Synthesis and photoinduced electron transfer of phthalocyanine- perylenebisimide pentameric arrays

Article abstract of DOI:10.1021/jo900672j

(Figure Presented) Zinc phthalocyanine-perylenebisimide pentameric arrays, ZnPc(PDI)₄ 1 and 2, have been synthesized. ZnPc(PDI)₄ 1 has no substituents in the PDI bay positions, while ZnPc(PDI)₄ 2 presents four phenoxy grou

Full text of DOI:10.1021/jo900672j

pubs.acs.org/joc
Synthesis and Photoinduced Electron Transfer of
Phthalocyanine-Perylenebisimide Pentameric Arrays
†
F. Javier Cespedes-Guirao, Kei Ohkubo, Shunichi Fukuzumi,* Angela Sastre-Santos,*
‡
,‡
,†
ꢀ
ꢀ
,†
ꢀ
and Fernando Fernandez-Lazaro*
ꢀ
†
ꢀ ꢀ
´
Division de Quımica Organica, Instituto de Bioingenierıa, Universidad Miguel Hernandez, Elche 03202,
´
ꢀ
Spain, and ‡Department of Material and Life Science, Graduate School of Engineering, Osaka University and
SORST (JST), 2-1 Yamada-oka, Suita, Osaka 565-0871, Japan
fukuzumi@chem.eng.osaka-u.ac.jp; asastre@umh.es; fdofdez@umh.es
Received April 16, 2009
Zinc phthalocyanine-perylenebisimide pentameric arrays, ZnPc(PDI)4 1 and 2, have been synthesized.
ZnPc(PDI)4 1 has no substituents in the PDI bay positions, while ZnPc(PDI)4 2 presents four phenoxy
groups in the bay positions of eachperylene. In both cases, the PDI moietiesare directly connected to the
ZnPc. As a consequence of aggregation, photoexcitation of 1 affords the intermolecular exciplex rather
than the charge-separated state. In contrast to 1, photoexcitation of 2, which contains sterically
demanding substituents in the PDI moieties, affords the charge-separated (CS) state, which was clearly
detected by its transient absorption spectrum in femtosecond laser flash photolysis measurements. The
CS lifetime was determined to be 26 ps. The addition of Mg(ClO4)2 to a benzonitrile solution of 2 and the
photoexcitation affords the long-lived CS state with the lifetime of 480 μs, whereas no such long-lived CS
state was formed in the case of 1 under such conditions. The remarkable elongation of the CS lifetime
results from the strong binding of Mg2þ to the PDI•- moiety in the CS state.
Introduction
photonic systems, photovoltaic devices, etc.4-7 The presence
of porphyrins in natural photosynthetic systems has deter-
mined their prevalence in the artificial model as electron
donors.6-9 However, phthalocyanines10 (Pcs) are increasing
their presence in such systems due to some special features
they display, such as the more enhanced absorptive cross
sections at those wavelengths corresponding to maxima of
emission in the solar spectrum as compared with porphyrins,
Photoinduced electron transfer is a key process in photo-
synthesis1-3 and has attracted great scientific attention in
order to prepare artificial photosynthetic systems, wires for
(1) (a) Deisenhofer, J., Norris, J. R., Eds. The Photosynthetic Reaction
Center; Academic Press: San Diego, CA, 1993; Vols. 1, 2. (b) Blankenship, R. E.,
Ed. Molecular Mechanisms of Photosynthesis; Blackwell Science: Oxford,
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(2) (a) Wasielewski, M. R. In Photoinduced Electron Transfer; Fox, M. A.,
Chanon, M., Eds.; Elsevier: Amsterdam, 1988; Part A, pp 161-206. (b) Wasielewski,
M. R. Chem. Rev. 1992, 92, 435–461. (c) Wasielewski, M. R. J. Org. Chem. 2006, 71,
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Smith, K. M., Guilard, R., Eds.; Academic Press: San Diego, CA, 2000; Vol. 8, pp
153-190. (b) Gust, D.; Moore, T. A.; Moore A. L. In Electron Transfer in
Chemistry; Balzani, V., Ed.; Wiley-VCH: Weinheim, Germany, 2001; Vol. 3, pp
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(3) (a) Fukuzumi, S.; Guldi, D. M. In Electron Transfer in Chemistry;
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DOI: 10.1021/jo900672j
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Published on Web 07/27/2009
J. Org. Chem. 2009, 74, 5871–5880 5871
2009 American Chemical Society

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or the possibility of intense absorption almost in the near-
infrared. Moreover, as it has been so many times stated, they
are versatile building blocks, which depending on the nature
of the central atom can undergo covalent functionalization
both in the peripheral and in the axial positions, or even
coordinative linkage in the axial positions. Thus, in recent
years, Pcs bearing interesting electro- or photoactive species
have been reported as light-harvesting systems and charge-
transfer complexes.11 However, few reports described the
occurrence of a long-lived charge-separated state based in
phthalocyanines, as opposed to porphyrins, due to the
presence of a low-lying triplet excited state.12
linked to electron-rich systems as porphyrins or phthalocya-
nines to study their possible electronic interactions.
Although much effort has been paid to the study of linked
porphyrin-PDI and phthalocyanine-PDI systems,14-16
there have been only a few systems that afforded long-lived
charge-separated states.16 Phthalocyanine-PDI systems
containing multiple PDI units to enhance the light-harvest-
ing efficiency, which afford long-lived charge-separated
states, have yet to be reported.
Here we describe the synthesis and photophysics of two
different phthalocyanine-PDI pentameric arrays, namely,
1 and 2 (see Figure 1), in which the perylenebisimide moieties
are directly connected to the phthalocyanine core. To the
best of our knowledge, there is only one example about
another Pc-(PDI)4 system reported by Wasielewski et al.
showing fast energy transfer.15d In this case, the phthalocya-
nine moiety bears also imide substituents, which contribute
to enhance its electron affinity. This means that all of the
subunits of the array are electron acceptors, thus making the
electron-transfer process thermodynamically unfavorable,
as experimentally observed. Perylene chromophores possess
two differentiated sites for easy covalent linking, the nitrogen
atoms at the imido functions and the so-called bay positions
(locations 1, 6, 7, and 12 of the skeleton). With the aim to
achieve long-lived charge-separated states, we have gambled
for the substitution at the imido positions. In fact, a recent
work compared the photophysics of N,N0-(porphyrin)2-
PDI and 1,7-(porphyrin)2-PDI ensembles, showing that
both systems have a similar charge separation rate constant,
with the charge recombination being much slower in the N,
N0-disubstituted system, which yields the longer-living
charge-separated state.17
On the other hand, perylenebisimides13 (PDIs) exhibit a
number of unique properties that make them of great interest
in many different scientific and technological areas. These
compounds, which normally behave as electron acceptors,
are therefore interesting chromophores to be covalently
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Results and Discussion
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Synthesis of Phthalocyanine-Perylenebisimide Arrays.
The synthesis of phthalocyanine-perylenebisimide arrays
ZnPc(PDI)4 1 and ZnPc(PDI)4 2 was accomplished using
different strategies. The first approach consisted of the
synthesis of a perylene-substituted phthalonitrile derivative,
followed by its direct cyclotetramerization using the usual
procedures for Pc synthesis.10 Thus, the new phthalonitrile 3,
bearing a perylenebisimide moiety, was synthesized by con-
densation of the monoanhydride monoimide perylene deri-
vative 4 with 4-aminophthalonitrile18 (see Scheme 1).
Unfortunately, attempts of cyclization of 3 to obtain ZnPc-
(PDI)4 pentad 1 were unsuccessful, despite of the different
conditions investigated. Only decomposition products were
obtained, as previously reported by Lindsey,15b for a differ-
ent phthalonitrile-perylenebisimide derivative.
Photochem. Photobiol. 2002, 76, 116–121. (c) Rodrıguez-Redondo, J. L.;
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FIGURE 1. Chemical structures of ZnPc(PDI)4 1 and ZnPc(PDI)4 2.
connected through the imide nitrogen by a flexible linker. So, we
decided to synthesize a bisperylenebisimide-substituted phtha-
lonitrile 5 (Scheme 2) where the PDI moieties would be spatially
disconnected from the Pc core, in order to avoid electronic
interactions in the cyclotetramerization step. Moreover, using a
3,4-disubstituted phthalonitrile, we would obtain an octakisper-
ylenebisimide-substituted phthalocyanine, avoiding the pre-
sence of the four regioisomers obtained in the tetrasubstituted
ones. The new bisperylenebisimide phthalonitrile 5 was pre-
pared in 50% yield by esterification of the previously reported
phthalonitrile 619 with N-(2-ethylhexyl)-N0-(hydroxyethyl)-
1,6,7,12-tetrabromoperylenebisimide 7 (Scheme 2). There
are several reasons for the selection of a 1,6,7,12-tetrabromo-
perylenebisimide. In addition to prevent aggregation, thus
improving solubility of the phthalocyanine system, the presence
of four bromo atoms in the so-called bay position of the PDI
makes this system more electron acceptor than the unsubsti-
tuted one. Asymmetric substituted PDI 7 was easily synthesized
in 25% yield, in an analogous way to that described for related
PDI systems,20 by the one-step statistical condensation of
2-ethylhexylamine and ethanolamine with 1,6,7,12-tetra-
bromoperylenebisanhydride (8).21 The two other conden-
sation products, namely, bisethylhexylperylenebismide 9
and bishydroxyethylperylenebisimide 10, were separated
from the desired one by column chromatography
(Scheme 3). Unfortunately, we were not able to achieve
the cyclotetramerization of phthalonitrile 5, although
different reported synthetic procedures for the prepara-
tion of Pcs were tried.
We also tried to prepare octakisperylenebisimide-substi-
tuted phthalocyanines [ZnPc(PDI)8] by esterification of
the already known phthalocyanineoctakiscarboxylic acid22
and N-(2-ethylhexyl)-N0-(hydroxyethyl)-1,6,7,12-tetrabro-
moperylenebisimide 7 using different activating agents such
SCHEME 1. Synthesis of Perylene-Substituted Phthalonitrile Derivative 3
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SCHEME 2. Synthesis of Bisperylene-Substituted Phthalonitrile Derivative 5
SCHEME 3. Synthesis of N-(2-Ethylhexyl)-N0-(hydroxyethyl)-1,6,7,12-tetrabromoperylenebisimide 7
as thionyl chloride or carbonyldiimidazole. However, this
approach was ineffective for the synthesis of ZnPc(PDI)8 due
to the isolation of complex mixtures of phthalocyanine
derivatives with different degrees of esterification, which
were impossible to separate by column chromatography.
Finally, taking advantage of the high effectivity of the
condensation reaction between amino derivatives and peryle-
necarboxyanhydrides,16a,16c we were able to synthesize ZnPc-
(PDI)4 pentads 1 and 2 in 41 and 30% yield, respectively, by
reaction of the tetraamino-substituted phthalocyanine 1123
with the corresponding perylene derivatives 424 and 1225
(Scheme 4). It is worth mentioning that perylene monoimide
12 with four tert-octylphenoxy groups in the so-called bay
positions of the perylene moiety precludes π-π stacking,25
giving rise to a much higher solubility in organic solvents of
ZnPc(PDI)4 2 than ZnPc(PDI)4 1.
All new compounds were characterized by 1H NMR, 13
C
NMR, UV/vis, and IR spectroscopies, mass spectrometry,
and elemental analysis (see Experimental Section). The MS
spectra (MALDI-TOF) display clusters at m/z=2881-2890
(ZnPc(PDI)4 1) and 5844-5854 (ZnPc(PDI)4 2), which
correspond to the theoretically calculated patterns for [M]þ
(see Supporting Information). The FT-IR spectra of com-
pounds 1 and 2 show the typical imido carbonyl bands at
€
(19) Wohrle, D.; Eskes, M.; Shigehara, K.; Yamanda, A. Synthesis 1993,
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1705 and 1668 cm-1
.
It is important to mention that compound 2, being a
mixture of four regioisomers, shows broad signals all over
the NMR spectrum, although these are easily assigned
(see Supporting Information). This situation is even more
complicated for compound 1, due to its tendency to aggre-
gate, thus precluding the obtention of a useful NMR spec-
trum.
(21) Qiu, W.; Chen, S.; Sun, X.; Liu, Y.; Zhu, D.-B. Org. Lett. 2006, 8,
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SCHEME 4. Synthesis of ZnPc(PDI)4 1 and ZnPc(PDI)4 2
Spectroscopic and Redox Properties. The UV/vis spectra of
compounds 1 and 2 show a high absorption in the entire UV/
vis region from 300 to 700 nm, or even longer wavelengths for
1 (see Figure 2). In both cases, splitting of the phthalocyanine
Q-band at ca. 636 and 671 nm (in compound 1, the latter
appears as a shoulder) is observed. The blue shift of the
maxima of the Q-bands in 1 and 2, when compared with that
of the tetra-tert-butylphthalocyaninato zinc(II) (ZnPc,
typical of H-type aggregation,28 the same behavior also
noted for compound 2. From the above-mentioned facts, it
is clear that UV/vis spectra for 1 and 2 do not correspond
with the simple superimposition of the spectra of a Pc and a
PDI, thus strengthening the hypothesis of a ground-state
interaction between the moieties.
Cyclic and differential pulse voltammograms of ZnPc-
(PDI)4 1 and ZnPc(PDI)4 2 are shown in the Supporting
Information. The energies of the charge-separated state,
ZnPc•þ-PDI•-, for pentads 1 and 2 are quite similar and
are estimated as 1.36 and 1.32 eV, respectively, from the Eox
value of the ZnPc moiety and the Ered value of the PDI
moiety. It is worth mentioning the cathodic shift of Eox
(0.55 V vs SCE) and Ered (-0.77 V vs SCE) values of the
ZnPc(PDI)4 2 versus Eox (0.73 V vs SCE) and Ered (-0.63 V
vs SCE) values of the ZnPc(PDI)4 1, as a consequence of
the lower acceptor character of the tetraphenoxy-substi-
tuted perylene derivative compared to the unsubstituted
one,13 thus making the ZnPc moiety easier to be oxidized
and the PDI moiety more difficult to be reduced in ZnPc-
(PDI)4 2.
λ
max=680 nm) (Figure 2), is noteworthy. The broad absorp-
tion in the longer wavelength region for the Q-band
in 1, which is absent in 2, suggests the existence of inter-
molecular charge-transfer interaction between the ZnPc and
PDI moieties in 1, probably due to aggregation pheno-
mena.26 Such intermolecular charge-transfer interaction
may be absent because of bulky substituents of the PDI
moiety in 2.
It is also interesting to mention that the bands between 400
and 600 nm in compound 2, which correspond to the
perylene chromophore, are red-shifted when compared with
the corresponding ones in 1 (see Figure 2). This behavior can
be explained in terms of the influence of the four phenoxy
groups present in the perylene bay positions (see the spectra
for PDI reference compounds 1324 and 1427 in Figure 3).
Moreover, a dramatic change is observed in the ratio of the
relative intensities of the PDI absorptions in the 450-550 nm
region (0-0/0-1/0-2 peaks) of 1 compared with the corre-
sponding ones of the PDI reference compound, which is
Calculated Structures. HOMO and LUMO orbitals of
ZnPc(PDI)4 1 have been calculated with the optimized
structure using a semiempirical method (AM1).29 The results
are shown in Figure 4, indicating that the HOMO orbital is
localized on the ZnPc moiety and the LUMO orbital is
placed on the PDI moiety. The spin distributions of
LUMOþ1, LUMOþ2, and LUMOþ3 are localized on each
(26) (a) Mulliken, R. S.; Person, W. B. Molecular Complexes, a Lecture and
Reprint Volume; Wiley-Interscience: New York, 1969. (b) Foster, R. Organic
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Chem. Soc. 1985, 107, 3902–3909.
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(27) Cespedes-Guirao, F. J.; Garcı
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a-Santamarı
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a, S.; Fernandez-Lazaro,
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F.; Sastre-Santos, A.; Bolink, H. J. J. Phys. D: Appl. Phys. 2009, 42, 105106.
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FIGURE 2. UV-vis spectra of 1, 2, and ZnPc(t-Bu)4 in DMF.
FIGURE 4. HOMO and LUMO orbitals of ZnPc(PDI)4 1, calcu-
lated by the AM1 method.
FIGURE 5. Optimized structures of (a) ZnPc(PDI)4 1 and (b)
ZnPc(PDI)4 2, calculated by the AM1 method.
lack of steric hindrance. In contrast, the bulky substituents of
the PDI moiety in ZnPc(PDI)4 2 preclude such intermole-
cular charge-transfer interaction between the ZnPc and the
PDI moieties.
Photoinduced Charge Separation. The occurrence of
photoinduced electron transfer was examined by femtose-
cond laser flash photolysis measurements. A deaerated
PhCN solution containing ZnPc(PDI)4 2 gave rise upon a
450 nm femtosecond laser pulse to transient absorption
bands at 836, 1000, and 1100 nm with strong bleaching
at 690 nm, as shown in Figure 6a. The strong bleaching at
690 nm is ascribed to the fluorescence and absorption of
the ZnPc moiety. The absorption band at 836 nm is assigned
to ZnPc•þ by comparison with those of ZnPc•þ produced
by the electron-transfer oxidation of ZnPc(PDI)4 2 with
[Fe(bpy)3]3þ (λmax=834 nm) (see Figure 7). The absorption
bands in the NIR region between 1000 and 1100 nm are
FIGURE 3. (a) UV/vis spectra of ZnPc(PDI)4 1 and reference PDI
13 in DMF. (b) UV/vis spectra of ZnPc(PDI)4 2 and reference PDI
14 in DMF.
other’s PDI moiety. The energy difference between LUMO
and LUMOþ3 is small (0.26 eV).
The optimized structures of 1 and 2 are compared in
Figure 5. In the case of ZnPc(PDI)4 1, the intermolecular
charge-transfer interaction may be possible because of the
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FIGURE 7. Spectral change in the electron-transfer oxidation of
ZnPc(PDI)4 2 with Fe(bpy)3(PF6)3 in deaerated PhCN at 298 K.
FIGURE 6. (a) Transient absorption spectra of ZnPc(PDI)4 2 (1.0 ꢀ
10-5 M) in deaerated PhCN at 298 K after laser excitation at 450 nm.
(b) Time profile at 840 nm. Gray curve represents the best fit to the
two-exponential rise and decay.
assigned to PDI•- by comparison with those due to PDI•-
produced by the electrochemical reduction of the reference
compound PDI 14 (Figure 8a; λmax = 974 and 1083 nm).30
Although the transient absorption maxima observed in
Figure 6a are slightly red-shifted as compared to those of
PDI•- reference, the absorption bands due to PDI•- and
ZnPc•þ in Figure 6a are quite distinct and well-separated. This
clearly indicates formation of the charge-separated (CS) state.
From the rise in absorbance at 840 nm in Figure 6b, the
CS rate constant in ZnPc(PDI)4 2 is determined to be 2.1 ꢀ
1011 s-1. The photoexcitation of 2 at 450 nm affords initially
the singlet excited state of the PDI moiety because there is no
absorption at 450 nm due to the ZnPc moiety (see Figure 2).
FIGURE 8. Spectral changes in the electrochemical reduction of
PDI (a) 14 and (b) 13 in deaerated PhCN containing TBAPF6
(0.10 M) with an applied potential at -0.9 V vs SCE for 15 and
-0.7 V for 14 at 298 K.
1
The observation of the fluorescence of the ZnPc* moiety
indicates the occurrence of efficient energy transfer from the
1PDI* moiety to the ZnPc moiety. Then, intramolecular
1
spectra of ZnPc-PDI4 1 (1.0 ꢀ 10-5 M) obtained after
femtosecond laser excitation at 450 nm exhibit no clear
absorption bands due to ZnPc•þ and PDI•-, as shown in
Figure 9a. The featureless broad transient absorption ob-
served in Figure 9a, which is quite different from distinctive
transient absorption bands due to the CS state in Figure 6a,
results from aggregation of 1 as indicated by the broader
absorption band of 1 in Figure 3a and also by the 1H NMR
data (vide supra). Thus, the broad absorption bands in the
electron transfer from ZnPc* to PDI occurs to produce
the CS state, ZnPc•þ-PDI•-(PDI)3. The lifetime of the CS
state in PhCN is determined to be 26 ps from the decay of
absorbance at 840 nm in Figure 6b.
Formation of Intermolecular Exciplex. In contrast to the
case of ZnPc-PDI4 2 in Figure 6a, transient absorption
(30) Gosztola, D.; Niemczyk, M. P.; Svec, W.; Lukas, A. S.; Wasielewski,
M. R. J. Phys. Chem. A 2000, 104, 6545–6551.
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FIGURE 10. (a) Transient absorption spectrum of 2 (1.0 ꢀ 10-5 M)
in deaerated PhCN containing Mg(ClO4)2 (10 mM) at 298 K taken
at 1 μs after nanosecond laser excitation at 450 nm. (b) Time
profile at 830 nm. Gray curve represents the best fit to the single-
exponential decay.
Figure 10a. The transient absorption bands at 600 and 830
nm are assigned to ZnPc•þ, as shown in Figure 7. On the
other hand, with regard to PDI•-, no transient absorption
band around 1000 nm was observed in the presence of Mg2þ
.
FIGURE 9. (a) Transient absorption spectra of ZnPc(PDI)4 1 (1.0
ꢀ 10-5 M) in deaerated PhCN at 298 K after laser excitation at 450
nm. (b) Time profile at 840 nm. Gray curve represents the best fit to
the two-exponential rise and decay.
The absorption band of PDI•- in the presence of Mg2þ is
significantly shifted from that of PDI•- since it has been
reported that PDI•- forms a strong complex with Mg2þ 16
.
The broad absorption at 500 nm agrees with that due to
PDI•-/Mg2þ complex.16c
The decay of the CS state in the presence of Mg2þ (10 mM)
was monitored at 830 nm due to ZnPc•þ (see Figure 10b).
The decay curve obeys first-order kinetics. The decay rate
constant was determined to be 2.1 ꢀ 103 s-1. The lifetime of
the CS state is determined to be 480 μs.
region of 700-1200 nm may be ascribed to formation of the
intermolecular exciplex due to the aggregation. Such a strong
interaction results from less steric hindrance of the PDI
moiety in 1 as compared with 2. The rate of formation of
the exciplex is too fast to be determined with our equipment
(>3 ꢀ 1012 s-1), and this is much faster than the CS rate
constant in 2 (2.1 ꢀ 1011 s-1). The decay rate constant of the
exciplex of 1, determined from the decay of absorbance at
840 nm (6.2 ꢀ 1010 s-1), is also faster than that of the CS state
in 2 (3.9 ꢀ 1010 s-1). No transient absorption spectrum of
1 was observed after nanosecond laser excitation, sugges-
ting that the strong aggregation of 1 gave no formation of
the triplet excited state of ZnPc, PDI, or any long-lived
component. On the other hand, nanosecond transient ab-
sorption spectrum of 2 revealed the characteristic absorption
band due to the triplet excited state of PDI. The triplet PDI is
formed via energy transfer from the triplet excited state of
ZnPc to PDI (see Supporting Information S14).16
Conclusion
Photoexcitation of the zinc phthalocyanine-perylenebisi-
mide pentameric array 1 affords the intermolecular exciplex
in which strong interaction between the ZnPc and the PDI
moieties is recognized because of the aggregation. In con-
trast, photoexcitation of the zinc phthalocyanine-perylene-
bisimide pentameric array 2, with bulky substituents on the
PDI moieties, results in formation of the CS state. The
lifetime of the CS state of 2 is remarkably elongated by the
binding of Mg2þ to the CS state to attain a lifetime of 480 μs,
which is one of the longest CS lifetimes ever reported in
electron donor-acceptor ensembles.
Formation of a Long-Lived CS State with Mg(ClO4)2.
Addition of Mg(ClO4)2 (10 mM) to a PhCN solution of
ZnPc(PDI)4 2 results in drastic change in the photodynamics
to generate the long-lived CS state (vide infra). Nanosecond
laser excitation (λ=430 nm) of ZnPc(PDI)4 2 in deaerated
PhCN gave formation of the CS state, as shown in
Experimental Section
2,9,16,23-Tetrakis-[N0-(200,500-di-tert-butylphenyl)perylene-
30,40:90,100-bis(dicarboximide)-N(-yl)]phthalocyaninato zinc(II)
(1). Perylene 4 (145 mg, 0.25 mmol),24 tetraaminophthalocyanine
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11 (20 mg, 0.031 mmol),23 and imidazole (2 g) were stirred under
argon for 60 h at 180 °C. After being cooled to room temperature,
the reaction mixture was treated with 100 mL of MeOH and 70
mL of glacial acetic acid and stirred for 4 h. The purple precipitate
obtained was centrifuged and washed twice with MeOH/glacial
acetic acid and MeOH, respectively. Flash chromatography
(SiO2, CH2Cl2 /MeOH 9.5:0.5) yielded ZnPc-PDI4 1 (37 mg,
41%) as a dark purple powder:mp >300 °C;1H NMR(300MHz,
TFA-d1, 25 °C, TMS) δ= 10.30-9.40 (4H, broad), 9.26-8.70
(36H, broad), 8.70-8.00 (4H, broad), 7.85-7.40 (12H, broad),
1.38-1.19 (72H, broad); FT-IR (KBr) ν = 2957, 1705 (CdO
imide), 1668 (CdO imide), 1594, 1578, 1432, 1402, 1345, 1253,
1176, 1148, 1097 cm-1; UV/vis (DMF) λmax/nm (log ε) = 266
(4.87), 337 (4.80), 494 (5.00), 529 (4.90), 580 (4.38), 636 (5.02);
MS (MALDI-TOF-dithranol) m/z 2881 [Mþ], 2882 [Mþ þ 1],
34.8 mg (0.087 mmol) of 4,5-di-(p-carboxyphenoxy)phthalonitrile
619 and 150 mg (0.17 mmol) of perylene 7 were added to the
mixture and stirred at 0 °C for 5 min. After that, 45.4 mg
(0.22 mmol) of dicyclohexylcarbodiimide (DCC) was added,
and the mixture was stirred under argon for 3 days at rt. After
solvent distillation, purification by chromatography (SiO2,
CH2Cl2/AcOEt 40:1) gave 91 mg (50%) of 5 as a red powder:
mp 237-240 °C; 1H NMR (300 MHz, CDCl3, 25 °C, TMS)
δ=8.80 (8H, s), 8.04 (4H, d, J=7.6 Hz), 7.35 (2H, s), 7.00 (4H,
d, J=7.6 Hz), 4.67 (8H, m), 4.12 (4H, m), 1.92 (2H, m), 1.39-
1.25 (16H, m), 0.94-0.89 (12H, m); 13C NMR (75 MHz,
CDCl3, 25 °C, TMS) δ = 165.2, 162.4, 162.3, 158.2, 150.7,
136.2, 136.1, 132.3, 132,0, 131.4, 131.4, 131.4, 127.0, 124.4,
124.1, 124.0, 123.9, 123.8, 122.8, 122.2, 118.4, 114.3, 112.1, 62.6,
44.6, 39.6, 38.0, 30.6, 28.6, 23.9, 23.0, 14.1, 10.5; FT-IR (KBr)
ν = 3067, 2954, 2925, 2857, 2232 (CtN), 1705 (CdO imida),
1667 (CdO imida), 1585, 1499, 1433, 1381, 1339, 1271, 1233, 1155,
1111, 804, 744, 528 cm-1; UV/vis (CH2Cl2) λmax/nm (log ε) 251
(4.90), 441 (4.43), 499 (4.65), 531 (4.79); MS (MALDI-TOF-
dithranol) m/z 2080 [Mþ], 2081 [Mþ þ 1], 2000 [Mþ - Br]. Anal.
2883 [Mþ þ 2], 2304 [Mþ - perylene]. Anal. Calcd for C184H128
-
N16O16Zn 10H2O: C, 72.11; H, 4.87; N, 7.31. Found: C, 72.20; H,
3
5.10; N, 7.01.
2,9,16,23-Tetrakis-{N0-(200-ethylhexyl)-10,60,70,120-tetrakis-
[400(1000,1000,3000,3000-tetramethylbutyl)phenoxy]perylene-30,40:90,100-
bis(dicarboximide)-N(-yl)}-phthalocyaninatozinc(II) (2). Perylene
12 (300 mg, 0.23 mmol),25 tetraaminophthalocyanine 11 (20 mg,
0.031 mmol),23 and imidazole (2 g) were stirred under argon
for 60 h at 180 °C. After being cooled to room temperature,
the reaction mixture was repeatedly washed with MeOH.
Flash chromatography (SiO2, CH2Cl2/petroleum ether 1:1)
afforded ZnPc(PDI4) 2 (55 mg, 30%) as a dark purple powder:
Calcd for C90H60Br8N6O14 H2O: C, 51.31; H, 2.97; N, 3.99.
3
Found: C, 51.17; H, 2.98; N, 4.07.
N-(20-Ethylhexyl)-N0-(20-hydroxyethyl)-1,6,7,12-tetrabromo-
perylene-3,4:9,10-tetracaboxydimide (7). 2-Ethylhexylamine
(388 mg, 3 mmol), ethanolamine (183 mg, 3 mmol), 1,6,7,12-
tetrabromoperylene-3,4:9,10-tetracarboxyanhydride 8 (2 g, 2.8
mmol),21 and toluene (15 mL) were stirred under argon for 24 h
at reflux. After being cooled to room temperature, 50 mL of
CH2Cl2 was added, obtaining a red precipitate. This solid was
washed with water and dried, yielding diol 10 (869 mg, 40%).
Purification by chromatography (SiO2, CH2Cl2/MeOH 9:1)
1
mp >300 °C; H NMR (300 MHz, CDCl3, 25 °C, TMS) δ=
10.15-8.39 (8H, broad), 8.39-7.87 (16H, broad), 7.73 (4H,
broad), 7.17 (32H, broad), 6.90 (16H, broad), 6.49 (16H, broad),
4.04 (8H, broad), 1.81 (4H, broad), 1.66 (32H, broad), 1.46-1.15
(128H, broad), 1.02-0.58 (168H, broad); FT-IR (KBr) ν=2955,
1704 (CdO imide), 1666 (CdO imide), 1591, 1503, 1432, 1408,
1365, 1339, 1284, 1214, 1173, 1095, 1015 cm-1; UV/vis (CH2Cl2)
1
was used to characterize compound 10: H NMR (300 MHz,
DMSO-d6, 40 °C, TMS) δ=8.70 (4H, s), 4.83 (2H, t, J=5.9 Hz),
4.17 (4H, t, J=5.3 Hz), 3.65 (4H, dt, J=5.9 and 5.3 Hz); 13
C
λ
max/nm (log ε)=266 (5.37), 286 (5.34), 335 (5.15), 448 (4.89), 542
NMR (75 MHz, CDCl3/MeOD 5:1, 25 °C, TMS) δ 162.6, 136.0,
131.6, 131.2, 123.8, 122.3, 59.4, 42.4; FT-IR (KBr) ν = 3418
(OH), 3053, 2952, 1700 (CdO imide), 1663 (CdO imide),
1584, 1432, 1385, 1340, 1284, 1234, 1171, 1054, 804, 744, 647,
529 cm-1; UV/vis (DMSO) λmax/nm (log ε)=259 (4.50), 441
(4.07), 500 (4.34), 531 (4.46); MS (MALDI-TOF-dithranol) m/z
790 [Mþ], 791 [Mþ þ 1], 711 [Mþ - Br]. Anal. Calcd for
C28H14Br4N2O6: C, 42.35; H, 1.78; N, 3.53. Found: C, 42.26;
H, 2.03; N, 3.49.
The organic phase (with CH2Cl2) was recovered, and solvent
was evaporated. Purification by chromatography (SiO2,
CH2Cl2) gave 789 mg (30%) of symmetrical perylene 9 (first
fraction) as a red powder: mp 290-294 °C; 1H NMR (300 MHz,
CDCl3, 25 °C, TMS) δ=8.80 (4H, s), 4.13 (4H, m), 1.93 (2H, m),
1.40-1.25 (16H, m), 0.95 (6H, m), 0.90 (6H, m); 13C NMR (75
MHz, CDCl3, 25 °C, TMS) δ 162.4, 136.1, 131.5, 131.3, 123.9,
122.6, 44.5, 37.9, 30.6, 28.6, 23.9, 23.9, 23.0, 14.1, 10.5, 10.5; FT-
IR (KBr) ν=2956, 2927, 2857, 1704 (CdO imide), 1666 (CdO
imide), 1583, 1434, 1411, 1386, 1365, 1279, 1232, 1180, 1155,
805, 646, 529 cm-1; UV/vis (CH2Cl2) λmax/nm (log ε) = 231
(4.85), 272 (4.39), 439 (4.11), 497 (4.36), 529 (4.51); MS
(MALDI-TOF-dithranol) m/z 926 [Mþ], 927 [Mþ þ 1], 847
[Mþ - Br]. Anal. Calcd for C40H38Br4N2O4: C, 51.64; H, 4.12;
N, 3.01. Found: C, 51.41; H, 4.12; N, 3.12.
Finally, perylene 7 was collected from chromatography as the
second fraction using CH2Cl2/AcOEt 9:1. This purification gave
608 mg (25%) of unsymmetrical substituted perylene 7 as a
red powder: mp 290-294 °C; 1H NMR (300 MHz, CDCl3,
25 °C, TMS) δ=8.82 (2H, s), 8.81 (2H, s), 4.47 (2H, m), 4.13 (2H,
m), 3.99 (2H, t, J=4.65 Hz), 2.15 (1H, broad s), 1.93 (1H, m),
1.47-1.31 (8H, m), 0.94 (3H, m), 0.89 (3H, m); 13C NMR
(75 MHz, CDCl3, 25 °C, TMS) δ=162.9, 162.5, 136.3, 136.1,
131.9, 131.5, 131.4, 131.3, 124.1, 124.0, 123.9, 123.8, 122.7,
122.3, 61.2, 44.6, 42.9, 38.0, 30.7, 28.6, 24.0, 23.9, 23.0, 23.0,
(5.17), 582 (5.12), 638 (5.51), 671 (5.05); MS (MALDI-TOF-
dithranol) m/z 5843 [Mþ], 5844 [Mþ þ 1], 5845 [Mþ þ 2], 5779
[Mþ - Zn]. Anal. Calcd for C384H432N16O32 10H2O: C, 76.50;
3
H, 7.56; N, 3.72. Found: C, 76.73; H, 7.60; N, 3.55.
N-(20,50-Di-tert-butylphenyl)-N0-(30,40-dicianophenyl)perylene-
3,4:9,10-bis(carboximide) (3). Perylene 4 (100 mg, 0.17 mmol),24 4-
aminophthalonitrile (49.3 mg, 0.34 mmol),18 and imidazole (1 g)
were stirred under argon for 24 h at 125 °C. After being cooled to
room temperature, the reaction mixture was dissolved with CH2Cl2,
washed with 2 N HCl, water, and saturated solution of NaHCO3
sequentially, and dried with anhydrous MgSO4. Purification by
column chromatography (SiO2, CH2Cl2/AcOEt 40:1) gave 16 mg
(15%) of 3 as a red powder: mp 280-285 °C; 1H NMR (300 MHz,
CDCl3, 25 °C, TMS) δ=8.73 (2H, d, J=7.9 Hz), 8.69 (2H, d, J=
7.9 Hz), 8.59 (2H, d, J=8.1 Hz), 8.57 (2H, d, J=8.1 Hz), 8.01 (1H,
d, J=8.1 Hz), 7.88 (1H, s), 7.87 (1H, d, J=8.1 Hz), 7.60 (1H, d,
J=8.6 Hz), 7.48 (1H, dd, J=8.6 and 1.5 Hz), 7.14 (1H, d, J=
1.5 Hz), 1.31 (9H, s), 1.26 (9H, s); 13C NMR (75 MHz, CDCl3,
25 °C, TMS) δ= 164.1, 162.6, 150.3, 143.5, 141.8, 141.0, 139.5,
135.6, 134.5, 134.4, 134.1, 133.7, 132.3, 132.1, 131.6, 129.5, 129.5,
128.8, 127.9, 126.5, 126.4, 125.0, 124.1, 123.7, 123.2, 122.2, 117.0,
116.0, 114.9, 114.6, 35.5, 34.3, 31.7, 31.1; FT-IR (KBr) ν=3076,
2962, 2237 (CtN), 1707 (CdO imide), 1668 (CdO imide), 1594,
1578, 1403, 1356, 1345, 1254, 1175, 972, 811, 748 cm-1; UV/vis
(CH2Cl2) λmax/nm (log ε)=229 (4.68), 259 (4.58), 460 (4.14), 491
(4.57), 528 (4.77); MS (MALDI-TOF-dithranol) m/z 704 [Mþ], 705
[Mþ þ 1]. Anal. Calcd for C46H32N4O4 H2O: C, 76.44; H, 4.74; N,
3
7.75. Found: C, 76.08; H, 4.86; N, 7.59.
4,5-Bis{p-[20-(N0-2000-ethylhexyl-100,600,700,1200-tetrabromoper-
ylene-3,4:9,10-tetracaboxydimide-N-yl)ethoxycarbonyl]phenoxy}-
phthalonitrile (5). 1-Hydroxybenzotriazole (HOBt) (23.5 mg,
0.17 mmol), 4-dimethylaminopyridine (DMAP) (21.26 mg,
0.17 mmol), and CH2Cl2 (8 mL) were stirred at 0 °C. Then
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14.1, 10.5; FT-IR (KBr) ν=3446 (OH), 2956, 2928, 1704 (CdO
imide), 1665 (CdO imide), 1585, 1434, 1386, 1282, 1233, 804,
529 cm-1; UV/vis (CH2Cl2) λmax/nm (log ε)=238 (4.90), 276
(4.40), 440 (4.13), 497 (4.37), 529 (4.51); MS (MALDI-TOF-
dithranol) m/z 858 [Mþ], 859 [Mþ þ 1], 778 [Mþ - Br]. Anal.
Calcd for C34H26Br4N2O5: C, 47.36; H, 3.04; N, 3.25. Found: C,
47.38; H, 3.09; N, 3.35.
2010 project HOPE CSD2007-00007, MAT2005-07369-C03-
02, CTQ2007-67888/BQU, and CTQ2008-05901/BQU,
ACOMP/2009/039 and ACOMP/2009/056 from MICINN,
FEDER and Generalitat Valenciana. F.J.C.-G. thanks the
Spanish Government MICINN for a FPU fellowship.
Supporting Information Available: Text describing the
Experimental Section (chemical information, laser flash photo-
lysis, theoretical calculations, and cyclic voltammetry),
1H spectra of 1 and 2, 1H and 13C spectra of 3, 5, 7, 9, and 10,
MALDI-TOF spectra of 1 and 2, voltammograms of 1 and 2,
and transient absorption spectra of 2 and 14 (obtained by
nanosecond laser flash photolysis). This material is available
free of charge via the Internet at http://pubs.acs.org.
Acknowledgment. This work was partially supported by
Grants-in-Aid (Nos. 21750146, 19205019 and 19750034) from
the Ministry of Education, Culture, Sports, Science and
Technology, Japan, KOSEF/MEST through WCU project
(R31-2008-000-10010-0), and by Grants Consolider-Ingenio
5880 J. Org. Chem. Vol. 74, No. 16, 2009