Novel syntheses and properties of meso-tetraaryl-octabromo-tetranaphtho[2, 3]porphyrins (Ar4Br8TNPs)

Article abstract of DOI:10.1039/c2ob00041e

O-Quinodimethane (o-QDM) generated from benzosultine was used to extend the pyrrole system for the preparation of octabromo-tetranaphtho[2,3]porphyrins via oxidative aromatization. The properties of these bromoporphyrins were presented and chemical transformation via Pd-catalyzed Suzuki reaction was also effectively achieved. The Royal Society of Chemistry 2012.

Full text of DOI:10.1039/c2ob00041e

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PAPER
Novel syntheses and properties of meso-tetraaryl-octabromo-tetranaphtho-
[2,3]porphyrins (Ar4Br8TNPs)†
Xiu-Zhao Jiang,a Chen-Xin Cai,*a Jin-Tao Liu*a and Hidemitsu Unob
Received 6th January 2012, Accepted 13th February 2012
DOI: 10.1039/c2ob00041e
o-Quinodimethane (o-QDM) generated from benzosultine was used to extend the pyrrole system for the
preparation of octabromo-tetranaphtho[2,3]porphyrins via oxidative aromatization. The properties of these
bromoporphyrins were presented and chemical transformation via Pd-catalyzed Suzuki reaction was also
effectively achieved.
precursors, known extended porphyrins with extra substituents in
Introduction
the annelated rings are very scarce.8e It still remains a challenge
π-Extended porphyrins continued to be an active research field
due to their strong intermolecular interaction, and the unique
optical and electronic properties they possess, which mean they
have many potential applications for the preparation of molecular
scale electronic and optoelectronic devices,1 photo-sensitizers
for photodynamic therapy,2 nonlinear optical (NLO) materials,3
and dye-sensitized solar cells (DSSCs).4 Among the π-extended
porphyrins, the linear fusion of aromatic rings to the porphyrins
exhibited significant red-shift and intensification of Q-band.5
Especially, naphtho[2,3]porphyrins, which began to absorb at
the near-infrared region, had been applied in the fields including
organic field effect transistors (OFETs), near-infrared electropho-
sphorescence, the process of blue green up-conversion, and
phosphorescent probes for oxygen imaging in biological
systems.6
However, the naphtho[2,3]porphyrins have only been syn-
thesized and investigated by a few groups because of their syn-
thetic difficulty and low solubility in most solvents. Due to the
extreme instabilities of isoindoles and their π-expanded ana-
logues, the conjugation has to be completed after the formation
of porphyrin macrocycle. So far, two synthetic strategies have
been employed to construct this conjugated architecture: retro-
Diels–Alder reaction developed by Ono’s group,7 and oxidative
aromatization used by Vinogradov and Cheprakov’s groups.8
Nevertheless, limited by the synthetic accessibility of versatile
to introduce various substituents into the annelated rings, which
would tune the properties of the π-extended porphyrins more
profoundly.
o-Quinodimethane (o-QDM), as a highly reactive diene, had
been extensively exploited to extend the aromatic system,9 which
inspired us to extend the conjugated system of porphyrin with a
readily accessible diversity of o-QDM. Benzosultine could gen-
erate o-QDM under relatively mild conditions, and then react
with an electron-deficient dienophile to afford the synthetic
equivalent of nitroalkene, a very useful precursor for the classic
Barton–Zard pyrrole synthesis (Scheme 1).
Considering the facile and various transformation of carbon–
bromine bond in synthetic chemistry,10 the β-bromo substituted
naphtho[2,3]porphyrins could be quite desirable in the
π-extended molecular architectures, since the multiple β substitu-
ents may enlarge the conjugated system more efficiently. To the
best of our knowledge, β-bromo substituted naphthoporphyrins
have never been reported in the literature until now, despite the
bromo-substituted porphyrins on meso- or β-position have been
extensively investigated.10a,11 Accordingly, exploring a valid
synthetic procedure for the introduction of bromine is of great
significance. Herein we present a novel route to the synthesis of
a series of symmetrical tetraaryl-octabromo-tetranaphtho[2,3]-
porphyrins (Ar4Br8TNPs). Furthermore, the Pd-catalyzed Suzuki
coupling reaction of bromo-substituted naphtho[2,3]porphyrin
was also effectively achieved in good yield.
aKey Laboratory of Organofluorine Chemistry, Shanghai Institute of
Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Road,
Shanghai 200032, China. E-mail: caicx@sioc.ac.cn, jtliu@sioc.ac.cn;
Fax: +86 21 64166128; Tel: +86 21 54925188
bGraduate School of Science and Engineering, Ehime University, 2-5
Bunkyo-cho, Matsuyama, 790-857, Japan. E-mail:
uno@dpc.ehime-u.ac.jp; Fax: +81 89-927-5510
†Electronic supplementary information (ESI) available: Characterization
data and spectra. CCDC 823739. For ESI and crystallographic data in
CIF or other electronic format see DOI: 10.1039/c2ob00041e
Scheme 1 Synthetic procedure.
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Scheme 2 Synthesis of pyrrole 4.
phenyl with porphyrin ring, and a single broad peak at
−2.29 ppm with two protons assigned to the NH group, which
proved the only formation of the non-extended porphyrin core.
After further dehydrogenation by DDQ at elevated temperature
to reflux, naphtho[2,3]porphyrin 7a was obtained in 53% yield.
The aromatization was identified by the disappearance of
methylene groups at 3.70 ppm and the appearance of a new
singlet peak at the aromatic zone corresponding to eight protons
1
on the naphthalene ring in H NMR spectrum. Additionally, it
also resulted in downfield shift of protons adjacent to bromine
due to the enlargement of π-conjugation. It was noteworthy that
1
a well-resolved H NMR spectrum was obtained by the addition
of a trace of trifluoroacetic acid (TFA) and the comparison
among them was shown in Fig. 1. MALDI-TOF mass spectra
gave the additional evidence for the formation of 6a and 7a
(ESI†).
With the same procedure, five different naphthoporphyrins
7b–f were successfully synthesized as illustrated in Scheme 3.
Both aldehydes containing electron-donating and electron-
withdrawing substituent could afford the desired naphtho[2,3]-
porphyrins in acceptable yields. For the sake of convenience,
all these naphthoporphyrins were prepared in one step without
isolation of the intermediate porphyrins corresponding to 6.
The π-extended molecular skeleton was also unambiguously
identified by the X-ray crystallographic structure of 7e‡ and the
saddle type distortion conformation has formed as shown in
Fig. 2. The dihedral angle between the two opposite pyrroles
fused with naphthalene was about 136°, which was similar to the
reported Pd-complex of naphtho[2,3]porphyrin derivatives.8a
Scheme 3 Synthesis of naphtho[2,3]porphyrin.
Results and discussion
Syntheses of Ar4Br8TNPs
As shown in Scheme 2, dibromo-benzosultine 1 was chosen as a
precursor for the generation of o-QDM, because it could be con-
veniently prepared from easily available reagents, and react ther-
mally with dienophile under mild conditions. Thus, bis-sulfone
2 was prepared via Diels–Alder cycloaddition of cis-1,2-bis-
(phenylsulfonyl)ethylene and benzosultine
1 in refluxing
UV-vis absorption and thermal behaviors
toluene. Then, the condensation of bis-sulfone 2 and isocyano-
acetate was conducted via Barton–Zard reaction by the elimin-
ation of phenylsulfone with t-BuOK to provide pyrrole ester 3 in
excellent yield. Pyrrole 4, the key precursor for the syntheses of
naphthoporphyrins, was obtained by the saponification and de-
carboxylation of 3 using KOH as a base in ethylene glycol at
175 °C in moderate yield.
With pyrrole 4 in hand, we succeeded in the preparation of
meso-tetraaryl-tetranaphtho[2,3]porphyrins (Ar4Br8TNPs) by the
conventional Lindsey condensation.12 As shown in Scheme 3,
pyrrole 4 reacted with benzaldehyde in CHCl3 in the presence of
BF3·OEt2, followed by oxidation with 2,3-dichloro-5,6-dicyano-
benzoquinone (DDQ) at room temperature for additional 3 hours
to afford octahydronaphthalene fused porphyrin 6a. The 1H
NMR showed a single broad peak at 3.70 ppm with sixteen
protons assigned to the eight methylene groups connecting the
In spite of the lower solubility of naphtho[2,3]porphyrins 7a–f
due to the molecular aggregation, their electronic absorption
spectra could still be obtained as free-base at the concentration
of 10−5 M in CH2Cl2 as orange-yellow solution. As shown in
Fig. 3, all naphthoporphyrins 7a–f showed three split Soret
bands, which were presumably caused by the lower symmetry of
molecules. Due to the extension of π-system and conformation
distortion of the macrocycles, 7a–f exhibited largely red-shifted
and intensified Q-band absorption and the maximum absorption
was at 740 nm for 7d. The maximum molar absorption coeffi-
cients of both Soret and Q band could reach 105 scale and the
spectral data were summarized in Table S1 (ESI†). In order to
identify the electronic effect of bromine on the naphthopor-
phyrin, a direct comparison of electronic absorption was made
between 7c and meso-tetrakis(4-methoxyphenyl)tetranaphtho-
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Fig. 1 1H NMR spectra comparison of porphyrin 6a, 7a, and 7a + TFA.
Fig. 3 UV-vis absorption spectra of 7a–f as free-base.
naphthoporphyrins, especially fluorine-containing naphthopor-
phyrins 7e and 7f with fast decomposition temperature at 560 °C
and beyond 600 °C, respectively, exhibited excellent thermal
stability (see Fig. S3 and Table S3 in ESI†).
Chemical transformation via Suzuki coupling reaction
Fig. 2 X-ray crystal structure of 7e.
To illustrate the synthetic potential of these bromo-containing
porphyrins, the zinc complex of 7c was prepared and its Pd-cata-
lyzed coupling reaction with phenylboronic acid was performed
(Scheme 4). Under the usual Suzuki reaction conditions, the
reaction took place readily and the corresponding octa-phenyl-
ated product 8c was obtained in 60% yield. As expected, product
8c did possess much better solubility in common organic sol-
vents such as CH2Cl2, toluene, and THF, which made it con-
venient to explore the multiple properties of these analogues in
solutions.
[2,3]porphyrin (TMPTNP) in CH2Cl2 (see Fig. S2 in ESI†). The
introduction of bromine atoms induced a red-shift of the Soret
band by 14 nm and the Q-band by 7 nm, which might be caused
by the lower of LUMO energy level due to the presence of an
electron-withdrawing group. Additionally, it is worth noting that
the maximum absorption coefficient ratio of Q-band to Soret-
band was also enhanced from 0.48 to 0.54. The UV-vis absorp-
tion spectra of the corresponding dications of 7a–f in CH2Cl2 as
a purple solution showed further red-shift of both Soret and
Q-band absorption (see Table S2 and Fig. S1 in ESI†), which
suggested the formation of a more distorted and “frozen” saddle-
shaped conformation.
Conclusions
In summary, we have developed a reliable and effective method
for the linear extension of porphyrin and successful introduction
of bromine on the naphthoporphyrin periphery using a highly
The thermal behaviors of naphtho[2,3]porphyrins 7a–f were
investigated by thermogravimetric analysis. All these
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Scheme 4 Chemical transformation of 7c via Suzuki coupling reaction.
reactive o-QDM intermediate generated from benzosultine. A
series of novel bromo-substituted naphtho[2,3]porphyrins
(Ar4Br8TNPs) were synthesized, and their structures were ident-
ified by single crystal X-ray diffraction, as well as significantly
red-shifted and intensified Q-band absorption. Further transform-
ation of the carbon–bromine bond via Suzuki coupling reaction
has also been successfully demonstrated. The potential ap-
plications of these large conjugated molecules in biological and
materials fields are under investigation in our laboratory.
filtration to give 1.515 g of the desired product 2 (yield 60%).
White solid; mp 277–279 °C; H NMR (300 MHz, CDCl3): δ
1
7.99–7.96 (m, 4H), 7.71–7.56 (m, 6H), 7.33 (s, 2H), 4.06–4.02
(m, 2H), 3.60 (dd, J = 7.5 Hz, 17.7 Hz, 2H), 2.99 (dd, J = 7.5
Hz, 17.7 Hz, 2H); ESI MS (m/z): 592.8 (M + Na+); HRMS
(ESI): calcd for C22H18Br2O4S2Na+1 [M + Na+]: 590.8911;
Found: 590.8924; Anal. Calcd for C22H18Br2O4S2: C, 46.33; H,
3.18. Found: C, 46.21; H, 3.27.
Ethyl
6,7-dibromo-4,9-dihydro-2H-benzo[f]isoindole-1-
carboxylate (3). 0.5M t-BuOK solution in THF (25 mL,
12.5 mmol) was added over 2 hours to a stirred mixture of 2
(3.0 g, 5.3 mmol) and ethyl isocyanoacetate (0.85 mL,
7.7 mmol) in dry THF (30 mL) at room temperature under N2
atmosphere. After the addition was completed, the mixture was
stirred for additional 3 hours and aq. HCl solution (30 mL, 5%)
was dropped slowly into the reaction system. The precipitate was
collected by suction filtration and dried to afford 2.020 g of the
Experimental section
General procedures
Melting points were measured on a Melt-Temp apparatus and are
uncorrected. 1H NMR spectra were recorded on a Bruker
AM-300 (300 MHz) spectrometer with TMS as the internal stan-
dard. 19F NMR spectra were recorded on a Bruker AM-300
(282 MHz) spectrometer with CFCl3 as external standard (nega-
tive for upfield). 13C NMR spectra were recorded on a Bruker
AM-400 (100 MHz) spectrometer. Mass spectra were taken on a
HP5989A spectrometer. High-resolution mass data were
obtained on a high-resolution mass spectrometer in the EI or
MALDI-TOF mode. UV-vis spectra were measured with a
Varian Cary 100 spectrophotometer. Elementary analyses were
obtained on Perkin Elmer 2400 Series II Elemental Analyzer.
Thermogravimetric analysis was conducted on TA instruments
TGA 500 under N2 atmosphere (heating rate of 20 °C min−1).
THF was freshly distilled over Na–benzophenone. DMF was
distilled over CaH2 under reduced pressure. Unless otherwise
stated, all commercial reagents were used as received without
further purification.
desired product
3 (yield 95%). Pale yellow solid; mp
209–211 °C; 1H NMR (300 MHz, CDCl3): δ 8.97 (br, 1H), 7.57
(s, 1H), 7.50 (s, 1H), 6.81 (d, J = 2.1 Hz, 1H), 4.35 (q, J = 7.5
Hz, 2H), 4.09 (s, 2H), 3.82 (s, 2H), 1.40 (t, J = 7.5 Hz, 3H); 13
C
NMR (100 MHz, CDCl3): δ 154.82, 136.52, 136.23, 134.05,
133.73, 128.26, 124.86, 121.70, 121.55, 119.28, 118.02, 60.30,
27.60, 26.38, 14.65; EIMS (m/z, %): 400 (M+ + H, 8.90), 399
(M+, 39.32), 370 (M+ − Et, 100.00); HRMS (EI): calcd for
C15H13Br2NO2 [M+]: 396.9313; Found: 396.9308. Anal. Calcd
for C15H13Br2NO2: C, 45.14; H, 3.28; Br, 40.04; N, 3.51.
Found: C, 45.39; H, 3.64; Br, 39.96; N, 3.51.
6,7-Dibromo-4,9-dihydro-2H-benzo[f]isoindole (4). A suspen-
sion of 3 (1.475 g, 3.7 mmol) and KOH (1.1 g, 19.6 mmol) in
ethylene glycol (30 mL) was heated at 175 °C for 40 minutes
under N2 atmosphere. After cooling to room temperature, the
dark solution was poured into ice water (30 mL) and extracted
with CH2Cl2 (100 mL). The organic phase was washed with
brine and dried over anhydrous Na2SO4. The solvent was
removed under reduced pressure and the residue was purified by
silica gel chromatography (eluting with 1 : 5 EtOAc–petroleum)
to give 0.720 g of 4 as a pale white solid (yield 60%). mp
175–177 °C; 1H NMR (300 MHz, CDCl3): δ 8.06 (br, 1H), 7.50
(s, 2H), 6.65 (s, 2H), 3.82 (s, 4H); 13C NMR (100 MHz,
CDCl3): δ 137.80, 133.62, 121.13, 117.29, 112.88, 26.96; EIMS
1,2-Bis(bromomethyl)-4,5-dibromobenzene,13 1,2-bis(phenyl-
sulfonyl)ethene14 and 6,7-dibromo-1,4-dihydro-2,3-benzox-
athiin-3-oxide (1)15 were synthesized according to the literature
procedures.
6,7-Dibromo-2,3-bis(phenylsulfonyl)-1,2,3,4-tetrahydronaphthalene
(2). 1,2-Bis(phenylsulfonyl)ethene (1.445 g, 4.5 mmol) in
toluene (40 mL) was slowly added over one hour to a solution of
1 (1.367 g, 4.5 mmol) in toluene (10 mL) under reflux. The
mixture was refluxed for an additional 3 hours and cooled
to room temperature. The precipitate was collected by suction
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(m/z, %): 327 (M+, 97.01), 326 (M+ − H, 100.00), 247
(M+ − Br–H, 34.22), 167 (M+ − 2Br–H, 50.48); HRMS (EI):
calcd for C12H9Br2N: 324.9102; Found: 324.9107.
7c Green solid; yield 58%; mp > 300 °C; 1H NMR
(300 MHz, CDCl3 + TFA): δ 8.44 (d, J = 8.4 Hz, 8H), 8.07
(s, 8H), 7.92 (s, 8H), 7.49 (d, J = 8.4 Hz, 8H), 4.24 (s, 12H),
2.65 (br, 4H); UV-vis: CH2Cl2, λ nm (lg ε): 453 (4.97), 486
(5.08), 517 (5.31), 686 (4.42), 735 (5.04); MS (MALDI) m/z:
1765.1 (M+ − 1); HRMS (MALDI): calcd for C80H46Br8N4O4:
1757.6986; Found: 1757.6980; Anal. Calcd for C80H46Br8N4O4:
C, 54.39; H, 2.62; N, 3.17; Found: C, 54.50; H, 2.90; N, 3.07.
7d Green solid; yield 34%; mp > 300 °C; 1H NMR
(300 MHz, CDCl3 + TFA): δ 8.68 (s, 16H), 8.02 (s, 8H), 7.79
(s, 8H), 4.24 (s, 12H), 2.95 (br, 4H); UV-vis: CH2Cl2, λ nm
(lg ε): 451 (4.94), 486 (5.08), 512 (5.33), 686 (4.39), 740 (5.02);
MS (MALDI) m/z: 1877.7 (M+ − 1); Anal. Calcd for
C84H46Br8N4O8: C, 53.71; H, 2.47; N, 2.98. Found: C, 53.66;
H, 2.42; N, 2.76.
Procedure for the synthesis of naphthoporphyrin precursor via
modified Lindsey method8a,12
Synthesis of porphyrin 6a. A round bottom flask shaded from
light was charged with CHCl3 (80 mL) followed by the addition
of benzaldehyde (0.084 mL, 0.8 mmol) and pyrrole 4 (0.267 g,
0.8 mmol) under N2 atmosphere. The mixture was stirred for ten
minutes, and BF3·OEt2 (0.08 mmol) was added with a micro-
scale syringe. Three hours later, triethylamine (TEA) (one drop)
and 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) (0.150 g,
0.6 mmol) were added. After stirring for an additional two hours
at room temperature, the solvent was evaporated in vacuo and
the residue was purified by silica gel chromatography (eluting
with CH2Cl2). The green band was collected and recrystallized
from CH2Cl2–CH3OH to give 6a as a blue solid. yield 38%; mp
1
7e Reddish brown solid; yield 65%; mp > 300 °C; H NMR
(300 MHz, CDCl3 + TFA): δ 8.57–8.52 (m, 8H), 8.09 (s, 8H),
7.86 (s, 8H), 7.75–7.69 (m, 8H), 2.62 (br, 4H); 19F NMR
(282 MHz, CDCl3 + TFA): δ −107.41 (s); UV-vis: CH2Cl2, λ
nm (lg ε): 447 (4.97), 483 (5.09), 510 (5.33), 684 (4.43), 736
(5.06); MS (MALDI) m/z: 1717.0 (M+); HRMS (MALDI): calcd
for C76H34Br8F4N4 : 1709.6187; Found: 1709.6181; Anal. Calcd
for C76H34Br8F4N4: C, 53.12; H, 1.99; N, 3.26. Found: C,
53.35; H, 2.32; N, 3.30.
1
> 300 °C; H NMR (300 MHz, CDCl3): δ 8.31 (d, J = 6.0 Hz,
8H), 7.97–7.85 (m, 12H), 7.08 (s, 8H), 3.70 (br, 16H), −2.29
(br, 2H, NH); UV-vis: CH2Cl2, λ nm (relative intensity): 465
(31), 550 (1), 621 (1), 673 (2); MS (MALDI) m/z: 1654.7 (M+);
HRMS (MALDI): Found: 1646.7262. Calcd for C76H47Br8N4:
1646.7268; Anal. Calcd for C76H46Br8N4·CH2Cl2: C, 53.17; H,
2.78; N, 3.22. Found: C, 52.88; H, 2.85; N, 3.20.
7f Green solid; yield 46%; mp > 300 °C; 1H NMR (300 MHz,
CDCl3 + TFA): δ 8.74 (d, J = 7.8 Hz, 8H), 8.30 (d, J = 7.8 Hz,
8H), 8.01 (s, 8H), 7.74 (s, 8H), 2.87 (br, 4H); 19F NMR
(282 MHz, CDCl3 + TFA): δ –62.47 (s); UV-vis: CH2Cl2, λ nm
(lg ε): 445 (5.01), 481 (5.13), 507 (5.37), 684 (4.46), 738 (5.10);
MS (MALDI) m/z: 1919.5 (M + H+); Anal. Calcd for
C80H34Br8F12N4: C, 50.09; H, 1.79; N, 2.92. Found: C, 50.15;
H, 1.54; N, 2.71.
Typical procedure for the synthesis of naphthoporphyrins 7a–f
without isolation of the intermediate porphyrins
A round bottom flask shaded from light was charged with
CHCl3 (50 mL) followed by the addition of aromatic aldehyde
(0.5 mmol) and precursor pyrrole 4 (0.5 mmol) under N2 atmos-
phere. The mixture was stirred for ten minutes, and BF3·OEt2
(0.05 mmol) was added with a micro-scale syringe. Three hours
later, TEA (one drop) and DDQ (0.2 g, 0.88 mmol) were added.
The mixture was stirred under reflux for an additional three
hours. When cooled to room temperature, the crude dark purple
mixture was charged into the top of a long silica gel column and
eluted with CH2Cl2. The first dark band was collected and preci-
pitated by adding methanol. After filtration and drying, the solid
was pure enough for element analysis.
The chemical transformation of porphyrin 7c to 8c via Suzuki
coupling reaction
Porphyrin 7c (50 mg, 0.028 mmol) and Zn(OAc)2·2H2O (58 mg,
0.1 mmol) were dissolved in CHCl3 (20 mL) and CH3OH
(2 mL), and the mixture was refluxed for 2 hours. The resulting
solution was washed with water and brine. The product Zn-7c
was obtained as a green solid after purifying on a silica gel
column (eluting with 50 : 1 CH2Cl2–CH3OH) and precipitated
with CH3OH. Anhydrous DMF was added to the mixture of
Zn-7c (44 mg, 0.024 mmol), 4-methylphenylboric acid
(100 mg, 0.735 mmol), Pd(PPh3)2Cl2 (6 mg, 0.008 mmol) and
K2CO3 (100 mg, 0.724 mmol) in a Schlenk tube under Ar, and
the system was stirred at 100 °C for 18 hours. After extracting
with CH2Cl2 (20 mL) and acidifying with 6 M HCl (10 mL), the
organic phase was washed with brine and purified on a silica gel
column (eluting with CH2Cl2). The first fraction was collected
and precipitated with CH3OH. The precipitate was filtered and
dried to give porphyrin 8c as a green solid. Yield: 60% (32 mg)
7a Green solid; yield 53%; mp > 300 °C; 1H NMR
(300 MHz, CDCl3 + TFA): δ 8.56–8.54 (m, 8H), 8.16–7.99
(m, 20H), 7.83 (s, 8H), 2.38 (br, 4H); UV-vis: CH2Cl2, λ nm
(lg ε): 447 (5.01), 483 (5.16), 510 (5.33), 684 (4.43), 734 (5.07);
MS (MALDI) m/z: 1647.5 (M+ + 1); HRMS (MALDI): calcd
for C76H38Br8N4: 1637.6563; Found: 1637.6558. Anal. Calcd
for C76H38Br8N4·0.4CH2Cl2: C, 54.61; H, 2.33; N, 3.33. Found:
C, 54.64; H, 2.39; N, 3.44.
7b Green solid; yield 45%; mp > 300 °C; 1H NMR
(300 MHz, CDCl3 + TFA): δ 8.42 (d, J = 7.2 Hz, 8H), 8.03
(s, 8H), 7.86 (s, 8H), 7.79 (d, J = 7.2 Hz, 8H), 2.89 (s, 12H),
2.60 (br, 4H); UV-vis: CH2Cl2, λ nm (lg ε): 449 (4.98), 486
(5.10), 513 (5.35), 682 (4.44), 734 (5.08); MS (MALDI) m/z:
1701.7 (M+ − 1); Anal. Calcd for C80H46Br8N4: C, 56.44; H,
2.72; N, 3.29. Found: C, 56.64; H, 2.58; N, 3.13.
1
for three steps. mp > 300 °C; H NMR (300 MHz, CDCl3 +
TFA): δ 8.52 (d, J = 8.4 Hz, 8H), 8.07 (s, 8H), 7.76 (s, 8H), 7.44
(d, J = 8.4 Hz, 8H), 7.07 (s, 32H), 4.15 (s, 12H), 2.77 (br, 4H),
2.33 (s, 24H); 13C NMR (100 MHz, CDCl3): δ 160.72, 139.19,
138.77, 136.20, 135.69, 134.88, 130.63, 130.48, 129.91, 128.67,
115.01, 113.87, 55.93, 21.20; UV-vis: CH2Cl2, λ nm (relative
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intensity): 450 (3.665), 518 (7.915), 689 (1.000), 748 (4.192);
MS (MALDI) m/z: 1855.8 (M+); Anal. Calcd for C136H102N4O4:
C, 88.00; H, 5.54; N, 3.02; Found: C, 87.85; H, 5.44; N, 3.08.
Acknowledgements
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Notes and references
‡Crystal data for 7e: C76H34Br8F4N4, M = 1718.35, monoclinic, a =
10.0612(10) Å, b = 18.1279(19) Å, c = 17.8048(18) Å, α = 90.00°, β =
98.285(3)°, γ = 90.00°, V = 3213.5(6) Å3, T = 296(2) K, space group
Pc, Z = 2, 31 992 reflections measured, 9390 independent reflections
(Rint = 0.0418). The final R1 values were 0.0474 (I > 2σ(I)). The final
wR(F2) values were 0.1225 (I > 2σ(I)). The final R1 values were 0.0593
(all data). The final wR(F2) values were 0.1317 (all data).
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