Synthesis and two-photon properties of small dendritic chromophores with symmetrical and unsymmetrical substituted skeletons

Article abstract of DOI:10.1002/ejoc.201101485

A set of novel multi-branched chromophores consisting of two groups of fluorene/oxadiazole-based analogues with generic skeletons of donor-π-acceptor (unsymmetrical) and donor-π-acceptor-π-donor (symmetrical) type has been synthesized and shown to display strong and broadly dispersed two-photon absorptivities in the near infrared (NIR) region on irradiation with femtosecond laser pulses. It is also demonstrated that structural parameters such as the number of donor units attached and the substitution pattern are closely connected to the molecular two-photon activities of these model compounds.

Full text of DOI:10.1002/ejoc.201101485

FULL PAPER
DOI: 10.1002/ejoc.201101485
Synthesis and Two-Photon Properties of Small Dendritic Chromophores with
Symmetrical and Unsymmetrical Substituted Skeletons
Tzu-Chau Lin,*[a] Ying-Hsuan Lee,[a] Chia-Ling Hu,[a] Yu-Kai Li,[a] and Yu-Jhen Huang[a]
Keywords: Dendritic chromophores / Two-photon absorption / Palladium-catalyzed amination
A set of novel multi-branched chromophores consisting of
two groups of fluorene/oxadiazole-based analogues with ge-
neric skeletons of donor-π-acceptor (unsymmetrical) and do-
nor-π-acceptor-π-donor (symmetrical) type has been synthe-
sized and shown to display strong and broadly dispersed
two-photon absorptivities in the near infrared (NIR) region
on irradiation with femtosecond laser pulses. It is also dem-
onstrated that structural parameters such as the number of
donor units attached and the substitution pattern are closely
connected to the molecular two-photon activities of these
model compounds.
compounds with extended excited-state lifetimes might ben-
efit the apparent nonlinear absorption because of two-pho-
ton-assisted excited-state absorption (2PA-assisted ESA)[10]
Introduction
Two-photon absorption (2PA) occurs when a molecule is
promoted from the ground state to an excited state through
simultaneous absorption of two photons. Although the
theory of this nonlinear optical phenomenon was predicted
by Maria Göppert-Mayer in 1931,[1] experimental evidence
was to appear only about thirty years later, with the obser-
vation of up-converted emission from media on irradiation
with laser light of wavelengths far from the linear absorp-
tion bands of the studied media.[2] In the past fifteen years,
the availability of stable and high-peak-power lasers has
provided the momentum for exploration of two-photon
technologies. Many potential applications based on 2PA in
the emerging field of photonics and biophotonics have been
proposed and explored, including optical power limiting,
frequency-up-converted lasing, 3D data storage, 3D micro-
fabrication, nondestructive bio-imaging and tracking, and
two-photon-assisted photodynamic therapy.[3] For use in
these applications, organic compounds that undergo large
2PA in desired spectral regions are consequently in great
demand. So far, it has been established that molecular 2PA
governed by combinations of several structural parameters
such as intramolecular charge-transfer efficiency and/or ef-
fective size of π-conjugation domain within a molecule.[4–9]
For various practical requirements, depending on the de-
sired application, different photophysical properties in ad-
dition to strong molecular 2PA might also be required for
the designed molecules. For utilization as, for instance, op-
tical power limiters operating in the nanosecond regime,
[a] Photonic Materials Research Laboratory, Department of
Chemistry, National Central University,
300 Jhong-Da Rd., Jhong-Li 32001, Taiwan
Fax: +886-3-4227664
E-mail: tclin@ncu.edu.tw
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejoc.201101485.
Figure 1. Molecular structures of the studied model chromophores.
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim 1737
Eur. J. Org. Chem. 2012, 1737–1745

T.-C. Lin, Y.-H. Lee, C.-L. Hu,Y.-K. L., Y.-J. Huang
FULL PAPER
so that their effective optical power restriction perform-
ances will be enhanced. In our investigations of the relation-
ships between structural parameters and nonlinear absorp-
Results and Discussion
The chemical structures of the studied model compounds
tion properties in conjugated systems, we were interested in and the synthetic routes to them are illustrated in Figure 1
exploring the influence of the arrangements of building and Scheme 1, respectively. This model compound set con-
units and substitution patterns on molecular 2PA in the tains four multi-branched congeners and can be categorized
construction of multi-branched π-frameworks. Here we into two groups according to their substitution patterns.
present the synthesis of a new series of two-photon-active Compounds 1 and 2 have a generic donor-π-acceptor (D-
model chromophores (1–4; Figure 1) derived from function- π-A) structure based on the use of functionalized fluorene
alized fluorene and oxadiazole moieties, together with ini- and oxadiazole units to construct their unsymmetrical skel-
tial investigations of their 2PA properties in the femto- etons, whereas model compounds 3 and 4 utilize the same
second time domain.
building units to make up their symmetrical scaffolds with
Scheme 1. Synthetic routes to key intermediates (8a, 11, 16, and 18) and model chromophores.
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Synthesis and Two-Photon Properties of Small Dendritic Chromophores
donor-π-acceptor-π-donor (D-π-A-π-D) backbone. In 11) as the standard. Figure 4 shows the measured degener-
theory, the dumbbell-shaped structures of chromophores 3 ate two-photon absorption spectra of these model com-
and 4 can be regarded as “dimerized” versions of com- pounds in THF, and the combined photophysical data are
pounds 1 and 2, respectively. The original design concept summarized in Table 1.
for these model compounds involved the tentative construc-
tion of a set of structurally symmetrical and unsymmetrical
π-frameworks with various numbers of electron-donating
units attached such that the resulting fluorophores might
exhibit charge-transfer/redistribution in different manners
upon light excitation. On the other hand, the pendent alkyl
chains on all fluorenyl moieties in these model chromo-
phores can be expected to enhance their solubilities in com-
mon organic solvents; this is an important parameter to
consider in the molecular design from the aspects both of
experiment and of applications. The synthetic procedures
for these model dye molecules are relatively straightforward
and mainly involve consecutive functionalization processes
on the fluorene moiety followed by Buchwald–Hartwig-
type amination to prepare the key intermediates and the
final model compounds as shown in Scheme 1. The synthe-
ses of these key intermediates and the final model chromo-
phores are described in detail in the Experimental Section.
Figure 2 shows linear absorption and fluorescence spec-
tra of the studied dye molecules in solution phase by using mic plots of power-squared dependences of the 2PA-induced fluo-
Figure 3. (a) Normalized two-photon excited up-conversion spectra
of fluorophores 1–4 in THF at 1ϫ10–4 m. (b), (c), (d), (e) Logarith-
rescence intensities on the input intensities of these compounds in
THF.
THF as the solvent. Intense one-photon absorption (1PA)
of these compounds was found around 400 nm (with εmax
≈ 1.01ϫ105 cm–1 m–1 for 1, εmax ≈ 2.17ϫ105 cm–1 m–1
for 2, εmax ≈ 1.70ϫ105 cm–1 m–1 for 3, and εmax
≈
3.70ϫ105 cm–1 m–1 for 4). These model chromophores also
exhibit strong two-photon-excited up-conversion emission,
which can be readily seen with the naked eye even on illumi-
nation with a ca. 790 nm unfocused femtosecond laser
beam at low intensity level. Figure 3(a) shows the 2PA-in-
duced fluorescence spectra of compounds 1–4, and the
curves in Figure 3(b)–(e) confirm that the 2PA process is
responsible for the detected up-conversion emission in all
cases. In order to probe and compare the dispersion of 2PA
behavior of these dye molecules as a function of wavelength,
we conducted degenerate two-photon-excited fluorescence
(2PEF) measurement in the near-IR region (700–850 nm)
with use of fluorescein (ca. 80 μm in NaOH solution, pH =
Figure 4. Measured degenerate two-photon absorption spectra of
model chromophores 1–4 by the 2PEF method in THF solution at
1ϫ10–4 m (experimental error ca. Ϯ15%).
With use of compound 1 as a reference point, it is no-
table from Figure 4 that all these model chromophores not
only exhibit nearly identical dispersion patterns of their
two-photon activities but also show ascending overall mag-
nitude of 2PA from compound 1 to compound 4. These
features indicate that either simply increasing the number
of attached electron-donating units (as in the case of com-
pound 2) or extending the size of the π-domain by construc-
Figure 2. Linear absorption and fluorescence spectra (inset) of
compounds 1–4 in solution phase (1ϫ10–5 m in THF).
Eur. J. Org. Chem. 2012, 1737–1745
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FULL PAPER
Table 1. Photophysical properties of the studied model chromophores 1–4.[a]
abs
em
[d]
λ
logεmax
λ
ΦF
τ1PA–FL
δ2max
Neπff[g]
δ2max
/
max
max
[nm][b]
[nm][c]
[ns][e]
[GM][f]
Neπff
1
2
3
4
396
397
396
396
5.00
5.34
5.23
5.57
518
519
518
518
0.40
0.43
0.47
0.51
3.25
3.27
2.95
2.95
ca. 675
30.3
40.4
40.6
55.6
ca. 22.3
ca. 33.4
ca. 67.2
ca. 124.6
ca. 1350
ca. 2730
ca. 6930
[a] Concentrations were 1ϫ10–5 m and 1ϫ10–4 m for 1PA-related and 2PA-related measurements, respectively. [b] One-photon absorption
maxima. [c] 1PA-induced fluorescence emission maxima. [d] Fluorescence quantum efficiencies. [e] 1PA-induced fluorescence lifetimes.
[f] Maximum 2PA cross-section values (experimental error ca. Ϯ15%); 1 GM = 1ϫ10–50 cm4 s/photon-molecule. [g] Effective π-electron
numbers.
tion of a D-π-A-π-D scaffold based on the original D-π-A enhance the molecular 2PA without shifting the major 2PA
framework of compound 1 (as in the case of compound 3) band in this dye system. Moreover, the measured nano-
will enhance the molecular 2PA without shifting the major second excited-state lifetimes suggest that these model com-
2PA band in this dye system. Molecules with properties of pounds could be potential candidates as broad-band optical
this kind could be very beneficial for some particular appli- power limiters for laser pulses with long duration.
cations when large multi-photon absorptivities in a specific
spectral region are required. According to this line of design
concept, the structure of model compound 4 represents a
combination of the two previous structural motifs, and –
because no deterioration in molecular 2PA was observed –
it can be assumed that these two structural parameters are
additive for the studied molecular system. Furthermore, the
relative increment in the magnitude of the observed overall
and maximum 2PA for these model chromophores (see Fig-
ure 4 and Table 1) suggests that extending the size of the π-
system from the original D-π-A framework to a D-π-A-π-
Experimental Section
General: All commercially available reagents for the preparation of
the intermediates and targeted chromophores were obtained from
Aldrich Chemical Co. and were used as received, unless stated
otherwise. THF was distilled from sodium benzophenone ketyl. 1H
and 13C NMR spectra were recorded either with 200 or 300 MHz
spectrometers and referenced to TMS or residual CHCl3. HRMS
measurements were conducted with a Waters LCT ESI-TOF mass
D skeleton provides a more effective approach to enhanced spectrometer. MALDI-TOF mass spectra were obtained with a
Voyager DE-PRO mass spectrometer (Applied Biosystem, Hous-
ton, USA).
molecular 2PA. Additionally, it is notable that the excited-
state lifetimes of the studied model chromophores in this
work are in the nanosecond range, which suggests that a
significant excited-state population can be retained and
should consequently display excited-state absorption during
excitation by longer laser pulses. This feature is particularly
desirable in relation to optical power-limiting applications
in the nanosecond regime based on 2PA-induced excited-
state absorption (2PA-induced ESA), because the effective
three-photon absorption coefficient increases significantly
with the excited-state lifetime.[10f,10g] The power restriction
performances of these compounds on subjection to nanose-
cond laser pulses are currently under investigation and will
be reported in due course.
Synthesis: In Scheme 1, compound 5 (2,7-dibromo-9,9-dihexyl-9H-
fluorene) is the major starting material for the synthesis of the
backbone of each intermediate and model chromophore. This com-
pound was obtained in a total yield of ca. 80% by bromination[1]
and subsequent alkylation[2] of a fluorene unit. For the synthesis
of other key intermediates and the targeted model compounds, a
series of functionalization steps by starting from compound 5 were
conducted.
7-Bromo-9,9-dihexyl-N,N-diphenyl-9H-fluoren-2-amine (6a): BI-
NAP (1.14 g, 1.8 mmol), Pd2(dba)3 (0.56 g, 0.6 mmol), and sodium
tert-butoxide (8.2 g, 0.084 mol) were added to a mixture of com-
pound 5 (30 g, 0.06 mol) and diphenylamine (11.34 g, 0.067 mol)
in toluene (120 mL), and the mixture was stirred at 80 °C under Ar
for 24 h. After the mixture had cooled to room temperature, H2O
(ca. 100 mL) was added. The above solution was then extracted
with ethyl acetate and dried with MgSO4. After removal of the
solvent, the crude product was purified by column chromatography
Conclusions
We have synthesized a novel multipolar chromophore set
consisting of four analogues with symmetrical and unsym- on silica gel with hexane as eluent to give the final purified product
as a pale yellow oil in a yield of ca. 55% (19.44 g). 1H NMR
(200 MHz, CDCl3): δ = 7.54–7.50 (m, 1 H), 7.50–7.44 (d, J =
8.1 Hz, 1 H), 7.45–7.40 (dd, J1 = 8.1 Hz, J2 = 3 Hz, 2 H), 7.30–
7.22 (m, 4 H), 7.14–7.09 (dd, J1 = 8.1 Hz, J2 = 3 Hz, 2 H), 7.14–
metrical substituted skeletons through the use of function-
alized fluorene and oxadiazole moieties as the major build-
ing units. The initial experimental results indicate that these
model fluorophores manifest strong and widely dispersed
two-photon absorptivities in the near-IR region. Tentative
analysis of the correlation between molecular structures
and the observed overall 2PA behavior found that both in-
creasing the number of electron-donating units and ex-
7.09 (m, 2 H), 7.05–6.98 (m, 4 H), 1.87–1.79 (m, 4 H), 1.17–0.99
(m, 12 H), 0.81 (t, J = 7.04 Hz, 6 H), 0.64 (m, 4 H) ppm. 13C NMR
(300 MHz, CDCl3): δ = 152.79, 151.67, 147.82, 147.49, 139.88,
135.00, 129.87, 129.13, 125.89, 123.41, 122.85, 120.41, 122.58,
120.43, 120.36, 120.14, 119.01, 55.26, 40.10, 31.44, 29.51, 23.66,
22.50, 14.03 ppm. HRMS (FAB): calcd. for C37H42BrN [M]+
tending the size of the π-domain by construction of a D-π-
A-π-D scaffold based on the original D-π-A framework will 579.2501; found 579.2507 [(79Br)M]+, 581.2483 [(81Br)M]+.
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Synthesis and Two-Photon Properties of Small Dendritic Chromophores
9,9-Dihexyl-N2,N2-diphenyl-9H-fluorene-2,7-diamine(7a): Two-step
reaction. (i) Potassium phthalimide (4.77 g, 0.258 mol) and CuI
(4.92 g, 0.258 mol) were added to a solution of compound 6a (15 g,
0.258 mol) in DMAc (135 mL). The resulting solution was stirred
and heated at reflux for 24 h. After the mixture had cooled to room
temperature, it was extracted with diethyl ether and then dried with
MgSO4. After removal of the solvent, the crude product was ob-
tained as dark brown solid. (ii) NH2NH2·H2O (1.293 g, 0.258 mol)
was added to a solution of the crude product from the first step in
ethanol (150 mL). The resulting solution was stirred and heated at
reflux for 6 h. After the mixture had cooled to room temperature,
it was extracted with ethyl acetate (3ϫ30 mL) and then dried with
MgSO4. After removal of the solvent, the crude product was puri-
fied by column chromatography on silica gel with diethyl ether/
hexane (1:10) as eluent to give the final purified product in a yield
of ca. 62% (8.31 g). 1H NMR (300 MHz, CDCl3): δ = 7.43–7.40
(t, J = 7.2 Hz, 2 H), 7.23–7.18 (t, J = 7.2 Hz, 4 H), 7.11–7.07 (m,
5 H), 7.00–6.92 (m, 3 H), 6.61–6.59 (m, 2 H), 3.689–3.66 (s, 2 H),
1.87–1.79 (m, 4 H), 1.17–0.99 (m, 12 H), 0.81 (t, J = 8.4 Hz, 6 H),
0.64 (m, 4 H) ppm. 13C NMR (300 MHz, CDCl3): δ = 152.51,
–0.89 ppm. HRMS (FAB): calcd. for C28H41BrSi [M]+ 484.2161;
found 484.2150 [(79Br)M]+, 486.2164 [(81Br)M]+.
9,9-Dihexyl-7-(trimethylsilyl)-9H-fluoren-2-amine (7b): Two-step re-
action. (i) Potassium phthalimide (7.26 g, 0.039 mol), and CuI
(7.44 g, 0.039 mol) were added to a solution of compound 6b (19 g,
0.039 mol) in DMAc (45 mL), and the mixture was stirred and
heated at reflux for 24 h. After the mixture had cooled to room
temperature, it was extracted with diethyl ether and dried with
MgSO4. After removal of the solvent, the crude product was ob-
tained as brown solid. (ii) NH2NH2·H2O (2.46 g, 0.039 mol) was
added to a solution of the crude product from the first step in
ethanol (300 mL), and the resulting solution was stirred and heated
at reflux for 6 h. After cooling to room temperature, the reaction
mixture was extracted with ethyl acetate (3ϫ30 mL), and the com-
bined organic layers were dried with MgSO4. After removal of the
solvent, the crude product was purified by column chromatography
on silica gel with diethyl ether/hexane (1:10) as eluent to give the
final purified product in a yield of 70.5% (11.62 g). HRMS (FAB):
calcd. for C28H43NSi [M]+ 421.3165; found 421.7332.
Bis[9,9-dihexyl-7-(trimethylsilyl)-9H-fluoren-2-yl]amine
(8b):
Pd2(dba)3 (0.0976 g, 0.1064 mmol), sodium tert-butoxide (2.48 g,
0.256 mol), and P(tBu)3 (0.044 g, 0.2132 mmol) were added to a
mixture of compound 7b (9 g, 0.0213 mol) and 6b (10.36 g,
0.0213 mol) in dry toluene (60 mL), and the mixture was stirred at
90 °C under Ar for 12 h. After the mixture had cooled to room
temperature, H2O (ca. 100 mL) was added. The above solution was
then extracted with ethyl acetate (3ϫ30 mL) and dried with
MgSO4. After removal of the solvent, the crude product was puri-
fied by column chromatography on silica gel with ethyl acetate/
hexane (1:40) as eluent to give the final purified product in a yield
151.09, 148.08, 145.38, 137.25, 132.15, 128.96, 124.03, 123.22,
121.93, 119.97, 119.89, 118.89, 113.87, 109.68, 54.72, 40.42, 31.46,
29.60, 23.65, 22.49, 13.97 ppm. HRMS (FAB): calcd. for C37H44N2
[M]+ 516.3504; found 516.3505.
N2-[7-(Diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl]-9,9-dihexyl-
N7,N7-diphenyl-9H-fluorene-2,7-diamine (8a): Pd2(dba)3 (0.073 g,
0.0803 mmol), sodium tert-butoxide (1.852 g, 0.193 mol), and
P(tBu)3 (0.0322 g, 0.161 mmol) were added to a mixture of com-
pounds 7a (8.3 g, 0.161 mol) and 6a (9.3 g, 0.161 mol) in dry tolu-
ene (15 mL), and the mixture was stirred at 90 °C under Ar for
12 h. After the mixture had cooled to room temperature, H2O (ca.
100 mL) was added. The solution was then extracted with ethyl
acetate (3ϫ30 mL) and then dried with MgSO4. After removal of
the solvent, the crude product was purified by column chromatog-
raphy on silica gel with diethyl ether/hexane (1:20) as eluent to give
the final purified product in a yield of ca. 60.2% (4.91 g). 1H NMR
(300 MHz, CDCl3): δ = 7.26–7.20 (t, J = 8.1 Hz, 12 H), 7.12–7.10
(t, J = 8.1 Hz, 12 H), 7.02–6.95 (m, 8 H), 5.01 (s, 1 H), 1.84–1.79
(m, 4 H), 1.15–1.08 (m, 12 H), 0.81 (t, 6 H), 0.64 (m, 4 H) ppm.
13C NMR (300 MHz, CDCl3): δ = 148.06, 134.28, 132.46, 131.23,
129.03, 127.06, 123.83, 123.60, 123.44, 122.53, 122.14, 54.91, 40.43,
31.54, 29.68, 23.80, 22.54, 13.98 ppm. HRMS: [M]+ calcd. for
C74H85N3 1015.6743; found 1015.6738.
1
of 55.6% (4.9 g). H NMR (300 MHz, CDCl3): δ = 7.59–7.56 (m,
6 H), 7.47–7.43 (m, 6 H), 2.02–2.01 (m, 8 H), 1.14–1.12 (m, 24 H),
0.79–0.75 (m, 12 H), 0.30 (m, 8 H) ppm. 13C NMR (300 MHz,
CDCl3): δ = 152.44, 152.14, 149.21, 141.93, 137.35, 134.38, 131.82,
127.31, 120.70, 118.05, 116.85, 111.64, 54.88, 40.45, 31.46, 29.71,
23.73, 22.55, 14.01 ppm. HRMS: calcd. for C56H83NSi2 [M]+
825.6064; found 825.6063.
tert-Butyl
Bis[9,9-dihexyl-7-(trimethylsilyl)-9H-fluoren-2-yl]carb-
amate (9): (Boc)2O (2.59 g, 0.012 mol) and 4-DMAP (0.362 g,
0.003 mmol) were added to a mixture of compound 8b (4.9 g,
6 mmol) in dry THF (45 mL), and the mixture was stirred at 90 °C
under N2 for 12 h. After the mixture had cooled to room tempera-
ture, it was extracted with ethyl acetate and then dried with MgSO4.
After removal of the solvent, the crude product was purified by
column chromatography on silica gel with ethyl acetate/hexane
(1:50) as eluent to give the final purified product in a yield of ca.
(7-Bromo-9,9-dihexyl-9H-fluoren-2-yl)trimethylsilane (6b): n-Butyl-
lithium in hexane (26.9 mL, 1.6 m, 0.043 mol) was added at –78 °C
under N2 to a solution of 5 (20 g, 0.041 mol) in dry diethyl ether
(150 mL), and the mixture was stirred for 1 h. Chlorotrimethylsil-
ane (6 mL, 0.0462 mol) was added slowly at –78 °C, and the reac-
tion mixture was allowed to warm slowly to room temperature and
stirred overnight. The reaction mixture was quenched with satu-
rated brine, and the resulting solution was extracted with diethyl
ether. The organic layer was washed with brine and H2O three
times and dried with MgSO4. After removal of the solvent, the
crude product was purified by chromatography on silica with hex-
1
81% (4.45 g). H NMR (300 MHz, CDCl3): δ = 7.69–7.64 (t, J =
7.8 Hz, 4 H), 7.54–7.52 (d, J = 8.1 Hz, 2 H), 7.29–7.28 (d, J =
8.1 Hz, 2 H), 7.24–7.21 (d, J = 7.8 Hz, 2 H), 2.02–1.95 (m, 8 H),
1.11–1.16 (m, 24 H), 0.85–0.76 (m, 12 H), 0.68 (m, 8 H), 0.36 (s, 9
H) ppm. 13C NMR (300 MHz, CDCl3): δ = 153.75, 152.11, 151.27,
149.98, 142.64, 141.20, 138.65, 138.33, 131.79, 127.35, 125.16,
121.75, 119.79, 118.82, 80.86, 54.93, 40.12, 31.38, 29.55, 28.28,
23.62, 22.46, 13.98 ppm. HRMS: calcd. for C56H83NSi2 [M]+
925.6588; found 925.6487.
ane as eluent to give the final purified product as a colorless oil
1
(19.16 g, 97%). H NMR (300 MHz, CDCl3): δ = 7.85–7.84 (d, J tert-Butyl Bis(9,9-dihexyl-7-iodo-9H-fluoren-2-yl)carbamate (10):
= 7.8 Hz, 1 H), 7.77–7.73 (m, 2 H), 7.63–7.61 (m, 2 H), 7.54–7.52 Iodine monochloride (1.64 g, 0.01 mol) was added at 0 °C to a
(d, J = 7.8 Hz, 1 H), 2.13–2.12 (m, 4 H), 1.20–1.19 (m, 12 H), 0.91 solution of compound 9 (4.45 g, 0.048 mol) in CH2Cl2 (20 mL).
(t, J = 7.8 Hz, 6 H), 0.64 (m, 4 H), 0.46 (s, 9 H) ppm. 13C NMR
(300 MHz, CDCl3): δ = 153.26, 153.07, 149.39, 149.17, 140.68,
139.71, 136.03, 132.09, 129.89, 127.41, 126.19, 121.44, 122.32,
The resulting solution was then allowed to warm to room tempera-
ture and stirred for 4 h, after which saturated NaHSO3 solution
(ca. 50 mL) was added. The reaction mixture was extracted with
121.07, 119.06, 55.20, 40.03, 31.30, 29.50, 23.57, 22.45, 14.00, dichloromethane (3ϫ30 mL) and then dried with MgSO4. After
Eur. J. Org. Chem. 2012, 1737–1745
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T.-C. Lin, Y.-H. Lee, C.-L. Hu,Y.-K. L., Y.-J. Huang
FULL PAPER
removal of the solvent, the crude product was purified by column
chromatography on silica gel with ethyl acetate/hexane (1:40) as
eluent to give the final purified product in a yield of ca. 75%
(3.72 g). 1H NMR (300 MHz, CDCl3): δ = 7.68–7.62 (t, 4 H), 7.52–
7.51 (d, 2 H), 7.29–7.28 (d, 2 H), 7.24–7.22 (d, 2 H), 1.81–1.78 (m,
8 H), 1.10–1.05 (m, 24 H), 0.84–0.76 (m, 12 H), 0.65 (m, 8 H),
0.368 (s, 9 H) ppm. 13C NMR (300 MHz, CDCl3): δ = 152.75,
151.11, 150.87, 149.87, 141.54, 141.10, 138.95, 137.25, 130.24,
128.91 124.56, 120.25, 118.59, 118.26, 92.18, 80.88, 54.89, 39.84,
31.26, 29.48, 28.18, 22.89, 21.83 12.85 ppm. HRMS: calcd. for
C55H73I2NO2 [M]+ 1033.3731; found 1033.8998.
22.46, 13.90 ppm. HRMS: calcd. for C26H33BrN 438.1718
[M + H]+; found [(79Br)M + H]+ = 438.1794; [(81Br)M + H]+
440.1794.
=
7-Bromo-9,9-dihexyl-9H-fluorene-2-carboxylic Acid (13): A mixture
of compound 12 (2.7 g, 0.006 mol) in CH3COOH (6 mL), H2SO4
(6 mL), and H2O (6 mL) was stirred and heated at reflux for 24 h.
After the mixture had cooled to room temperature, NaOH(aq.) (ca.
50 mL) was added. The above mixed solution was extracted with
ethyl acetate and then dried with MgSO4. After removal of the
solvent, the crude product was purified by column chromatography
on silica gel with ethyl acetate/hexane (1:1) as eluent to give the
final purified product in a yield of ca. 97% (2.73 g). 1H NMR
(300 MHz, CDCl3): δ = 8.17, 8.14 (d, J = 7.5 Hz, 1 H), 8.10 (s, 1
H), 7.77, 7.74 (d, J = 7.5 Hz, 1 H), 7.64, 7.61 (d, J = 8.1 Hz, 1 H),
7.52–7.48 (m, 2 H), 2.16–1.91 (m, 4 H), 1.14–1.05 (m, 12 H), 0.78–
0.74 (t, 6 H), 0.59 (m, 4 H) ppm. 13C NMR (300 MHz, CDCl3): δ
= 172.68, 154.10, 150.51, 145.61, 138.74, 130.31, 129.75, 128.10,
126.39, 124.60, 122.77, 122.06, 119.62, 55.61, 40.08, 31.43, 29.54,
23.68, 22.52, 13.95 ppm. HRMS: calcd. for C26H34BrO2 [M + H]+
457.1664; found 457.1751 [(79Br)M + H]+, 459.1799 [(81Br)M +
H]+.
N2-[7-(7-{Bis[7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl]-
amino}-9,9-dihexyl-9H-fluoren-2-ylamino)-9,9-dihexyl-9H-fluoren-
2-yl]-N2-[7-(diphenylamino)-9,9-dihexyl-9H-fluoren-2-yl]-9,9-di-
hexyl-N7,N7-diphenyl-9H-fluorene-2,7-diamine (11): Two-step reac-
tion. (i) Pd2(dba)3 (0.085 g, 0.093 mmol), sodium tert-butoxide
(0.468 g, 4.874 mmol), and P(tBu)3 (0.038 g, 0.186 mmol) were
added to a mixture of compound 10 (2.4 g, 2.321 mol) and com-
pound 8a (4.718 g, 4.642 mol) in dry toluene (15 mL), and the mix-
ture was stirred at 90 °C under Ar for 12 h. After the mixture had
cooled to room temperature, H2O (ca. 100 mL) was added. The
above solution was extracted with ethyl acetate (3ϫ30 mL) and
then dried with MgSO4. After removal of the solvent, the crude
product was purified by column chromatography on silica gel with
ethyl acetate/hexane (1:20) as eluent to give the final purified prod-
Methyl 7-Bromo-9,9-dihexyl-9H-fluorene-2-carboxylate (14):
A
mixture of compound 13 (2.6 g, 5.6 mmol) in methanol (20mL) and
H2SO4 (4 mL) was stirred and heated at reflux for 6 h. After the
mixture had cooled to room temperature, NaOH(aq.) (ca. 50 mL)
was added. The above mixed solution was extracted with ethyl acet-
ate and then dried with MgSO4. After removal of the solvent, the
crude product was purified by column chromatography on silica gel
with ethyl acetate/hexane (1:20) as eluent to give the final purified
product in a yield of ca. 93% (2.49 g). 1H NMR (300 MHz,
CDCl3): δ = 8.06–8.02 (dd, J1 = 7.8 Hz, J2 = 1.2 Hz, 1 H), 7.99 (s,
1 H), 7.71, 7.68 (d, J = 7.8 Hz, 1 H), 7.61, 7.58 (d, J = 7.8 Hz, 1
H), 7.49–7.46 (m, 2 H), 3.95 (s, 3 H), 2.06–1.88 (m, 4 H), 1.13–1.01
(m, 12 H), 0.78–0.73 (t, J = 6.9 Hz, 6 H), 0.61–0.51 (m, 4 H) ppm.
13C NMR (300 MHz, CDCl3): δ = 167.31, 153.91, 150.35, 144.61,
138.86, 130.17, 128.90, 126.30, 123.99, 122.40, 121.83, 119.42,
55.53, 52.03, 40.05, 31.37, 29.48, 23.60, 22.45, 13.86 ppm. HRMS:
1
uct in a yield of ca. 78% (5.08 g). H NMR (300 MHz, CDCl3): δ
= 7.61–7.39 (m, 12 H), 7.25–6.95 (m, 64 H), 1.85–1.80 (m, 24 H),
1.09–1.08 (m, 72 H), 0.82–0.78 (m, 36 H), 0.65 (m, 24 H), 0.368 (s, 9
H) ppm. 13C NMR (300 MHz, CDCl3): δ = 152.79, 151.67, 147.82,
147.49, 139.88, 135.00, 129.87, 129.13, 125.89, 123.41, 122.85,
120.41, 122.58, 120.43, 120.36, 120.14, 119.01, 80.98, 55.26, 40.10,
31.44, 29.51, 23.66, 22.50, 14.03 ppm. HRMS: calcd. for
C
203H242N7O [M + H]+ 2811.1313; found 2812.8954. (ii) TFA
(1.44 g, 0.013 mol) was added to a solution of the compound from
the first step in CH2Cl2 (30 mL), and the mixture was stirred at
room temperature under Ar for 2 h. NaOH(aq.) (ca. 50 mL) was
then added, and the mixed solution was extracted with dichloro-
methane (3ϫ30 mL) and then dried with MgSO4. After removal
of the solvent, the crude product was purified by column
chromatography on silica gel with ethyl acetate/hexane (1:20) as
eluent to give the final purified product in a yield of 84.6% (4.17 g).
1H NMR (300 MHz, CDCl3): δ = 7.52–7.49 (m, 12 H), 7.25–7.20
(m, 20 H), 7.13–7.10 (d, J = 8.4 Hz, 24 H), 7.01–6.95 (m, 20 H),
5.98 (s, 1 H), 2.04–1.82 (m, 24 H), 1.25–1.23 (m, 72 H), 0.80–0.78
(m, 36 H), 0.65 (m, 24 H) ppm. 13C NMR (300 MHz, CDCl3): δ
= 152.83, 151.89, 147.21, 147.05, 139.22, 135.28, 130.85, 129.83,
124.81, 123.41, 122.85, 120.29, 122.37, 120.51, 120.36, 120.14,
119.01, 55.26, 40.10, 31.44, 29.51, 23.66, 22.50, 14.03 ppm. HRMS:
calcd. for C198H234N7 [M + H]+ 2712.0155; found 2712.0996.
calcd. for C27H36BrO2 471.182 [M
+
H]+; found 471.1900
[(79Br)M + H]+, 473.1921 [(81Br)M + H]+.
7-Bromo-9,9-dihexyl-9H-fluorene-2-carbohydrazide (15): NH2NH2·
H2O (0.637 g, 0.01 mol) was added to a mixture of compound 14
(2.4 g, 5.1 mmol) in methanol (20mL), and the resulting solution
was then stirred and heated at reflux for 24 h. The reaction mixture
was extracted with dichloromethane (3ϫ30 mL) and then dried
with MgSO4. After removal of the solvent, the crude product was
purified by column chromatography on silica gel with ethyl acetate/
hexane (1:1) as eluent to give the final purified product in a yield
1
of 91.6% (2.28 g). H NMR (300 MHz, CDCl3): δ = 8.05 (s, 1 H),
7.84–7.74 (m, 2 H), 7.70, 7.67 (d, J = 7.8 Hz, 1 H), 7.59, 7.56 (d,
J = 7.8 Hz, 1 H), 7.49 (s, 1 H), 4.24 (s, 3 H), 2.10–1.86 (m, 4 H),
1.12–1.01 (m, 12 H), 0.77–0.72 (t, J = 6.6 Hz, 6 H), 0.65–0.51 (m, 4
H) ppm. 13C NMR (300 MHz, CDCl3): δ = 168.79, 153.56, 150.83,
143.69, 138.76, 131.30, 130.17, 126.26, 125.76, 122.27, 121.74,
121.66, 119.68, 55.60, 40.09, 31.37, 29.48, 23.62, 22.45, 13.87 ppm.
HRMS: calcd. for C26H36BrN2O [M + H]+ 471.1933; found
471.2009 [(79Br)M + H]+, 473.2011 [(81Br)M + H]+.
7-Bromo-9,9-dihexyl-9H-fluorene-2-carbonitrile (12): CuCN (1.3 g,
14.6 mmol) was added to a mixture of compound 5 (8 g, 0.016 mol)
and dry DMF (50 mL), and the mixture was stirred at 110 °C for
24 h. After the mixture had cooled to room temperature, NaOH(aq.)
(ca. 50 mL) was added. The above solution was extracted with ethyl
acetate and then dried with MgSO4. After removal of the solvent,
the crude product was purified by column chromatography on silica
gel with ethyl acetate/hexane (1:20) as eluent to give the final puri-
fied product in a yield of ca. 45% (3.21 g). 1H NMR (300 MHz, 2-(7-Bromo-9,9-dihexyl-9H-fluoren-2-yl)-5-(4-tert-butylphenyl)-
CDCl3): δ = 7.75–7.72 (dd, 1 H), 7.65–7.58 (m, 3 H), 7.52–7.49 (m, 1,3,4-oxadiazole (16): Two-step reaction. (i) 4-tert-Butylbenzoyl
2 H), 2.00–1.90 (m, 4 H), 1.15–1.03 (m, 12 H), 0.88–0.75 (m, 6 H), chloride (1.03 g, 5.2 mmol) and pyridine (3 mL) were added to a
0.61–0.49 (m, 4 H) ppm. 13C NMR (300 MHz, CDCl3): δ = 153.46, mixture of compound 15 (2.25 g, 4.7 mmol) and THF (60 mL), and
150.99, 144.51, 138.08, 131.40, 130.51, 126.44, 126.38, 123.17,
the resulting mixed solution was heated (ca. 60 °C) and stirred for
122.09, 120.29, 119.59, 110.34, 55.75, 39.95, 31.36, 29.42, 23.60, 12 h. After the mixture had cooled to room temperature, the sol-
1742
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Org. Chem. 2012, 1737–1745

Synthesis and Two-Photon Properties of Small Dendritic Chromophores
vent was removed by filtration, and the crude solid product was
collected and recrystallized from hexane. The purified product was
obtained as a white powder in a yield of 90.3% (2.72 g). H NMR
7.52–7.49 (m, 4 H), 2.14–1.95 (m, 8 H), 1.17–0.99 (m, 24 H), 0.78–
0.73 (t, 12 H), 0.66–0.59 (m, 8 H) ppm. 13C NMR (300 MHz,
CDCl3): δ = 165.00, 153.54, 151.25, 143.61, 138.83, 130.30, 126.32,
126.16, 122.68, 122.46, 121.72, 121.32, 120.26, 55.78, 40.17, 31.42,
29.50, 23.68, 22.47, 13.91 ppm. HRMS: calcd. for C52H65Br2N2O
[M + H]+ 891.3385; found 891.3464 [(79,79Br)M + H]+, 893.3422
[(79,81Br)M + H]+, 895.3465 [(81,81Br)M + H]+.
1
(300 MHz, CDCl3): δ = 10.16, 10.14 (d, J = 7.2 Hz, 1 H), 9.81,
9.79 (d, J = 7.2 Hz, 1 H), 7.96–7.92 (m, 2 H), 7.85, 7.82 (d, J =
7.5 Hz, 2 H), 7.69, 7.66 (d, J = 7.5 Hz, 1 H), 7.57, 7.54 (d, J =
7.5 Hz, 1 H), 7.48–7.43 (m, 4 H), 1.95–1.89 (m, 4 H), 1.32 (s, 9 H),
1.11–0.93 (m, 12 H), 0.74–0.68 (t, J = 6.9 Hz, 6 H), 0.50 (m, 4 H)
ppm. 13C NMR (300 MHz, CDCl3): δ = 164.73, 164.36, 156.09,
153.77, 150.87, 144.26, 138.80, 130.22, 130.14, 128.44, 127.17,
126.91, 126.33, 125.70, 122.43, 121.84, 121.79, 119.84, 55.72, 40.12,
35.02, 31.45, 31.09, 29.52, 23.70, 22.52, 13.93 ppm. HRMS: calcd.
for C37H48BrN2O2 [M + H]+ 631.2821; found 631.2908 [(79Br)M +
H]+, 633.2911 [(81Br)M + H]+. (ii) A mixture of the compound
from the first step and POCl3 (45 mL) was stirred and heated at ca.
90 °C for 6 h. After the mixture had cooled to room temperature, it
was poured into ice/water (ca. 50 mL) and stirred for 30 min. After
filtration, the crude solid product was collected and recrystallized
from methanol. The purified product was obtained as a white pow-
Compound 1: Pd2(dba)3 (9.55 mg, 0.011 mmol), sodium tert-butox-
ide (0.06 g, 0.626 mmol), and P(tBu)3 (4.2 mg, 0.021 mmol) were
added to a mixture of compound 16 (0.32 g, 0.521 mmol) and com-
pound 8a (0.53 g, 0.521 mmol) in dry toluene (15 mL), and the re-
sulting mixture was stirred at 90 °C under Ar for 12 h. After the
mixture had cooled to room temperature, H2O (ca. 100 mL) was
added. The above solution was then extracted with ethyl acetate
and dried with MgSO4. After removal of the solvent, the crude
product was purified by column chromatography on silica gel with
ethyl acetate/hexane (1:10) as eluent to give the final purified prod-
1
uct in a yield of 80.6% (0.65 g). H NMR (300 MHz, CDCl3): δ =
8.11–8.06 (m, 4 H), 7.73, 7.70 (d, J = 7.8 Hz, 1 H), 7.59–7.54 (m,
3 H), 7.50–7.47 (d, J = 7.8 Hz, 4 H), 7.26–7.21 (m, 12 H), 7.12–
7.09 (d, J = 7.8 Hz 10 H), 7.06–6.96 (m, 8 H), 2.06–1.76 (m, 12 H),
1.38 (s, 9 H), 1.19–1.07 (m, 36 H), 0.84–0.71 (m, 30 H) ppm. 13C
NMR (300 MHz, CDCl3): δ = 165.16, 164.38, 155.14, 152.74,
151.94, 151.86, 151.15, 148.32, 148.00, 146.49, 146.16, 144.73,
136.26, 136.21, 133.99, 129.10, 126.75, 126.00, 123.81, 123.61,
123.41, 122.32, 122.12, 121.22, 121.04, 119.74, 119.54, 119.22,
118.61, 116.93, 115.11, 55.06, 40.18, 35.06, 31.66, 31.12, 29.65,
23.92, 22.57, 14.09 ppm. HRMS: calcd. for C111H129N5O [M]+
1548.0197; found 1548.0194.
1
der in a yield of ca. 79% (2.09 g). H NMR (300 MHz, CDCl3): δ
= 8.14–8.09 (m, 4 H), 7.80, 7.78 (d, J = 8.1 Hz, 1 H), 7.62–7.47
(m, 5 H), 2.13–1.94 (m, 4 H), 1.37 (s, 9 H), 1.14–1.05 (m, 12 H),
0.77–0.72 (t, J = 7.2 Hz, 6 H), 0.65–0.60 (m, 4 H) ppm. 13C NMR
(300 MHz, CDCl3): δ = 164.76, 164.49, 155.18, 153.47, 151.13,
143.43, 138.80, 130.23, 126.70, 126.24, 126.02, 125.94, 122.72,
122.35, 121.65, 121.19, 121.07, 120.20, 55.69, 40.12, 34.97, 31.37,
31.02, 29.46, 23.63, 22.44, 13.87 ppm. HRMS: calcd. for
C37H45BrN2O [M]+ 612.2715; found 612.2709 [(79Br)M + H]+,
614.2722 [(81Br)M + H]+.
7-Bromo-9,9-dihexyl-9H-fluorene-2-carbonyl Chloride (17): A mix-
ture of compound 13 (6.4 g, 0.014 mol) and thionyl chloride
(70mL), was stirred and heated at reflux under Ar for 12 h. After
the mixture had cooled to room temperature, the solvent was evap-
orated under low pressure. The crude product was obtained in a
yield of ca. 89% (5.93 g) and was used for the next step without
further purification.
Compound 2: Pd2(dba)3 (3 mg, 0.003 mmol), sodium tert-butoxide
(0.018 g, 0.1955 mmol), and P(tBu)3 (1.3 mg, 0.006518 mmol) were
added to a mixture of compound 16 (0.1 g, 0.163 mmol) and com-
pound 11 (0.44 g, 0.163 mmol) in dry toluene (15 mL), and the re-
sulting reaction mixture was stirred at 90 °C under Ar for 12 h.
After the mixture had cooled to room temperature, H2O (ca.
100 mL) was added. The above mixed solution was extracted with
ethyl acetate and then dried with MgSO4. After removal of the
solvent, the crude product was purified by column chromatography
on silica gel with ethyl acetate/hexane (1:15) as eluent to give the
final purified product in a yield of 73.1% (0.386 g). 1H NMR
(300 MHz, CDCl3): δ = 8.11–8.07 (m, 8 H), 7.73, 7.70 (d, J =
8.1 Hz, 2 H), 7.60–7.55 (m, 8 H), 7.51, 7.48 (d, J = 8.1 Hz, 8 H),
7.27–7.22 (m, 28 H), 7.13–7.10 (m, 18 H), 7.07–6.97 (m, 14 H),
2.06–1.77 (m, 28 H), 1.38 (s, 9 H), 1.17–1.08 (m, 84 H), 0.85–0.75
(m, 70 H) ppm. 13C NMR (300 MHz, CDCl3): δ = 165.13, 164.33,
155.09, 152.70, 151.90, 151.81, 151.10, 148.28, 147.95, 146.45,
146.11, 144.70, 136.22, 136.16, 135.65, 133.95, 129.65, 129.06,
126.71, 125.97, 123.75, 123.57, 122.28, 121.20, 121.02, 119.76,
119.49, 119.20, 118.56, 116.87, 55.02, 40.15, 35.02, 31.62, 31.08,
29.62, 23.88, 22.54, 14.06 ppm. HRMS: calcd. for C235H278N9O [M
+ H]+ 3244.77; found 3244.8767.
2,5-Bis(7-bromo-9,9-dihexyl-9H-fluoren-2-yl)-1,3,4-oxadiazole (18):
Two-step reaction. (i) N2H4·2HCl (0.653 g, 0.006 mol) and pyridine
(15 mL) were added to a mixture of compound 17 (5.92 g,
0.012 mol) and NMP (50 mL), and the resulting mixture was then
stirred at 50 °C for 12 h. After the mixture had cooled to room
temperature, it was poured into ice/water (50 mL). The crude solid
product was collected by filtration and recrystallized from ethyl
acetate/methanol. The purified product was obtained as a brown
1
powder in a yield of 60.3% (3.41 g). H NMR (300 MHz, CDCl3):
δ = 9.34 (s, 2 H), 7.89 (s, 2 H), 7.87–7.86 (m, 2 H), 7.78, 7.75 (d, J
= 7.2 Hz, 2 H), 7.64, 7.61 (d, J = 7.8 Hz, 2 H), 7.51–7.49 (m, 4 H),
2.04–1.94 (m, 8 H), 1.14–1.03 (m, 24 H), 0.78–0.74 (t, J = 6.6 Hz,
12 H), 0.59–0.54 (m, 8 H) ppm. 13C NMR (300 MHz, CDCl3): δ
= 164.74, 153.72, 150.90, 144.41, 138.69, 130.25, 129.94, 126.94,
126.31, 122.52, 121.80, 119.90, 55.70, 40.10, 31.43, 29.52, 23.68,
22.51, 13.93 ppm. HRMS: calcd. for C52H67Br2N2O2 [M + H]+
909.3491; found 909.3497 [(79,79Br)M + H]+, 911.3495 [(79,81Br)M
+ H]+, 913.3547 [(81,81Br)M + H]+. (ii) A mixture of the compound
from the first step and POCl3 (25 mL) was stirred and heated at
reflux for 6 h. After the mixture had cooled to room temperature,
it was poured into ice/water (50 mL). The above solution was then
extracted with ethyl acetate and then dried with MgSO4. After re-
moval of the solvent, the crude product was purified by column
chromatography on silica gel with ethyl acetate/hexane (1:10) as
eluent to give the final purified product in a yield of ca. 91.2%
Compound 3: Pd2(dba)3 (3 mg, 0.00326 mmol), sodium tert-butox-
ide (0.145 g, 1.5 mmol), and P(tBu)3 (0.01 g, 0.05 mmol) were
added to a mixture of compound 18 (0.56 g, 0.6271 mmol) and
compound 8a (0.44 g, 1.254 mmol) in dry toluene (15 mL), and the
mixture was stirred at 90 °C under Ar for 12 h. After the mixture
had cooled to room temperature, H2O (ca. 100 mL) was added.
The above solution was extracted with ethyl acetate and then dried
with MgSO4. After removal of the solvent, the crude product was
purified by column chromatography on silica gel with ether/hexane
(3.04 g). 1H NMR (300 MHz, CDCl3): δ = 8.16–8.13 (m, 4 H), (1:8) as eluent to give the final purified product in a yield of 79.4%
7.84, 7.81 (d, J = 7.2 Hz, 2 H), 7.65, 7.62 (d, J = 7.2 Hz, 2 H),
(0.386 g). 1H NMR (300 MHz, CDCl3): δ = 8.15–8.10 (m, 4 H),
Eur. J. Org. Chem. 2012, 1737–1745
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
1743

T.-C. Lin, Y.-H. Lee, C.-L. Hu,Y.-K. L., Y.-J. Huang
FULL PAPER
land, Y. Yi, Z. Shuai, G. A. Pagani, J.-L. Bredas, J. W. Perry,
S. R. Marder, J. Am. Chem. Soc. 2006, 128, 14444–14445.
7.74, 7.72 (d, J = 8.1 Hz, 2 H), 7.61, 7.58 (d, J = 8.1 Hz, 2 H),
7.50, 7.47 (d, J = 7.8 Hz, 8 H), 7.27–7.22 (m, 26 H), 7.13–7.07 (m,
18 H), 7.03–9.67 (m, 16 H), 2.08–1.76 (m, 24 H), 1.20–1.08 (m, 72
H), 0.85–0.72 (m, 60 H) ppm. 13C NMR (300 MHz, CDCl3): δ =
165.12, 152.73, 151.94, 151.85, 151.16, 148.31, 148.00, 146.49,
146.16, 144.69, 136.21, 134.02, 129.09, 126.14, 123.81, 123.60,
123.40, 122.31, 121.30, 121.06, 119.78, 119.55, 118.60, 116.95,
55.06, 40.18, 31.66, 29.65, 23.92, 22.56, 14.08 ppm. HRMS: calcd.
for C200H233N8O [M + H]+ 2765.0351; found 2765.1206.
[5]
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L. Moreaux, J. Mertz, M. Blanchard-Desce, Org. Lett. 2002, 4,
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M. Blanchard-Desce, J. Mol. Struct. 2004, 704, 17–24; e) L.
Porres, O. Mongin, C. Katan, M. Charlot, T. Pons, J. Mertz,
M. Blanchard-Desce, Org. Lett. 2004, 6, 47–50; f) C. Katan, F.
Terenziani, O. Mongin, M. H. V. Werts, L. Porres, T. Pons, J.
Mertz, S. Tretiak, M. Blanchard-Desce, J. Phys. Chem. A 2005,
109, 3024–3037; g) M. Charlot, L. Porres, C. D. Entwistle, A.
Beeby, T. B. Marder, M. Blanchard-Desce, Phys. Chem. Chem.
Phys. 2005, 7, 600–606; h) M. Charlot, N. Izard, O. Mongin,
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297–302; i) F. Terenziani, C. L. Droumaguet, C. Katan, O.
Mongin, M. Blanchard-Desce, ChemPhysChem 2007, 8, 723–
734.
For selected examples, see: a) M. Drobizhev, A. Karotki, A.
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Compound 4: Pd2(dba)3 (3 mg, 0.00326 mmol), sodium tert-butox-
ide (0.019 g, 0.196 mmol), and P(tBu)3 (1.3 mg, 0.007 mmol) were
added to a mixture of compound 16 (0.074 g, 0.083 mmol) and
compound 11 (0.45 g, 0.166 mmol) in dry toluene (15 mL), and the
resulting mixed solution was stirred at 90 °C under Ar for 12 h.
After the mixture had cooled to room temperature, H2O (ca.
100 mL) was added. The above solution was extracted with ethyl
acetate and then dried with MgSO4. After removal of the solvent,
the crude product was purified by column chromatography on silica
gel with ethyl acetate/hexane (1:30) as eluent to give the final puri-
[6]
[7]
1
fied product in a yield of ca. 50% (0.386 g). H NMR (300 MHz,
CDCl3): δ = 8.15–8.10 (m, 8 H), 7.74, 7.72 (d, J = 7.8 Hz, 4 H),
7.61, 7.58 (d, J = 7.8 Hz 4 H), 7.51, 7.48 (d, J = 7.8 Hz, 16 H),
7.72–7.22 (m, 56 H), 7.13–7.10 (m, 42 H), 7.05–6.97 (m, 34 H),
2.08–1.76 (m, 56 H), 1.25–1.08 (m, 168 H), 0.86–0.72 (m, 140 H)
ppm. 13C NMR (300 MHz, CDCl3): δ = 165.12, 152.75, 151.95,
151.86, 151.17, 148.34, 148.00, 146.50, 146.18, 144.69, 136.27,
136.21, 134.02, 129.09, 126.13, 123.81, 123.61, 123.44, 122.32,
121.31, 121.03, 119.79, 119.55, 119.22, 118.63, 116.96, 55.06, 40.18,
31.65, 29.64, 23.92, 22.55, 14.07 ppm. HRMS: calcd. for
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C
448H529N16O [M + H]+ 6149.1757; found 6149.0358.
Supporting Information (see footnote on the first page of this arti-
cle): Optical experiment details.
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Acknowledgments
We thank the National Science Council (NSC), Taiwan for finan-
cial support.
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Received: October 12, 2011
Published Online: February 8, 2012
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