Block modification of rod-shaped π conjugated carbon frameworks with donor and acceptor groups toward highly fluorescent molecules: Synthesis and emission characteristics

Article abstract of DOI:10.1039/b717832h

To create organic molecules that are highly fluorescent at a longer wavelength region, we investigated the synthesis (using Pd-catalyzed cross-coupling) and photophysical properties (Φ _f, λ _em, τ , λ _abs, and ε ) of the following π conjugated molecular rods consisting of p-phenyleneethynylene units modified by donor (OMe) and/or acceptor (CN) groups: (1) side-donor modification systems (SD systems), (2) side-acceptor modification systems (SA systems), and (3) systems consisting of a donor block and an acceptor block (BL systems). As a consequence, very high Φ _f values (>0.95) were obtained for BL systems. Bathochromic shifts of λ _em for the same π conjugation length were largest for BL systems. Thus we succeeded in creating highly efficient light emitters at a longer wavelength region by block modification (e.g., Φ _f = 0.97, λ _em = 464 nm for BL-9). Considerably intense solid emission (Φ _f ～ 0.5) at a longer wavelength region (500- 560 nm) was also found for BL systems. It has been found that BL-6 and BL-8 exhibit interesting two photon absorption characteristics. This journal is The Royal Society of Chemistry.

Full text of DOI:10.1039/b717832h

View Article Online / Journal Homepage / Table of Contents for this issue
PAPER
www.rsc.org/obc | Organic & Biomolecular Chemistry
Block modification of rod-shaped p conjugated carbon frameworks with donor
and acceptor groups toward highly fluorescent molecules: synthesis and
emission characteristics†
Takanori Ochi, Yoshihiro Yamaguchi,* Tateaki Wakamiya, Yoshio Matsubara and Zen-ichi Yoshida*
Received 19th November 2007, Accepted 17th January 2008
First published as an Advance Article on the web 27th February 2008
DOI: 10.1039/b717832h
To create organic molecules that are highly fluorescent at a longer wavelength region, we investigated
the synthesis (using Pd-catalyzed cross-coupling) and photophysical properties (Uf, kem, s, kabs, and e) of
the following p conjugated molecular rods consisting of p-phenyleneethynylene units modified by donor
(OMe) and/or acceptor (CN) groups: (1) side-donor modification systems (SD systems), (2)
side-acceptor modification systems (SA systems), and (3) systems consisting of a donor block and an
acceptor block (BL systems). As a consequence, very high Uf values (>0.95) were obtained for BL
systems. Bathochromic shifts of kem for the same p conjugation length were largest for BL systems. Thus
we succeeded in creating highly efficient light emitters at a longer wavelength region by block
modification (e.g., Uf = 0.97, kem = 464 nm for BL-9). Considerably intense solid emission (Uf ∼ 0.5) at
a longer wavelength region (500–560 nm) was also found for BL systems. It has been found that BL-6
and BL-8 exhibit interesting two photon absorption characteristics.
report the synthesis and fluorescence emission characteristics of
the following rod-shaped p conjugated carbon frameworks mod-
Introduction
Recent progress in biological,1 chemical,2 and materials3 science
utilizing organic fluorescent materials has resulted in a great need
ified by donor and acceptor groups: (1) side-donor modification
systems (SD systems),5 (2) side-acceptor modification systems (SA
systems),4a and (3) side-donor and acceptor modification systems
for highly efficient fluorophores. However, general concepts or
methods for the creation of highly fluorescent materials at the
desired wavelength regions have not yet been established, even
though various attempts at achieving this goal have been made.4
Thus the development of methods for the creation of highly fluo-
rescent materials should be an urgent and significant subject. For
this purpose we considered p conjugated molecular rods consisting
of p-phenyleneethynylene units, because a marked increase in
both the emission efficiency and emission wavelength should be
expected by side modification with appropriate groups. Here, we
of block type (BL systems),6 which are outlined in Chart 1.
Results and discussion
Molecular design and synthesis
With regard to the p-conjugated backbone of SD, SA, and BL
systems, we considered oligophenyleneethynylenes that contain
two to six benzene rings respectively, as shown in Fig. 1. As
for the side modification groups, a methoxy (MeO) group was
selected as an electron donating group, and a cyano (CN) group
as an electron withdrawing group, because of their stability to the
various synthetic processes employed and the photostability of the
final products.
The synthesis of the oligophenyleneethynylenes was carried out
by repeating the Sonogashira cross-coupling reaction,7 in which
the reactivity difference between iodine and bromine on the same
benzene ring is key to obtaining the desired arrangement of the
donor and acceptor units. The combination of Pd(PPh3)2Cl2 and
CuI in Et3N–THF was appropriate as the catalytic system for
synthesis of the SD, SA, and BL systems.
Chart 1
The synthesis of SD systems is shown in Scheme 1. Firstly,
five kinds of donor units (1–5) were prepared. SD-1 and SD-
2, containing two and three benzene rings, were synthesized by
the cross-coupling of 2-iodoanisole with donor units 2 and 4,
respectively. SD-3, containing four benzene rings, was obtained
in good yields by the same procedure using 5 as a donor unit.
Donor unit 5 was reacted at the more reactive iodo-substituted
position of 5-bromo-2-iodoanisole to give 6, followed by a second
Department of Chemistry, Faculty of Science and Engineering, Kinki
University, 3-4-1 Kowakae, Higashi-Osaka, Osaka 577-8502, Japan. E-
mail: yamaguch@chem.kindai.ac.jp, yoshida@chem.kindai.ac.jp; Fax: +81
6 6723 2721; Tel: +81 6 6721 2332
† Electronic Supplementary Information (ESI) available: Synthetic routes
to donor units (1–3 and 9–11) and acceptor units (4, 5, and 13), UV–vis
and fluorescence spectra for BL systems, and typical Z-scan traces of BL-6
and BL-8. See DOI: 10.1039/b717832h
1222 | Org. Biomol. Chem., 2008, 6, 1222–1231
This journal is
The Royal Society of Chemistry 2008
©

View Article Online
Fig. 1 Structures of side-donor- and/or acceptor-modified phenyleneethynylene molecular rods.
Scheme 1 Synthesis of SD systems.
cross-coupling with donor units 1 and 3 at the remaining bromo-
substituted position, providing SD-4 and SD-5, respectively.
The synthesis of SA systems is shown in Scheme 2. SA-1, con-
taining two benzene rings, was synthesized by the cross-coupling
of acceptor unit 7 with 3-bromobenzonitrile. Synthesis of SA-2,
containing three benzene rings, was realized by the cross-coupling
of acceptor unit 9 with 2-bromobenzonitrile. Acceptor unit 9
was first reacted at the more reactive iodo-substituted position
of 5-bromo-2-iodobenzonitrile to give 10, followed by a second
cross-coupling with acceptor unit 7 at the remaining bromo-
substituted position, providing SA-3. The bromo-derivative 10
was converted into the new acceptor unit 11 by cross-coupling
with trimethylsilylacetylene, followed by alkaline hydrolysis. Then
11 was coupled at the more reactive iodo-substituted position
of 5-bromo-2-iodobenzonitrile to give 12, followed by a second
cross-coupling with acceptor units 7 and 8 at the remaining bromo-
substituted position, providing SA-4 and SA-5, respectively.
Block modification systems (BL-1–BL-9) were synthesized by
way of (1) preparation of donor units (1, 3, and 13), (2) preparation
of acceptor units (7 and 8), and (3) cross-coupling between
donor units and acceptor units, utilizing the reactivity difference
between aryl iodides and aryl bromides as shown in Scheme 3.
BL-1 and BL-2, containing two and three benzene rings, were
synthesized by the cross-coupling of acceptor units 7 and 8
with 2-iodoanisole, respectively. BL-4 and BL-7, containing three
and four benzene rings, were synthesized by the cross-coupling
of 2-bromobenzonitrile with donor units 3 and 13, respectively.
Donor units 1, 3, and 13 were reacted at the more reactive iodo-
substituted position of 5-bromo-2-iodobenzonitrile to give 14, 15,
and 16, followed by a second cross-coupling with acceptor units
7 and 8 at the remaining bromo-substituted position, providing
BL-3, BL-5, BL-6, BL-8, and BL-9, respectively.
The structures of SD, SA, and BL systems were confirmed by
spectral data (1H and 13C NMR spectroscopy and HR-FAB MS).8
This journal is
The Royal Society of Chemistry 2008
Org. Biomol. Chem., 2008, 6, 1222–1231 | 1223
©

View Article Online
Scheme 2 Synthesis of SA systems.
Scheme 3 Synthesis of BL systems.
This journal is
1224 | Org. Biomol. Chem., 2008, 6, 1222–1231
The Royal Society of Chemistry 2008
©

View Article Online
Photophysical properties
systems such as SD-4 (n = 3), SD-5 (n = 4), SA-5 (n =
4), BL-3 (n = 2), BL-7 (n = 2), BL-8 (n = 3), and BL-9
(n = 4).
The photophysical properties of SD, SA, and BL systems and the
parent systems (PR)9 are summarized in Table 1. So far we have
reported4a–e the fluorescence quantum yield values using quinine
sulfate as the fluorescence standard and the lifetime (s) values
obtained from the absorption spectra (e). Strictly speaking, the
emission characteristics should be discussed on the basis of the
absolute quantum yield (Uf) values and the directly measured
lifetime (s) values, which are shown in Table 1.
Measurement of s values was made for the efficiently fluorescent
compounds (n: 2–4, Uf > ca. 0.9) in each system. This is because
our particular attention is focused on the emission characteristics
of highly efficient fluorophores at longer wavelength regions. From
s values and Uf values in Table 1, it is shown that the emission is
typical fluorescence, and the intersystem crossing (ISC) to the
triplet state is negligible for the compounds (n ≥2). It is worth
noting that the emission characteristics, in particular the quantum
yield of SD, SA, BL and PR, change strikingly between the
n = 0 and n = 1 systems, suggesting that diphenylacetylenes
(n = 0) have different p systems from oligophenyleneethynylenes
(n ≥1) with respect to emission characteristics. A similar phe-
nomenon is observed for trans-stilbene (Uf 0.04, n = 0) and p-
distyrylbenzene (Uf 0.87, n = 1) by Saltiel et al.10 and Sandros
et al.11 Interestingly, while Uf values essentially increase with
the p conjugation length of the parent systems, donor/acceptor
modificationalsoeffectivelyincreases theUf values. Thus very high
Uf values (>0.95) are observed for donor/acceptor modification
Although the parent systems (PR-1–PR-4) only emit in the UV
region, this problem was overcome by donor and/or acceptor
modification. Among them, the block modification was most
effective for the bathochromic shift of the fluorescence maximum
(kem) for the same p conjugation length (for example, in the case
of n = 2: BL-5 (434 nm) > BL-3 (419 nm) > BL-7 (407 nm) >
SD-3 (397 nm) > PR-3 (389 nm) > SA-3 (388 nm)). Thus we
succeeded in the creation of highly efficient light-emitters in a
longer wavelength region, by the block modification of the longer
p conjugated backbones (e.g., Uf = 0.97, kem = 464 nm for BL-
9 (n = 4) and Uf = 0.94, kem = 455 nm for BL-6 (n = 3), see
Fig. 2). The superiority in emission wavelength of BL-9 and BL-
6 over others can be explained by the smallest HOMO–LUMO
gap (Table 2) and the biggest Stokes shift (Table 1). It should be
noted that BL-9 and BL-6 have such high Uf values (close to unity)
despite having possible decreases in Uf values due to the twisted
intramolecular charge transfer (TICT), which is well known for
donor/acceptor-substituted p conjugated systems.12
We examined the solvent effect on the photophysical properties
of BL-6 and BL-8. The results are summarized in Table 3. It is
noted that an increase in solvent polarity does not appreciably af-
fect kabs, but considerably affects kem (increases) and Uf (decreases)
for BL-6 and BL-8.
Interestingly kem for BL systems in the solid state was remarkably
shifted to longer wavelengths. On the other hand, the Uf value
Table 1 The photophysical properties of SD, SA, and BL systems and the parent systems (PR) in chloroforma
b
Compound
n
Uf
s/ns
kem/nm
loge
kabs /nm
Stokes shift/nm
SD-1
SD-2
SD-3
SD-4
SD-5
0
1
2
3
4
0.23
0.83
0.94
0.96
0.97
331
371
397
412
420
4.31
4.65
4.75
4.95
5.13
311
344
360
371
380
20
27
37
41
40
4.14
5.43
4.55
SA-1
SA-2
SA-3
SA-4
SA-5
0
1
2
3
4
0.35
0.83
0.88
0.90
0.95
328
363
388
402
410
4.32
4.69
4.89
4.94
5.14
317
339
354
371
373
11
24
34
31
37
5.70
4.59
6.17
BL-1
BL-2
BL-3
BL-4
BL-5
BL-6
BL-7
BL-8
BL-9
0
1
2
1
2
3
2
3
4
0.44
0.86
0.95
0.84
0.93
0.94
0.95
0.95
0.97
374
403
419
392
434
455
407
443
464
4.40
4.61
4.87
4.66
4.81
4.92
4.90
4.96
4.99
326
358
370
352
380
386
365
387
392
47
45
49
40
54
69
42
56
72
4.93
5.36
5.02
4.73
5.51
5.31
PR-1
PR-2
PR-3
PR-4
0
1
2
3
0.01
0.83
0.87
0.93
320
348
389
389
4.41
4.59
4.77
5.13
299
328
343
354
21
20
46
35
6.01
6.29
a All spectra were measured at 295 K. b Absolute quantum yield (Uf) values were determined with a Hamamatsu C9920-01 calibrated integrating sphere
system. c Parent systems (PR):
This journal is
The Royal Society of Chemistry 2008
Org. Biomol. Chem., 2008, 6, 1222–1231 | 1225
©

View Article Online
Table 2 HOMO–LUMO gaps of BL systems calculated by the DFT method
Calcd (DFT and TD-DFT)
Compound
n
HOMO/eV
LUMO/eV
HOMO–LUMO gap/eV
BL-1
BL-2
BL-3
BL-4
BL-5
BL-6
BL-7
BL-8
BL-9
0
1
2
1
2
3
2
3
4
−6.79
−6.73
−6.72
−6.36
−6.37
−6.37
−6.17
−6.18
−6.19
−0.75
−1.44
−1.80
−0.98
−1.49
−1.81
−1.09
−1.51
−1.80
6.04
5.30
4.92
5.38
4.88
4.56
5.08
4.67
4.38
a Functional: BHandHLYP. Basis set: cc-pVDZ.
Table 4 The photophysical properties of BL systems in chloroform
solution and in the solid statea
b
Compound
BL-1
Uf
kem/nm
Dkem/nm c
CHCl3
Solid
CHCl3
Solid
CHCl3
Solid
CHCl3
Solid
CHCl3
Solid
CHCl3
Solid
CHCl3
Solid
CHCl3
Solid
0.44
0.02
0.86
0.02
0.95
0.51
0.84
0.49
0.93
0.16
0.94
0.48
0.95
0.33
0.95
0.46
0.97
0.11
374
378
403
477
419
499
392
515
434
527
455
562
407
512
443
532
464
585
4
74
BL-2
BL-3
80
BL-4
123
93
BL-5
BL-6
107
105
89
BL-7
Fig. 2 Absorption (left) and fluorescence (right) spectra of BL-6 (grey)
and BL-9 (black) in chloroform.
BL-8
BL-9
CHCl3
Solid
121
Table 3 Effect of solvent on absorption and fluorescence spectra of BL-6
and BL-8a
a All spectra were measured at 295 K. b Absolute quantum yield (Uf) values
were determined with a Hamamatsu C9920-01 calibrated integrating
sphere system. c Dkem/nm = kem (Solid) − kem (CHCl3).
b
Compound
Solvent
Uf
kem/nm
loge
kabs /nm
BL-6
Benzene
THF
CH3CN
DMF
Benzene
THF
CH3CN
DMF
0.99
0.88
0.67
0.61
0.99
0.95
0.83
0.72
437
459
482
493
432
446
464
468
4.86
4.90
4.91
4.85
4.89
4.92
4.91
4.85
388
383
375
379
387
385
384
379
p-phenylenevinylene units.15 Thus we have investigated the TPA
for BL-6 and BL-8.
As shown in Fig. 3, we have found that BL-6 and BL-8 exhibit an
interesting two photon absorption. The real TPA maximum peak
for BL-6 and BL-8 appeared at 760 nm (13 157 cm−1) with values
BL-8
a All spectra were measured at 295 K. b For examination of solvent effect
on quantum yield, we calculated the quantum yield relative to quinine
(Uf = 0.55 in 0.1 M H2SO4)
tends to decrease compared with that for systems in solution.
However, it is noted that BL-3, BL-4, BL-6 and BL-8 are still
intense (Uf >0.5) fluorophores even in the solid state (Table 4).
The design and synthesis of highly emissive organic materials
that can fluoresce even in the solid state is a fundamental and
important requirement for various optoelectronic applications,
such as two photon absorption (TPA), two photon fluorescence,
blue-emitting electroluminescence, and organic thin film transistor
(TFT).13 In particular, with respect to the TPA of p conjugated
molecular rods consisting of p-phenyleneethynylene units, only
a few papers appear in the literature14 in contrast with that of
Fig. 3 Two photon absorption spectra of BL-6 (squares) and BL-8
(triangles) in pyridine (7 mM).
1226 | Org. Biomol. Chem., 2008, 6, 1222–1231
This journal is
The Royal Society of Chemistry 2008
©

View Article Online
of 1108 222 GM and 357 71 GM respectively. The effective
r(2) values obtained herein are clearly large compared with those of
other donor/acceptor p conjugated systems (1.3–116 GM)16 and
meso-tetraphenylporphyrin (H2TPP) (29 GM)17 obtained by using
the same nanosecond pulses. Therefore, BL systems could also be
valuable for wavelength convertors.
to say, our HR MS data are based on the results obtained by the
analysis of molecular ion peaks observed in the LR MS spectra.
Thin layer chromatography (TLC) was performed on aluminium
plates precoated with 0.25 mm thick silica-gel 60 F254 (Merck).
Column chromatography was performed using silica gel (PSQ
100B, Fuji Silysia).
Synthetic procedures
Conclusions
General procedure for the Sonogashira cross-coupling reaction.
A Schlenk flask charged with the halogen-derivative (1.0 equiv.),
Pd(Ph3P)2Cl2 (0.1 equiv.) and CuI (0.05 equiv.) was evacuated and
back-filled with Ar three times. Then dry Et3N and THF (2 : 1,
v/v) was added to the flask. The mixture was stirred under an
Ar atmosphere at ambient temperature, then a solution of the
acetylene-derivative (1.2 equiv.) in dry THF was added slowly. The
reaction mixtures were stirred or refluxed under an Ar atmosphere.
The reaction was monitored by TLC. After the reaction was
complete, the solvent was removed by rotary evaporation, and the
crude product was purified by column chromatography followed
by recrystallization.
In conclusion, we synthesized many novel p conjugated molecular
rods modified by donor and/or acceptor groups (SD-1–SD-5, SA-
1–SA-5, and BL-1–BL-9) by devising reaction conditions, and
disclosed their fluorescence emission characteristics in solution
and in solid form. Consequently, it has been demonstrated that
the block modification is most effective for the enhancement of
fluorescence emission characteristics (increases in Uf, and the
bathochromic shift of kem) of rod-shaped p conjugated carbon
frameworks. Considerably intense emissions (Uf ∼ 0.5) in a longer
wavelength region (500–560 nm) were observed from solids. It
is worth noting that very interesting two photon absorption
characteristics have been found for BL systems.
2-Methoxy-1-[(3-methoxyphenyl)-ethynyl]-benzene (SD-1). By
the general procedure the reaction of 2 (243 mg, 1.84 mmol)
with 2-iodoanisole (358 mg, 1.53 mmol) was completed after
0.5 h at ambient temperature. The crude product was purified
by column chromatography (hexane–benzene, 2 : 1) followed by
recrystallization from hexane to provide SD-1 (335 mg, 92%) as
colorless crystals. M.p. 39–40 C. H NMR (300 MHz, CDCl3):
d 3.82 (s, 3H), 3.92 (s, 3H), 6.88 (ddd, J = 1.2, 2.7, 7.8 Hz, 1H),
6.90 (dd, J = 1.2, 8.1 Hz, 1H), 6.95 (dd, J = 1.5, 7.5 Hz, 1H), 7.09
(dd, J = 1.5, 2.4 Hz, 1H), 7.16 (ddd, J = 2.4, 2.7, 7.8 Hz, 1H),
7.23 (d, J = 8.4 Hz, 1H), 7.31 (ddd, J = 1.8, 7.2, 8.4 Hz, 1H), 7.50
(dd, J = 1.8, 7.5 Hz, 1H). 13C NMR (75.4 MHz, CDCl3): d 55.26,
55.80, 85.48, 93.30, 110.63, 114.84, 114.84, 116.23, 120.44, 124.24,
124.47, 129.24, 129.78, 133.56, 159.21, 159.87. HR MS (FAB,
positive ion mode) calcd for C16H14O2 238.0994, found 238.0988.
Experimental
General
UV–vis absorption spectra and fluorescence spectra measure-
ments in spectral grade solvents were performed with a Shimadzu
UV-3100PC spectrometer and a Hitachi F-4500 spectrometer,
respectively. Absolute quantum yields (Uf) were determined by
the Hamamatsu C9920-01 calibrated integrating sphere system.
Time-resolved fluorescence spectra were measured by a Photon
Technology International GL-3300 with a Photon Technology
International GL-302 and a nitrogen laser–pumped dye laser
system equipped with a four-channel digital delay–pulse generator
(Stanford Research Systems Inc. DG535) and a motor driver
(Photon Technology International MD-5020). The excitation
wavelength was 337 nm from a nitrogen laser without laser dye.
The fluorescence lifetimes s were fitted by a single-exponential
curve using a microcomputer. 10-Methylacridinium perchlorate,
newly prepared, was used to check the reliability of the measured
s value.18 To avoid oxygen quenching, the bubbling of argon
in the solution and/or the freeze–pump–thaw were performed
immediately before the measurement of Uf and s. The effective
TPA cross sections r(2) of 7.0 mM solutions of BL-6 and BL-8
in pyridine were determined by single-beam, open-aperture Z-
scan measurements, conducted by using an optical parametric
oscillator (Continuum Surelight OPO) pumped with a Q-switched
Nd:YAG laser (Continuum Surelight I-10), frequency tripled
(k = 355 nm) from the fundamental wavelength of 1064 nm to give
5 ns pulses (FWHM) with a repetition rate of 10 Hz. The laser
intensities were attenuated with a filter to give a peak power of 24
GW cm−2. The laser beam was focused by using a plano-convex
lens with a focal length of 100 nm. The samples were placed in a
2 mm quartz cuvette and scanned at a range of 60 mm around the
focal point. 1H and 13C NMR spectra were recorded on a Varian
Mercury 300 spectrometer in CDCl3 (300 MHz for 1H, 75 MHz for
13C). The method for the determination of the molecular formula
from a HR MS spectrum is described in the literature.19 Needless
◦
1
2-Methoxy-4- [(2-methoxyphenyl)-ethynyl]-1- [(3-methoxyphe-
nyl)ethynyl]-benzene (SD-2). By the general procedure the re-
action of 4 (245 mg, 0.93 mmol) with 2-iodoanisole (183 mg,
0.78 mmol) was completed after 1 h at ambient temperature. The
crude product was purified by column chromatography (hexane–
benzene, 1 : 1) to provide SD-2 (258 mg, 90%) as a yellow oil. 1H
NMR (300 MHz, CDCl3): d 3.82 (s, 3H), 3.93 (s, 3H), 3.94 (s, 3H),
6.89 (dd, J = 1.2, 2.7, 8.1 Hz, 1H), 6.91 (d, J = 8.7 Hz, 1H), 6.95
(ddd, J = 1.2, 7.2, 7.2 Hz, 1H), 7.09 (m, 2H), 7.16 (ddd, J = 1.5,
2.4, 7.2 Hz, 2H), 7.25 (dd, J = 7.5, 7.8 Hz, 1H), 7.33 (ddd, J =
1.8, 7.5, 8.4 Hz, 1H), 7.46 (d, J = 8.1 Hz, 1H), 7.51 (dd, J = 1.5,
7.5 Hz, 1H). 13C NMR (75.4 MHz, CDCl3): d 55.28, 55.82, 55.94,
85.39, 87.39, 93.21, 94.85, 110.65, 112.03, 112.47, 113.58, 115.02,
116.24, 120.51, 124.09, 124.26, 124.31, 124.69, 129.30, 130.05,
133.27, 133.60, 159.25, 159.51, 159.92. HR MS (FAB, positive
ion mode) calcd for C25H20O3 368.1412, found 368.1421.
2-Methoxy-4- [[2-methoxy-4- [(2-methoxyphenyl)-ethynyl]-phe-
nyl]-ethynyl]-1-[(3-methoxyphenyl)-ethynyl]-benzene (SD-3). By
the general procedure the reaction of 5 (478 mg, 1.22 mmol) with
2-iodoanisole (236 mg, 1.01 mmol) was completed after 1 h at
ambient temperature. The crude product was purified by column
chromatography (hexane–benzene, 1 : 2) followed by recrystalliza-
This journal is
The Royal Society of Chemistry 2008
Org. Biomol. Chem., 2008, 6, 1222–1231 | 1227
©

View Article Online
tion from hexane–benzene to p◦rovide SD-3 (455 mg, 90%) as pale
2-[(3-Cyanophenyl)-ethynyl]-benzonitrile (SA-1). By the gen-
eral procedure the reaction of 7 (219 mg, 1.72 mmol) with 3-
bromobenzonitrile (260 mg, 1.43 mmol) was completed after
12 h under reflux. The crude product was purified by column
chromatography (benzene) followed by recrystallization from
hexane–benzene to provide SA-1 (261 mg, 80%) as colorless
crystals. M.p. 117–118 C. H NMR (300 MHz, CDCl3): d 7.50
(ddd, J = 1.5, 6.9, 7.5 Hz, 1H), 7.53 (d, J = 7.8 Hz, 1H), 7.62 (dd,
J = 1.2, 7.5 Hz, 1H), 7.65 (s, 1H), 7.67 (m, 1H), 7.73 (bd, J =
7.5 Hz, 1H), 7.84 (ddd, J = 1.5, 1.5, 7.8 Hz, 1H), 7.88 (m, 1H).
13C NMR (75.4 MHz, CDCl3): d 87.61, 93.02, 113.04, 117.30,
117.82, 123.63, 126.14, 129.01, 129.44, 132.25, 132.33, 132.53,
132.74, 133.68, 135.07, 136.04. HR MS (FAB, positive ion mode)
calcd for C16H8N2 228.0687, found 228.0665.
1
yellow crystals. M.p. 151–152 C. H NMR (300 MHz, CDCl3):
d 3.83 (s, 3H), 3.94 (s, 3H), 3.95 (s, 3H), 3.96 (s, 3H), 6.89 (ddd,
J = 1.2, 2.7, 8.1 Hz, 1H), 6.92 (d, J = 7.8 Hz, 1H), 6.96 (ddd,
J = 1.2, 7.5, 7.5 Hz, 1H), 7.08 (d, J = 1.5 Hz, 1H), 7.09 (d, J =
1.5 Hz, 2H), 7.16 (dd, J = 1.5, 8.1 Hz, 1H), 7.16 (ddd, J = 1.5, 1.5,
7.8 Hz, 1H), 7.26 (dd, J = 7.8, 7.8 Hz, 2H), 7.34 (ddd, J = 1.8, 7.5,
8.1 Hz, 1H), 7.46 (d, J = 8.1 Hz, 2H), 7.51 (dd, J = 1.8, 7.5 Hz,
1H). 13C NMR (75.4 MHz, CDCl3): d 55.29, 55.83, 55.96, 55.96,
85.37, 87.28, 87.61, 93.15, 94.74, 94.98, 110.65, 111.98, 112.17,
112.66, 113.55, 114.19, 115.05, 116.24, 120.52, 124.09, 124.13,
124.28, 124.47, 124.98, 129.31, 130.11, 133.30, 133.45, 133.61,
133.61, 159.25, 159.51, 159.51, 159.93. HR MS (FAB, positive
ion mode) calcd for C34H26O4 498.1831, found 498.1826.
◦
1
5-[(2-Cyanophenyl)-ethynyl]-2-[(3-cyanophenyl)-ethynyl]-benzo-
nitrile (SA-2). By the general procedure the reaction of 9
(359 mg, 1.42 mmol) with 2-bromobenzonitrile (215 mg, 1.18
mmol) was completed after 12 h (reflux). The crude product
was purified by column chromatography (benzene) followed by
recrystallization from benzene to provide SA-2 (335 mg, 80%)
as colorless crystals. M.p. 196–197 ◦C. 1H NMR (300 MHz,
CDCl3): d 7.50 (ddd, J = 1.5, 6.9, 7.8 Hz, 1H), 7.53 (dd, J = 7.8,
7.8 Hz, 1H), 7.62 (dd, J = 1.2, 7.8 Hz, 1H), 7.65 (s, 1H), 7.67 (s,
1H), 7.69 (ddd, J = 1.5, 1.5, 8.1 Hz, 1H), 7.73 (bd, J = 8.1 Hz,
1H), 7.83 (dd, J = 1.8, 8.4 Hz, 1H), 7.84 (m, 1H), 7.88 (ddd,
J = 1.5, 1.5, 8.4 Hz, 1H), 7.92 (bd, J = 1.5 Hz, 1H). 13C NMR
(75.4 MHz, CDCl3): d 87.40, 89.51, 92.73, 95.20, 113.15, 115.62,
116.09, 116.41, 117.25, 117.75, 123.32, 123.37, 125.90, 126.22,
129.25, 129.52, 132.29, 132.36, 132.59, 132.59, 132.80, 135.15,
135.60, 135.64, 136.11. HR MS (FAB, positive ion mode) calcd
for C25H11N3 353.0953, found 353.0942.
2-Methoxy-4-[[2-methoxy-4-[[2-methoxy-4-[(2-methoxyphenyl)-
ethynyl]- phenyl]-ethynyl]- phenyl]-ethynyl]-1- [(3-methoxyphenyl)-
ethynyl]-benzene (SD-4). The reaction of 5 (825 mg, 2.10 mmol)
with 5-bromo-2-iodoanisole (543 mg, 1.74 mmol) for 1 h at
ambient temperature provided bromide 6 (711 mg, 1.23 mmol,
71%). By the general procedure the reaction of 1 (65 mg, 0.49
mmol) with the obtained bromide 6 (237 mg, 0.41 mmol) was
completed after 12 h under reflux. The crude product was
purified by column chromatography (benzene) followed by
recrystallization from benzene◦to provide SD-4 (128 mg, 50%) as
1
yellow crystals. M.p. 212–213 C. H NMR (300 MHz, CDCl3):
d 3.83 (s, 3H), 3.94 (s, 3H), 3.95 (s, 3H), 3.96 (s, 6H), 6.89 (ddd,
J = 1.2, 2.4, 7.8 Hz, 1H), 6.92 (d, J = 7.8 Hz, 1H), 6.96 (ddd,
J = 1.2, 7.8, 7.8 Hz, 1H), 7.08 (d, J = 1.5 Hz, 1H), 7.09 (d, J =
1.5 Hz, 1H), 7.10 (d, J = 1.8 Hz, 2H), 7.16 (dd, J = 1.5, 7.8 Hz,
1H), 7.15–7.19 (m, 3H), 7.26 (dd, J = 7.8, 7.8 Hz, 1H), 7.34
(ddd, J = 1.8, 7.8, 8.4 Hz, 1H), 7.46 (d, J = 7.8 Hz, 2H), 7.47
(d, J = 7.8 Hz, 1H), 7.51 (dd, J = 1.8, 7.8 Hz, 1H). 13C NMR
(75.4 MHz, CDCl3): d 55.30, 55.84, 55.98, 55.98, 55.98, 85.37,
87.26, 87.51, 87.66, 93.15, 94.68, 94.87, 95.00, 110.66, 111.98,
112.12, 112.36, 112.69, 113.56, 113.56, 113.56, 115.07, 116.26,
120.53, 124.11, 124.15, 124.15, 124.28, 124.28, 124.46, 124.78,
125.05, 129.31, 130.13, 133.32, 133.32, 133.62, 133.62, 159.26,
159.54, 159.54, 159.54, 159.94. HR MS (FAB, positive ion mode)
calcd for C43H32O5 628.2250, found 628.2246.
5-[[2-Cyano-4- [(2-cyanophenyl)-ethynyl]-phenyl]-ethynyl]-2- [(3-
cyanophenyl)-ethynyl]-benzonitrile (SA-3). The reaction of 9
(820 mg, 3.25 mmol) with 5-bromo-2-iodobenzonitrile (832 mg,
2.40 mmol) for 1 h at ambient temperature provided bromide 10
(933 mg, 2.16 mmol, 80%). By the general procedure described
the reaction of 7 (83 mg, 0.65 mmol) with bromide 10 (233 mg,
0.54 mmol) was completed after 12 h (reflux). The crude product
was purified by column chromatography (benzene) followed
by recrystallization from benzene–chloroform to provide SA-3
(233 mg, 90%) as pale yellow crystals. M.p. 284–285 ◦C. 1H NMR
(300 MHz, CDCl3): d 7.50 (ddd, J = 1.5, 6.3, 7.2 Hz, 1H), 7.53 (dd,
J = 7.5, 7.5 Hz, 1H), 7.61 (dd, J = 1.5, 7.8 Hz, 1H), 7.66 (m, 2H),
7.68 (m, 1H), 7.69 (ddd, J = 1.5, 1.5, 7.2 Hz, 1H), 7.73 (bd, J =
7.5 Hz, 1H), 7.83 (dd, J = 1.5, 8.4 Hz, 2H), 7.88 (ddd, J = 1.5, 1.5,
8.4 Hz, 1H), 7.90 (bs, 1H), 7.92 (bd, J = 1.5 Hz, 2H). 13C NMR
(75.4 MHz, CDCl3): d 87.38, 89.28, 89.71, 92.69, 94.88, 95.43,
113.17, 115.65, 116.14, 116.37, 117.24, 117.74, 123.01, 123.34,
123.58, 125.86, 125.93, 126.51, 129.29, 129.52, 132.29, 132.39,
132.42, 132.59, 132.59, 132.63, 132.81, 135.16, 135.63, 135.63,
135.68, 135.68, 135.68, 136.13. HR MS (FAB, positive ion mode)
calcd for C34H14N4 478.1219, found 478.1224.
2-Methoxy-4-[[2-methoxy-4-[[2-methoxy-4- [[2-methoxy-4-[(2-
methoxyphenyl)- ethynyl]-phenyl]- ethynyl]-phenyl]- ethynyl]-phe-
nyl]-ethynyl]-1-[(3-methoxyphenyl)-ethynyl]-benzene (SD-5). By
the general procedure the reaction of 3 (210 mg, 0.80 mmol)
with bromide 6 (386 mg, 0.67 mmol) was completed after 12 h
(reflux). The crude product was purified by column chromatog-
raphy (benzene–EtOAc, 9 : 1) followed by recrystallization from
benzene–chloroform to◦ provide SD-5 (152 mg, 30%) as yellow
1
crystals. M.p. 257–258 C. H NMR (300 MHz, CDCl3): d 3.83
(s, 3H), 3.94 (s, 3H), 3.95 (s, 3H), 3.96 (s, 9H), 6.90 (ddd, J = 1.2,
2.7, 8.1 Hz, 1H), 6.92 (d, J = 7.8 Hz, 1H), 6.96 (ddd, J = 1.2,
7.8, 7.8 Hz, 1H), 7.08 (d, J = 1.2 Hz, 1H), 7.10 (bs, 4H), 7.16 (dd,
J = 1.2, 7.8 Hz, 1H), 7.15–7.20 (m, 4H), 7.26 (dd, J = 7.8, 7.8 Hz,
1H), 7.34 (ddd, J = 2.1, 7.8, 8.4 Hz, 1H), 7.46 (d, J = 8.1 Hz, 1H),
7.47 (d, J = 7.8 Hz, 2H), 7.51 (dd, J = 1.5, 7.5 Hz, 1H), 7.55 (dd,
J = 2.1, 5.7 Hz, 1H). HR MS (FAB, positive ion mode) calcd for
C52H38O6 758.2668, found 758.2676.
5-[[2-Cyano-4-[[2-cyano-4-[(2-cyanophenyl)-ethynyl]-phenyl]-
ethynyl]-phenyl]-ethynyl]-2-[(3-cyanophenyl)-ethynyl]-benzonitrile
(SA-4). The reaction of trimethylsilylacetylene (191 mg, 1.94
mmol) with bromide 10 (700 mg, 1.62 mmol) for 12 h under
reflux, followed by alkaline hydrolysis (2 M aq. KOH 2 ml,
1228 | Org. Biomol. Chem., 2008, 6, 1222–1231
This journal is
The Royal Society of Chemistry 2008
©

View Article Online
MeOH 3 ml, CHCl3 5 ml) for 1 h at ambient temperature
provided 11 (460 mg, 1.22 mmol, 75%). The reaction of 11 with
5-bromo-2-iodobenzonitrile (314 mg, 1.02 mmol) for 1 h at
ambient temperature provided bromide 12 (457 mg, 0.82 mmol,
80%). By the general procedure described the reaction of 7 (70 mg,
0.55 mmol) with bromide 12 (256 mg, 0.46 mmol) was completed
after 12 h (reflux). The crude product was purified by column
chromatography (chloroform) followed by recrystallization from
chloro◦form to provide SA-4 (110 mg, 40%) as yellow crystals. M.p.
1H), 7.65 (d, J = 8.1 Hz, 2H), 7.71 (ddd, J = 0.9, 1.8, 7.5 Hz,
1H), 7.77 (dd, J = 1.5, 8.1 Hz, 1H), 7.88 (d, J = 1.5 Hz, 1H). 13
C
NMR (75.4 MHz, CDCl3): d 55.82, 88.84, 89.49, 93.21, 95.22,
110.70, 110.77, 111.07, 115.66, 116.73, 117.31, 120.62, 122.09,
126.15, 127.87, 131.30, 131.80, 132.07, 133.21, 133.77, 134.56,
135.00, 136.38, 136.63, 160.49. HR MS (FAB, positive ion mode)
calcd for C25H14N2O 358.1106, found 358.1140.
5-[[2-Cyano-4- [(2-cyanophenyl)-ethynyl]-phenyl]-ethynyl]-2-[(2-
methoxyphenyl)-ethynyl]-benzonitrile (BL-3). The reaction of 1
(141 mg, 1.07 mmol) with 5-bromo-2-iodobenzonitrile (274 mg,
0.89 mmol) for 1 h at ambient temperature provided bromide
14 (256 mg, 0.82 mmol, 92%). By the general procedure the
reaction of 8 (227 mg, 0.90 mmol) with bromide 14 (234 mg, 0.75
mmol) was completed after 12 h under reflux. The crude product
was purified by column chromatography (benzene) followed by
recrystallization from benzene to provide BL-3 (153 mg, 42%)
1
>300 C. H NMR (300 MHz, CDCl3): d 7.50 (ddd, J = 1.5,
6.3, 7.5 Hz, 1H), 7.53 (dd, J = 7.5, 7.5 Hz, 1H), 7.58–7.63 (m,
1H), 7.66 (bs, 2H), 7.68 (bs, 1H), 7.68 (ddd, J = 1.2, 1.5, 7.5 Hz,
1H), 7.74 (bd, J = 7.2 Hz, 1H), 7.78 (dd, J = 1.5, 7.5 Hz, 1H),
7.82–7.86 (m, 1H), 7.83 (dd, J = 1.2, 8.4 Hz, 2H), 7.89 (ddd, J =
1.2, 1.2, 8.4 Hz, 1H), 7.90 (bs, 1H), 7.93 (bs, 3H). HR MS (FAB,
positive ion mode) calcd for C43H17N5 603.1484, found 603.1489.
◦
1
5-[[2-Cyano-4-[[2-cyano-4-[[2-cyano-4-[(2-cyanophenyl)-ethy-
nyl]-phenyl]-ethynyl]-phenyl]-ethynyl]-phenyl]-ethynyl]-2-[(3-cyano-
phenyl)-ethynyl]-benzonitrile (SA-5). By the general procedure
the reaction of 8 (87 mg, 0.35 mmol) with bromide 12 (162 mg,
0.29 mmol) was completed after 12 h (reflux). The crude product
was purified by column chromatography (chlorofor◦m) to provide
as pale yellow crystals. M.p. 218–219 C. H NMR (300 MHz,
CDCl3): d 3.95 (s, 3H), 6.94 (d, J = 8.1 Hz, 1H), 6.98 (ddd, J =
1.2, 7.5, 7.5 Hz, 1H), 7.30–7.38 (m, 1H), 7.38 (ddd, J = 1.8, 7.5,
7.8 Hz, 1H), 7.49 (ddd, J = 1.8, 7.5, 7.8 Hz, 1H), 7.59 (dd, J =
1.8, 7.5 Hz, 1H), 7.62–7.67 (m, 1H), 7.66 (d, J = 8.1 Hz, 2H),
7.72 (m, 1H), 7.78 (dd, J = 1.8, 7.8 Hz, 1H), 7.81 (dd, J = 1.8,
8.1 Hz, 1H), 7.89 (d, J = 1.2 Hz, 1H), 7.91 (d, J = 1.2 Hz,
1H). 13C NMR (75.4 MHz, CDCl3): d 55.82, 88.64, 89.50, 89.50,
92.76, 95.38, 95.50, 110.76, 111.03, 112.16, 115.72, 116.02, 116.44,
116.66, 117.24, 120.62, 121.75, 123.34, 125.90, 126.25, 128.15,
128.58, 130.27, 131.32, 131.79, 132.16, 133.29, 133.78, 134.62,
135.01, 136.10, 136.48, 136.68, 160.50. HR MS (FAB, positive
ion mode) calcd for C34H17N3O 483.1372, found 483.1367.
1
SA-5 (42 mg, 20%) as a yellow solid. M.p. >300 C. H NMR
(300 MHz, CDCl3): d 7.50 (ddd, J = 1.5, 6.9, 7.5 Hz, 1H), 7.53
(dd, J = 7.5, 7.5 Hz, 1H), 7.58–7.63 (m, 2H), 7.66 (bs, 2H), 7.68
(bs, 1H), 7.68 (ddd, J = 1.5, 1.5, 7.5 Hz, 1H), 7.75 (bd, J = 7.5 Hz,
1H), 7.78 (dd, J = 1.5, 7.5 Hz, 1H), 7.82–7.88 (m, 2H), 7.83 (dd,
J = 1.5, 8.4 Hz, 2H), 7.89 (ddd, J = 1.2, 1.2, 8.4 Hz, 1H), 7.90
(bs, 1H), 7.93 (bs, 4H). HR MS (FAB, positive ion mode) calcd
for C52H20N6 728.1749, found 728.1755.
2-[[2-Methoxy-4- [(2-methoxyphenyl)-ethynyl]-phenyl]-ethynyl]-
benzonitrile (BL-4). By the general procedure the reaction of
3 (500 mg, 1.91 mmol) with 2-bromobenzonitrile (290 mg, 1.59
mmol) was completed after 12 h (reflux). The crude product
was purified by column chromatography (hexane–benzene, 1 : 2)
followed by recrystallization from hexane–benzene t◦o provide BL-
2-[(2-Methoxyphenyl)-ethynyl]-benzonitrile (BL-1). By the
general procedure the reaction of 7 (261 mg, 2.05 mmol) with
2-iodoanisole (400 mg, 1.71 mmol) was completed after 0.5 h
at ambient temperature. The crude product was purified by
column chromatography (hexane–benzene, 2 : 1) followed by
recrystallization from EtOH to provide BL-1 (263 mg, 66%) as
colorless crystals. M.p. 82–83 C. H NMR (300 MHz, CDCl3):
d 3.94 (s, 3H), 6.92 (d, J = 8.1 Hz, 1H), 6.97 (ddd, J = 1.5, 7.5,
7.5 Hz, 1H), 7.34 (dd, J = 1.8, 7.8 Hz, 1H), 7.38 (ddd, J = 1.5,
7.8, 7.8 Hz, 1H), 7.54 (dd, J = 1.5, 8.1 Hz, 1H), 7.58 (ddd, J =
1.8, 7.5, 7.5 Hz, 1H), 7.65 (ddd, J = 0.9, 1.5, 8.1 Hz, 1H), 7.67
(ddd, J = 0.9, 1.5, 7.8 Hz, 1H). 13C NMR (75.4 MHz, CDCl3): d
55.83, 89.51, 92.63, 110.73, 111.32, 115.15, 117.62, 120.52, 127.55,
127.95, 130.79, 132.11, 132.23, 132.62, 133.95, 160.32. HR MS
(FAB, positive ion mode) calcd for C16H11NO 233.0841, found
233.0858.
1
4 (365 mg, 63%) as yellow crystals. M.p. 109–110 C. H NMR
◦
1
(300 MHz, CDCl3): d 3.94 (s, 3H), 3.97 (s, 3H), 6.92 (d, J = 8.1 Hz,
1H), 6.97 (ddd, J = 0.9, 7.5, 7.5 Hz, 1H), 7.10 (d, J = 1.5 Hz, 1H),
7.17 (dd, J = 1.5, 8.1 Hz, 1H), 7.34 (ddd, J = 1.5, 7.5, 8.1 Hz, 1H),
7.40 (ddd, J = 1.2, 7.5, 7.5 Hz, 1H), 7.51 (dd, J = 1.8, 7.5 Hz,
1H), 7.54 (d, J = 8.1 Hz, 1H), 7.56 (ddd, J = 1.2, 7.5, 8.1 Hz,
1H), 7.65 (ddd, J = 0.9, 1.2, 6.0 Hz, 1H), 7.67 (ddd, J = 0.9, 1.5,
6.0 Hz, 1H). 13C NMR (75.4 MHz, CDCl3): d 55.80, 55.97, 87.89,
90.91, 92.41, 93.12, 110.58, 110.64, 111.43, 111.93, 113.90, 115.18,
117.59, 120.53, 124.50, 125.75, 125.83, 127.41, 131.35, 132.66,
133.21, 133.60, 134.58, 159.91, 159.96. HR MS (FAB, positive
ion mode) calcd for C25H17NO2 363.1259, found 363.1267.
5-[(2-Cyanophenyl)-ethynyl]-2-[(2-methoxyphenyl)-ethynyl]-ben-
zonitrile (BL-2). By the general procedure the reaction of 8
(433 mg, 1.72 mmol) with 2-iodoanisole (335 mg, 1.43 mmol) was
completed after 1 h at ambient temperature. The crude product
was purified by column chromatography (hexane–benzene, 1
: 1) followed by recrystallization from hexane–benzene (1 :
1) to provide BL-2 (322 mg, 63%) as colorless crystals. M.p.
168–169 ◦C. 1H NMR (300 MHz, CDCl3): d 3.95 (s, 3H), 6.93 (d,
J = 8.1 Hz, 1H), 6.98 (ddd, J = 1.2, 7.5, 7.5 Hz, 1H), 7.38 (ddd,
J = 1.8, 7.5, 7.5 Hz, 1H), 7.48 (ddd, J = 1.8, 7.2, 7.5 Hz, 1H),
7.59 (dd, J = 1.8, 7.5 Hz, 1H), 7.61 (ddd, J = 0.9, 7.5, 7.5 Hz,
5-[(2-Cyanophenyl)-ethynyl]-2- [[2-methoxy-4-[(2-methoxyphe-
nyl)-ethynyl]-phenyl]-ethynyl]-benzonitrile (BL-5). The reaction
of 3 (627 mg, 2.39 mmol) with 5-bromo-2-iodobenzonitrile
(613 mg, 1.99 mmol) for 1 h at ambient temperature provided
bromide 15 (871 mg, 1.97 mmol, 99%). By the general procedure
the reaction of 7 (153 mg, 1.20 mmol) with bromide 15 (442 mg,
1.00 mmol) was completed after 12 h (reflux). The crude product
was purified by column chromatography (hexane–benzene, 1 :
2) followed by recrystallization from benzene to provide BL-5
(210 mg, 43%) as deep yellow crystals. M.p. 186–187 ◦C. 1H NMR
This journal is
The Royal Society of Chemistry 2008
Org. Biomol. Chem., 2008, 6, 1222–1231 | 1229
©

View Article Online
(300 MHz, CDCl3): d 3.94 (s, 3H), 3.97 (s, 3H), 6.92 (d, J = 7.8 Hz,
1H), 6.96 (ddd, J = 1.2, 7.5, 7.5 Hz, 1H), 7.10 (d, J = 1.2 Hz, 1H),
7.17 (dd, J = 1.2, 7.8 Hz, 1H), 7.33 (ddd, J = 1.8, 7.8, 8.1 Hz, 1H),
7.47 (ddd, J = 1.5, 7.2, 7.5 Hz, 1H), 7.51 (dd, J = 1.2, 7.2 Hz, 1H)
7.54 (d, J = 8.1 Hz, 1H), 7.61 (ddd, J = 1.2, 7.8, 7.8 Hz, 1H), 7.64
(d, J = 7.8 Hz, 1H), 7.65 (dd, J = 0.3, 8.4 Hz, 1H), 7.71 (ddd,
J = 0.3, 1.5, 7.8 Hz, 1H), 7.77 (dd, J = 1.5, 8.4 Hz, 1H), 7.88 (d,
J = 1.5 Hz, 1H). 13C NMR (75.4 MHz, CDCl3): d 55.95, 56.11,
88.20, 88.95, 90.89, 93.09, 93.15, 95.01, 110.58, 110.73, 111.09,
111.89, 113.86, 113.88, 115.50, 115.54, 115.61, 116.66, 116.69,
117.29, 122.21, 126.12, 126.17, 126.22, 127.60, 127.63, 132.13,
132.74, 133.18, 133.46, 134.60, 135.89, 159.96, 160.06. HR MS
(FAB, positive ion mode) calcd for C34H20N2O2 488.1525, found
488.1520.
5-[(2-Cyanophenyl)-ethynyl]-2- [[2-methoxy-4- [[2-methoxy-4-
[(2-methoxyphenyl)-ethynyl]- phenyl]-ethynyl]- phenyl]- ethynyl]-
benzonitrile (BL-8). The reaction of 13 (797 mg, 2.03 mmol)
with 5-bromo-2-iodobenzonitrile (520 mg, 1.69 mmol) for 1 h at
ambient temperature provided bromide 16 (842 mg, 1.47 mmol,
87%). By the general procedure the reaction of 7 (140 mg, 1.10
mmol) with bromide 16 (527 mg, 0.92 mmol) was completed
after 12 h (reflux). The crude product was purified by column
chromatography (benzene) followed by recrystallization from
benzene to provide BL-8 (455 mg, 80%) as yellow crystals. M.p.
194–195 ◦C. 1H NMR (300 MHz, CDCl3): d 3.94 (s, 3H), 3.96 (s,
3H), 3.98 (s, 3H), 6.92 (d, J = 7.5 Hz, 1H), 6.96 (ddd, J = 1.2, 7.8,
7.8 Hz, 1H), 7.10 (bs, 2H), 7.17 (ddd, J = 1.5, 1.5, 7.8 Hz, 2H),
7.34 (ddd, J = 1.8, 7.2, 7.5 Hz, 1H), 7.46 (dd, J = 1.8, 7.2 Hz,
1H), 7.47 (d, J = 8.1 Hz, 1H), 7.50 (ddd, J = 1.8, 7.2, 7.2 Hz, 1H),
7.55 (d, J = 7.8 Hz, 1H), 7.61 (ddd, J = 1.5, 8.1, 8.1 Hz, 1H), 7.65
(ddd, J = 0.9, 1.2, 8.1 Hz, 1H), 7.66 (d, J = 8.1 Hz, 1H), 7.72 (ddd,
J = 0.9, 1.5, 7.2 Hz, 1H), 7.77 (dd, J = 1.8, 8.1 Hz, 1H), 7.88 (d,
J = 1.2 Hz, 1H). 13C NMR (75.4 MHz, CDCl3): d 55.85, 56.13,
56.13, 87.71, 88.08, 88.97, 91.00, 93.15, 93.15, 94.59, 94.98, 110.54,
111.24, 111.96, 113.37, 113.81, 113.81, 113.81, 115.50, 115.63,
116.69, 117.30, 120.63, 122.24, 123.90, 124.43, 125.16, 125.99,
126.12, 127.60, 131.32, 132.17, 132.41, 132.78, 133.59, 134.42,
134.60, 135.54, 135.88, 136.64, 159.59, 159.93, 160.07. HR MS
(FAB, positive ion mode) calcd for C43H26N2O3 618.1943, found
618.1941.
5-[[2-Cyano-4- [(2-cyanophenyl)-ethynyl]-phenyl]-ethynyl]-2-[[2-
methoxy-4- [(2-methoxyphenyl)-ethynyl]-phenyl]-ethynyl]-benzo-
nitrile (BL-6). By the general procedure the reaction of 8
(293 mg, 1.16 mmol) with bromide 15 (429 mg, 0.97 mmol)
was completed after 12 h (reflux). The crude product was
purified by column chromatography (benzene) followed by
recrystallization from benzene◦to provide BL-6 (386 mg, 65%) as
1
yellow crystals. M.p. 221–222 C. H NMR (300 MHz, CDCl3):
d 3.94 (s, 3H), 3.98 (s, 3H), 6.92 (d, J = 7.5 Hz, 1H), 6.96 (ddd,
J = 1.2, 7.5, 7.5 Hz, 1H), 7.10 (d, J = 1.2 Hz, 1H), 7.17 (dd,
J = 1.2, 7.5 Hz, 1H), 7.34 (ddd, J = 1.8, 7.8, 8.4 Hz, 1H), 7.49
(ddd, J = 1.5, 7.2, 7.5 Hz, 1H), 7.51 (dd, J = 1.2, 7.2 Hz, 1H),
7.53 (d, J = 7.8 Hz, 1H), 7.62 (ddd, J = 1.2, 7.8, 7.8 Hz, 1H),
7.65 (dd, J = 1.2, 8.1 Hz, 1H), 7.66 (dd, J = 0.9, 8.4, Hz, 1H),
7.66 (d, J = 8.1 Hz, 1H), 7.72 (ddd, J = 0.9, 1.5, 7.2 Hz, 1H),
7.77 (dd, J = 1.5, 8.1 Hz, 1H), 7.81 (dd, J = 1.5, 8.4 Hz, 1H),
7.88 (d, J = 1.5 Hz, 1H), 7.90 (d, J = 1.5 Hz, 1H). 13C NMR
(75.4 MHz, CDCl3): d 55.83, 56.12, 88.26, 88.76, 89.57, 90.91,
92.77, 93.09, 95.31, 95.36, 110.79, 111.04, 111.89, 113.44, 113.87,
115.67, 115.67, 116.02, 116.43, 116.63, 117.25, 120.65, 121.87,
123.32, 123.90, 125.91, 126.23, 126.27, 127.92, 131.36, 132.20,
132.27, 132.45, 132.81, 133.26, 133.53, 133.93, 134.67, 135.58,
135.95, 136.70, 159.96, 160.13. HR MS (FAB, positive ion mode)
calcd for C43H23N3O2 613.1790, found 613.1783.
5-[[2-Cyano-4- [(2-cyanophenyl)-ethynyl]-phenyl]-ethynyl]-2-[[2-
methoxy-4- [[2-methoxy-4- [(2-methoxyphenyl)- ethynyl]-phenyl]-
ethynyl]-phenyl]-ethynyl]-benzonitrile (BL-9). By the general pro-
cedure the reaction of 8 (166 mg, 0.66 mmol) with bromide 16
(315 mg, 0.55 mmol) was completed after 12 h (reflux). The
crude product was purified by column chromatography (benzene–
EtOAc, 9 : 1) followed by recrystallization from benzene to provide
BL-9 (229 mg, 56%) as yellowish orange crystals. M.p. 270–271 ◦C.
1H NMR (300 MHz, CDCl3): d 3.94 (s, 3H), 3.96 (s, 3H), 3.98 (s,
3H), 6.92 (d, J = 7.8 Hz, 1H), 6.96 (ddd, J = 1.2, 7.2, 7.8 Hz,
1H), 7.10 (bs, 2H), 7.17 (ddd, J = 1.5, 1.5, 7.5 Hz, 2H), 7.34
(ddd, J = 1.5, 7.2, 7.5 Hz, 1H), 7.47 (d, J = 8.1 Hz, 1H), 7.51
(d, J = 7.5 Hz, 1H), 7.51 (ddd, J = 1.8, 1.8, 7.5 Hz, 1H), 7.55
(d, J = 7.5 Hz, 1H), 7.62 (ddd, J = 1.5, 8.1, 8.1 Hz, 1H), 7.65
(dd, J = 0.9, 8.1 Hz, 1H), 7.67 (d, J = 8.1 Hz, 2H), 7.73 (ddd,
J = 0.9, 1.5, 7.5 Hz, 1H), 7.78 (dd, J = 1.8, 8.1 Hz, 1H), 7.82
(dd, J = 1.5, 8.1 Hz, 1H), 7.90 (d, J = 1.8 Hz, 1H), 7.91 (d, J =
1.2 Hz, 1H). 13C NMR (75.4 MHz, CDCl3): d 55.85, 56.13, 56.13,
87.70, 88.11, 88.76, 89.56, 91.01, 91.01, 92.76, 93.14, 94.60, 95.25,
110.51, 111.24, 111.93, 111.96, 113.35, 113.37, 113.79, 113.81,
115.50, 115.63, 115.67, 115.67, 115.99, 116.00, 116.03, 116.61,
117.27, 120.64, 121.90, 122.00, 122.24, 123.32, 123.90, 124.41,
125.15, 125.89, 126.12, 127.60, 131.32, 132.23, 133.94, 134.42,
134.60, 134.66, 135.93, 136.72, 159.57, 160.07, 160.07. HR MS
(FAB, positive ion mode) calcd for C52H29N3O3 743.2209, found
743.2215.
2-[[2-Methoxy-4- [[2-methoxy-4- [(2-methoxyphenyl)-ethynyl]-
phenyl]-ethynyl]-phenyl]-ethynyl]-benzonitrile (BL-7). By the gen-
eral procedure the reaction of 13 (372 mg, 0.95 mmol) with 2-
bromobenzonitrile (144 mg, 0.79 mmol) was completed after 12 h
(reflux). The crude product was purified by column chromatog-
raphy (benzene) followed by recrystallization from benzene to
provide BL-7 (121 mg, 31%) as yellow crystals. M.p. 127–128 ◦C.
1H NMR (300 MHz, CDCl3): d 3.93 (s, 3H), 3.96 (s, 3H), 3.97 (s,
3H), 6.92 (d, J = 7.5 Hz, 1H), 6.96 (ddd, J = 1.2, 7.5, 7.5 Hz,
1H), 7.09 (d, J = 1.2 Hz, 2H), 7.16 (dd, J = 1.5, 8.1 Hz, 2H), 7.34
(ddd, J = 1.5, 7.8, 8.1 Hz, 1H), 7.40 (ddd, J = 1.5, 7.8, 7.8 Hz,
1H), 7.47 (d, J = 7.8 Hz, 1H), 7.51 (dd, J = 1.5, 7.5 Hz, 1H), 7.55
(d, J = 7.8 Hz, 1H), 7.56 (ddd, J = 1.2, 7.2, 7.2 Hz, 1H), 7.65
(ddd, J = 0.9, 1.2, 6.0 Hz, 1H), 7.68 (ddd, J = 0.9, 1.5, 6.0 Hz,
1H). 13C NMR (75.4 MHz, CDCl3): d 55.85, 55.96, 56.12, 87.69,
87.81, 91.04, 92.41, 93.15, 94.62, 110.73, 111.57, 111.97, 112.06,
113.38, 113.81, 113.81, 115.14, 115.18, 117.59, 120.65, 123.87,
124.40, 125.07, 125.12, 125.56, 127.36, 132.08, 132.70, 133.06,
133.59, 133.87, 159.94, 159.94, 159.97. HR MS (FAB, positive
ion mode) calcd for C34H23NO3 493.1678, found 493.1682.
Acknowledgements
We thank Dr Yukihiro Shimoi (National Institute of Advanced
Industrial Science and Technology (AIST)) for the DFT and
TD-DFT calculations, and Dr Kazuya Ogawa (Nara Institute
1230 | Org. Biomol. Chem., 2008, 6, 1222–1231
This journal is
The Royal Society of Chemistry 2008
©

View Article Online
of Science and Technology (NAIST)) for the measurement of
TPA. This work was supported by Grants-in-Aid for Creative
Scientific Research (No. 16GS0209) and Scientific Research (No.
16550131) from the Ministry of Education, Culture, Sports,
Science and Technology of Japan.
J. Am. Chem. Soc., 2005, 127, 4124–4125; (b) J. A. Marsden, J. J.
Miller, L. D. Shircliff and M. M. Haley, J. Am. Chem. Soc., 2005,
127, 2464–2476; (c) J. N. Wilson, P. M. Windscherf, U. Evans and
U. H. F. Bunz, Macromolecules, 2002, 35, 8681–8683; (d) P. Nguyen,
Z. Yuan, L. Agocs and T. B. Marder, Inorg. Chim. Acta, 1994, 220,
289–296.
7 K. Sonogashira, in Comprehensive Organic Synthesis, ed. B. M. Trost
and I. Fleming, Pergamon, Oxford, 1991. vol. 3, pp. 521–549.
8 The compounds were thoroughly purified by repeated column chro-
matography followed by recrystallization.
Notes and references
1 (a) R. B. Thompson, Fluorescence Sensors and Biosensors, CRC Press
LLC, Boca Raton, FL, 2006; (b) T. Nishioka, J. Yuan, Y. Yamamoto, K.
Sumitomo, Z. Wang, K. Hashino, C. Hosoya, K. Ikawa, G. Wang and
K. Matsumoto, Inorg. Chem., 2006, 45, 4088–4096; (c) K. Yoshimoto,
S. Nishizawa, M. Minagawa and N. Teramae, J. Am. Chem. Soc., 2003,
125, 8982–8983; (d) X. Song, J. Nolan and B. I. Swanson, J. Am. Chem.
Soc., 1998, 120, 11514–11515; (e) N. H. Norton, Biomedical Sensors,
Fundamentals, and Applications, Noys Publications, Park Ridge, NJ,
1982.
2 (a) J. Shi, E. Forsythe, D. C. Morton and B. M. Bolotin, Organic Lumi-
nescent Materials, U.S. Pat. Appl. Publ., 2005; (b) B. M. Krasovitskii
and B. M. Bolotin, Organic Luminescent Materials, VCH, Weinheim,
Germany, 1988.
9 PR-1, see: (a) A. Beeby, K. S. Findlay, P. J. Low and T. B. Marder,
J. Am. Chem. Soc., 2002, 124, 8280–8284; (b) K. S. Findlay, P. J. Low
and T. B. Marder, Chem. Commun., 2003, 2406–2407.
10 J. Saltiel, A. S. Waller, D. F. Sears Jr. and C. Z. Garrett, J. Phys. Chem.,
1993, 97, 2516–2522.
11 K. Sandros, M. Sundahl, O. Wennerstrom and U. Norinder, J. Am.
Chem. Soc., 1990, 112, 3082–3086.
12 B. Valeur, Molecular Fluorescence, Wiley-VCH, Weinheim, 2005.
13 For example, see: (a) H. Langhals, O. Krotz, K. Polborn and P. Mayer,
Angew. Chem., Int. Ed., 2005, 44, 2427–2428; (b) S. H. Lee, B.-B. Jang
and Z. H. Kafali, J. Am. Chem. Soc., 2005, 127, 9071–9078; (c) Y. Kim,
J. Bouffard, S. E. Kooi and T. M. Swager, J. Am. Chem. Soc., 2005,
127, 13726–13731.
3 (a) J. Shinar, Organic Light-Emitting Devices, Springer, New York,
2004; (b) K. Mu¨llen and U. Scherf, Organic Light Emitting Devices,
Wiley-VCH, Weinheim, 2006.
14 (a) Y. Zhao, Y. Shirai, A. D. Slepkov, L. Cheg, L. B. Alemany, T. Sasaki,
F. A. Hegmann and J. M. Tour, Chem.–Eur. J., 2005, 11, 3643–3658;
(b) R. Schroeder, J. N. Wilson, U. H. F. Bunz and B. Ullrich, J. Phys.
Chem. B, 2003, 107, 11604–11607.
15 S. Barlow and S. R. Marder, in Functional Organic Materials, ed.
T. J. J. Mu¨ller and U. H. F. Bunz, Wiley-VCH, Weinheim, 2007, pp.
418–437.
16 B. A. Reinhardt, L. L. Brott, S. J. Clarson, A. G. Dillard, J. C. Bhatt,
R. Kannan, L. Yuan, G. S. He and P. N. Prasad, Chem. Mater., 1998,
10, 1863–1874.
17 J. T. Dy, K. Ogawa, A. Satake, A. Ishizumi and Y. Kobuke, Chem.–
Eur. J., 2007, 13, 3491–3500.
4 For example, see: (a) Y. Yamaguchi, T. Ochi, T. Wakamiya, Y.
Matsubara and Z. Yoshida, Org. Lett., 2006, 8, 717–720; (b) Y.
Yamaguchi, S. Kobayashi, T. Wakamiya, Y. Matsubara and Z. Yoshida,
Angew. Chem., Int. Ed., 2005, 44, 7040–7044; (c) Y. Yamaguchi, T.
Tanaka, S. Kobayashi, T. Wakamiya, Y. Matsubara and Z. Yoshida,
J. Am. Chem. Soc., 2005, 127, 9332–9333; (d) Y. Yamaguchi, T. Ochi, S.
Miyamura, T. Tanaka, S. Kobayashi, T. Wakamiya, Y. Matsubara and
Z. Yoshida, J. Am. Chem. Soc., 2006, 128, 4504–4505; (e) T. Ochi, Y.
Yamaguchi, S. Kobayashi, T. Wakamiya, Y. Matsubara and Z. Yoshida,
Chem. Lett., 2007, 36, 794–795.
18 S. Fukuzumi, K. Ohkubo, T. Suenobu, K. Kato, M. Fujitsuka and O.
Ito, J. Am. Chem. Soc., 2001, 123, 8459–8467.
19 Y.-C. Ning, Structural Identification of Organic Compounds with
Spectroscopic Techniques, Wiley-VCH, Weinheim, 2005.
5 U. H. F. Bunz, Chem. Rev., 2000, 100, 1605–1644.
6 Fluorescent non-block type donor/acceptor oligo(phenylene-
ethynylene)s (OPEs), see: (a) J. N. Wilson and U. H. F. Bunz,
This journal is
The Royal Society of Chemistry 2008
Org. Biomol. Chem., 2008, 6, 1222–1231 | 1231
©