Synthesis and photophysical properties of doubly porphyrin-substituted cyanine dye

Article abstract of DOI:10.1142/S1088424611003616

New porphyrin-(cyanine dye) composites, in which two porphyrins are bridged by a cyanine dye through triple bonds, were synthesized. In the UV-vis absorption spectra of the composites, the Soret band and Q-band were red-shifted to 436 and 575640 nm, respectively. The absorption originating from the cyanine dye portion was also red-shifted from 710 nm to 764 nm, suggesting the expansion of πconjugation over the porphyrin and cyanine dye parts. Fluorescence studies suggested that energy transfer from the porphyrin portion to the cyanine dye moiety occurred. The fluorescence intensity decreased with increasing dielectric constants of solvents, suggesting intramolecular photoinduced electron transfer from the porphyrin to the cyanine dye parts. The effective two-photon absorption (2PA) cross-section values were measured using a nanosecond open aperture Z-scan method. The maximum effective 2PA cross-section and two-photon excited fluorescence cross-section values were 33,000 GM and 4,800 GM, respectively, at 860 nm in toluene/pyridine (95:5).

Full text of DOI:10.1142/S1088424611003616

Journal of Porphyrins and Phthalocyanines
J. Porphyrins Phthalocyanines 2011; 15: 678–685
DOI: 10.1142/S1088424611003616
Published at http://www.worldscinet.com/jpp/
Synthesis and photophysical properties of doubly
porphyrin-substituted cyanine dye
†

††
Kazuya Ogawa* , Yasunori Nagatsuka and Yoshiaki Kobuke*
Graduate School of Materials Science, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma,
Nara 630-0101, Japan
th
Dedicated to Professor Karl M. Kadish on the occasion of his 65 birthday
Received 19 April 2011
Accepted 23 May 2011
ABSTRACT:Newporphyrin-(cyaninedye)composites, inwhichtwoporphyrinsarebridgedbyacyanine
dye through triple bonds, were synthesized. In the UV-vis absorption spectra of the composites, the Soret
band and Q-band were red-shifted to 436 and 575–640 nm, respectively. The absorption originating
from the cyanine dye portion was also red-shifted from 710 nm to 764 nm, suggesting the expansion
of π-conjugation over the porphyrin and cyanine dye parts. Fluorescence studies suggested that energy
transfer from the porphyrin portion to the cyanine dye moiety occurred. The fluorescence intensity
decreased with increasing dielectric constants of solvents, suggesting intramolecular photoinduced
electron transfer from the porphyrin to the cyanine dye parts. The effective two-photon absorption (2PA)
cross-section values were measured using a nanosecond open aperture Z-scan method. The maximum
effective 2PA cross-section and two-photon excited fluorescence cross-section values were 33,000 GM
and 4,800 GM, respectively, at 860 nm in toluene/pyridine (95:5).
KEYWORDS: porphyrin, cyanine dye, two-photon absorption.
growth, neuronal cell activity, and the blood stream in
INTRODUCTION
functional brains can be obtained. In this imaging tech-
A three-dimensional fluorescence imaging technique
nique, both the fluorescence and incident excitation light
observes the fluorescence from a fluorescent agent excited
wavelengths should be in the near-infrared region (NIR)
by two-photon absorption (2PA) in a cell and can acquire
between 700 and 1,300 nm [1]. This region is known as
an image at depths of hundreds of micrometers beneath
the optical window of biological tissues [2].
the tissue surface. Therefore, deep-site information on a
Recently, porphyrin derivatives with large two-photon
variety of processes, for example, cancer-cell size and
(2)
absorption cross-section values (σ ), for example,
expanded porphyrins [3, 4] and squaraine-conjugated
oligo-pyrroles [5, 6], have been reported. Although the
penetration depth of the incident excitation light can be
improved by using the two-photon excitation of porphy-
rins in the NIR, the fluorescence quantum yield is lower
than 0.1. Cyanine dyes are known to be fluorescent dye in
the NIR with a relatively high quantum yield of over 0.2.
The HOMO–LUMO absorption band of cyanine dyes is
around 650 nm, with a large molar extinction coefficient

SPP full member in good standing
*
Correspondence to: Kazuya Ogawa, tel: +81 55-220-8511,
fax: +81 55-220-8511, email: kogawa@yamanashi.ac.jp and
Yoshiaki Kobuke, tel: +81 774-38-4956, fax: +81 774-38-4951,
email: kobuke@iae.kyoto-u.ac.jp
†
Current address: Interdisciplinary Graduate School of Medical
and Engineering, Division of Medicine and Engineering
Science, Life Environment Medical Engineering, University of
Yamanashi, 4-3-11 Takeda, Kofu, Yamanashi 400-8511, Japan
-1
-1
of 260,000 M .cm , which is slightly longer than that
of zincporphyrin. Therefore, by connecting a porphy-
rin to a cyanine dye, it is postulated that the excitation
†
†
Current address: Institute of Advanced Energy, Kyoto
University, Gokasho, Uji, Kyoto 611-0011, Japan
Copyright © 2011 World Scientific Publishing Company

SꢀꢁꢂꢃꢄSIS ꢅꢁD PꢃOꢂOPꢃꢀSICꢅꢆ PꢇOPꢄꢇꢂIꢄS Oꢈ DOꢉꢊꢆꢀ POꢇPꢃꢀꢇIꢁ-SꢉꢊSꢂIꢂꢉꢂꢄD CꢀꢅꢁIꢁꢄ Dꢀꢄ
679
energy resulting from the two-photon absorp-
two-photon excitation
tion by the porphyrin portion will transfer to
the cyanine dye moiety, resulting in stron-
(
2)
N
N
ger fluorescence emissions. The σ values
N
energy transfer
N
Zn
Zn
of monomeric porphyrins, which have only
N
N
-
50
4
-1
a few tens of GM (= 10 cm .s.molecule .
N
N
-
1
photon ), can be improved by connecting
the π-conjugation systems using an ethynyl
group as a bridge [7–10]. Considering this, we
designed a novel bisporphyrin-(cyanine dye)
conjugate 1 bridged through ethynyl groups.
As shown in Scheme 1, two porphyrins were
used to expand the π-conjugation system
over the entire molecule, which we believed
to be advantageous for the enhancement of
S
N
S
N
1
C12H25
C12H25
fluorescence
Scheme 1. Structure of 1
2
PA, when compared to the mono-porphyrin-(cyanine
RESULTS AND DISCUSSION
dye), which is difficult to synthesize. Furthermore, the
cyanine dye will function as an energy/electron acceptor
relative to porphyrin and is expected to enhance the σ
value. Herein, we report the synthesis and photophysical
properties of 1, including the nonlinear absorption
properties measured using a nanosecond Z-scan method.
Scheme 2 shows a synthetic route to 1. Both cyanine
dyes and porphyrins have high coplanarity and low
solubility in organic solvents, which created difficulties.
In order to avoid these problems, two 1-ethyl-n-pentyl
groups and one dodecyl group were introduced at the
(2)
(
a)
S
N
(b)
O2N
S
N
(c)
H2N
S
N
(d)
I
S
N
C12H24OH
C12H24I
2
3
4
5
6
7
I
I
I
(
e)
S
(f)
S
S
(
g)
NH
N
N
R
I
N
N
I
NH HN
R
R
N
HN
8
9
10
11
(
h)
NH
N
N
(i)
N
N
N
(j)
N
N
N
(k)
N
N
N
Br
Zn
Br
Zn
TMS
Zn
H
HN
N
N
N
1
2
13
14
15
N
Zn
N
N
Zn
N
N
N
TMS
TMS
N
N
(
l)
(
m)
9
+
15
9
S
S
S
S
N
R
N
R
I
N
N
R
I
R
1
16
R = -C12H25
Scheme 2. Synthetic route to 1. (a) lauryl alcohol, P, I , reflux, 99.9%; (b) 2-methyl-1,3-benzothiazole 4, HNO , H SO , rt, 52.4%;
2
3
2
4
(
c) 10% Pd/C, HCOONH , THF, MeOH, 79.2%; (d) (1) HCl, NaNO , H O, 0 °C, (2) KI, rt, 72.2%; (e) lauryl iodide 3, CH CN, reflux,
4
2
2
3
5
d, 65.0%; (f) malonaldehyde bis(phenylimine)monohydrochloride, TEA, acetic anhydride, MeOH, rt, 31.0%; (g) 2-ethylhexanal,
TFA, CHCl , p-chloranil, rt, 39.5%; (h) NBS, CHCl , -40 °C, 35.0%; (i) Zn(OAc) , CHCl , rt, 99.9%; (j) TMS-acetylene, Pd (PPh )-
3
3
2
3
2
3
Cl , CuI, TEA, THF, rt, 86.5%; (k) TBAF, CHCl , rt, 92.5%; (l) Pd (dba) , AsPh , TEA, THF, rt, 40.5%; (m) TMS-acetylene,
2
3
2
3
3
Pd (PPh )Cl , CuI, TEA, THF, rt, 40.9%
2
3
2
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 679–685

6
80
K. OꢋꢅWꢅ ꢀꢁ ꢂꢃ.
Fig. 1. MALDI-TOF mass spectrum of 1
Fig. 3. UV-vis absorption spectra of 1 (bold line), 14 (thin line),
and 16 (dashed line) in toluene. The spectra were normalized
at the porphyrin Soret band for 1 and 14, and the absorption
peak of cyanine dye part for 1 and 16, respectively. The real
porphyrin meso-positions and at the 3-position of the
cyaninedye,respectively.AstheSonogashiracouplingisa
suitable method for the connection of hetero π-conjugated
systems with a triple bond, ethynylporphyrin 15 and a
diiodo-cyanine dye 9 were first prepared, and then the
coupling reaction was conducted. The diiodo-cyanine
dye 9 was synthesized following literature procedures
-7
concentrations of each compound were 1.7 × 10 M for 1, 5.0 ×
-7
-7
1
0 M for 14, and 3.0 × 10 M for 16, respectively
1
5, is no longer observed. Two aromatic peaks originating
[
11–13]. Porphyrin 11 was prepared from 2-ethylhexanal
from the cyanine dye portion, which were observed
and dipyrromethane 10 with trifluoroacetic acid (TFA),
followed by chloranil oxidation in a 39.5% yield [14].
One of the meso-positions was brominated by N-bromo-
succineimide (NBS) to give 12 (35.0%). After zinc inser-
tion (13), a cross-coupling reaction with TMS-acetylene,
using a Pd(PPh ) Cl /CuI catalytic system, was performed
at 8.26 and 8.06 ppm for 9, have shifted downfield to
8
.54 and 8.36 ppm because of ring-current effects of the
1
porphyrin. The assignment of each H signal is shown in
the figure.
The UV-vis absorption spectra of 1, 14, and 16 are
shown in Fig. 3. The Soret band and Q-band of porphyrin
3
2
2
to yield 14 (86.5%). Finally, the deprotected compound
5 was reacted with 9 using a Pd (dba) /AsPh catalytic
1
4 were observed at 434 and 570–620 nm, whereas those
1
2
3
3
of1werered-shiftedto436and575–640nm, respectively.
Ethynylcyanine dye 16 showed a strong HOMO–LUMO
transition band at 710 nm, and the corresponding strong
absorption was observed at 764 nm in 1. The red-shifts
system to afford the target 1 as a green solid (40.5%).
Figure 1 shows the MALDI-TOF mass spectrum of 1.
An ion peak was observed at 1853, corresponding to the
cationic part of 1 (the calculated value for [C H N -
-1
-1
1
15 139 10
of the Q-band (406 cm ) and cyanine dye part (976 cm )
are indicative of the expansion of π-conjugation over
both the porphyrin and the cyanine dye units in 1. In con-
trast to porphyrin dimers such as meso-meso-linked [15],
butadiyne-bridged [16], or phenylene-
bridged [17] ones, which exhibit split
Soret bands as a result of exciton inter-
action between porphryins, 1 showed a
single broad band, indicating relatively
weak interaction between the two por-
phyrins. This suggests that 2PA will
occur at either of the two porphyrins,
as shown in Scheme 1.
1
S Zn ] + H was 1852.92). The H NMR spectrum of 1 in
2
2
pyridine-d is shown in Fig. 2. The ethynyl proton peak,
5
which was observed at 5.08 ppm in the NMR spectrum of
The fluorescence spectra of 1 excited
at 435 nm in toluene, chloroform, and
pyridine are shown in Fig. 4. Although
the porphyrin part was excited,
fluorescence was observed at around
7
90 nm. This was probably emitted
from the cyanine dye portion, as the
wavelength is too long to be porphyrin
fluorescence.This observation suggests
that energy transfer from the porphyrin
1
Fig. 2. H NMR spectrum of 1 in pyridine-d
5
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 680–685

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681
Fig. 4. Fluorescence spectra of 1 in toluene (bold line), in
chloroform (dashed line), and in pyridine (thin line)
Fig. 5. Typical Z-scan traces of 1 in toluene/pyridine = 95.5
cross) and in pyridine (circle) with theoretically fitted curves
(
at 860 nm
to the cyanine dye moiety occurred [18]. The weak
fluorescence observed at around 640 nm may be attributed
to the porphyrin portion, whose area ratio was 2.5%. The
fluorescence quantum yield Φ of 1 in toluene was 0.14
when excited at 435 and 570 nm, which is four times
larger than that of zinctetraphenylporphyrin (ZnTPP)
represents typical Z-scan traces of 1 in toluene/pyridine
(
1
95:5) and pyridine (both concentrations were 5.3 ×
0 M) with theoretically fitted curves at 860 nm. In
-4
these figures, the normalized transmittance was plot-
ted as a function of the sample position, z. A dip was
observed around the focal position. The curve-fit was
performed according to theoretical equations [7, 8, 19,
(
0.033). The quantum yield increased to 0.30 by direct
excitation of the cyanine dye part at 680 nm. As shown
in Fig. 4, the fluorescence intensity of 1 was dependent
on the solvent. Table 1 summarizes the fluorescence
quantum yields for each compound measured in toluene,
chloroform, and pyridine. Fluorescence quenchings of
2
0], assuming 2PA:
2
(-α(1)L)
(
1 - R) e
∞
-x2
(
)
T(ζ) =
q(ζ) =
ln[1+ q(ζ)e ]dx
(1)
∫-
∞
πq(ζ)
8
0% and 97% were observed in chloroform (ε = 4.89)
0
q0
and pyridine (ε = 13.22), compared to that in toluene
0
(2)
2
(
ε0 = 2.38). The fluorescence intensity changed only
slightly on addition of a small amount of pyridine (0 to
%) to the chloroform or toluene solution, indicating that
1 + ζ
(2)
q = α (1 - R)I L
(3)
(4)
0
0
eff
5
(1)
(1)
coordination of pyridine molecules does not quench the
fluorescence of 1. The fluorescence observed decreased
with increasing dielectric constants of the solvents,
suggesting intramolecular photoinduced electron transfer
from the porphyrin to the cyanine dye part. The quenching
observed in chloroform seems too high, considering
the dielectric constant. The absorption spectrum in
chloroform was considerably broadened compared with
those in aromatic solvents, suggesting that π–π stack-
ing between composites may be another reason for the
quenching.
Leff = [1 - exp(-α L)]/α
eff (2)
(2)
σ
= ħω α /N
(5)
where ζ is the normalized z-position [ζ = (z - z
and z are the focal position and the Rayleigh range,
R
)/z
], and
0
R
z
0
(1)
respectively. α is a one-photon absorption coefficient,
R denotes the Fresnel reflectance, and L is the path length
(2 mm); α is the 2PA coefficient, Leff denotes the effec-
tive path length, and I is the peak intensity at the focal
position; N is the number density of the molecules and
ħω is the photon energy of the incident light. Finally, the
effective 2PA cross-section value, σ , was obtained
from Equation 5. The Z-scan curves at all wavelengths
could be fitted well with a reasonable Rayleigh range of
5 mm, which agreed with that obtained for a standard
sample of rhodamine B [14, 21].
(
2)
0
eff (2)
Nonlinear absorption measurements were performed
using a nanosecond Z-scan method in toluene/pyridine
(
95:5) and pyridine, and analyzed as the effective 2PA
including the excited-state absorption [8]. Figure 5
One-photon and effective two-photon absorption spec-
tra of 1 are shown in Fig. 6. The effective 2PA values σ
were measured in the wavelength range from 860 to 920
nm, corresponding to the two-photon excitation energy
for the porphyrin Soret band (the peaks of the Soret band
were observed at the same wavelength of 436 nm in both
solvents).Almost no one-photon absorption was observed
Table 1. Fluorescence quantum yields of 1, 14, and 16
eff (2)
Compound
1
14
16
toluene
0.14
0.03
—
0.38
0.35
0.30
chloroform
pyridine
0.010
0.0040
—
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 681–685

6
82
K. OꢋꢅWꢅ ꢀꢁ ꢂꢃ.
eff (2)
4
00 to 450 nm, a large σ value of 1,000 GM at 850 nm
was observed, suggesting that resonance enhancement
also contributed to the value. One of the reasons for the
eff (2)
smaller
σ
value of 1 in pyridine compared to that in
toluene may be weaker resonance enhancement because
the one-photon absorption observed at 750 nm in pyridine
was shorter than that observed in toluene. Another reason
is thought to be a small contribution from the excited-
state absorption since the excited-state life-time in pyri-
dine is anticipated to be much shorter, judging from the
fluorescence quantum yield data.
The two-photon excited fluorescence cross-section
Fig. 6. One- and two-photon absorption spectra of 1 in toluene/
pyridine = 95.5 (straight line and triangle) and in pyridine
eff
eff (2)
σ′ (=
σ
× Φ) of 1, which evaluates the two-photon
fluorescence efficiency, was 4,800 GM, which is 4,800,
(
dashed line and square)
1
3, and 12 times larger than those of ZnTPP, 16, and 17,
respectively. Furthermore, the fluorescence wavelength of
at 795 nm is longer than those of reference compounds,
R
R
1
and is located within the optical window suitable for
three-dimensional fluorescence imaging. Femtosecond
N
N
N
N
N
N
N
N
Zn
R
Zn
R
2
PA measurement for 1 will be measured and reported
in due course.
1
7
R =
COOEt
EXPERIMENTAL
Scheme 3. Reference compound 17
General procedures
eff (2)
over 860 nm in either solvent. The
σ
value increased
1
H NMR spectra were recorded on a JEOL ECP-600
with decreasing wavelength and no peak was observed
in this wavelength range. The maximum σ value was
obtained as 33,000 GM in toluene/pyridine (95:5) and
,700 GM in pyridine at 860 nm. For comparison, the
PA and fluorescence properties of 1, ZnTPP, 16, and
reference compound 17 (Scheme 3) [14] are summarized
in Table 2. All of the effective 2PA values were measured
by our Z-scan system. As the effective 2PA property
depends strongly on measurement conditions such as
pulse duration and peak intensity, we can compare only
or JEOL EX-270 spectrometer with Me Si as the inter-
4
eff (2)
nal standard (δ = 0 ppm). UV-vis spectra were measured
using a Shimadzu UV-1650PC UV-visible spectropho-
tometer. Fluorescence measurements were performed
on a Hitachi F-4500 fluorescence spectrophotometer.
MALDI-TOF mass spectra were obtained on a PerSep-
tive Biosystems Voyager DE-STR or a Shimadzu/KRA-
TOS Axima-CFR MALDI spectrometer with dithranol
6
2
(Aldrich) as the matrix. Reactions were monitored on
silica gel 60 F254 TLC plates (Merck). The silica gel used
for column chromatography was purchased from Kanto
Chemical Co. Inc.: Silica Gel 60N (spherical, neutral)
2
PA data measured with our system. The value of 33,000
GM obtained for 1 in toluene/pyridine is 1,100, 33, and 4.3
times larger than those of ZnTPP, 16, and 17, respectively.
6
0–210 μm and 40–50 μm (flash). Dry tetrahydrofuran
eff (2)
The large enhancement of the
σ
value for 1 may be
(THF) was obtained by distillation from a refluxing solu-
attributed not only to expansion of the π-conjugation but
also to resonance enhancement [14] from the strong one-
photon absorption around 770 nm near the two-photon
resonance wavelength. As shown in Fig. 3, although 16
has weak one-photon absorption in the wavelength range
tion of benzophenone in THF over sodium.
Preparation of lauryl iodide (3) [13]. A mixture of
lauryl alcohol 2 (5.25 g, 25.9 mmol, 1.0 equiv.), phos-
phorus red (240.9 mg, 7.78 mmol, 0.3 equiv.), and iodine
(7.23 g, 28.5 mmol, 1.10 equiv.) was heated at 150 °C for
5
h. After cooling to room temperature, the mixture was
diluted with ether. The precipitate was removed by filtra-
tion and the filtrate was evaporated. The residue was dis-
solved in CHCl and washed sequentially with Na S O
Table 2. 2PA and fluorescence properties of 1, ZnTPP, 16,
and 17
3
2
2
3
Compound
1
ZnTPP
16
17
aq., NaHCO aq., and water. The solvent was removed
3
eff (2)
σ , GM
33,000
0.14
29
0.03
1
1,000
0.30
380
7,700
0.05
390
by evaporation to give 3 as a brown liquid (7.75 g, 26.2
1
mmol, 99.9%). H NMR (270 MHz, CDCl ): δ, ppm 3.18
Φ
3
eff
(t, 2H, J = 7.0 Hz, -CH I), 1.82 (quint, 2H, J = 7.0, 6.75
2
σ′, GM
4,800
795
Hz, methylene), 1.38–1.35 (m, 18H, methylene), 0.89 (t,
λem, nm
610
725
690
3
H, J = 1.9 Hz, CH CH -), 8.36 (d, J = 8.1 Hz, 4H, Ph),
3 2
Copyright © 2011 World Scientific Publishing Company
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683
4
6
.61 (q, J = 7.0 Hz, 4H, -CH CH ), 1.58 (t, J = 7.0 Hz,
0.36mmol),malonaldehydebis(phenylimine)monohydro-
chloride (42.3 mg, 0.16 mmol, triethylamine (0.3 mL), and
aceticanhydride(1.0mL)weredissolvedinMeOH(10mL)
and stirred for 3 h at room temperature. The reaction
solution was poured into 20 mL of ether. The precipitates
were purified by silica gel column chromatography (elu-
2
3
H, -CH3).
Preparation of 2-methyl-6-nitro-1,3-benzothiazole
5) [12]. 2-methyl-1,3-benzothiazole 4 (2.95 g, 23.3
mmol, 1.0equiv.)wasaddedto12mLofH SO .Amixture
(
2
4
of HNO (2.30 mL) and H SO (1.70 mL, 67.1 mmol,
3
2
4
2
.9 equiv.) was slowly added to this solution. After stir-
ent: CHCl /EtOAc/MeOH = 1/8/1) to give 9 (117.2 mg,
3
1
ring for 4 h at room temperature, the reaction solution
was poured to ice and left for 7 h. The resulting yellow
precipitate was collected by filtration and washed with
water. The crude material was recrystallized from MeOH
to yield 5 as pale yellow needle crystals (2.36 g, 12.2
mmol, 52.4%). H NMR (270 MHz, CDCl ): δ, ppm
0.11 mmol, 31.0%). H NMR (270 MHz, CDCl ): δ, ppm
3
8.26 (d, 2H, J = 1.2 Hz), 8.06 (t, 2H, J = 12.6 Hz), 7.93
(dd, 2H, J = 1.2, 8.4 Hz), 7.51 (d, 2H, J = 8.4 Hz), 6.92 (t,
1H, J = 12.6 Hz), 6.82 (d, 2H, J = 12.6 Hz), 4.35 (t, 4H,
J = 7.2 Hz), 1.77 (quint, 4H, J = 7.2, 8.4 Hz), 1.43–1.23
(m, 36H), 0.88 (t, 6H, J = 6.9 Hz).
1
3
8
8
.77 (d, 1H, J = 2.3 Hz), 8.32 (dd, 1H, J = 2.3, 9.0 Hz),
.04 (d, 1H, J = 9.0 Hz), 2.92 (s, 3H).
Preparation of 6-amino-2-methyl-benzothiazole (6)
Preparation of 5,15-bis(1-ethyl-n-pentyl)porphyrin
(11). Under a nitrogen atmosphere, trifluoroacetic acid
(0.7 mL, 9.3 mmol) was added to a solution of 2-ethyl-
hexanal (1.19 g, 9.30 mmol) and 10 (679.2 mg, 4.65
[
12]. HCOONH (9.74 g, 150 mmol, 15.0 equiv.), 10%
4
Pd/C (750.0 mg), and 5 (2.00 g, 10.3 mmol, 1.0 equiv.)
were added into THF/MeOH (40 mL:20 mL) and the
resultant mixture was stirred at room temperature for 2.5 d.
The solution was filtered and washed with hot MeOH.
The filtrate was evaporated and the residue was dissolved
mmol) in 900 mL of CHCl . After stirring for 20 h in
3
the dark at room temperature, triethylamine (1.3 mL, 9.3
mmol) and chloranil (3.44 g, 13.95 mmol) were added.
The reaction mixture was stirred for a further 12 h at
room temperature. After removing the solvent, the crude
material was purified by silica-gel column chromatogra-
in CHCl and washed with water. The crude material
3
was purified by silica-gel column chromatography (elu-
phy with CHCl /hexane (1:1) as the eluent to yield 11 as
a purple solid (930.7 mg, 1.84 mmol, 39.5%). H NMR
3
1
ent: CHCl /MeOH = 15:1) to give 6 (1.34 g, 8.16 mmol,
3
1
7
9.2%). H NMR (270 MHz, CDCl ): δ, ppm 7.70 (d, 1H,
(270 MHz, CDCl ): δ, ppm 10.21 (s, 2H, Por meso), 9.69
3
3
J = 8.6 Hz), 7.06 (d, 1H, J = 2.3 Hz), 6.79 (dd, 1H, J =
(d, J = 4.6 Hz, 4H, Por meso), 9.40–9.38 (m, 4H, Por b),
5.13–5.04 (m, 2H), 3.04–2.91 (m, 4H), 2.89–2.71 (m,
4H), 1.52–1.05 (m, 8H), 0.97 (t, 6H, J = 7.2 Hz), 0.64
(t, 6H, J = 7.2 Hz), -2.45 (s, 2H, NH). MS (MALDI-
2
.3), 3.77 (br, 2H), 2.75 (s, 3H).
Preparation of 6-iodo-2-methyl-benzothiazole (7)
[
12]. An aqueous solution of NaNO (275.7 mg, 4.00
2
+
mmol, 1.8 equiv. in 2 mL of water) was added to a solu-
tion of 6 (365.4 mg, 2.22 mmol, 1.0 equiv.) in 2 mL of 6 N
HCl at 0 °C. After 30 min, a solution of KI (666.3 mg,
TOF, dithranol): m/z found 506.79 [M + H] , calcd. for
C H N , 506.34.
3
4
42
4
Preparation of 5,15-bis(1-ethyl-n-pentyl)-10-bro-
4
.00 mmol, 1.8 equiv.) in 2 mL of water was added and the
moporphyrin (12). N-bromosuccinimide (57.6 mg, 0.32
mmol) was added to a solution of 11 (469.2 mg, 0.93
reaction mixture was stirred for 10 min. The temperature
was raised to 30 °C and stirred for a further 20 min. The
mmol) in 30 mL of CHCl at -40 °C. After stirring for
3
precipitate was dissolved in CHCl and washed with 5%
20 min in the dark, the solvent was removed. The residue
3
NaHSO . The crude material was purified by silica-gel
was dissolved in CHCl , washed with water, and dried
3
3
column chromatography (eluent: CHCl /MeOH = 20:1)
to afford 7 (440.9 mg, 1.60 mmol, 72.2%). H NMR (270
over anhydrous Na SO . Purification by silica-gel column
3
2
4
1
chromatography (eluent: CHCl /hexane = 3:2) yielded
3
1
MHz, CDCl ): δ, ppm 8.15 (d, 1H, J = 1.5 Hz), 7.65–7.75
12 (190.3 mg, 0.33 mmol, 35.0%). H NMR (270 MHz,
3
(
m, 2H), 2.82 (s, 3H).
CDCl ): δ, ppm 10.04 (s, 1H, Por meso), 9.83 (d, J = 3.6
3
Preparation of 3-dodecyl-6-iodo-2-methyl-1,3-
Hz, 4H, Por b), 9.62 (d, 4H, J = 12.9 Hz, Por b), 9.31 (d,
2H, J = 3.6 Hz, Por b), 5.07–5.00 (m, 2H), 2.95–2.81 (m,
4H), 2.80–2.67 (m, 4H), 1.52–1.05 (m, 8H), 0.94 (t, 6H,
J = 7.2 Hz), 0.65 (t, 6H, J = 7.2 Hz), -2.49 (s, 2H, NH).
MS (MALDI-TOF, dithranol): m/z found 585.12 [M +
benzothiazole iodide (8) [12]. Compounds 7 (276.2 mg,
.00 mmol, 1.0 equiv.) and 3 (1.49 g, 5.00 mmol, 5.0
1
equiv.) were dissolved in CH CN (10 mL) and heated
3
under reflux for 5 d. After cooling to room temperature,
the reaction solution was poured into 20 mL of ether.
The precipitate was collected by filtration and washed
+
H] , calcd. for C H BrN , 584.25.
3
4
41
4
Preparation of 5,15-bis(1-ethyl-n-pentyl)-10-bromo-
porphyrinatozinc (13). Zinc acetate dihydrate (790.2 mg,
3.60 mmol) in 10 mL of MeOH was added to 12
1
with ether (120.0 mg, 0.21 mmol, 21.0%). H NMR (270
MHz, CDCl /CD OD = 15/1): δ, ppm 8.65 (d, 1H, J = 1.4
3
3
Hz), 8.16 (dd, 1H, J = 1.4, 8.6 Hz), 7.89 (d, 1H, J = 8.6
Hz), 4.76 (t, 2H, J = 7.8 Hz), 3.31 (s, 3H, a), 1.99 (quint,
(140.3 mg, 0.24 mmol) in 20 mL of CHCl . After stirring
3
for 1 h, the mixture was washed well with water, extracted
with CHCl , and dried over anhydrous Na SO . The crude
2
H, J = 7.0, 8.1 Hz), 1.52–1.26 (m, 18H, J = 7.8 Hz), 0.88
3
2
4
(
t, 3H, J = 6.5 Hz).
product was purified by silica-gel column chromatogra-
Preparation of 3,3′-dodecy-6,6′-diiodothiadicarbo-
cyanine iodide (9) [11]. Compound 8 (207.2 mg,
phy (eluent: CHCl ) to give 6 as a pink solid (169.1 mg,
3
1
0.26 mmol, 99.9%). H NMR (270 MHz, CDCl ): δ, ppm
3
Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 683–685

6
84
K. OꢋꢅWꢅ ꢀꢁ ꢂꢃ.
1
0.06 (s, 1H, Por meso), 9.84–9.73 (m, 6H, Por b), 9.33
(br, 1H), 6.15 (br, 2H), 5.47–5.41 (m, 4H), 4.03 (m, 4H),
3.21–3.15 (m, 8H), 2.90–2.83 (m, 8H), 1.65–1.09 (m),
0.86 (t, 6H, J = 6 Hz), 0.66 (t, 12H, J = 6 Hz). MS (MAL-
(
(
d, 2H, J = 13.2 Hz, Por b), 5.18–5.13 (m, 2H), 2.94–2.93
m, 4H), 2.81–2.72 (m, 4H), 1.50–1.04 (m, 8H), 0.92 (t,
+
6
H, J = 7.2 Hz), 0.68 (t, 6H, J = 7.2 Hz). MS (MALDI-
DI-TOF, dithranol): m/z found 1853.0 [M + H] , calcd.
+
TOF, dithranol): m/z found 647.01 [M + H] , calcd. for
for C H N S Zn , 1851.92.
1
15 139 10
2
2
C H BrN Zn, 646.16.
Preparation of 3,3′-dodecy-6,6′-ditrimethylsilyl-ethy-
34
39
4
Preparation of 5,15-bis(1-ethyl-n-pentyl)-10-trimethyl-
nylthiadicarbocyanine iodide (16). A vacuum-dried
-2
silylethynylporphyrin (14). Avacuum-driedSchlenk flask
waschargedwith13(169.1mg, 0.26mmol)andfilledwith
argon. THF (10 mL), TEA (1.0 mL), Pd(PPh ) Cl (21.9
mg, 0.03 μmol), CuI (3.00 mg, 0.02 μmol), and trimethyl-
silylacetylene (76.4 mg, 0.78 mmol) were added under an
argon atmosphere. After stirring in the dark at room tem-
perature for 3 h, the reaction mixture was washed with
Schlenk flask was charged with 9 (19.6 mg, 1.93 × 10
mmol) and filled with argon. THF (5 mL), TEA (0.5 mL),
-
3
Pd(PPh ) Cl (2.0 mg, 2.24 × 10 mmol), CuI (0.5 mg,
3
2
2
3 2
2
-3
1.23 × 10 mmol), and trimethylsilylacetylene (5.5 mg,
-2
5.61 × 10 mmol) were added under an argon atmo-
sphere. After stirring in the dark at room temperature for
3 h, the reaction mixture was washed sequentially with
saturated aqueous NH Cl solution and water, extracted
saturated aqueous NH Cl solution and water, extracted
4
4
with CHCl , and dried over anhydrous Na SO . The crude
with CHCl , and dried over anhydrous Na SO . The crude
3
2
4
3
2
4
product was purified by silica-gel column chromatogra-
product was purified by silica gel column chromatogra-
phy (eluent: CHCl /hexane = 1:1) to give 14 (149.9 mg,
phy (eluent: CHCl /hexane = 1:1) to give 16 (6.6 mg,
3
3
1
-3
1
0
1
.22 mmol, 86.5%). H NMR (270 MHz, CDCl ): δ, ppm
7.64 × 10 mmol, 40.9%). H NMR (600 MHz, d -pyri-
3
5
0.08 (s, 1H, Por meso), 9.84–9.74 (m, 6H, Por b), 9.36
dine): δ, ppm 8.01 (s, 2H), 7.96 (t, 2H, J = 12.6 Hz), 7.79
(d, 2H, J = 8.4 Hz), 7.68 (d, 2H, J = 8.4 Hz), 6.91 (t,
1H, J = 12.6 Hz), 6.86 (d, 2H, J = 12.6 Hz), 4.34 (t, 4H,
J = 7.2 Hz), 1.71 (quint, 4H, J = 7.2, 8.4 Hz), 1.43–1.23
(m, 36H), 0.88 (t, 6H, J = 6.9 Hz), 0.33 (s, 18H). MS
(
(
d, 2H, J = 13.2 Hz, Por b), 5.18–5.13 (m, 2H), 2.98–2.93
m, 4H), 2.86–2.76 (m, 4H), 1.50–1.04 (m, 8H), 0.92 (t,
6
H, J = 7.2 Hz), 0.68 (t, 6H, J = 7.2 Hz), 0.63 (s, 9H). MS
+
(
MALDI-TOF, dithranol): m/z found 665.30 [M + H] ,
+
calcd. for C H N SiZn, 664.29.
(MALDI-TOF, dithranol): m/z found 864.50 [M + H] ,
3
9
48
4
Preparation of 5,15-bis(1-ethyl-n-pentyl)-10-tri-
methylsilylethynylporphyrin (15). Compound 14 (245.4
calcd. for C H N S Si , 863.52.
5
3
79
2
2
2
Measurement of nonlinear absorption
mg, 0.37 mmol) was dissolved in 10 mL of CHCl and
3
6
30 μL of 1 M tetrabutylammonium fluoride (TBAF)
Nanosecond open-aperture Z-scan measurements were
performedusinganopticalparametricoscillator(Continuum
Surelight OPO) pumped with a THG beam (355 nm) from a
Q-switched Nd:YAG laser (Continuum Surelight I-10) rang-
ing from 860 to 920 nm [8, 14]. The pulse width and the rep-
etition rate were 5 ns and 10 Hz, respectively. The laser beam
was focused using a plano-convex lens ( f = 100 mm) with a
beam waist of around 0.035 mm at the focal point. The peak
in THF were added. After stirring for 30 min at room
temperature in the dark, the reaction mixture was washed
with saturated aqueous NaHCO and water, extracted
with CHCl , and dried over anhydrous Na SO . The target
compound was purified by silica-gel column chromatog-
raphy (eluent: acetone/CHCl /hexane = 1:1:10) to give
the desired compound (203.4 mg, 0.34 mmol, 92.5%). H
NMR (600 MHz, d -pyridine): δ, ppm 10.10 (s, 1H, Por
meso), 9.84–9.75 (m, 6H, Por b), 9.36 (d, 2H, J = 13.2 Hz,
Por b), 5.18–5.13 (m, 2H), 2.98–2.93 (m, 4H), 2.86–2.76
3
3
2
4
3
1
5
intensity of the incident pulses at the focal point I was 1.0 to
0
14
-2
1
.3 × 10 W.m . The sample solution was placed in a 2 mm
quartz cuvette and stirred using a magnetic bar during the
measurements.
(
(
m, 4H), 1.50–1.04 (m, 8H), 0.95 (t, 6H, J = 7.2 Hz), 0.66
t, 6H, J = 7.2 Hz). MS (MALDI-TOF, dithranol): m/z
+
found 593.11 [M + H] , calcd. for C H N Zn, 592.25.
3
6
40
4
Acknowledgements
Preparation of compound 1. Under an argon atmo-
-
2
This work was supported by Grant-in-Aids for Young
Scientists (B) (No. 18750118) from Ministry of Educa-
tion, Culture, Sports, Science and Technology, Japan
(Monbu Kagakusho).
sphere, 9 (13.8 mg, 1.32 × 10 mmol) and 15 (17.2 mg,
2
ethylamine (1 mL), Pd (dba) (1.6 mg, 1.58 × 10 ), and
AsPh (4.0 mg, 1.32 × 10 mmol) were then added. After
-
2
.89 × 10 mmol) were dissolved in 10 mL of THF. Tri-
-
3
2
3
-
2
3
stirring for 1.5 h, the solvent was removed by evapora-
tion. The residue was dissolved in chloroform and washed
Supporting information
with saturated aqueous NH Cl solution. The crude mate-
rial was purified by silica-gel column chromatography
(Figs S1–S4) are given in the supplementary material.
This material is available free of charge via the Internet at
http://www.worldscinet.com/jpp/jpp.shtml.
4
(
1
eluent: CHCl /MeOH = 6:1) to give 1 (10.6 mg, 5.35 ×
0 mmol, 40.5%). H NMR (600 MHz, d -pyridine):
5
3
-
3
1
δ, ppm 10.34 (d, 4H, J = 18 Hz, Por b), 10.24 (s, 2H,
Por meso), 10.16 (d, 4H, J = 18 Hz, Por b), 9.96 (d, 4H,
J = 18 Hz, Por b), 9.54 (d, 4H, J = 18 Hz, Por b), 8.54
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J. Porphyrins Phthalocyanines 2011; 15: 684–685

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Copyright © 2011 World Scientific Publishing Company
J. Porphyrins Phthalocyanines 2011; 15: 685–685