) were dissolved in 3 mL of N-methylpyrrolidinone under
an argon atmosphere and the reaction mixture was stirred at 125 °C
for 14 h. After cooling to room temperature, the solution was diluted
with deionized water, a saturated aqueous solution of Na2SO3, and
dichloromethane. The aqueous phase was extracted several times with
small portions of dichloromethane, and the combined organic phases
were washed with brine and dried with anhydrous sodium sulfate, and
the solvents were removed in vacuo. The residue was chromatographed
on silica gel (n-hexane/ethyl acetate 30:1 to 10:1) to give 1.04 g (55%)
of compound 1e as a yellow viscous oil. 1H NMR (500 MHz, acetone-
d6): δ 0.88 (t, J = 6.9 Hz, 6 H), 1.16−1.49 (m, 40 H), 1.96−2.03 (m, 1
H), 4.02 (d, J = 7.3 Hz, 2 H), 7.26 (d, J = 8.6 Hz, 1 H), 7.28 (d, J = 8.5
Hz, 1 H), 7.54 (d, J = 1.9 Hz, 1 H), 7.62 (dd, J = 1.9, 8.5 Hz, 1 H),
7.67 (d, J = 1.9 Hz, 1 H), 7.79 (dd, J = 1.9, 8.4 Hz, 1 H), 9.88 (s, 1
H).13C NMR (125.5 MHz, acetone-d6): δ 14.5 (two CH3), 23.4 (two
̃
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Table 4. Experimental Details of the Suzuki Cross-Coupling Reaction (GP1)
pinacolylboronate [g] (mmol)
1c [g] (mmol)
K2CO3 [g] (mmol)
Pd(PPh3)4 [mg] (μmol)
product [g] (%)
p-tolyl-pinacolyl boronate 0.31 (1.40)
0.60 (1.54)
0.54 (1.38)
1.39 (10.1)
1.24 (9.00)
49 (42)
43 (38)
0.51 (90) of 1f
0.66 (89) of 1g
10-hexyl-phenothiazine-3-pinacolyl boronate 0.51 (1.25)
Table 5. Experimental Details of the Buchwald-Hartwig Cross-Coupling Reaction (GP2)
1d [g] (mmol)
amine [g] (mmol)
NaOC(CH3)3 [g] (mmol)
[(t-Bu)3PH]BF4 [mg] (mmol)
Pd(dba)2 [mg] (mmol)
product [g] (%)
2.00 (3.11)
1.72 (2.68)
phenothiazine 0.71 (3.60)
carbazole 0.52 (3.08)
0.42 (4.35)
0.36 (3.75)
90 (0.31)
80 (0.27)
90 (0.15)
80 (0.14)
0.52 (22) of 1h
0.55 (28) of 1i
CH2), 26.7 (two CH2), 30.2 (three CH2), 30.35 (CH2), 30.36 (CH2),
30.39 (CH2), 30.41 (CH2), 30.45 (CH2), 30.46 (CH2), 30.49 (CH2),
30.6 (two CH2), 31.9 (two CH2), 32.7 (two CH2), 35.5 (CH), 52.7
(CH2), 107.5 (Cquat), 118.1 (CH), 118.4 (CH), 118.9 (Cquat), 125.8
(Cquat), 126.8 (Cquat), 129.2 (CH), 131.0 (CH), 131.5 (CH), 133.1
(CH), 133.6 (Cquat), 149.5 (Cquat), 150.6 (Cquat), 190.6 (CH).
MALDI-TOF MS m/z = 588.36. UV/vis λmax (ε) [nm] = 248
(11000), 258 (11000), 283 (37000), 384 (7000), 299 (14000). IR
CD2Cl2): δ 14.30 (CH3), 14.32 (CH3), 23.15 (CH2), 23.17 (CH2),
27.0 (CH2), 27.1 (CH2), 27.2 (CH2), 27.3 (CH2), 31.9 (CH2), 32.0
(CH2), 48.0 (CH2), 48.6 (CH2), 115.3 (CH), 116.0 (CH), 116.1
(CH), 116.7 (CH), 122.9 (CH), 124.5 (Cquat), 124.7 (Cquat), 124.9
(Cquat), 125.4 (CH), 125.5 (CH), 125.7 (CH), 125.9 (CH), 127.8
(CH), 127.9 (CH), 128.5 (CH), 130.7 (CH), 131.7 (Cquat), 134.1
(Cquat), 135.8 (Cquat), 142.8 (Cquat), 142.9 (Cquat), 145.1 (Cquat), 145.6
(Cquat), 150.9 (Cquat), 190.3 (CH). MALDI-TOF MS m/z = 592.2.
UV/vis λmax (ε) [nm] = 289 (48000), 399 (12000). IR (KBr): v
[cm−1] = 2924 (m), 2825 (m), 1686 (s), 1602 (m), 1578 (m), 1459
(s), 1414 (m), 1376 (m), 1333 (m), 1242 (s), 1196 (s), 873 (w), 806
(m), 745 (m). Anal. Calcd. for C37H40N2OS2 (592.9): C 74.96, H
6.80, N 4.73. Found: C 74.94, H 7.08, N 4.65.
(film): v [cm−1] = 2926 (m), 2854 (m), 2723 (w), 2226 (m), 1896
̃
̃
(w), 1694 (m), 1602 (m), 1578 (m), 1464 (s), 1375 (w), 1341 (w),
1283 (w), 1197 (s), 1100 (m), 884 (w), 820 (m), 723 (m), 592 (w),
526 (w). Anal. Calcd. for C38H56N2OS (588.9): C 77.50, H 9.58, N
4.76. Found: C 77.21, H 9.64, N 4.72.
General Procedure for the Suzuki Cross-Coupling Reaction
(GP1). Under a nitrogen atmosphere, 1.0 equiv of the pinacolylbor-
onic ester and 7.2 equiv of K2CO3 were dissolved in 9 mL of a mixture
(2:1) of dimethoxyethane and distilled water (for experimental details,
see Table 4). The solution was degassed with nitrogen for 20 min.
Then, 1.1 equiv of 7-bromo-10-hexyl-10H-phenothiazine-3-carbalde-
hyde (1c) and 3 mol % of Pd(PPh3)4 were added and the reaction
mixture was stirred at 95 °C for 10 h. After cooling to room
temperature, the solution was diluted with deionized water, a saturated
aqueous solution of Na2SO3, and dichloromethane. The aqueous
phase was extracted several times with small portions of dichloro-
methane, the combined organic phases were washed with brine and
dried with anhydrous sodium sulfate, and the solvents were removed in
vacuo. The residue was chromatographed on silica gel to give the
aldehydes 1f and 1g as yellow resins.
General Procedure for the Buchwald-Hartwig Cross-Cou-
pling Reaction (GP2). Under a nitrogen atmosphere, 1.0 equiv of 7-
bromo-10-(2-decyltetradecyl)-10H-phenothiazine-3-carbaldehyde
(1d), 1.15 equiv of the amine, 1.4 equiv of sodium tert-butoxide, 0.10
equiv of tris-tert-butylphosphonium tetrafluoroborate and 0.05 equiv
of bis(dibenzylidene acetone)palladium(0) were dissolved in 4 mL of
dry 1,4-dioxane (for experimental details, see Table 5). Then, the
reaction mixture was stirred at 110 °C for 26 h. After cooling to room
temperature, the solution was diluted with deionized water, a saturated
aqueous solution of Na2SO3, and dichloromethane. The aqueous
phase was extracted several times with small portions of dichloro-
methane, the combined organic phases were washed with brine, dried
with anhydrous sodium sulfate, and the solvents were removed in
vacuo. The residue was chromatographed on silica gel to give the
products 1h and 1i as resins.
10-Hexyl-7-p-tolyl-10H-phenothiazine-3-carbaldehyde (1f). Ac-
cording to GP1 and flash chromatography on silica gel (n-hexane/
acetone 50:1), 0.51 g (90%) of compound 1f were obtained as a
10-(2-Decyltetradecyl)-10H-[3,10′-biphenothiazine]-7-carbalde-
hyde (1h). According to the GP2 and flash chromatography on silica
gel (n-hexane/diethylether 20:1), 0.52 g (22%) of compound 1h were
obtained as a yellow highly viscous resin. 1H NMR (300 MHz,
acetone-d6): δ 0.86 (t, J = 7.0 Hz, 3 H), 0.87 (t, J = 7.0 Hz, 3 H),
1.15−1.53 (m, 40 H), 2.07−2.15 (m, 1 H), 4.04 (d, J = 7.2 Hz, 2 H),
6.25−6.30 (m, 2 H), 6.72−6.92 (m, 4 H), 6.99−7.04 (m, 2 H), 7.23−
7.30 (m, 3 H), 7.38 (d, J = 8.5 Hz, 1 H), 7.67 (d, J = 1.9 Hz, 1 H), 7.79
(dd, J = 1.9, 8.4 Hz, 1 H), 9.84 (s, 1 H). 13C NMR (75 MHz, acetone-
d6): δ 14.4 (two CH3), 23.4 (two CH2), 26.78 (CH2), 26.81 (CH2),
29.1 (CH2), 29.3 (CH2), 29.6 (CH2), 29.8 (CH2), 30.1 (CH2), 30.16
(CH2), 30.18 (CH2), 30.35 (two CH2), 30.41 (CH2), 30.6 (CH2),
32.02 (CH2), 32.04 (two CH2), 32.7 (two CH2), 35.4 (CH), 52.6
(CH2), 117.0 (two CH), 117.4 (CH), 119.7 (CH), 121.0 (two Cquat),
123.5 (two CH), 126.2 (Cquat), 127.5 (CH), 127.95 (two CH), 128.0
(Cquat), 129.1 (CH), 130.3 (CH), 130.8 (CH), 131.0 (CH), 132.9
(Cquat), 137.2 (Cquat), 145.0 (two Cquat), 145.2 (Cquat), 151.7 (Cquat),
190.5 (CH). MALDI-TOF MS m/z = 760.4. UV/vis λmax (ε) [nm] =
1
yellow highly viscous resin. H NMR (500 MHz, CD2Cl2): δ 0.88−
0.94 (m, 3 H), 1.30−1.36 (m, 4 H), 1.41−1.48 (m, 2 H), 1.76−1.83
(m, 2 H), 2.38 (s, 3 H), 3.85 (t, J = 7.3 Hz, 2 H), 6.88 (d, J = 8.5 Hz, 1
H), 6.90 (d, J = 8.5 Hz, 1 H), 7.23 (d, J = 8.1 Hz, 2 H), 7.32 (d, J = 2.0
Hz, 1 H), 7.38 (dd, J = 2.0, 8.4 Hz, 1 H), 7.42 (d, J = 8.0 Hz, 2 H),
7.54 (d, J = 1.6 Hz, 1 H), 7.60 (dd, J = 1.6, 8.4 Hz, 1 H), 9.76 (s, 1 H).
13C NMR (125.5 MHz, CD2Cl2): δ 14.4 (CH3), 21.4 (CH3), 23.2
(CH2), 27.0 (CH2), 27.1 (CH2), 31.9 (CH2), 48.5 (CH2), 115.2
(CH), 116.4 (CH), 124.4 (Cquat), 124.8 (Cquat), 125.8 (CH), 126.3
(CH), 126.7 (two CH), 128.4 (CH), 130.1 (two CH), 130.7 (CH),
131.6 (Cquat), 136.8 (Cquat), 137.0 (Cquat), 137.6 (Cquat), 142.8 (Cquat),
150.8 (Cquat), 190.2 (CH). UV/vis λmax (ε) [nm] = 260 (24000), 289
(41000), 395 (9000). IR (KBr): v [cm−1] = 2925 (m), 2854 (m), 2346
̃
(w), 1686 (s), 1579 (s), 1467 (s), 1244 (m), 1197 (m), 883 (w), 804
(m), 737 (w). ESI HR MS calcd. for (C26H27NOSNa) m/z =
424.1706. Found: 424.1703.
258 (48000), 277 (44000), 382 (12000). IR (film): v [cm−1] = 2920
̃
(s), 2851 (m), 2722 (w), 1690 (s), 1591 (m), 1574 (w), 1497 (w),
1460 (s), 1443 (s), 1402 (w), 1373 (w), 1337 (w), 1306 (m), 1267
(m), 1236 (m), 1198 (m), 1153 (w), 1128 (w), 1098 (w), 1082 (w),
1043 (w), 995 (w), 957 (w), 922 (w), 897 (w), 881 (w), 820 (m), 741
(s), 717 (m), 703 (w), 687 (w), 635 (m), 617 (w). Anal. Calcd. for
C49H64N2OS2 (760.5): C 77.32, H 8.47, N 3.68. Found: C 77.01, H
8.56, N 3.51.
7-(9H-Carbazol-9-yl)-10-(2-decyltetradecyl)-10H-phenothiazine-
carbaldehyde (1i). According to the GP2 and flash chromatography
on silica gel (n-hexane/diethylether 20:1), 0.55 g (28%) of compound
10,10′-Dihexyl-10H,10H′-3,3′-bisphenothiazine-7-carbaldehyde
(1g). According to the GP1 and flash chromatography on silica gel (n-
hexane/acetone 50:1) 0.66 g (89%) of compound 1g were obtained as
a yellow highly viscous resin. 1H NMR (500 MHz, CD2Cl2): δ 0.88 (t,
J = 6.9 Hz, 3 H), 0.89 (t, J = 7.0 Hz, 3 H), 1.28−1.38 (m, 8 H), 1.39−
1.50 (m, 4 H), 1.74−1.86 (m, 4 H), 3.85 (t, J = 7.2 Hz, 2 H), 3.90 (t, J
= 7.3 Hz, 2 H), 6.87−6.95 (m, 5 H), 7.12 (dd, J = 1.4, 7.6 Hz, 1 H),
7.14 - 7.19 (m, 1 H), 7.29 (dd, J = 2.1, 8.1 Hz, 2 H), 7.33 (dd, J = 2.4,
5.7 Hz, 1 H), 7.34 (dd, J = 2.3, 5.6 Hz, 1 H), 7.56 (d, J = 1.9 Hz, 1 H),
7.63 (dd, J = 1.9, 8.4 Hz, 1 H), 9.77 (s, 1 H). 13C NMR (125.5 MHz,
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1i were obtained as a yellow highly viscous resin. 1H NMR (300 MHz,
acetone-d6): δ 0.79−0.90 (m, 6 H), 1.15−1.50 (m, 40 H), 2.07−2.13
(m, 1 H), 3.98 (d, J = 7.1 Hz, 2 H), 7.18 (d, J = 8.4 Hz, 1 H), 7.23−
7.45 (m, 9 H), 7.66 (d, J = 1.8 Hz, 1 H), 7.72 (dd, J = 1.8, 8.4 Hz, 1
H), 8.19 (d, J = 7.7 Hz, 2 H), 9.83 (s, 1 H). 13C NMR (75 MHz,
acetone-d6): δ 14.4 (two CH3), 23.3 (two CH2), 26.75 (CH2), 26.78
(CH2), 30.1 (CH2), 30.16 (CH2), 30.18 (CH2), 30.3 (CH2), 30.36
(two CH2), 30.38 (two CH2), 30.42 (two CH2), 30.60 (CH2), 30.62
(CH2), 31.98 (CH2), 32.00 (CH2), 32.62 (CH2), 32.64 (CH2), 35.3
(CH), 52.5 (CH2), 110.5 (two CH), 117.2 (CH), 118.9 (CH), 120.7
(two CH), 121.1 (two CH), 124.1 (two Cquat), 126.1 (Cquat), 126.6
(CH), 126.9 (two CH), 127.2 (CH), 127.3 (Cquat), 129.0 (CH), 130.8
(CH), 132.8 (Cquat), 133.8 (Cquat), 141.7 (two Cquat), 144.4 (Cquat),
151.7 (Cquat), 190.4 (CH). MALDI-TOF MS m/z = 728.4. UV/vis
λmax (ε) [nm] = 282 (46000), 293 (44000), 328 (13000), 341
Table 6. Experimental Details of the Knoevenagel-
Condensation Reaction (GP3)
rhodanine N-
acetic acid [g]
(mmol)
ammonium
acetate [mg]
(mmol)
acetic
acid
[mL]
aldehyde 1 [g]
dye 2 [g]
(mmol)
(%)
1.130 (2.000)
0.420 (2.200)
0.404 (2.113)
0.379 (1.980)
0.128 (0.674)
0.133 (0.697)
0.149 (0.781)
0.147 (0.772)
0.163 (0.851)
154 (2.00)
148 (1.92)
139 (1.80)
47 (0.61)
49 (0.63)
55 (0.71)
54 (0.70)
60 (0.77)
4.0
4.0
3.5
1.2
1.3
1.4
1.4
1.5
1.402 (95)
of 1b
of 2a
1.240 (1.920)
of 1d
1.473 (94)
of 2b
1.060 (1.800)
of 1e
1.262 (92)
of 2c
0.246 (0.613)
of 1f
0.235 (67)
of 2d
0.751 (0.634)
of 1g
0.330 (68)
of 2e
(13000), 386 (12000). IR (film): v [cm−1] = 3055 (w), 2922 (s), 2851
̃
0.540 (0.710)
of 1h
0.623 (94)
(m), 2722 (w), 1690 (s), 1599 (m), 1580 (m), 1557 (w), 1503 (m),
1464 (s), 1452 (s), 1412 (m), 1373 (m), 1333 (m), 1312 (m), 1273
(m), 1228 (s), 1198 (s), 1148 (m), 1119 (w), 1098 (w), 1026 (w),
1016 (w), 1003 (w), 970 (w), 918 (m), 897 (m), 881 (m), 818 (m),
748 (s), 723 (s), 685 (m), 642 (m), 615 (m). Anal. Calcd. for
C49H64N2OS (729.1): C 80.72, H 8.85, N 3.84. Found: C 80.49, H
8.94, N 3.83.
of 2f
0.511 (0.702)
of 1i
0.575 (91)
of 2g
0.490 (0.774)
of 1j
0.512 (82)
of 2h
were washed with brine, dried with sodium sulfate, and the solvents
were removed in vacuo. The residue was chromatographed on silica gel
to give the products 2 as red to violet solids.
(Z)-2-(5-((10-(2-Decyltetradecyl)-10H-phenothiazine-3-yl)-meth-
ylene)-4-oxo-2-thioxothiazolidine-3-yl)acetic Acid (2a). According
to the GP3 and flash chromatography on silica gel (dichloromethane
to dichloromethane/methanol/acetic acid 87:12:1), 1.402 g (95%) of
10-(2-Decyltetradecyl)-7-(pyrrolidin-1-yl)-10H-phenothiazine-3-
carbaldehyde (1j). Under a nitrogen atmosphere 7-bromo-10-(2-
decyltetradecyl)-10H-phenothiazine-3-carbaldehyde (1d) (1.53 g, 2.38
mmol) pyrrolidine (0.60 mL, 7.14 mmol), potassium carbonate (0.66
g, 4.76 mmol), copper(I)iodide (0.03 g, 0.24 mmol), and L-proline
(0.09 g, 0.48 mmol) were dissolved in 3 mL of dry DMSO. After 20 h
at 100 °C, pyrrolidine (0.30 mL, 3.57 mmol), potassium carbonate
(0.33 g, 2.38 mmol), copper(I)iodide (0.02 g, 0.16 mmol), and L-
proline (0.03 g, 0.16 mmol) were added, and the brown reaction
mixture was stirred for 24 h at 100 °C. After cooling to room
temperature, the solution was diluted with deionized water, a saturated
aqueous solution of Na2SO3, and dichloromethane. The aqueous
phase was extracted several times with small portions of dichloro-
methane, the combined organic phases were washed with brine and
dried with anhydrous sodium sulfate, and the solvents were removed in
vacuo. The residue was chromatographed on silica gel (n-hexane/
diethylether 20:1 to n-hexane/diethylether 10:1) to give 0.61 g (41%)
1
compound 2a were obtained as a red solid; mp 73−79 °C. H NMR
(500 MHz, DMSO-d6/CS2 1:1): δ 0.89 (m, 6 H), 1.17−1.44 (m, 40
H), 1.86−1.95 (m, 1 H), 3.83 (d, J = 7.1 Hz, 2 H), 4.69 (s, 2 H), 6.98
(dt, J = 0.9, 7.4 Hz, 1 H), 7.02 (d, J = 8.0 Hz, 1 H), 7.10 (d, J = 8.7 Hz,
1 H), 7.13 (dd, J = 1.4, 7.7 Hz, 1 H), 7.19 (dt, J = 1.4, 7.7 Hz, 1 H),
7.37 (d, J = 2.1 Hz, 1 H), 7.46 (dd, J = 2.1, 8.6 Hz, 1 H), 7.74 (s, 1 H).
13C NMR (125.5 MHz, DMSO-d6/CS2 1:1): δ 14.0 (two CH3), 22.4
(two CH2), 25.7 (two CH2), 28.99 (CH2), 29.00 (CH2), 29.05 (CH2),
29.06 (CH2), 29.21 (CH2), 29.23 (CH2), 29.26 (CH2), 29.29 (two
CH2), 29.31 (CH2), 29.57 (CH2), 29.58 (CH2), 30.8 (two CH2), 31.6
(two CH2), 34.2 (CH), 44.9 (CH2), 51.0 (CH2), 116.4 (CH), 116.7
(CH), 118.8 (Cquat), 123.3 (CH), 123.6 (Cquat), 125.4 (Cquat), 127.1
(Cquat), 127.2 (CH), 127.5 (CH), 129.3 (CH), 130.7 (CH), 132.8
(CH), 143.5 (Cquat), 147.8 (Cquat), 166.1 (Cquat), 167.0 (Cquat), 192.1
(Cquat). MALDI-TOF MS m/z = 736.34. UV/vis λmax (ε) [nm] = 252
1
of compound 1j as an orange highly viscous resin. H NMR (300
MHz, acetone-d6): δ 0.85−0.91 (m, 6 H), 1.19−1.46 (m, 40 H), 1.93−
2.02 (m, 5 H), 3.21 (t, J = 6.5 Hz, 4 H), 3.85 (d, J = 7.2 Hz, 2 H), 6.36
(d, J = 2.7 Hz, 1 H), 6.41 (dd, J = 2.7, 8.8 Hz, 1 H), 6.92 (d, J = 8.8
Hz, 1 H), 7.06 (d, J = 8.5 Hz, 1 H), 7.57 (d, J = 1.9 Hz, 1 H), 7.66 (dd,
J = 1.9, 8.4 Hz, 1 H), 9.76 (s, 1 H). 13C NMR (75 MHz, acetone-d6): δ
14.4 (two CH3), 23.4 (two CH2), 26.0 (two CH2), 26.8 (two CH2),
30.12 (two CH2), 30.14 (two CH2), 30.35 (two CH2), 30.37 (CH2),
30.41 (two CH2), 30.5 (CH2), 30.6 (two CH2), 32.0 (two CH2), 32.7
(two CH2), 35.5 (CH), 48.4 (two CH2), 52.3 (CH2), 110.9 (CH),
111.5 (CH), 115.9 (CH), 118.7 (CH), 126.0 (Cquat), 126.5 (Cquat),
128.6 (CH), 130.7 (CH), 131.4 (Cquat), 133.2 (Cquat), 146.1 (Cquat),
153.2 (Cquat), 190.1 (CH). MALDI-TOF MS m/z = 632.3. UV/vis
λmax (ε) [nm] = 268 (12000), 352 (5000), 422 (5000). IR (film): v
[cm−1] = 2920 (s), 2851 (s), 2718 (w), 1686 (s), 1607 (m), 1584 (m),
1551 (w), 1508 (s), 1474 (s), 1460 (s), 1422 (m), 1368 (m), 1342
(m), 1309 (m), 1298 (m), 1275 (m), 1244 (s), 1196 (s), 1167 (m),
1146 (m), 1103 (m), 1055 (w), 987 (m), 918 (w), 897 (w), 880 (w),
812 (m), 793 (m), 745 (m), 721 (m), 709 (m), 685 (w), 648 (w), 625
(w). Anal. Calcd. for C41H64N2OS (633.0): C 77.79, H 10.19, N 4.43.
Found: C 77.96, H 10.44, N 4.21.
General Procedure for the Knoevenagel-Condensation
Reaction (GP3). A mixture of 1.0 equiv of the phenothiazinyl
carbaldehydes 1, 1.0 equiv of ammonium acetate, and 1.1 equiv of
rhodanine-N-acetic acid at a 0.5 m concentration of glacial acetic acid
was stirred at 95 °C for 5 h (for experimental details, see Table 6).
After cooling to room temperature, the solution was diluted with
deionized water, a saturated aqueous solution of Na2SO3, and
dichloromethane. The aqueous phase was extracted several times
with small portions of dichloromethane, the combined organic phases
(18000), 305 (14000), 366 (14000), 478 (20000). IR (KBr): v [cm−1]
̃
= 2923 (s), 2825 (s), 1707 (m), 1585 (s), 1561 (m), 1492 (m), 1459
(s), 1403 (m), 1329 (s), 1270 (m), 1196 (s), 1108 (m), 1056 (m), 806
(w), 752 (w), 581 (w). ESI HRMS calcd. for C42H60N2O3S3:
736.37661. Found: 736.37764.
(Z)-2-(5-((7-Bromo-10-(2-decyltetradecyl)-10H-phenothiazine-3-
yl)-methylene)-4-oxo-2-thioxothiazolidine-3-yl)acetic Acid (2b).
According to the GP3 and flash chromatography on silica gel
(dichloromethane to dichloromethane/methanol/acetic acid 87:12:1),
1.473 g (94%) of compound (2b) were obtained as red solid; mp 97−
102 °C. 1H NMR (300 MHz, acetone-d6): δ 0.87 (t, J = 6.9 Hz, 3 H),
0.88 (t, J = 6.9 Hz, 3 H), 1.13−1.48 (m, 40 H), 1.91−2.02 (m, 1 H),
3.89 (d, J = 7.1 Hz, 2 H), 4.87 (s, 2 H), 7.02 (d, J = 8.7 Hz, 1 H), 7.18
(d, J = 8.6 Hz, 1 H), 7.30 (d, J = 2.2 Hz, 1 H), 7.34 (d, J = 2.2 Hz, 1
H), 7.37 (dd, J = 2.1, 8.7 Hz, 1 H), 7.47 (dd, J = 2.2, 8.6 Hz, 1 H), 7.66
(s, 1 H).13C NMR (75 MHz, acetone-d6): δ 14.4 (two CH3), 23.4
(two CH2), 26.7 (two CH2), 30.1 (four CH2), 30.32 (CH2), 30.34
(CH2), 30.38 (CH2), 30.42 (two CH2), 30.45 (CH2), 30.59 (CH2),
30.60 (CH2), 31.93 (two CH2), 32.68 (two CH2), 35.4 (CH), 45.4
(CH2), 52.4 (CH2), 116.0 (Cquat), 117.8 (CH), 119.3 (CH), 120.7
(Cquat), 126.3 (Cquat), 127.7 (Cquat), 128.7 (Cquat), 130.4 (CH), 130.5
(CH), 131.3 (CH), 131.8 (CH), 133.4 (CH), 144.5 (Cquat), 148.8
(Cquat), 167.4 (Cquat), 167.4 (Cquat), 193.8 (Cquat). MALDI-TOF MS
m/z = 814.3. UV/vis λmax (ε) [nm] = 256 (28000), 297 (20000), 361
̃
(21000), 473 (29000). IR (KBr): v [cm−1] = 2923 (s), 2852 (s), 1702
̃
(m), 1588 (s), 1589 (s), 1492 (m), 1460 (s), 1403 (m), 1329 (s),
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1251 (m), 1196 (s), 1111 (m), 1056 (m), 744 (m), 628 (w), 538 (w).
Anal. Calcd. for C42H59BrN2O3S3 (816.0): C 61.82, H 7.29, N 3.43.
Found: C 61.94, H 7.45, N 3.38.
765.22. UV/vis λmax (ε) [nm] = 265 (36000), 307 (16000), 359
(24000), 503 (18000). IR (KBr): v [cm−1] = 2923 (m), 2852 (m),
̃
2346 (w), 1719 (m), 1561 (s), 1459 (s), 1400 (m), 1328 (m), 1246
(m), 1192 (s), 1105 (m), 802 (m), 745 (m). ESI HRMS calcd. for
C42H43N3O3S4: 765.21873. Found: 765.21937.
(Z)-2-(5-((7-Cyano-10-(2-decyltetradecyl)-10H-phenothiazine-3-
yl)-methylene)-4-oxo-2-thioxothiazolidine-3-yl)acetic Acid (2c). Ac-
cording to the GP3 and flash chromatography on silica gel
(dichloromethane to dichloromethane/methanol/acetic acid 87:12:1)
1.262 g (92%) of compound (2c) was obtained as a red solid; mp 92−
(Z)-2-(5-((10-(2-Decyltetradecyl)-10H-3,10′biphenothiazine)-7-
yl)-methylene)-4-oxo-2-thioxothiazolidine-3-yl)acetic Acid (2f). Ac-
cording to the GP3 and flash chromatography on silica gel
(dichloromethane to dichloromethane/methanol/acetic acid 87:12:1)
1
97 °C. H NMR (500 MHz, acetone-d6/CS2 4:1): δ 0.79−0.93 (m, 6
1
H), 1.12−1.41 (m, 40 H), 1.80−1.88 (m, 1 H), 3.87 (d, J = 6.7 Hz, 2
H), 4.61 (s, 2 H), 7.18 (d, J = 8.4 Hz, 1 H), 7.20 (d, J = 8.4 Hz, 1 H),
7.39 (d, J = 1.7 Hz, 1 H), 7.48 (dd, J = 1.6, 8.6 Hz, 1H), 7.56 (d, J =
1.6 Hz, 1 H), 7.61 (dd, J = 1.6, 8.5 Hz, 1H), 7.72 (s, 1 H).13C NMR
(75 MHz, acetone-d6/CS2 4:1): δ 15.0 (two CH3), 23.8 (two CH2),
27.00 (CH2), 27.03 (CH2), 30.39 (CH2), 30.40 (CH2), 30.5 (two
CH2), 30.65 (three CH2), 30.69 (two CH2), 30.72 (CH2), 31.0 (two
CH2), 32.1 (two CH2), 32.9 (two CH2), 35.6 (CH), 39.9 (CH2), 52.4
(CH2), 107.4 (Cquat.), 117.3 (CH), 117.7 (CH), 118.4 (Cquat), 122.1
(Cquat), 125.9 (Cquat), 126.4 (Cquat), 129.3 (CH), 129.7 (Cquat), 130.2
(CH), 131.0 (CH), 131.3 (CH), 132.3 (CH), 146.6 (Cquat), 148.7
(Cquat), 167.0 (Cquat), 167.2 (Cquat), 192.2 (Cquat). MALDI-TOF MS
m/z = 761.3. UV/vis λmax (ε) [nm] = 265 (18000), 297 (21000), 363
0.623 g (94%) of (2f) was obtained as a red solid; mp 83−88 °C. H
NMR (500 MHz, acetone-d6): δ 0.83−0.89 (m, 6 H), 1.17−1.43 (m,
40 H), 2.06−2.13 (m, 1 H), 4.01 (d, J = 7.1 Hz, 2 H), 4.85 (s, 2 H),
6.27 (dd, J = 1.2, 8.1 Hz, 2 H), 6.78−6.89 (m, 4 H), 7.00 (dd, J = 1.7,
7.4 Hz, 2 H), 7.22−7.28 (m, 3 H), 7.34−7.39 (m, 2 H), 7.50 (dd, J =
2.1, 8.7 Hz, 1 H), 7.66 (s, 1 H). 13C NMR (125.5 MHz, acetone-d6): δ
14.4 (two CH3), 23.4 (two CH2), 26.78 (CH2), 26.81 (CH2), 30.1
(two CH2), 30.17 (CH2), 30.2 (CH2), 30.35 (CH2), 30.37 (CH2),
30.40 (CH2), 30.41 (CH2), 30.44 (two CH2), 30.60 (CH2), 30.63
(CH2), 32.01 (CH2), 32.03 (CH2), 32.66 (CH2), 32.67 (CH2), 35.4
(CH), 45.4 (CH2), 52.5 (CH2), 117.0 (two CH), 117.9 (CH), 119.6
(CH), 120.6 (Cquat), 120.9 (two Cquat), 123.5 (two CH), 126.6 (Cquat),
127.4 (two CH), 127.7 (Cquat), 127.9 (two CH), 128.8 (Cquat), 130.4
(CH), 130.5 (CH), 131.0 (CH), 131.8 (CH), 133.4 (CH), 137.1
(Cquat), 145.0 (two Cquat), 145.2 (Cquat), 148.8 (Cquat), 167.4 (Cquat),
167.5 (Cquat), 193.9 (Cquat). MALDI-TOF MS m/z = 933.3. UV/vis
λmax (ε) [nm] = 258 (62000), 300 (22000), 359 (19000), 472
(16000), 462 (22000). IR (KBr): v [cm−1] = 2924 (s), 2852 (s), 2224
̃
(m), 1707 (m), 1594 (m), 1572 (s), 1499 (w), 1461 (s), 1401 (m),
1329 (m), 1353 (m), 1196 (s), 1112 (m), 1055 (m), 885 (w), 817
(w), 719 (w), 581 (w). ESI HRMS calcd. for C43H59N3O3S3:
761.37185. Found: 761.36752.
(24000). IR: v [cm−1] = 2920 (s), 2851 (s), 1712 (s), 1587 (m), 1572
̃
(Z)-2-(5-((10-Hexyl-7-p-tolyl-10H-phenothiazine-3-yl)-methyl-
ene)-4-oxo-2-thioxothiazolidine-3-yl)acetic Acid (2d). According to
the GP3 and flash chromatography on silica gel (dichloromethane to
dichloromethane/methanol 22:3) and crystallization (dichlorome-
thane/n-hexane), 0.235 g (67%) of compound (2d) were obtained
as violet crystals; mp 125 °C. 1H NMR (500 MHz, THF-d8): δ 0.88 (t,
J = 6.8 Hz, 3 H), 1.25−1.40 (m, 4 H), 1.43−1.50 (m, 2 H), 1.82
(quint, J = 7.4 Hz, 2 H), 2.34 (s, 3 H), 3.96 (t, J = 7.1 Hz, 2 H), 4.79
(s, 2 H), 7.03 (d, J = 8.5 Hz, 1 H), 7.06 (d, J = 8.6 Hz, 1 H), 7.19 (d, J
= 8.0 Hz, 2 H), 7.32 (d, J = 1.8 Hz, 1 H), 7.37 (d, J = 1.5 Hz, 1 H),
7.38−7.44 (m, 2 H), 7.46 (d, J = 8.0 Hz, 2 H), 7.65 (s, 1 H). 13C NMR
(125.5 MHz, THF-d8): δ 14.5 (CH3), 21.3 (CH3), 23.7 (CH2), 27.5
(CH2), 27.8 (CH2), 32.6 (CH2), 45.4 (CH2), 48.5 (CH2), 116.6
(CH), 117.2 (CH), 120.8 (Cquat), 124.9 (Cquat), 126.0 (Cquat), 126.3
(CH), 126.7 (CH), 127.1 (two CH), 128.8 (Cquat), 130.4 (three CH),
131.5 (CH), 133.1 (CH), 137.4 (Cquat), 137.7 (Cquat), 137.8 (Cquat),
143.6 (Cquat), 148.5 (Cquat), 167.6 (Cquat), 167.7 (Cquat), 193.9 (Cquat).
MALDI-TOF MS m/z = 574.1. UV/vis λmax (ε) [nm] = 269 (29000),
(s), 1460 (s), 1442 (s), 1400 (s), 1366 (m), 1323 (s), 1312 (s), 1302
(s), 1267 (s), 1236 (s), 1194 (s), 1111 (s), 1055 (s), 1045 (m), 983
(m), 957 (m), 922 (m), 908 (m), 864 (w), 816 (m), 741 (s), 718 (m),
634 (m). Anal. Calcd. for C54H67N3O3S4 (934.4): C 69.41, H 7.23, N
4.50. Found: C 69.39; H 7.27; N 4.47.
(Z)-2-(5-((7-(9H-Carbazol-9-yl)-10-(2-decyltetradecyl)-10H-phe-
nothiazine-3-yl)-methylene)-4-oxo-2-thioxothiazolidine-3-yl)acetic
Acid (2g). According to the GP3 and flash chromatography on silica
gel (dichloromethane to dichloromethane/methanol/acetic acid
87:12:1), 0.575 g (91%) of compound (2g) were obtained as a red
1
solid; mp 79−85 °C. H NMR (300 MHz, acetone-d6): δ 0.80−0.88
(m, 6 H), 1.14−1.51 (m, 40 H), 2.07−2.09 (m, 1 H), 3.92 (d, J = 7.1
Hz, 2 H), 4.85 (s, 2 H), 7.09 (d, J = 8.6 Hz, 1 H), 7.21−7.42 (m, 11
H), 7.60 (s, 1 H), 8.17 (d, J = 7.7 Hz, 2 H). 13C NMR (75 MHz,
acetone-d6): δ 14.4 (two CH3), 23.3 (two CH2), 26.76 (CH2), 26.80
(CH2), 30.10 (CH2), 30.11 (CH2), 30.17 (CH2), 30.20 (CH2), 30.37
(CH2), 30.39 (CH2), 30.40 (two CH2), 30.44 (two CH2), 30.61
(CH2), 30.63 (CH2), 32.01 (CH2), 32.03 (CH2), 32.6 (CH2), 32.7
(CH2), 35.4 (CH), 45.4 (CH2), 52.4 (CH2), 110.5 (two CH), 117.7
(CH), 118.8 (CH), 120.5 (Cquat), 120.9 (two CH), 121.1 (two CH),
124.2 (two Cquat), 126.5 (Cquat), 126.6 (CH), 126.9 (two CH), 127.0
(Cquat), 127.1 (CH), 128.7 (Cquat), 130.5 (CH), 131.7 (CH), 133.4
(CH), 133.7 (Cquat), 141.7 (two Cquat), 144.4 (Cquat), 148.8 (Cquat),
167.4 (two Cquat), 193.9 (Cquat). MALDI-TOF MS m/z = 901.4. UV/
vis λmax (ε) [nm] = 294 (33000), 343 (17000), 363 (17000), 478
303 (25000), 358 (19000), 471 (23000). IR (KBr): v [cm−1] = 2924
̃
(m), 1707 (m), 1655 (w), 1637 (w), 1572 (s), 1473 (s), 1404 (m),
1364 (m), 1323 (s), 1193 (s), 1107 (m), 1051 (m), 804 (m). ESI
HRMS calcd. for C31H30N2O3S3: 574.14185. Found: 574.13156.
(Z)-2-(5-((10,10′-Dihexyl-10H,10′H-3,3′-biphenothiazine-7-yl)-
methylene)-4-oxo-2-thioxothiazolidine-3yl)acetic Acid (2e). Accord-
ing to the GP3 followed by flash chromatography on silica gel
(dichloromethane to dichloromethane/methanol 22:3) and crystal-
lization (dichloromethane/n-hexane) 0.330 g (68%) of compound
(2e) was obtained as violet crystals; mp 198 °C. 1H NMR (500 MHz,
DMSO-d6/CS2 4:1): δ 0.83−1.00 (m, 6 H), 1.26−1.39 (m, 6 H),
1.39−1.55 (m, 6 H), 1.76 (quint, J = 7.2 Hz, 4 H), 3.88 (t, J = 7.0 Hz,
2 H), 3.91 (t, J = 7.1 Hz, 2 H), 4.55 (s, 2 H), 6.88−6.97 (m, 3 H), 6.99
(d, J = 8.6 Hz, 1 H), 7.05 (d, J = 8.7 Hz, 1 H), 7.08 (dd, J = 1.1, 7.6
Hz, 1 H), 7.13−7.19 (m, 1 H), 7.25−7.31 (m, 3 H), 7.35 (d, J = 1.8
Hz, 1 H), 7.37 (d, J = 1.7 Hz, 1 H), 7.43 (dd, J = 1.8, 8.6 Hz, 1H), 7.65
(s, 1 H). 13C NMR (75 MHz, DMSO-d6/CS2 4:1): δ 13.9 (two CH3),
22.3 (two CH2), 25.9 (CH2), 26.0 (CH2), 26.2 (CH2), 26.3 (CH2),
31.0 (CH2), 31.1 (CH2), 45.4 (CH2), 46.6 (CH2), 47.0 (CH2), 115.6
(CH), 115.8 (two CH), 116.4 (CH), 118.7 (Cquat), 122.4 (CH), 122.8
(Cquat), 123.3 (Cquat), 123.6 (Cquat), 124.2 (Cquat), 124.28 (Cquat),
124.30 (CH), 124.34 (CH), 125.1 (CH), 125.3 (CH), 126.9 (Cquat),
127.0 (CH), 127.5 (CH), 129.2 (CH), 131.0 (CH), 132.8 (CH),
134.2 (Cquat), 141.6 (Cquat), 143.8 (Cquat), 144.4 (Cquat), 146.7 (Cquat),
166.3 (Cquat), 167.3 (Cquat), 192.4 (Cquat). MALDI-TOF MS m/z =
(22000). IR: v [cm−1] = 2920 (s), 2851 (m), 1711 (m), 1593 (m),
̃
1572 (m), 1461 (s), 1400 (m), 1323 (s) 1323 (m), 1229 (m), 1193
(s), 1111 (m), 1056 (m), 912 (w), 813 (m), 746 (s), 723 (s). Anal.
Calcd. for C54H67N3O3S3 (902.3): C 71.88, H 7.48, N 4.66. Found: C
71.72, H 7.63, N 4.65.
(Z)-2-(5-((10-(2-Decyltetradecyl)-7-(pyrrolidine-1-yl)-10H-pheno-
thiazine-3-yl)-methylene)-4-oxo-2-thioxothiazolidine-3-yl)acetic
Acid (2h). According to the GP3 and flash chromatography on silica
gel (dichloromethane to dichloromethane/methanol/acetic acid
87:12:1), 0.512 g (82%) of compound (2h) were obtained as a red
solid; mp 78−83 °C. 1H NMR (500 MHz, CD2Cl2): δ 0.90 (t, J = 6.9
Hz, 3 H), 0.91 (t, J = 6.9 Hz, 3 H), 1.16−1.43 (m, 40 H), 1.92−1.99
(m, 1 H), 2.02 (t, J = 6.4 Hz, 4 H), 3.26 (s, 4 H), 3.72 (d, J = 5.6 Hz, 2
H), 4.86 (s, 2 H), 6.36−6.44 (m, 2 H), 6.77 (d, J = 8.7 Hz, 1 H), 6.86
(d, J = 8.6 Hz, 1 H), 7.22 (s, 1 H), 7.30 (d, J = 7.6 Hz, 1 H), 7.62 (s, 1
H). 13C NMR (125.5 MHz, CD2Cl2): δ 14.7 (two CH2), 23.5 (two
CH2), 26.1 (two CH2), 26.99 (CH2), 27.01 (CH2), 30.17 (CH2),
30.18 (CH2), 30.3 (two CH2), 30.4 (two CH2), 30.47 (two CH2),
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30.50 (two CH2), 30.8 (two CH2), 32.2 (two CH2), 32.7 (two CH2),
35.6 (CH), 45.0 (CH2), 48.8 (two CH2), 52.3 (CH2), 111.4 (CH),
111.5 (CH), 115.9 (CH), 118.0 (CH), 118.8 (Cquat), 126.2 (Cquat),
126.5 (Cquat), 126.8 (Cquat), 130.1 (CH), 131.6 (CH), 133.4 (Cquat),
134.1 (CH), 145.4 (Cquat), 167.3 (Cquat), 167.4 (Cquat), 171.3 (Cquat),
192.9 (Cquat). MALDI-TOF MS m/z = 805.3. UV/vis λmax (ε) [nm] =
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ASSOCIATED CONTENT
■
S
* Supporting Information
1
Selected H and 13C NMR spectra of compounds 1b, 1d−1j,
2a−2h. This material is available free of charge via the Internet
at http://pubs.acs.org.
AUTHOR INFORMATION
Corresponding Author
*kleinermanns@uni-duesseldorf.de; thomasjj.mueller@uni-
duesseldorf.de
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
(14) (a) Li, X.; Kim, S.-H.; Son, Y.-A. Dyes Pigm. 2009, 82, 293−298.
(b) Park, S. S.; Won, Y. S.; Choi, Y. C.; Kim, J. H. Energy Fuels 2009,
23, 3732−3736. (c) Lin, H.-H.; Su, S.-Y.; Chang, C.-C. Org. Biomol.
Chem. 2009, 7, 2036−2039. (d) Cho, M. J.; Kim, J. Y.; Youn, K. J.;
Kim, J. H.; Lee, S. H.; Dalton, L. R.; Choi, D. H. Bull. Korean Chem.
Soc. 2005, 26, 77−84. (e) Petry, C.; Lang, M.; Staab, H. A.; Bauer, H.
Angew. Chem., Int. Ed. Engl. 1993, 32, 1711−1714.
Financial support from Evonik Stiftung (stipend for T.M.) and
the Fonds der Chemischen Industrie is gratefully acknowl-
edged.
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