A new approach toward light-harvesting reverse micelles from donor-acceptor miscible blends

Article abstract of DOI:10.1016/j.tet.2009.01.089

In the present paper, we report a new approach toward light-harvesting reverse micellar systems from molecular blends of anthracene and perylene building blocks. The self-assembly initiated by protonation of the molecular blends gave rise to the mixed rev

Full text of DOI:10.1016/j.tet.2009.01.089

Tetrahedron 65 (2009) 2669–2677
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Tetrahedron
journal homepage: www.elsevier.com/locate/tet
A new approach toward light-harvesting reverse micelles from
donor–acceptor miscible blends
,
a
a
a
b,
y
Masaki Takahashi a , Natsuko Nishizawa , Shuhei Ohno , Masahiro Kakita , Norifumi Fujita
,
*
Mitsuji Yamashita a, Tetsuya Sengoku a, Hidemi Yoda a
,
*
a Department of Materials Science, Faculty of Engineering, Shizuoka University, 3-5-1 Johoku, Naka-ku, Hamamatsu, Shizuoka 432-8561, Japan
b Department of Chemistry and Biochemistry, Graduate School of Engineering, Kyushu University, 744 Moto-oka, Nishi-ku, Fukuoka 819-0395, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
In the present paper, we report a new approach toward light-harvesting reverse micellar systems from
molecular blends of anthracene and perylene building blocks. The self-assembly initiated by protonation
of the molecular blends gave rise to the mixed reverse micelles, in which intermolecular energy transfer
from the anthracene to the perylene chromophores was observed. The atomic force microscope (AFM)
studies on the reverse micelles prepared from the donor and acceptor blends at a range of the feed ratios
showed a number of nanoscale-sized spherical objects homogeneously dispersed on the highly oriented
pyrolytic graphite (HOPG) substrate. The critical micelle concentration (cmc) values of the reversed
Received 19 November 2008
Received in revised form 21 January 2009
Accepted 22 January 2009
Available online 30 January 2009
micelles at the donor:acceptor ratios of 100:0, 50:50, and 0:100 were estimated to be 7, 3, and 10 mM by
fluorescence batch titrations, respectively, indicating that the cmc values should be almost equivalent
regardless of the constitution of each chromophoric component. Attempt to generate the mixed reverse
micelles through pairwise mixing of the donor- and acceptor-based reverse micelles resulted in spectral
behaviors identical with those obtained by the self-assembly employing the donor–acceptor blends. This
suggests that these two reverse micelles undergo thermodynamic exchange of the surfactant molecules
to afford the mixed reverse micelles when mixing the two discrete reverse micellar systems.
Ó 2009 Elsevier Ltd. All rights reserved.
1. Introduction
mechanism.3 From a standpoint of molecular design, reverse
micellar aggregates are particularly suited to use as scaffolds in the
The controlled organization of functional dyes into highly
ordered self-assembled arrays is an area of research with great
potential application in the design of advanced materials such as
optoelectronic devices because self-assembly of molecular com-
ponents through noncovalent interactions is widespread in natural
systems.1 In natural light-harvesting assemblies of photosynthetic
bacteria, light-absorbing chromophores are organized in a specific
geometry and encapsulated within nanoscopic protein matrices
where energy- and electron-transport processes can occur effi-
ciently across photosynthetic membranes.2 For the development of
artificial light-harvesting materials stimulated by the natural photo-
synthetic systems, confinement of photoactive units within nano-
scopic dimensions provides an important strategic advantage in
achieving efficient energy transfer directed by the Fo¨rster
construction of nanoscale assemblies of antenna pigments due to
the fact that the reverse micellar shell provides a unique nano-
meter-size environment for spatial heterogeneity to bring
intermolecular proximity of amphiphilic components.4 In our
previous work, we have studied anthracene–perylene conjugate 1
(Fig. 1), which exhibited efficient light-harvesting functionality
arising from intramolecular donor–acceptor interactions, could
self-assemble nanoscopic reverse micellar aggregates upon pro-
tonation of the tertiary amines (Scheme 1A).5 As part of our con-
tinuing interest in creating light-harvesting reverse micellar
systems, the present study focused attention on intermolecular
version of energy transfer between donor and acceptor molecules
bound in the self-assembled reverse micellar medium (Scheme 1B).
The idea of performing energy transfer depending on
intermolecular chromophoric interactions in a reverse micellar
system led us to synthesize two structurally similar dyes 2 and 3
(Fig. 1), whose anthracene and perylene chromophores fulfill
individual roles of the energy donor and acceptor, respectively.6
When these compounds blended in homogeneous solution are
used to generate reverse micellar aggregates through the self-
assembly process, the energy donor and acceptor species will be
* Corresponding authors. Tel./fax: þ81 53 478 1621/1150.
E-mail addresses: tmtakah@ipc.shizuoka.ac.jp (M. Takahashi), tchyoda@ipc.
shizuoka.ac.jp (H. Yoda).
y
Present address: Department of Chemistry and Biotechnology School of Engi-
neering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
0040-4020/$ – see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2009.01.089

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M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
Figure 1. Structures of 1, 2, and 3.
statistically distributed to form the molecular aggregates in hetero-
geneous (Path A) or homogeneous (Path B) fashion. In the former
case (Path A), interactions between the donor and acceptor ele-
ments are essentially feasible due to short interchromophore
distances that achieve efficient energy transfer, while in the latter
(Path B) it is the reverse. In this study, we discovered that the self-
assembly of the molecular blends at any feed ratio led to formation
of stable reverse micellar aggregates containing both the chromo-
phore elements, in which efficient energy transfer from the donor
to the acceptor was observed. Here, we present the details of our
studies on the new approach toward the light-harvesting reverse
micellar systems from the bichromophoric blends of the two
building blocks.
our previous work,5 the other amine, 1-(aminomethyl)-3,5-di(2-
ethylhexyloxy)benzene, was obtained through sequential steps as
follows. The preparation of this amine began with Williamson
alkylation of commercially available methyl 3,5-dihydroxybenzoate
with 2-ethylhexyl bromide to afford 6 in 85% yield. This compound
was reduced to the alcohol 7 with lithium aluminum hydride,
which was then transformed by treatment with carbon tetra-
bromide and triphenyl phosphine to give the bromide 8 in 83% for
two steps. By employing the Gabriel synthesis, this bromide
underwent substitution reaction to form the phthalimide 9, giving
rise to the desired amine 10 (87% for two steps). With these two
types of amines in hand, the syntheses of 2 and 3 were accom-
plished by following the two independent synthetic approaches as
described above. These products were fully characterized by
elemental analysis and a range of spectroscopies, and further
information regarding photophysical properties of the compounds
in toluene solutions was obtained by steady-state absorption and
fluorescence emission measurements.
In view of the absorption spectra (Fig. 2), 2 exhibited a feature-
less band attributed to the naphthalene chromophore in the
wavelength region around 300 nm as well as three vibrational
bands attributed to the anthracene chromophores in the wave-
length region from 350 to 410 nm, while 3 displayed a fine struc-
ture with two distinct absorption maxima in the wavelength region
from 410 to 470 nm, which was assigned to originate from the
perylene chromophore. Since the donor (anthracene) and acceptor
(perylene) absorptions are well separated in the spectral region,
changes of the two populations in the donor–acceptor blends can
be monitored by UV–vis absorption spectral measurements.
Figure 3A illustrates spectrophotometric titration of the donor–
acceptor blends in homogeneous toluene solutions with varying
molar ratios of the two components, whose net concentrations
were kept constant (c 10.0
mM) throughout the whole surveyed
range of the measurements. When changes in absorbance at 341
and 458 nm were plotted as a function of loaded acceptor con-
centration, linear downward and upward slopes were observed for
the donor and acceptor components, respectively (inset of Fig. 3A).
Subsequently, similar experiments were performed by the
fluorescence emission measurements on these compounds.
Figure 2 also illustrates the fluorescence emission spectra observed
upon excitation at 359 nm, exhibiting that the anthracene chromo-
phore of 2 emitted in the wavelength region from 400 to 450 nm,
while fluorescence emission from the perylene chromophore of 3
appeared in the wavelength region from 450 to 550 nm. These
observations led us to investigate fluorescence emission spectral
behavior of the series of donor–acceptor blends in homogeneous
toluene solutions. As can be seen in the fluorescence studies
(Fig. 3B), the shapes and positions of the donor and acceptor
emission bands corresponded apparently to those observed for the
two separate components. From the titration plots of the fluores-
cence intensities at 401 and 494 nm versus the loaded acceptor
concentrations (inset of Fig. 3B), we observed trends similar to
those found in the absorption behavior, which exhibited two linear
dependencies in the concentration region employed. Furthermore,
excitation spectra of a series of the donor–acceptor blends at
Scheme 1. Schematic representation of the reverse micelle formations.
2. Results and discussion
The two amines 2 and 3, precursors of the amphiphilic building
blocks for creating reverse micelles, were prepared by aluminum
hydride reduction of the corresponding naphthalene and perylene
bisimides
4 and 5 according to the literature, respectively
(Scheme 2).7 These two key intermediates could be accessed syn-
thetically through condensations of naphthalene and perylene
tetracarboxylic dianhydrides (NTCA and PTCA, respectively) with
the appropriate amines. While one of the requisite amine, 9-
(aminomethyl)-4,5-di(2-ethylhexyl)anthracene, was available from

M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
2671
HO
OH
Br
O
O
K2CO3 / DMF
OCH3
O
OCH3
O
Methyl 3,5-dihydroxybenzoate
6
O
NH
.
O
O
LiAlH4
/ THF
H2NNH2 H2O
/ THF
O
O
O
O
O
O
K2CO3 / DMF
N
X
NH2
O
(X = OH)
(X = Br)
7
8
CBr4/THF
9
10
O
N
O
O
N
O
O
O
O
O
AlH3
+
2
O
O
/ 1-PrOH.H2O
(50:50)
/ THF
NH2
NTCA
4
O
N
O
O
N
O
O
O
O
O
O
O
AlH3
+
O
O
3
7
O
O
/ NMP
/ THF
PTCA
5
Scheme 2. Preparation of 2 and 3.
lem equal to 550 nm exhibited no detectable peaks attributed to
the anthracene groups (Fig. 3C). The above results confirm
unambiguously that the two chromophores contained in 2 and 3
behave as monomeric species, suggesting that energy transfer
promoted by donor–acceptor interactions is unlikely, due to sepa-
ration distance or relative orientation of the individual molecules
dispersed in the highly diluted homogeneous solutions.
On the basis of these observations, we next subjected these
compounds to the self-assembly studies. In our previous report, we
have established self-assembling approaches with 1 upon pro-
tonation of the two tertiary amines at the edges of the perylene
core (Scheme 1A). According to the established procedure,5 an
excess (2.0 M equivalents per amines) of sulfuric acid in aqueous
solution was added to 2 and/or 3 (0.5 mM in anhydrous toluene)
followed by sonication for 3 min and stirring for 18 h at room
temperature to promote the self-assembly of the generated sur-
factants in all of the analytical experiments, in which water/
surfactant ratio (W0) was adjusted to be 50.8 Figure 4 shows
absorption and fluorescence emission spectra of the resulting
solutions that were individually prepared from 2 and 3. In both
cases, all absorption maxima observed in both dilute toluene
solutions were bathochromically shifted in comparison to the
wavelengths of the respective starting compounds, showing nota-
ble sign of aggregate formations. Furthermore, significant changes
were observed in the fluorescence spectra, which exhibited broad,
unstructured, and red-shifted emission bands likely due to exci-
mer-like interacting chromophores within the molecular aggre-
gates in both cases.
Since the protonated amines are self-assembled by relatively
weak and noncovalent interactions, one must consider the two
possible pathways when homogeneous blends of these two struc-
turally similar amines were used for the self-assembly studies
(Paths A and B in Scheme 1B). In order to understand fundamental
aspects of the self-assembly processes, we set out to explore photo-
physical behavior of the molecular aggregates formed by the
donor–acceptor blends. As can be seen in Figure 5A, the UV–vis
spectra in toluene reflected the presence of the donor and acceptor
species, whose relative absorbance exhibited linear dependencies
on the relevant concentrations. From these observations, the
absorption characteristics do not show any pronounced effect
related to donor–acceptor interactions between the anthracene
and perylene units incorporated within the self-assembled
systems.
In contrast, potentially interesting features have emerged when
the self-assembled molecular aggregates of the protonated donor–
acceptor blends were subjected to the fluorescence measurements
(Fig.5B). Obviously, directexcitationof theenergydonor(anthracene)
chromophores at 368 nm resulted in pronounced fluorescence
Figure 2. Normalized absorption (solid lines, c 10.0
(dotted lines, 0.1 M) spectra of
(blue lines, lex¼359 nm), and
lex¼430 nm) in toluene.
m
M) and fluorescence emission
c
m
2
3
(red lines,

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M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
Figure 5. Results of batch spectrophotometric titrations using the reverse micelles
(W0¼50) prepared from the donor–acceptor blends at the feed ratios of 100/0, 95/5,
Figure 3. Results of batch spectrophotometric titrations using the donor–acceptor
blends at the feed ratios of 100/0, 95/5, 91/9, 83/17, 75/25, 67/33, 50/50, 33/67, 25/75,
91/9, 83/17, 75/25, 67/33, 50/50, 33/67, 25/75, 17/83, 9/91, 5/95, and 0/100: (A) Ab-
sorption spectra of the blends (c 10.0
351 nm (blue solid circles) and 462 nm (red solid circles) vs content of the perylene
species. (B) Fluorescence emission spectra (lex¼368 nm, c 10.0 M) in toluene. (C)
Excitation emission spectra (lem¼550 nm, c 10.0 M) in toluene.
mM) in toluene. Inset: plots of absorbance at
17/83, 9/91, 5/95, and 0/100: (A) Absorption spectra (c 10.0
of absorbance at 341 nm (blue solid circles) and 458 nm (red solid circles) vs content of
M) in
mM) in toluene. Inset: plots
m
the perylene species. (B) Fluorescence emission spectra (lex¼359 nm, c 0.10
m
m
toluene. Inset: plots of emission intensity at 401 nm (blue solid circles) and 494 nm
(red solid circles) vs content of the perylene species. (C) Excitation emission spectra
(
lem¼550 nm, c 0.10
mM) in toluene.
achieved intermolecular efficient energy transfer from the anthra-
cene donor to the perylene acceptor species.10
emission bands from the acceptor (perylene) chromophores in lon-
ger-wavelength regions (450–600 nm).9 It should be noted that the
emission maxima for the molecular aggregates are sensitive to the
feed ratio of the donor and acceptor components. At low feed ratios
(2/3) greater than 83/17 (orange-colored lines), single emission
maxima arising from monomeric perylene acceptor species appeared
at 475 nm. By increasing the feed ratio less than 75/25, the fluores-
cence spectra were red-shifted and less efficient (green-colored
lines), leading to suppressed emission from excimer-like perylene
aggregates (red-colored lines) in the feed ratios below 50/50. On the
basis of these measurements, a reverse micellar model containing the
donor–acceptor elements miscible in nanoscopic environments can
be proposed to explain the complex photophysical behavior, which
Another compelling evidence for the energy transfer taking
place in the reverse micelles was provided by obtaining the exci-
tation spectra at lem equal to 550 nm, which corresponds mainly to
the acceptor emission (Fig. 5C). Compared with the respective ab-
sorption spectra, the excitation spectra are similar in shape, but
there are significant differences in the relative intensity ratios of the
donor and acceptor signals observed. In fact, the reverse micelles
prepared from 2 were found to exhibit three excitation peaks at
368, 386, and 406 nm, which were assigned to excitation region of
the anthracene chromophores (blue-colored line). Therefore, we
attribute the emission band at 550 nm for a given series of the
reverse micelles in part to the broad and red-shifted emission of
excimer-like interacting anthracene chromophores. By comparison
with the homogeneous reverse micellar systems, the excitation
spectral measurements on the mixed reverse micelles prepared
from the donor–acceptor blends (e.g., the feed ratio (2/3)¼95/5 or
91/9 or 83/17; orange-colored lines) showed significant enhance-
ment of the three anthracene peaks. The observed enhancement
can be ascribed to the ‘antenna effect’ involving the energy transfer
from the anthracene donors to the perylene acceptors.11 We
therefore conclude that the miscible blends of two amines 2 and 3
can self-assemble into the mixed reverse micelles, in which the
intermolecular energy transfer is effective as a result of favorable
intracluster arrangements of the donor and acceptor
chromophores.12
Figure 4. Normalized absorption (solid lines, c 10.0
(dotted lines, c 10.0
M) spectra of the reverse micelles (W0¼50) prepared from 2 (blue
lines, lex¼368 nm) and from 3 (red lines, lex¼430 nm) in toluene.
mM) and fluorescence emission
Considering the situation where all the chromophoric compo-
nents are confined within the nanoscopic reverse micellar shells,
m

M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
2673
micelle prepared from 3, unless alternative donor surfactant com-
patible with the perylene chromophore is available.
To explore nanoscopic features of the self-assembled aggregate
systems, the atomic force microscope (AFM) studies were carried
out on the reverse micelles prepared from the donor and acceptor
blends at a range of the feed ratios (2/3¼100/0, 75/25, 67/33, 50/50,
25/75, 33/67, and 0/100). As can be seen in Figure 7, there are
a number of small spherical objects dispersed on the highly
oriented pyrolytic graphite (HOPG) substrate, which can be
attributed to the individual reverse micelles or their assemblies.15
Throughout inspection of the given series of the AFM pictures, it
would appear that acceptor-rich reverse micelles have a tendency
to form relatively large spherical objects. At this point, it is rea-
sonable to assume that molecular size of the surfactant compo-
nents would play a critical role in determining size and shape of the
reverse micelles. In terms of structural description of our designed
donor and acceptor molecules, considerable size difference can be
found in end-to-end lengths of naphthalene (0.68 nm) and pery-
lene (1.11 nm) nuclei, whereas two different 2-ethylhexyl-cont
aining side groups are similar in size and shape. With this idea in
mind, we can deduce that this structural difference and the com-
position of the donor–acceptor blends may reflect overall average
size of the self-assembled aggregates. Zoomed AFM images and
cross-sectional views for the reverse micelles prepared from 2 are
shown in Figure 8, revealing that the small spherical objects
appeared to have an average height less than 3 nm.16 These results
suggest the reverse micelles are stabilized in the nanoscopic
globular forms, where the chromophoric components are in close
contact. The formation of these coherent domains may be a con-
sequence of noncovalent interactions between the amphiphilic
components, allowing the efficient energy transfer or fluorescence
radiationless deactivation due to the concentration quenching.
To determine critical micelle concentration (cmc) values of the
reverse micelles, we investigated titrations using various concen-
Figure 6. Normalized fluorescence emission spectra (lex¼368 nm) of the mixed re-
verse micelles at the feed ratios (2/3) from 18/1 to 25/1 (c 10.0 M) with respect to the
perylene concentrations. Inset: plots of relative fluorescence intensity at 475 nm vs the
feed ratio.
m
the intracluster energy transfer directed by the Fo¨rster mechanism
is highly efficient and results in amplification of the acceptor
emission upon excitation of the donor chromophores.13 Thus, the
above spectroscopic evidence can be obviously regarded as the
proposed reverse micellar system by taking into account the fact
that the energy transfer from the anthracene donor to the perylene
acceptor occurs with sufficiently high efficiency.14 Based on this
mechanistic model, we deduce that the presence of more than two
perylene species within a reverse micelle aggregate causes sup-
pression of the acceptor emissions due to collisional quenching
driven by non-negligible interactions among the neighboring
acceptors. In other words, a reverse micellar system containing
completely isolated perylene species among the anthracene donor
clusters leads to the most enhanced acceptor emission. To validate
this assumption, the fluorescence spectra were normalized with
respect to the donor concentrations and reexamined in the specific
range of the feed ratios from 18/1 to 25/1 (Fig. 6). For comparison,
the relative intensities of the acceptor emission maxima at 475 nm
were plotted in the inset of Figure 6 as a function of the feed ratio
(2/3). This titration plot shows a moderately growing curve that
reaches a plateau at the feed ratio of 23. We therefore conclude that
one set of the reverse micellar aggregate prepared from 2 is built up
of ca. 24 surfactant molecules. Unfortunately, there is no straight-
forward way to apply this estimation methodology to the reverse
trations of the surfactant molecules from 0.5 to 80 mM. As has been
observed previously, the cmc values for the homogeneous reverse
micellar systems can be defined phenomenologically from changes
in the fluorescence output, whose efficiency should decrease
steadily in a concentration range close to the cmc as a result of the
fluorescence deactivation due to the concentration quenching or
Figure 7. AFM images of drop-cast of the mixed reverse micelles (W0¼50) at the feed ratios of (A) 100/0, (B) 75/25, (C) 67/33, (D) 50/50, (E) 33/67, (F) 25/75, and (G) 0/100.

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M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
Figure 8. Two types of zoom-in images of Figure 7A; (A) 0.5ꢀ0.5
mm and (B) 0.2ꢀ0.2
mm (top). The height profiles on cross-sections of the solid lines in the AFM images (bottom).
energy transfer.17 In the cases of the homogeneous reverse micelles,
the titration plots of fluorescence intensities showed linear re-
lationship at lower concentrations and reached a plateau above
40 mM (Fig. 9A and 9B). From a given inflection point in the fluo-
rescence emission trajectory, we estimated the cmc values for the
homogeneous reverse micelles prepared from 2 and 3 as 7 and
3 mM, respectively. On the other hand, the cmc values for the mixed
reverse micellar systems involving the energy transfer (e.g., the
feed ratio¼50/50) can be approximated by monitoring consecu-
tively the fluorescence intensity of the donor species. Formation of
the mixed reverse micelles leads to introduction of the light-har-
vesting functionality, resulting in significant decrease of the donor
emission upon excitation of the donor chromophores due to the
energy transfer. For this reason, the monitoring runs were per-
formed by scanning the fluorescence emission at 405 nm with
excitation at 340 nm. Under this condition, the titration plot
showed a distinct reflection point at the concentration of 10 mM
(Fig. 9C), which corresponds to the cmc value for the mixed reverse
micelles. The results from these titration experiments on the three
different reverse micellar systems suggest that the cmc values are
almost equivalent regardless of the constitution of each chromo-
phoric component.
Alternate approach to the mixed reverse micelles was next ex-
plored in order to address a question concerning the feasibility of
molecular exchange between two types of the homogeneous re-
verse micelles (Scheme 3). To test this possibility, we attempted
pairwise mixing of the donor- and acceptor-based reverse micelles
prepared individually from 2 and 3, respectively, at the stoichio-
metric ratios of 10:1, 3:1, and 1:1 (c 0.5 mM, at room temperature
for 3 min). Formation of the mixed reverse micelles can be con-
firmed by comparison with control experiment on those prepared
from the donor–acceptor blends at the respective feed ratios. In-
deed, all the fluorescence spectra obtained from the mixing
approaches were found to be identical with those obtained from the
control experiments, indicating introduction of the light-harvesting
functionality. These spectroscopic observations suggest that these
two homogeneous reverse micelles undergo thermodynamic ex-
change of the surfactant molecules to afford the mixed reverse
micelles when mixing the two components. On the basis of these
Figure 9. Plots of fluorescence intensities of the reverse micelles prepared from (A) 2
and (B) 3 and (C) donor–acceptor blend at the feed ratio (2/3) of 50/50 vs concen-
trations of the analytes.

M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
2675
results, we believe that the dynamic nature of the blending tech-
niques would give many potential applications in generating
a dynamic combinatorial library of the light-harvesting reverse
micellar systems.18
flight (MALDI-TOF) mass spectra were recorded on an Applied
Biosystems Voyager-DE PRO mass spectrometer by carrying out
measurements in reflector mode with the matrix 1,8,9-trihydroxy
anthracene (dithranol) that were dissolved in THF and mixed with
the analytes at a molar ratio of approximately 1:500 (analyte:ma-
trix). High resolution mass spectrometry (HRMS) was performed
on a JEOL JMS-T100CS. Elemental analyses were performed by
Thermo Flash EA 1112 and JSL Model JM 10 instruments. The atomic
force microscope (AFM) analyses were performed on a Veeco
NanoScope IIIa microscope.
4.2. Preparation and characterization of new compounds
4.2.1. Methyl 3,5-di(2-ethylhexyloxy)benzoate (6)
A solution containing methyl 3,5-dihydroxybenzoate (0.100 g,
0.595 mmol), 2-ethylhexyl bromide (0.35 mL, 1.97 mmol), and
potassium carbonate (0.168 g, 1.21 mmol) in DMF (1 mL) was
heated at 100 ꢁC with stirring under argon atmosphere. After 10 h,
the reaction mixture was cooled to room temperature, filtered
through a pad of Celite, and then extracted with hexane (30 mL).
The organic layer was washed with water (100 mL) and brine
(20 mL), dried over anhydrous Na2SO4, filtered, and concentrated in
vacuo. The residue was purified by silica gel column chromatog-
raphy (hexane/ethyl acetate¼30/1) to give 6 (0.198 g, 85%) as
a colorless oil: IR (NaCl) 1173 cmꢂ1 (C–O), 1597 cmꢂ1 (C]C),
Scheme 3. Schematic representation of pairwise mixing of the donor- and acceptor-
based reverse micelles.
3. Conclusions
1724 cmꢂ1 (C]O); 1H NMR (CDCl3)
d 0.85–0.97 (m, 12H, Me), 1.25–
We have studied a new approach to the self-assembly of the do-
nor–acceptor miscible blends, which spontaneously generated the
mixed reverse micelles in nanoscopic dimensions. The interesting
finding here is that the mixed reverse micelles achieve in-
termolecular energy transfer from the anthracene donor to the per-
ylene acceptor, making it possible to introduce the light-harvesting
functionality. As a result of the heterogeneous nature, the mixed re-
verse micellar systems ensure the unique color emission profiles,
which can be tuned by adjusting the composition of the donor–ac-
ceptor elements. These studies would suggest that our self-assem-
bling approaches to the mixed reverse micelles via the combination
of photoactive species may provide a conceptual basis for creating
artificial light-harvesting nanostructured materials with diverse and
properly designed functionality.19 Further studies on the de-
velopment of this self-assembly approaches to novel light-harvesting
reverse micellar systems for practical uses and engineering new ap-
plications will be the subject of future work.
1.60 (m, 16H, CH2), 1.65–1.78 (m, 2H, CH), 3.86 (d, J¼5.6 Hz, 4H,
CH2), 3.90 (s, 3H, Me), 6.65 (t, J¼2.2 Hz, 1H, ArH), 7.17 (d, J¼2.2 Hz,
2H, ArH); 13C NMR (CDCl3)
d 11.2 (CH3), 14.1 (CH3), 23.1 (CH2), 24.0
(CH2), 29.2 (CH2), 30.6 (CH2), 39.5 (CH), 52.2 (CH3), 70.8 (CH2), 106.7
(CH), 107.8 (CH), 132.0 (C), 160.7 (C), 167.3 (C). Anal. Calcd for
C24H40O4: C, 73.43; H, 10.27. Found: C, 73.09; H, 10.25.
4.2.2. 3,5-Di(2-ethylhexyloxy)phenyl methanol (7)
To a solution of 6 (1.79 g, 4.56 mmol) in anhydrous THF (10 mL)
was added lithium aluminum hydride (0.173 g, 4.56 mmol) in small
portions over a period of 20 min at 0 ꢁC. After stirring for 3 h at
room temperature, the reaction was quenched by addition of water
(5 mL) and 3% aqueous HCl (10 mL) at 0 ꢁC. The resulting reaction
mixture was then extracted with hexane (100 mL). The organic
layer was washed with water (100 mL), saturated aqueous NaHCO3
(20 mL), and brine (20 mL). The extract was separated, dried over
anhydrous Na2SO4, filtered, and concentrated in vacuo to give 7
4. Experimental section
4.1. General
(1.48 g, 89%) as
1597 cmꢂ1 (C]C), 3346 cmꢂ1 (O–H); MS (MALDI-TOF) m/z 365.7
(MHþ); 1H NMR (CDCl3)
0.85–0.97 (m, 12H, Me), 1.25–1.56 (m,
a
colorless oil: IR (NaCl) 1171 cmꢂ1 (C–O),
d
16H, CH2), 1.61–1.76 (m, 3H, CH and OH), 3.83 (dd, J¼0.8 and 5.7 Hz,
All solvents and reagents were of reagent grade quality from
Wako Pure Chemicals and Tokyo Chemical Industry (TCI) used
without further purification. The 1H and 13C nuclear magnetic
resonance (NMR) spectra operating at the frequencies of 300 and
75 MHz, respectively, were recorded on a JEOL JNM-AL300 spec-
trometer in chloroform-d (CDCl3). Chemical shifts are reported in
parts per million (ppm) relative to TMS and the solvent used as
internal standards, and the coupling constants are reported in hertz
(Hz). Fourier transform infrared (FTIR) spectra were recorded on
Shimadzu FTIR-8200A spectrometers. UV–vis and fluorescence
(excitation) spectra were recorded on a JASCO V-530 spectropho-
tometer and a JASCO FP-6200 spectrofluorometer, respectively.
4H, CH2), 4.62 (d, J¼5.9 Hz, 2H, CH2), 6.39 (t, J¼2.2 Hz,1H, ArH), 6.51
(d, J¼2.2 Hz, 2H, ArH); 13C NMR (CDCl3)
d 11.2 (CH3), 14.1 (CH3), 23.1
(CH2), 24.0 (CH2), 29.2 (CH2), 30.6 (CH2), 39.5 (CH), 65.3 (CH2), 70.6
(CH2), 100.7 (CH), 105.2 (CH), 143.5 (C), 161.0 (C). Anal. Calcd for
C23H40O3: C, 75.77; H, 11.06. Found: C, 75.96; H, 11.08.
4.2.3. 3,5-Di(2-ethylhexyloxy)phenylmethyl bromide (8)
To a stirring mixture of 7 (1.49 g, 4.08 mmol), carbon tetra-
bromide (1.76 g, 5.30 mmol), and triphenyl phosphine (1.40 g,
5.30 mmol), was added anhydrous THF (2 mL) at room tempera-
ture. After stirring for 1 h at room temperature, hexane (100 mL)
was added to the reaction mixture, whereupon the resultant white
precipitate was filtered through a pad of Celite under vacuum. The
filtrate was washed with water (100 mL) and brine (50 mL), dried
over Na2SO4, filtered, and concentrated in vacuo. The residue was
purified by silica gel column chromatography (hexane/ethyl
acetate¼30/1) to give 8 (1.62 g, 93%) as a colorless oil: IR (NaCl)
1173 cmꢂ1 (C–O), 1597 cmꢂ1 (C]C); MS (MALDI-TOF) m/z 427.5
Molar absorption coefficients (3) were determined by batch spec-
trophotometric titrations. Plots of absorbance of analytes at
wavelengths of interest versus relevant concentrations should be
linear if the titration studies were performed at sufficient low
absorbance (A<1.0). The slopes of these linear plots allow the cal-
culation of the molar absorption coefficients for the analytes ex-
amined. Matrix-assisted laser desorption ionization time of
(MHþ); 1H NMR (CDCl3)
d 0.85–0.97 (m, 12H, Me), 1.25–1.55 (m,

2676
M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
16H, CH2), 1.63–1.77 (m, 2H, CH), 3.81 (dd, J¼0.8 and 5.7 Hz, 4H,
CH2), 4.41 (s, 2H, CH2), 6.39 (t, J¼2.2 Hz, 1H, ArH), 6.52 (d, J¼2.2 Hz,
(CDCl3) d 10.4 (CH3), 14.0 (CH3), 23.1 (CH2), 25.5 (CH2), 25.6 (CH2),
28.5 (CH2), 32.5 (CH2), 32.6 (CH2), 38.4 (CH2), 38.5 (CH2), 38.8 (CH2),
39.5 (CH), 121.1 (CH), 122.7 (CH), 125.6 (CH), 125.8 (CH), 126.3 (C),
126.4 (C), 128.3 (C), 130.0 (CH), 131.0 (C), 131.1 (C), 138.7 (C), 163.2
(C). Anal. Calcd for C76H90N2O4: C, 83.32; H, 8.28; N, 2.56. Found: C,
83.34; H, 8.08; N, 2.87.
2H, ArH); 13C NMR (CDCl3)
d 11.2 (CH3), 14.1 (CH3), 23.1 (CH2), 23.9
(CH2), 29.1 (CH2), 30.6 (CH2), 33.9 (CH2), 39.5 (CH), 70.6 (CH2), 101.6
(CH), 107.5 (CH), 139.7 (C), 160.9 (C). Anal. Calcd for C23H39BrO2: C,
64.63; H, 9.20. Found: C, 64.44; H, 9.38.
4.2.4. 3,5-Di(2-ethylhexyloxy)-1-(phthalimidomethyl)benzene (9)
A suspension of 8 (0.144 g, 0.337 mmol), phthalimide (0.064 g,
0.438 mmol), and potassium carbonate (0.070 g, 0.506 mmol) in
DMF (5 mL) was stirred at room temperature. After stirring for
additional 22 h, it was filtered through a pad of Celite under vac-
uum and washed with ethyl acetate (100 mL). The filtrate was
washed with water (100 mL) and brine (50 mL), dried over Na2SO4,
filtered, and concentrated in vacuo. Purification of the residue by
flash column chromatography on silica gel (hexane/ethyl
acetate¼20/1) gave 9 (0.163 g, 98%) as a colorless oil: IR (NaCl)
1597 cmꢂ1 (C]C), 1609 cmꢂ1 (C]C), 1717 cmꢂ1 (C]O), 1773 cmꢂ1
4.2.7. 2,9-Bis(3,5-di(2-ethylhexyloxy)phenylmethyl)-2,9-
diazadibenzo[cd,lm]perylene-1,3,8,10-tetraone (5)
A suspension of perylene-3,4,9,10-tetracarboxylic dianhydride
(0.344 g, 0.877 mmol) and 3 (0.654 g, 1.80 mmol) in N-methyl
pyrrolidinone (15 mL) was heated at 100 ꢁC with stirring. After
10 h, the reaction mixture was cooled to room temperature and
poured into water (300 mL) to form a dark red solid. This pre-
cipitate was collected by filtration, washed with water (50 mL), and
dissolved in hexane (100 mL). This solution was washed with water
(50 mL) and brine (30 mL), dried over Na2SO4, filtered, and con-
centrated in vacuo. Purification of the residue by flash column
chromatography on silica gel (hexane/ethyl acetate¼5/1) gave 4
(0.513 g, 54%) as a dark red solid: IR (NaCl) 1171 cmꢂ1 (C–O),
1595 cmꢂ1 (C]C), 1659 cmꢂ1 (C]O), 1697 cmꢂ1 (C]O); MS
(MALDI-TOF) m/z 1085.1 (MHþ); HRMS (ESI) m/z calcd for
(C]O); MS (MALDI-TOF) m/z 494.9 (MHþ); 1H NMR (CDCl3)
d 0.85–
0.95 (m, 12H, Me), 1.24–1.56 (m, 16H, CH2), 1.61–1.74 (m, 2H, CH),
3.80 (d, J¼5.5 Hz, 4H, CH2), 4.76 (s, 2H, CH2), 6.36 (t, J¼2.2 Hz, 1H,
ArH), 6.56 (d, J¼2.2 Hz, 2H, ArH), 7.69 (dd, J¼3.0 and 5.5 Hz, 2H,
ArH), 7.84 (dd, J¼3.0 and 5.5 Hz, 2H, ArH); 13C NMR (CDCl3)
d
10.9
C70H87N2O8: 1083.6462, found 1083.6514; 1H NMR (CDCl3)
d 0.82–
(CH3), 13.9 (CH3), 22.9 (CH2), 23.7 (CH2), 28.9 (CH2), 30.4 (CH2), 39.3
(CH), 41.6 (CH2), 70.3 (CH2), 100.6 (CH), 106.8 (CH), 123.3 (CH), 132.2
(C), 133.9 (CH), 138.3 (C), 160.8 (C), 168.0 (C). Anal. Calcd for
C31H43NO4: C, 75.42; H, 8.78. Found: C, 75.67; H, 8.94.
0.94 (m, 24H, Me), 1.23–1.54 (m, 32H, CH2), 1.61–1.74 (m, 4H, CH),
3.82 (d, J¼5.6 Hz, 8H, CH2), 5.33 (s, 4H, CH2), 6.37 (t, J¼2.1 Hz, 2H,
ArH), 6.70 (d, J¼2.1 Hz, 4H, ArH), 8.41 (d, J¼8.0 Hz, 4H, ArH), 8.58 (d,
J¼8.0 Hz, 4H, ArH); 13C NMR (CDCl3)
d 11.0 (CH3), 13.9 (CH3), 22.9
(CH2), 23.7 (CH2), 29.0 (CH2), 30.4 (CH2), 39.4 (CH), 70.4 (CH2), 100.5
(CH), 107.6 (CH),122.5 (C),122.9 (CH),125.4 (C),128.6 (C), 131.0 (CH),
133.7 (C), 139.1 (C), 160.7 (C), 162.8 (C). Anal. Calcd for C70H86N2O8:
C, 77.60; H, 8.00; N, 2.59. Found: C, 77.38; H, 7.68; N, 2.63.
4.2.5. 1-(Aminomethyl)-3,5-di(2-ethylhexyloxy)benzene (10)
To a solution of 9 (0.257 g, 0.521 mmol) in THF (5 mL) was
slowly added hydrazine monohydrate (0.1 mL, 3.15 mmol) at
ambient temperature and the resulting reaction mixture was
heated at reflux. After 3 h, it was cooled to ambient temperature,
filtered through a pad of Celite, and washed with hexane (50 mL).
The filtrate was washed with water (50 mL) and brine (20 mL),
dried over Na2SO4, filtered, and concentrated in vacuo to give 10
(0.168 g, 89%) as a colorless oil; IR (NaCl) 1171 cmꢂ1 (C–O),
1595 cmꢂ1 (C]C), 3421 and 3377 cmꢂ1 (N–H); MS (MALDI-TOF)
m/z 364.9 (MHþ); HRMS (ESI) m/z calcd for C23H42NO2: 364.3216,
4.2.8. 2,7-Bis(4,5-di(2-ethylhexyl)-9-anthracenemethyl)-1,3,6,8-
tetrahydro-2,7-diazadibenzo[de,ij]naphthalene (2)
To a solution of aluminum chloride (0.123 g, 0.922 mmol) in
anhydrous THF (7 mL) was added lithium aluminum hydride
(0.035 g, 0.922 mmol) in small portions at 0 ꢁC. After removal of the
ice-bath and stirring for 30 min, 4 (0.025 g, 0.0228 mmol) was
added in small portions and the reaction mixture was stirred at
room temperature. After an additional 2 h, the resulting reaction
mixture was quenched with water (3 mL) and 3% aqueous HCl
(3 mL) at 0 ꢁC. To the residue was added 15 wt % NaOH (5 mL) and
the resulting solid was dissolved in CH2Cl2 (30 mL), washed with
water (30 mL), and brine (30 mL). The organic layer was dried over
Na2SO4, filtered, and concentrated in vacuo to give 2 (0.022 g, 94%)
found 364.3195; 1H NMR (CDCl3)
d 0.85–0.97 (m, 12H, Me), 1.25–
1.58 (m, 18H, CH2 and NH2), 1.63–1.77 (m, 2H, CH), 3.78 (s, 2H, CH2),
3.82 (d, J¼5.5 Hz, 4H, CH2), 6.35 (t, J¼2.2 Hz, 1H, ArH), 6.45 (d,
J¼2.2 Hz, 2H, ArH); 13C NMR (CDCl3)
d 11.2 (CH3), 14.1 (CH3), 23.1
(CH2), 24.0 (CH2), 29.2 (CH2), 30.7 (CH2), 39.5 (CH), 46.8 (CH2), 70.5
(CH2), 99.8 (CH), 105.4 (CH), 145.9 (C), 161.1 (C). Anal. Calcd for
C23H41NO2: C, 75.98; H, 11.37; N, 3.85. Found: C, 76.10; H, 11.00; N,
4.03.
as a pale yellow solid: UV (toluene) 361 nm (3 11,300), 378 nm (3
19,100), 400 nm (3
17,800); IR (NaCl) 1601 cmꢂ1 (C]C), 1618 cmꢂ1
(C]C), 2926 cmꢂ1 (C–H), 2959 cmꢂ1 (C–H), 3020 cmꢂ1 (C–H); MS
(MALDI-TOF) m/z 1039.1 (Mþ); HRMS (ESI) m/z calcd for C76H99N2:
4.2.6. 2,7-Bis(4,5-di(2-ethylhexyl)-9-anthracenemethyl)-2,7-
diazadibenzo[de,ij]naphthalene-1,3,6,8-tetraone (4)
1039.7808, found 1039.7883; 1H NMR (CDCl3)
d 0.81–0.97 (m, 24H,
To a suspension of naphthalene-1,4,5,8-tetracarboxylic dianhy-
dride (0.0594 g, 0.222 mmol) and 9-(aminomethyl)-4,5-di(2-ethy-
lhexyl)anthracene (0.287 g, 0.665 mmol) in 1-propanol (40 mL)
was added water (40 mL) and the resulting mixture was heated at
reflux with stirring. After 6 h, the reaction mixture was cooled to
room temperature and poured into water (300 mL) to form a pale
yellow solid. This precipitate was collected by filtration, washed
with water (50 mL), and dissolved in chloroform (100 mL). This
solution was dried over Na2SO4, filtered, and concentrated in vacuo.
Purification of the residue by flash column chromatography on
silica gel (chloroform) gave 4 (0.211 g, 87%) as a pale yellow solid: IR
(NaCl) 1580 cmꢂ1 (C]C), 1668 cmꢂ1 (C]O), 1707 cmꢂ1 (C]O); 1H
Me), 1.20–1.48 (m, 32H, CH2), 1.85–2.05 (m, 4H, CH), 3.14 (d,
J¼7.2 Hz, 8H, CH2), 4.17 (s, 8H, CH2), 4.68 (s, 4H, CH2), 7.03 (s, 4H,
CH2), 7.25 (d, J¼6.7 Hz, 4H, ArH), 7.35 (dd, J¼6.7 and 8.9 Hz, 4H,
ArH), 8.29 (d, J¼8.9 Hz, 4H, ArH), 8.89 (s, 2H, ArH); 13C NMR (CDCl3)
d
10.7 (CH3), 14.1 (CH3), 23.3 (CH2), 25.9 and 26.0 (CH2), 28.9 (CH2),
32.9 (CH2), 38.7 (CH2), 39.9 (CH), 53.3 (CH2), 56.4 (CH2), 120.4 (CH),
122.2 (CH), 123.7 (CH), 125.5 (CH), 126.0 (CH), 128.1 (C), 130.4 (C),
130.8 (C), 131.9 (C), 138.6 (C). Anal. Calcd for C76H98N2: C, 87.80; H,
9.50; N, 2.69. Found: 87.76; H, 9.19; N, 2.89.
4.2.9. 2,9-Bis(3,5-di(2-ethylhexyloxy)phenylmethyl)-1,3,8,10-
tetrahydro-2,9-diazadibenzo[cd,lm]perylene (3)
NMR (CDCl3)
d
0.80–0.93 (m, 24H, Me), 1.17–1.45 (m, 32H, CH2),
This compound was prepared from 5 according to the procedure
for preparationof 2 and obtainedin 98% as brightorange-colored oil;
1.83–1.98 (m, 4H, CH), 3.09 (d, J¼6.9 Hz, 8H, CH2), 6.30 (s, 4H, CH2),
7.22 (d, J¼6.7 Hz, 4H, ArH), 7.39 (dd, J¼6.7 and 8.9 Hz, 4H, ArH), 8.33
(d, J¼8.9 Hz, 4H, ArH), 8.57 (s, 4H, ArH), 8.87 (s, 2H, ArH); 13C NMR
UV (toluene) 430 nm (3 31,000) and 458 nm (3 41,600); IR (NaCl)
1169 cmꢂ1 (C–O), 1595 cmꢂ1 (C]C); MS (MALDI-TOF) m/z 1027.4

M. Takahashi et al. / Tetrahedron 65 (2009) 2669–2677
2677
(Mþ); HRMS (ESI) m/z calcd for C70H95N2O4: 1027.7292, found
1027.7387; 1H NMR (CDCl3)
0.85–0.95 (m, 24H, Me), 1.25–1.55 (m,
Chem. Soc. 2006, 128, 7174; (p) Ajayaghosh, A.; George, S. J.; Praveen, V. K.
Angew. Chem., Int. Ed. 2003, 42, 332.
d
4. (a) Mondal, S. K.; Ghosh, S.; Sahu, K.; Mandal, U.; Bhattacharyya, K. J. Chem.
Phys. 2006, 125, 224710; (b) Cringus, D.; Bakulin, A.; Lindner, J.; Vo¨hringer, P.;
Pshenichnikov, M. S.; Wiersma, D. A. J. Phys. Chem. B 2007, 111, 14193; (c) Ryu,
J.-H.; Lee, M. J. Am. Chem. Soc. 2005, 127, 14170; (d) Chen, C.-Y.; Tian, Y.; Cheng,
Y.-J.; Young, A. C.; Ka, J.-W.; Jen, A. K.-Y. J. Am. Chem. Soc. 2007, 129, 7220.
5. Takahashi, M.; Ichihashi, Y.; Nishizawa, N.; Ohno, S.; Fujita, N.; Yamashita, M.;
Sengoku, T.; Yoda, H. J. Photochem. Photobiol. A: Chem., in press. doi:10.1016/
j.jphotochem.2008.12.022
32H, CH2), 1.63–1.74 (m, 4H, CH), 3.71 (s, 4H, CH2), 3.81 (d, J¼5.6 Hz,
8H, CH2), 3.93 (s, 8H, CH2), 6.41 (t, J¼2.2 Hz, 2H, ArH), 6.57 (d,
J¼2.2 Hz, 4H, ArH), 7.14 (d, J¼7.7 Hz, 4H, ArH), 8.02 (d, J¼7.7 Hz, 4H,
ArH); 13C NMR (CDCl3)
d 11.2 (CH3),14.1 (CH3), 23.1 (CH2), 24.0 (CH2),
29.2 (CH2), 30.6 (CH2), 39.6 (CH), 56.8 (CH2), 62.4 (CH2), 70.7 (CH2),
100.5 (CH), 107.6 (CH), 119.5 (CH), 123.4 (CH), 128.5 (C), 129.6 (C),
130.3 (C),133.0 (C),140.5 (C),160.9 (C). Anal. Calcd for C70H94N2O4: C,
81.82; H, 9.22; N, 2.73. Found: C, 81.93; H, 8.93; N, 2.60.
6. Melhuish, W. H. J. Phys. Chem. 1963, 67, 1681.
7. (a) Wu¨ rthner, F.; Sautter, A.; Thalacker, C. Angew. Chem., Int. Ed. 2001, 39, 1243;
(b) Takahashi, M.; Suzuki, Y.; Ichihashi, Y.; Yamashita, M.; Kawai, H. Tetrahedron
Lett. 2007, 48, 357.
8. In our previous study employing 1, we demonstrated that the reverse micelles
should have a uniform aggregate size independent of the W0 value. For this
reason, we used the W0 value of 50 as a representative self-assembly condition.
9. We previously demonstrated that nanoscopic-sized reverse micelles preparaed
from the related analogue 1 achieved either efficient intramolecular energy
transfer or collisional dissipation due to intermolecular chromophore
interactions.
10. Possibilities of energy transfer between the self-assembled aggregates can be
ruled out on the basis of the experimental conditions employing sufficiently
dilute solutions of the analytes.
4.3. Typical experimental procedure for AFM analyses
The reaction mixture diluted with dry toluene (c 0.1 mM) was
drop-cast on to the HOPG. Airdried sample of the reaction mixture
was examined by carrying out measurements in tapping mode.
Acknowledgements
11. (a) Takahashi, M.; Morimoto, H.; Miyake, K.; Kawai, H.; Sei, Y.; Yamaguchi, K.;
Yamashita, M.; Sengokua, T.; Yoda, H. New J. Chem. 2008, 32, 547; (b) Takahashi,
M.; Morimoto, H.; Miyake, K.; Yamashita, M.; Kawai, H.; Sei, Y.; Yamaguchi, K.
Chem. Commun. 2006, 3084; (c) Takahashi, M.; Morimoto, H.; Suzuki, Y.;
Yamashita, M.; Kawai, H. Polym. Prepr. (Am. Chem. Soc., Div. Polym. Chem.). 2004,
45, 959.
This research was supported by a Grant-in-Aid for Scientific
Research and Nanotechnology Network Project (Kyushu-area
Nanotechnology Network) from the Ministry of Education, Culture,
Sports, Science, and Technology (MEXT), Japan.
12. In order to gain further insight into the mechanism of the energy transfer
processes, fluorescence lifetime studies on the reverse micelles are needed.
However, our attempts to obtain the fluorescence lifetime data (
limited time resolution of the experimental setup.
s) failed due to
Supplementary data
13. Application of the Stern–Volmer plots yielded the Stern–Volmer constant KSV
1H and 13C NMR spectra for all new compounds. Supplementary
data associated with this article can be found in the online version,
at doi:10.1016/j.tet.2009.01.089.
(1.2ꢀ104
M
ꢂ1) for the series of the mixed reverse micelles. Thus, the rate
constant of energy transfer kET (3.1ꢀ1011
M
ꢂ1 sꢂ1) was estimated using the
s (1.4 ns (14%), 4.3 ns (23%) and 60.5 ns (63%))
reported fluorescence lifetimes
of the anthracene aggregate system in micelles, which was closely related to
the donor-based reverse micelles prepared from 2. As for this anthracene
aggregate system, see: Chen, K.-H.; Yang, J.-S.; Hwang, C.-Y.; Fang, J.-M. Org. Lett.
2008, 10, 4401.
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Lane, P. A.; Palilis, L. C.; Landis, C. A.; Delcamp, J.; Anthony, J. E.; Kafafi, Z. H. J.
Phys. Chem. B 2006, 110, 7928; (m) Ajayaghosh, A.; Praveen, V. K.; Vijayakumar,
C. Chem. Soc. Rev. 2008, 37, 109; (n) Praveen, V. K.; George, S. J.; Varghese, R.;
Vijayakumar, C.; Ajayaghosh, A. J. Am. Chem. Soc. 2006, 128, 7542; (o)
Ajayaghosh, A.; Vijayakumar, C.; Praveen, V. K.; Babu, S. S.; Varghese, R. J. Am.
14. For further details and some theoretical bases for the Fo
¨rster process, see: the
relative ratio of the peaks corresponding to the anthracene donor, while nor-
malizing for the peaks corresponding to the perylene acceptor, can be used to
estimate the energy transfer efficiency. According to this methodology, the
energy transfer efficiencies were estimated to be 0.71, 0.77, and almost quan-
titative for the reverse micelles at the feed ratios (2/3) of 95/5, 91/9, and the
other members of the series (i.e., 2/3¼83/17, 75/25, 67/33, 50/50, 33/67, 25/75,
17/83, 9/91, and 5/95), respectively Valeur, B. Molecular Fluorescence Principles
and Applications; Wiley-VCH: Weinheim, New York, Chichester, Brisbane, Sin-
gapore, Toronto, 2002; Chapter 9, pp 247–272.
15. In our previous study employing 1, we reproducibly obtained small-sized
spherical objects when the solutions at different concentrations in toluene
were cast on the HOPG substrates. Based on those reproducible observations,
we concluded that the small-sized peaks could be attributed to the individual
reverse micelles and thus the medium-sized peaks should correspond to their
assemblies.
16. For aggregate size determination, dynamic light scattering (DLS) measure-
ments have been performed on the reverse micelles. However, attempts to
record particle size distributions failed due to experimental limitations of the
setup.
17. At highly dilute concentrations of the surfactants below the cmc, where the
surfactants gathering in the reverse micellar forms should become dissociated,
the fluorescence spectra of the samples were identical to that of the monomeric
perylene emission, whose intensity should increase linearly with the solute
concentrations. On the other hand, the formation of the reverse micelles leads
to introduction of the radiationless deactivation channels due to the chromo-
phore clustering, resulting in nonlinear dependency of the fluorescence
intensities on the solute concentrations. For these reasons, we considered that
titration experiments performed by monitoring the intensity of the fluores-
cence emission from the chromophoric components allowed precise evaluation
of the cmc values. As for similar procedures for cmc estimations, see: (a)
´
Goodwin, A. P.; Mynar, J. L.; Ma, Y.; Fleming, G. R.; Frechet, J. M. J. J. Am. Chem.
Soc. 2005, 127, 9952; (b) Jung, C.; Mu¨ller, B. K.; Lamb, D. C.; Nolde, F.; Mu¨llen, K.;
Bra¨uchle, C. J. Am. Chem. Soc. 2006, 128, 5283; (c) Kang, L.; Wang, Z.; Cao, Z.; Ma,
Y.; Fu, H.; Yao, J. J. Am. Chem. Soc. 2007, 129, 7305; (d) Sutthasupa, S.; Sanda, F.;
Masuda, T. Macromolecules 2008, 41, 305.
18. (a) Xu, S.; Giuseppone, N. J. Am. Chem. Soc. 2008, 130, 1826; (b) Ma, Y.;
Kolotuchin, S. V.; Zimmerman, S. C. J. Am. Chem. Soc. 2002, 124, 13757.
19. (a) Wang, B.-B.; Gao, M.; Jia, X.-R.; Li, W.-S.; Jiang, L.; Wei, Y. J. Colloid Interface
Sci. 2008, 324, 225; (b) Beckers, E. H. A.; Jonkheijm, P.; Schenning, A. P. H. J.;
Meskers, S. C. J.; Janssen, R. A. J. ChemPhysChem 2005, 6, 2029.