Tetrathienyl-functionalized red- and NIR-absorbing BODIPY dyes appending various peripheral substituents

Article abstract of DOI:10.1039/c6ob02612e

A series of boron-dipyrromethene dyes (BODIPYs) 4a-g with different thienyl moieties at 2,3,5,6-positions of the BODIPY core were synthesized by the Stille cross-coupling reaction. The new compounds were characterized by ¹H NMR, ¹³C

Full text of DOI:10.1039/c6ob02612e

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Tetrathienyl-functionalized red- and NIR-absorbing BODIPY dyes
appending various peripheral substituents
Ping Liu,a,b Feng Gao,a Lina Zhou,a Yu Chen,b and Zhijian Chen*a
Received 00th January 20xx,
Accepted 00th January 20xx
A series of boron-dipyrromethene dyes (BODIPYs) 4a-g with different thienyl moieties at 2,3,5,6-positions of the BODIPY
core were synthesized by Stille cross-coupling reaction. The new compounds were characterized by 1H NMR, 13C NMR,
HRMS, and IR spectroscopy. The single crystal structure of compound 4e was obtained by X-ray crystallography. The
optical and electrochemical properties of these dyes were studied by UV/Vis spectroscopy, fluorescence spectroscopy, and
cyclic voltammetry. The DFT calculation of the frontier molecular orbitals of these dyes corroborates the observed effects
of peripheral substituents on the optical and redox properties. These results reveal a good tunability of the optical and
electronic properties of these BODIPYs by varying the peripheral groups at the α-positions of thienyl moieties, which leads
to the absorption and emission reaching to the NIR region.
DOI: 10.1039/x0xx00000x
www.rsc.org/
there are a few of reports on the BODIPYs bearing multiple
thienyl moieties at 1,3,5,7,8-positions or 2,3,5,6-positions of
the dipyrromethene core.23 Nevertheless, the influence of the
peripheral groups at the α-position of thienyl rings on the
optical and electrochemical properties of these dyes have not
been investigated yet. Herewith, we report the synthesis and
the optical and electrochemical properties of a series of new
Introduction
Functional dyes with low optical band gaps as well as near-
infrared (NIR) absorbing and emitting properties1 have been
investigated intensively in recent years, owing to their
practical applications in a variety of important fields such as
bio-imaging and sensing,2 photo dynamic therapy,3 optical
communication,4 as well as organic photovoltaics.5 With
rational molecular design, NIR dyes based on cyanines,6
porphyrins,7 phthalocyanines,8 rhodamines,9 squaraines,10
indigos,11 perylene bisimides,12 and diketopyrrolopyrroles,13
etc. have been developed. As a class of versatile functional
dyes, boron-dipyrromethenes (BODIPYs)14 have received
considerable attention in recent years due to their high molar
extinction coefficients, relatively high fluorescence quantum
yield, and excellent photostability. The simplest BODIPY dye15
without peripheral substituent displays absorption and
emission maxima at 504 nm and 512 nm respectively. To tune
the optical and electronic properties of this class of dyes,
synthetic strategies based on extending the conjugation length
of the π-system have been adopted to modify the
dipyrromethene core, including the introduction of phenyl,16
styryl,17 ethynylphenyl,18 or polymethine19 substituents, as
well as fusion with aromatic ring.20 Likewise, 3,5-dioligothienyl-
BODIPY derivatives21,16b and bis-vinyl-thienyl-BODIPYs22 have
been reported to exhibit spectra bands that are significantly
red-shifted with respect to their precursors. More recently,
BODIPY dyes 4a-g (Scheme 1) bearing four thienyl substituents
with various moieties R at the α-position.
Scheme 1 The synthesis of 2,3,5,6-tetrathienyl functionalized BODIPY dyes 4a-g with
various peripheral groups.
Results and discussion
The synthetic route of the tetrathienyl-functionalized BODIPYs
is outlined in Scheme 1. The starting compound
synthesized by condensation of pyrrole and p-tolualdehyde
and subsequent BF2-chelation using BF3•Et2O. The iodination
a.School of Chemical Engineering and Technology, Tianjin University, Collaborative
Innovation Center of Chemical Science and Engineering, Tianjin 300072, China.
Tel: +86 02227405754; E-mail: zjchen@tju.edu.cn
1 was
b.Department of Chemistry, School of Sciences, Tianjin University
Electronic Supplementary Information (ESI) available: cyclic voltammograms, DFT
calculation results, 1H NMR and 13C NMR spectra of the dyes 4a
-g. See
DOI: 10.1039/x0xx00000x
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was performed using I2/HIO3 as a halogenating bathochromic shifts of λabs were observed for comVpieowuAnrtidclse O4nblinge
of BODIPY
1
-
reagent.24 It was observed that the 2,3,5,6-tetraiodinated relative to the 4a (R = H), reflecting electronic interactions
DOI: 10.1039/C6OB02612E
BODIPY
diiodinated and 2,3,6-triiodinated by-products (for 1H NMR, core.
see ESI). To increase the yield of dye , an optimized iodination
conditions with a larger excess of iodine (molar ratio
2 was formed together with small amount of 2,6- between the electron-donating substituents and the BODIPY
2
a)
C14
C13
I2/HIO3/dye 1= 20/4/1) and a longer reaction time of 12h in
comparison with the reported procedures24 was applied.
Under this condition, the yield of tetraiodo-substituted BODIPY
C15
C16
C12
C11
C24
S4
C1
S1
C10
S3
2
was increased up to 81%. Meanwhile, minor amount of
C18
C19
C20
S2
C4
C9
C17
C7
C2
C8
C23
C22
triiodinated by-product was separated in ca. 1% yield by silica-
gel column chromatography. The palladium-catalyzed Stille
C5
C6
C31
C25
C21
C3
N2
B1
C26
F1
N1
F2
cross-coupling reactions of BODIPY
2 with 2-tri(n-butyl)-
C32
C33
S5
stannylthiophenes bearing different α-substituents were
performed to give the corresponding 2,3,5,6-tetrathienyl
BODIPY derivatives 4a-g. All these compounds were purified by
column chromatography (20-85% yields) and characterized by
1H and 13C NMR, IR spectroscopy and high-resolution mass
spectrometry (see experimental section).
S7
C35
C27
C28
C29
S6
C34
C36
S8
C30
b)
For further verification of the structure of the tetrathienyl-
substituted BODIPYs, efforts have been devoted to the single
crystals growth of the dyes. Fortunately, the single crystal of
BODIPY 4e was obtained by solvent diffusion method and
analysed by X-ray diffraction crystallography. This dye
crystallizes in the monoclinic space group P21/c with four
molecules in one unit cell. The crystal structure reveals that
the dipyrromethene unit and the boron atom constitute a rigid
planar structure while the four thienyl units are located at the
2,3,5,6-positions of the ring system (Figure 1). The F-B-F plane
is nearly orthogonal with respect to the plane of BODIPY core.
Meanwhile, the phenyl ring at the meso-position displays a
dihedral angle associated with carbon atoms C8–C9–C10–C16
of 60.2° with respect to the BODIPY plane. In comparison, for
the BODIPY dyes with two methyl groups at the 1,7-positions,
this dihedral angle is near to 90°.25 Owing to the sterically
encumbered effect among the thienyls, the four thienyl units
are not co-planar with the BODIPY core. The dihedral angles
between the thienyl rings and the BODIPY core are in a range
of 33°-65°.
Figure 1 a) ORTEP view of BODIPY 4e. Displacement ellipsoids are drawn at the 50%
probability level. b) View along the B1-C9 axis.
1.0
4a
4b
4c
4d
4e
0.8
0.6
4f
4g
0.4
0.2
0.0
300
400
500
600
 / nm
700
800
The optical properties of the newly synthesized BODIPY dyes
4a-g were studied by UV/Vis and fluorescence spectroscopy.
Figure 2 Normalized Absorption spectra of BODIPYs 4a-g in dichloromethane.
The absorption spectra of these dyes are depicted in Figure 2
and the data are collected in Table 1. In comparison with the
2,3,5,6-tetramethyl-substituted BODIPY dye, the thiophene-
functionalized BODIPY dyes exhibit bathochromically shifted,
less structured and broader S0-S1 transition bands located
between 550 and 850 nm. Accordingly, the solutions of these
dyes exhibit a deep green colour. The full-width-at-half-
Table 1 Absorption and emission spectroscopic properties of yield of dyes 4a-g in
dichloromethane.
a
b
c
λabs
ε
/104M-1cm-1
5.0
ΔEop
λem
Φd
/ nm
630
654
659
683
666
681
696
/eV
1.67
1.56
1.58
1.47
1.52
1.51
1.47
/nm
689
720
722
-
4a
4b
4c
4d
4e
4f
0.16
0.037
0.045
-
-
0.019
-
5.0
5.1
4.9
4.8
5.3
4.8
maximum (FWHM) values for the S0-S1 bands of the dyes 4a
are in a range of 2000-3000 cm-1 whereas the FWHM for the
precursor , a second absorption
is 514cm-1. For dyes 4a
-g
-
1
-g
740
-
band was observed at around 450 nm, which could be
attributed to the electronic transition from the ground state to
a higher excited state (S0-S2).26 On the other hand, the
peripheral substituents at the α-position of thienyls display
pronounced effect on the wavelength of the absorption
maximum of the dyes. Bearing various α-substituents R,
4g
aIn CH2Cl2 (3.0 ×10-5 M).bOptical gap estimated from the absorption edge. cIn
CH2Cl2 (1.0 ×10-6 M, λex = 450 nm), dUsing zinc phthalocyanine (Ф = 0.30 in 1-
chloronaphthalene) as standard.
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The dyes 4a
-
c
, and 4f are fluorescent while no fluorescence for The HOMO and LUMO levels of the dyes 4a
-

g
were estimated
View Article Online
DOI: 10.1039/C6OB02612E
red
the other dyes can be detected in dichloromethane. As shown according to the formula LUMO =

4.78 eV
E
, HOMO =
1/2
in Figure 3, the emission bands of these dyes are

4.78 eV

E1/2ox, where the value of
 4.78 eV is the energy
approximately the mirror image of their S0-S1 absorption bands level of Fc/Fc+ with respect to vacuum level.28 The resultant
with Stokes shift between 1170 and 1400 cm-1. For the dyes LUMO, HOMO levels and the electrochemical gaps of the
4a
-
c
and 4f, the emission bands are located between 620-900 BODIPYs 4a
-
g
are shown in Table 2. The lowest
nm. On the other hand, the emission properties of the dyes electrochemical bandgap (1.55 eV) was observed dye 4d
.
are strongly influenced by the α-substituents of the thienyl
moieties. For dye 4a without α-substituents at thienyls, λem
=
689 nm is observed. By introducing electron-donating alkyl
groups at the α-position of thienyl, the emission maxima of
dyes 4b and 4c are bathochromically shifted ca. 50 nm in
comparison with that of 4a. Meanwhile, the fluorescence
quantum yield of dye 4b and 4c are significantly lower than
that of 4a. Bearing strongly electron-donating methoxyl and
methylthio groups, the fluorescence of BODIPYs 4d and 4e are
totally quenched. This fluorescence quenching may be caused
by intramolecular charge transfer (ICT) processes.27 In
accordance with this assumption, the fluorescence quantum
10 μA
4b
4d
yields of the dyes 4a-c and 4f are significantly improved upon
decreasing the solvent polarity (Table S2).
-2.0
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
E / V (v.s. Fc / Fc+)
4a
4b
4c
4f
1.0
0.8
0.6
0.4
0.2
0.0
Figure 4 Cyclic voltammogram of BODIPY 4b and 4d in CH2Cl2, the scan rate is 0.10 V s–1
.
Table 2 Electrochemical properties of dyes 4a-g
red
ox
c
E1/2
E1/2
HOMOb
/eV
LUMOb
/eV
ΔEel
/V
/V
/eV
1.83
1.73
1.75
1.55
1.62
1.72
1.64
4a
4b
4c
4d
4e
4f
-1.18
-1.21
-1.25
-1.24
-1.14
-1.15
-1.13
0.65a
-5.43
-5.30
-5.28
-5.09
-5.26
-5.35
-5.29
-3.60
-3.57
-3.53
-3.54
-3.64
-3.63
-3.65
0.52, 0.84a
0.50, 0.86a
0.31, 0.58a, 0.79a
0.48, 0.67a
0.57, 0.85a
0.51, 0.75a
600
650
700
750
800
850
4g
 / nm
a Irreversible process. bCalculated from E1/2ox / E1/2red using 4.78 eV as potential
for ferrocene, cΔEel = LUMO – HOMO.
Figure 3 Fluorescence spectra of BODIPYs 4a–c and 4f in dichloromethane.
The electrochemical properties of the thienyl-functionalized
BODIPYs 4a have been investigated by cyclic voltammetry
Furthermore, the electrochemical bandgaps ΔEel of the dyes
-
g
4a
1). The figure 5 shows that the data points of dyes 4a
4f
could be well fitted with a linear relationship (R2 = 0.92),
-
g
were correlated with the optical bandgaps ΔEop (see Table
(Figure 4 and S1) and the resultant redox potentials are
compiled in Table 2. For the BODIPYs 4a-g, reversible reduction
waves at half-wave potentials between –1.13 to –1.25 V vs.
Fc/Fc+ (Fc: Ferrocene) were detected. In comparison,
irreversible and less negative reduction potentials have been
-
c
and
,g
indicating that the α-substituents of these dyes have
comparable effects on both optical and electrochemical
reported for 3,5-dithienyl functionalized BODIPYs.21 For dye 4a
,
bandgaps. Nevertheless, for the dyes 4d
located below the line and obvious deviation from the linear
trend can be observed. Since the dyes 4d bear relatively
,e the data points are
an irreversible oxidation process was observed at 0.65 V. In
contrast, dyes 4b exhibit more than one oxidation waves. For
,
e
-
g
strong electron-donating moieties (-OCH3, -SCH3), this result
indicates that these strong electron-donating moieties (-OCH3,
-SCH3) are more effective on lowering the electrochemical
bandgaps of the dyes than the π-conjugated (phenyl, thienyl)
or alkyl substituents. Accordingly, the strong electron-donating
α-substituents of the thienyls have more impact on
these dyes, the first reversible oxidation waves were observed
at 0.31-0.57 V while the second irreversible oxidations were
observed at 0.67-0.86 V. The variation of the first oxidation
potentials of 4b-g could be ascribed to the electronic effect of
the groups at the α-position of thienyl substituents.
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electrochemical bandgaps of the dyes than their optical
bandgaps.
Experimental section
Materials
View Article Online
DOI: 10.1039/C6OB02612E
All the reagents and solvents were obtained from commercial
suppliers and purified and dried according to standard
R = H
1.85
1.80
1.75
1.70
1.65
1.60
1.55
1.50
4a
procedures. Methyl-5-[tri(n-butyl)-stannyl]-thiophene 3b 30
,
2-
R = C6H13
Hexyl-5-[tri(n-butyl)-stannyl]-thiophene 3c 31
,
2-Methoxy-5-
2-(Methylthio)-5-[tri(n-
2-Phenly-5-[tri(n-butyl)-
4c
[tri(n-butyl)-stannyl]-thiophene 3d 32
,
R =4f
butyl)-stannyl]-thiophene
3e 33
,
4b
stannyl]-thiophene 3f34 and 2-Thienyl-5-[tri(n-butyl)-stannyl]-
thiophene 3g35 ware prepared according to the literature
procedures.
R = CH3

4g
R =
4d
R = OCH3
General Methods
1H and 13C NMR spectra were recorded on a Bruker AV400
4e
R =SCH3
1
spectrometer. TMS was used as the internal standard for H
1.45
1.50
1.55
Eop / eV
1.60
1.65
1.70
NMR and a solvent signal (CDCl3, 77.16 ppm) was used as a
reference for 13C NMR. High-resolution mass spectra (HRMS)
were recorded on a Bruker ESI-Q/TOF mass spectrometer.
Infrared (IR) spectra were recorded on a Thermo Nicolet
Avatar 330 FT-IR spectrometer. Fluorescence spectroscopic
measurements were performed under ambient conditions on
a Hitachi F-4600 spectrofluorometer. All the fluorescence
spectra were corrected. The fluorescence quantum yields (Φ)
of the dyes were determined by using zinc phthalocyanine (Φ
= 0.30 in 1-chloronaphthalene)36 as standard. The given
quantum yield is the averaged value of data obtained at three
different excitation wavelengths.
Figure 5 The correlation between the electrochemical gap ΔEel and the optical gap ΔEop
The line was obtained by least-squares linear fitting of the data points for 4a-c and 4f-g.
.
For further elucidation of the observed optical and electronic
properties of the dyes, DFT calculation was performed at the
B3LYP/6-31G(d) level to evaluate the frontier molecular
orbitals of dyes 4a-g (Figure S2, Table S1). In comparison with
the HOMO and LUMO energy levels obtained by CV, all the
calculated energy levels are overestimated, which could be
attributed to the solvent effects that was neglected in
calculation.29 The obtained frontier molecular orbitals indicate
that the LUMOs of dyes are mainly localized at the
dipyrromethene core with a strong contribution of the pyrrole
nitrogen atoms. This is in agreement with the CV experimental
result that the reduction potentials of the dyes are only slightly
influenced by the α-substituents of thienyls.29 On the other
hand, the HOMOs of the dyes are extended over the
dipyrromethene π-system and the thienyl moieties. Moreover,
obviously more contribution of the thienyls at the 3,5-
positions of the BODIPY core than the substituents at the 2,6-
positions can be observed, implying that the 3,5-substituents
have stronger impact on the optical and electronic properties
of the dyes than the 2,6-substituents.
Cyclic voltammetry was performed with an Ivium potentiostat
in
a
three-electrode single compartment cell using
dichloromethane as solvent (20 mL). Working electrode:
platinum disk; counter electrode: platinum wire; reference
electrode: Ag/Ag+. All the given potentials were internally
referenced to the Fc/Fc+ couple. Tetrabutylammonium
hexafluorophosphate that was recrystallized twice from
ethanol/water and dried in a high vacuum was used as the
supporting electrolyte (0.1 M).
X-ray crystal structure analysis
The dark-green single crystals of BODIPY 4e were slowly grown
from a solution of the dye using mixed solvent (hexane /
dichloromethane, 3:1, v/v) at ambient conditions over two
weeks. The crystal investigated by XRD (crystal size 0.15 × 0.20
× 0.25mm) belongs to the monoclinic system with cell
parameters of a = 16.674(3) Å, b = 11.067(2) Å, c = 20.438(4) Å,
Conclusions
In summary, seven new thienyl-functionalized BODIPY dyes
were synthesized and characterized. These dyes bear four
thienyl moieties with various peripheral electron-donating (4b

= 90°,  = 117.38(3)°, 
= 90° and V = 3599.2(12) Å3. The
-
space group was P21/c and Z = 4. The empirical formula is
C36H29BF2N2S8 and the molar mass was 794.90. The calculated
density was 1.467 g cm-3. The three-dimensional X-ray data
were collected at 293(2) K with graphite-monochromated Mo
e
) or electronically conjugated (4f ) groups at the α-position,
-g
enabling a systematic study on the structure-properties
relationship of these compounds. The optical and
electrochemical studies of these dyes reveal a good tunability
of their properties by peripheral substituents, which lead to
optical absorption and emission reaching the NIR region.
Meanwhile, the observed strong effect of the α-substituents of
the thienyls on the electrochemical bandgaps as well as the
optical bandgaps of the dyes provides a useful guidance for the
further modification of this class of dyes.
K radiation ( = 71.073 pm) in the range min = 3.07° to max =
27.48°using R-axis rapid IP diffractometer. The intensity data
of 33711 independent reflections were collected, and 8145
unique reflections ( 0 > 2 0
I  I ) were solved by direct methods
and refined on F2 using the full matrix least-square methods of
SHELXL 97. No absorption correction was done. Hydrogen
atoms were calculated and included in the refinement. Non-
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hydrogen atoms were assigned anisotropic and hydrogen UV/Vis (CH2Cl2): λmax (ε) = 659 (51 000), 441 (13 000), 320 nm
View Article Online
DOI: 10.1039/C6OB02612E
atoms isotropic temperature factors, converging to a final R (20 000 M-1cm-1).
factor of 0.0801. The crystal structure data have been
4,4'-Difluoro-2,3,5,6-tetra-(5-methoxylthienyl)-8-(4-methyl
deposited with the Cambridge Crystallographic Data Center phenyl)-4-bora-3a,4a-diaza-s-indacene (4d). Yield: 55%; m.p.
1
and allocated the deposition number: CCDC 1519933.
245-248 °C; H NMR (CDCl3, 400 MHz, ppm): δ = 7.48 (d, J = 8
Hz , 2H), 7.40 (d, J = 4 Hz , 2H), 7.34 (d, J = 8 Hz , 2H), 6.80 (m,
2H), 6.51 (d, J = 4 Hz , 2H), 6.26 (d, J = 4 Hz , 2H), 6.08 (d, J = 4
General procedure for Pd-catalysed Stille Cross-Coupling reactions
BODIPY
2
(0.1 mmol, 79 mg), Compound 3a-g (0.4 mmol) and Hz , 2H), 3.94 (s, 6H), 3.87 (s, 6H), 2.49 (s, 3H); 13C NMR
Pd(PPh3)4 (0.04 mmol, 46 mg) were mixed in dry toluene (7 mL) (CDCl3,100 MHz, ppm): δ = 170.7, 166.7, 140.4, 134.9, 131.6,
under argon. The system was heated to 100°C and stirred 130.6, 129.1, 127.7, 124.5, 121.6, 117.4, 104.7, 104.0, 60.2,
overnight. After cooling to room temperature, water (10 mL) 60.1, 21.4; IR (KBr): 3098.2, 3010.1, 2932.2, 2825.3, 1608.4,
was added. Then the reaction mixture was extracted with 1554.5, 1517.9 1425.2, 1342.8, 1231.4, 1202.4, 1083.4, 908.4,
CH2Cl2 (20 mL × 3). After the solvent was evaporated under 873.2, 824.4, 756.5, 695.8, 613.8, 570.9 cm-1; HRMS (ESI):
reduced pressure, the crude material was purified by column calculated for C36H29BF2N2O4S4 [M + Na]+ 753.0952 m/z, found
chromatography (hexane/CH2Cl2= 2/1, v/v) to give the 753.0955 m/z; UV/Vis (CH2Cl2): λmax (ε) = 683 (49 000), 472 (14
products 4a-g
.
000), 325 nm (21 000 M-1cm-1).
4,4'-Difluoro-2,3,5,6-tetrathienyl-8-(4-methylphenyl)-4-
4,4'-Difluoro-2,3,5,6-tetra-(5-methylthiothienyl)-8-(4-methyl
bora-3a,4a-diaza-s-indacene (4a).Yield: 85%; m.p. 223-226 °C; phenyl)-4-bora-3a,4a-diaza-s-indacene (4e). Yield: 65%; m.p.
1
1H NMR (CDCl3, 400 MHz, ppm): δ= 7.53 (s, 4H), 7.49 (d, J = 4 247-251 °C; H NMR (CDCl3, 400 MHz, ppm): δ = 7.51 (d, J = 8
Hz, 2H), 7.37 (d, J = 8 Hz, 2H), 7.19 (d, J = 4 Hz, 2H), 7.09 (s, 2H), Hz , 2H), 7.47 (d, J = 4 Hz , 2H), 7.38 (d, J = 8 Hz , 2H), 7.03 (d, J
6.98 (s, 2H), 6.91 (s, 2H), 6.75 (s, 2H), 2.50 (s, 3H); 13C NMR = 8 Hz , 2H), 6.91-6.90 (m, 4H), 6.67 (d, J = 4 Hz , 2H), 2.56 (s,
(CDCl3,100 MHz, ppm): δ = 148.8, 143.9, 141.1, 135.3, 135.1, 6H), 2.52 (s, 3H), 2.47 (s, 6H); 13C NMR (CDCl3,100 MHz, ppm):
132.3, 131.1, 131.0, 130.7, 129.6, 129.3, 129.0, 128.1, 127.2, δ = 147.7, 143.5, 141.1, 137.7, 137.3, 135.2, 132.9, 131.7,
126.2, 125.5, 21.5; IR (KBr): 3104.4, 3078.8, 2951.6, 2916.0, 131.0, 130.6, 129.3, 129.1, 128.0, 126.8, 22.0, 21.5, 21.0; IR
1544.1, 1452.8, 1427.4, 1392.8, 1350.3, 1177.9, 1067.7, 987.6, (KBr): 3107.4, 3075.7, 2984.7, 2954.9, 2915.1, 2853.6, 1605.3,
848.6, 754.2, 700.1, 636.4 cm-1; HRMS (ESI): calculated for 1568.1, 1543.8, 1477.2, 1450.8, 1272.1, 1224.1, 1181.3, 1083.8,
C32H21BF2N2S4 [M + Na]+ 633.0605 m/z, found 633.0607 m/z; 988.3, 910.1, 875.9, 840.0, 799.84, 699.6, 640.8, 605.8 cm-1;
UV/Vis (CH2Cl2): λmax (ε) = 630 (50 000), 420 (14 000), 314 nm HRMS (ESI): calculated for C36H29BF2N2S8 [M + Na]+ 817.9301
(18 000 M-1cm-1).
4,4'-Difluoro-2,3,5,6-tetra-(5-methylthienyl)-8-
m/z, found 817.9332 m/z; UV/Vis (CH2Cl2): λmax (ε) = 666 (48
000), 472 (12 000), 336 nm (24 000 M-1cm-1).
(4methylphenyl)-4-bora-3a,4a-diaza-s-indacene (4b). Yield:
4,4'-Difluoro-2,3,5,6-tetra-(5-phenylthienyl)-8-(4-
1
76%; m.p. 231-233 °C; H NMR (CDCl3, 400 MHz, ppm): δ = methylphenyl)-4-bora-3a,4a-diaza-s-indacene (4f). Yield: 37%;
7.49 (s, 1H), 7.48 (s, 1H), 7.36 (s, 1H), 7.35 (s, 2H), 7.33 (s, 1H), m.p. 267-269 °C; 1H NMR (CDCl3, 400 MHz, ppm): δ = 7.64-7.54
6.85 (s, 2H), 6.76 (d, J = 4 Hz , 2H), 6.58 (s, 4H), 2.5 (s, 6H), 2.48 (m, 13H), 7.42 (d, J = 8 Hz, 2H), 7.39-7.31 (m, 13H), 7.17 (d, J =
(s, 3H), 2.42 (s, 6H); 13C NMR (CDCl3,100 MHz, ppm): δ = 148.7, 4 Hz, 2H), 7.02 (s, 2H), 6.82 (d, J = 4 Hz, 2H), 2.54 (s, 3H); 13C
144.6, 140.7, 140.0, 134.9, 133.2, 132.6, 131.4, 130.6, 129.2, NMR (CDCl3,100 MHz, ppm): δ = 148.8, 144.7, 144.3, 134.7,
128.9, 127.6, 126.2, 125.9, 125.5, 21.5, 15.5, 15.3; IR (KBr): 134.3, 134.1, 134.0, 133.9, 130.7, 130.3, 129.3, 128.9, 128.0,
3065.1, 3039.3, 2915.1, 2856.6, 2731.9, 2534.3, 1607.6, 1536.5, 127.5, 126.1, 125.6, 123.6, 123.4, 21.5; IR (KBr): 2955.2, 2924.7,
1404.1, 1329.9, 1275.7, 1233.3, 1084.8, 989.0, 878.1, 791.9, 2854.2, 1731.3, 1596.8, 1537.7, 1463.9, 1407.2,1378.0, 1178.7,
755.4, 700.4, 674.5 cm-1; HRMS (ESI): calculated for 1086.3, 986.5, 888.3, 798.3, 687.2 cm-1; HRMS (ESI): calculated
C36H29BF2N2S4 [M + Na]+ 689.1187 m/z, found 689.1185 m/z; for C56H37BF2N2S4 [M + Na]+ 937.1794 m/z, found 937.1797
UV/Vis (CH2Cl2): λmax (ε) = 654 (50 000), 436 (11 000), 318 nm m/z; UV/Vis (CH2Cl2): λmax (ε) = 681 (53 000), 466 (13 000), 348
(17 000 M-1cm-1).
(35 000), 292 nm (41 000 M-1cm-1).
4,4'-Difluoro-2,3,5,6-tetra-(5-hexylthienyl)-8-(4-methyl
4,4'-Difluoro-2,3,5,6-tetra-(5-thienylthienyl)bithienyl-8-(4-
phenyl)-4-bora-3a,4a-diaza-s-indacene (4c). Yield: 60%; m.p. methyl phenyl)-4-bora-3a,4a-diaza-s-indacene (4g). Yield: 20%;
1
227-230 °C; H NMR (CDCl3, 400 MHz, ppm): δ = 7.49 (d, J = 8 m.p. 275-277 °C; 1H NMR (CDCl3, 400 MHz, ppm): δ =7.55-7.52
Hz , 2H), 7.40 (d, J = 4 Hz , 2H), 7.33 (d, J = 8 Hz , 2H), 6.85 (s, (m, 4H), 7.39 (d, J = 4 Hz, 2H), 7.23-7.18 (m, 8H), 7.10 (d, J = 4
2H), 6.77 (d, J = 4 Hz , 2H), 6.56-6.55 (m, 4H), 2.80 (t, J = 7.6Hz, Hz, 2H), 7.01-6.96 (m, 8H), 6.73 (d, J = 4 Hz, 2H), 2.51 (s, 3H);
4H), 2.72 (t, J = 8.0 Hz, 4H), 2.48 (s, 3H), 1.67 (t, J = 8.0 Hz, 4H), 13C NMR (CDCl3, 100 MHz,ppm): δ = 149.1, 145.9, 142.0, 139.2,
1.60 (t, J = 8.0 Hz, 4H), 1.31-1.28 (m, 24H), 0.89-0.87 (m, 12H); 137.5, 137.2, 136.9, 134.1, 133.8, 131.1, 130.6, 129.6, 129.3,
13C NMR (CDCl3,100 MHz, ppm): δ = 150.7, 148.8, 140.6, 134.9, 128.7, 128.5, 128.4, 127.9, 127.8, 127.3, 125.1, 124.7, 124.6,
133.0, 132.3, 131.5, 130.6, 129.1, 128.7, 127.5, 126.0, 124.5, 124.4, 124.1, 124.0, 123.7, 123.5, 118.6, 118.5, 116.0, 114.0,
124.2, 31.6, 31.5, 31.3, 30.2, 30.1, 28.7, 22.6, 22.5, 21.5, 14.1; 21.5; IR (KBr): 3104.4, 3067.7, 2953.4, 2920.8, 2851.3, 1742.5,
IR (KBr): 3117.8, 3068.0, 2925.2, 2853.6, 1608.0, 1542.8, 1606.5, 1536.8, 1468.4, 1421.9, 1405.3, 1361.8, 1179.2, 1087.6,
1509.6, 1477.8, 1404.8, 1230.5, 1179.6, 1080.4, 984.1, 912.2, 988.2, 836.6, 793.7, 697.3 cm-1; HRMS (ESI): calculated for
878.8, 798.6, 761.5, 702.7 cm-1; HRMS (ESI): calculated for C48H29BF2N2S8 [M + Na]+ 962.0918 m/z, found 962.0915 m/z;
C56H69BF2N2S4 [M + Na]+ 969.4248 m/z, found 969.4242 m/z;
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J. Name., 2013, 00, 1-3 | 5
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Organic & Biomolecular Chemistry
Page 6 of 6
ARTICLE
Journal Name
Tamaru, S. Yamaguchi, Y. Matsuo, A. Saeki, S. Seki, Y.
UV/Vis (CH2Cl2): λmax (ε) = 696 (48000), 496 (12 100), 350 nm
View Article Online
(37 000 M-1cm-1).
Kureishi, S. Saito, S. Yamaguchi and H. Shinokubo, Org. Lett.,
DOI: 10.1039/C6OB02612E
2012, 14, 866–870. (d) J. Wang, Q. Wu, C. Yu, Y. Wei, X. Mu,
E. Hao and L. Jiao, J. Org. Chem., 2016, 81, 11316–11323.
21 A. Poirel, A. De Nicola and R. Ziessel, Org. Lett., 2012, 14
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,
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We are grateful to the National Natural Science Foundation of
China (Grant No. 21176184, No. 21676186) and the Tianjin
Research Program of Application Foundation and Advanced
Technology (Grant No. 15JCZDJC31400) for financial support.
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