A novel D-A-D-A-D type molecule based on substituted dihydroindolo [3, 2-b] carbazole with large two-photon absorption cross section and excellent aggregation-induced enhanced emission property

Article abstract of DOI:10.1016/j.tet.2015.11.047

Two novel D-A-D-A-D type molecules T1 and T2 based on substituted dihydroindolo [3, 2-b] carbazole with large two-photon absorption (2PA) cross section and excellent aggregation-induced enhanced emission (AIEE) property have been synthesized and characterized. Both compounds emit weakly fluorescent in THF, while a significant AIEE property is observed in water/THF (v/v 50%/50%) for T1 and water/THF (v/v 90%/10%) for T2 with a sharp increase in fluorescence intensity. The solid fluorescence of T1 and T2 is located at 575 nm and 588 nm, and their quantum efficiencies are determined to be 3.2% and 5.8%, respectively. The corresponding 2PA cross section values for T1 and T2 at 800 nm are 867 GM and 1300 GM by the open-aperture Z-scan technique. These excellent performances of both compounds make them as attractive alternatives for biophotonic and optoelectronic applications.

Full text of DOI:10.1016/j.tet.2015.11.047

Tetrahedron 72 (2016) 298e303
Contents lists available at ScienceDirect
Tetrahedron
journal homepage: www.elsevier.com/locate/tet
A novel D-A-D-A-D type molecule based on substituted
dihydroindolo [3, 2-b] carbazole with large two-photon absorption
cross section and excellent aggregation-induced enhanced emission
property
Guojian Tian a, Ning Xiang a, Haitao Zhou a, Yiru Li a, Bo Li b, Qiaochun Wang a,
,
Jianhua Su a
*
a Key Laboratory for Advanced Materials and Institute of Fine Chemicals, East China University of Science & Technology, Shanghai, 200237, PR China
b Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai, 200241, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Two novel D-A-D-A-D type molecules T1 and T2 based on substituted dihydroindolo [3, 2-b] carbazole
with large two-photon absorption (2PA) cross section and excellent aggregation-induced enhanced
emission (AIEE) property have been synthesized and characterized. Both compounds emit weakly
fluorescent in THF, while a significant AIEE property is observed in water/THF (v/v 50%/50%) for T1 and
water/THF (v/v 90%/10%) for T2 with a sharp increase in fluorescence intensity. The solid fluorescence of
T1 and T2 is located at 575 nm and 588 nm, and their quantum efficiencies are determined to be 3.2% and
5.8%, respectively. The corresponding 2PA cross section values for T1 and T2 at 800 nm are 867 GM and
1300 GM by the open-aperture Z-scan technique. These excellent performances of both compounds
make them as attractive alternatives for biophotonic and optoelectronic applications.
Received 20 September 2015
Received in revised form 28 October 2015
Accepted 16 November 2015
Available online 24 November 2015
Keywords:
Dihydroindolo [3, 2-b] carbazole
Two-photon absorption
Aggregation-induced enhanced emission
Quantum efficiency
Ó 2015 Published by Elsevier Ltd.
1. Introduction
highly efficient 2PA materials is restricted. So it is considerable to
investigate the 2PA dyes that can be soluble or dispersible in water
The two-photon absorption (2PA) materials have attracted sci-
entists to research the progressive field such as two-photon dy-
namic therapy, up-converted lasing,1 optical power limiting
materials, two-photon microscopy and bioimaging.2 Recently,
a series of novel organic fluorophores with large 2PA cross section
and remain highly fluorescent in aqueous media.6 Recently, Tang
and co-workers observed a phenomenon that some fluorophores
have enhanced emission in aggregation, namely aggregation-
induced emission (AIE). The inferential mechanism of AIE was re-
stricted intramolecular vibrational and rotational motions (RIR) in
the aggregated solid. This phenomenon had opened up a new av-
enue for the materials with large 2PA cross section.7 Prasad and co-
workers investigated some dyes with aggregation-enhanced fluo-
rescence and two-photon absorption properties.8 Tang and co-
workers also investigated some organic molecules and polymers
displaying 2PA and AIE properties. Our group also researched some
dyes with significant AIE and 2PA features.9
The triphenylamine and carbazole have been widely used in
optical and electroactive materials for their excellent electron-
donating and transporting capabilities.10 Due to their special mo-
lecular structure, the triphenylamine and carbazole have aroused
great interest and become the focus of progressive research in the
2PA field. Furthermore, cyano-substituted materials exhibit excel-
lent optical and electrical properties due to their favorable electron
affinities.11 In this work, taking it into consideration that extending
(s
) and good processability have been investigated.3 Its structure
include asymmetrical donor-
rical donor- -bridge-donor (D-
-bridge-acceptor- -bridge-donor (D-
p
-bridge-acceptor (D-
-D), and donor- -bridge-acceptor-
-A- -A- -D). The intra-
p-A), symmet-
p
p
p
p
p
p
p
p
molecular charge transfer from the donor to the accepter de-
termines the 2PA cross section. Moreover, the solvent polarity,
molecular coplanarity, and hydrogen-bonding can also fortify the
2PA cross section.4
Most 2PA dyes can be dissolved in organic solvent, while their
fluorescence will become weak in aqueous media, the reason is its
self-aggregation driven by limited solubility as well as
p-p in-
teractions.5 The biophotonic application in aqueous media for those
* Corresponding author. Tel./fax: þ86 21 6425 2288; e-mail address: bbsjh@
p-conjugation length largely and facilitating the effect of
ecust.edu.cn (J. Su).
http://dx.doi.org/10.1016/j.tet.2015.11.047
0040-4020/Ó 2015 Published by Elsevier Ltd.

G. Tian et al. / Tetrahedron 72 (2016) 298e303
299
intramolecular charge transfer efficiently would enlarge the 2PA
cross section, we introduce the substituted dihydroindolo [3, 2-b]
carbazole as the central donor to a novel D-A-D-A-D type molecule.
Combining the strong donating ability of the central donor and the
peripheral donor, the 2PA cross section will be enlarged largely.
Thus, these two compounds T1 and T2 (Fig. 1) with the substituted
dihydroindolo [3, 2-b] carbazole as the central donor, the di-
phenylamine and carbazole as the peripheral donor and the cyano
group as the accepter have been synthesized. In view of the effec-
tive intramolecular charge transfer (ICT) effect and the strong
electron-donating ability of these two dyes, excellent 2PA values
and favorable AIEE properties can be anticipated.
Scheme 1. The synthetic route of compounds T1 and T2.
3
T1
T2
Fig. 1. The molecular structures of T1 and T2.
2
1
0
2. Results and discussion
2.1. Synthesis
The synthetic routes of two compounds T1 and T2 are depicted
in Scheme 1. Both two molecules were prepared via Knoevenagel
condensation and Suzuki coupling reaction. The key intermediate
compound D-Br was synthesized according to the previous litera-
ture12 (ESIy). Both the final compounds were confirmed by proton
300
350
400
450
500
Wavelength/nm
Fig. 2. One-photon absorption of T1 and T2 in THF at a concentration of 1.0ꢀ10ꢁ5 M.
and carbon nuclear magnetic resonance spectroscopy (1H NMR, 13
NMR) and MALDI-TOF mass spectroscopy (MS).
C
disperse T1 and T2 in the primary way with adding different
amounts of water to the anhydrous THF solution and making the
water fraction (fw) at 0e90%. Fig. 3a showed the corresponding
emission spectra of T1 at a concentration of 1.0ꢀ10ꢁ5 M. When
fw<40%, the PL intensity of T1 was little changed, but, which be-
came dramatically increased from fw¼40% to fw¼50% and its
maximum was located at fw¼50%. When fw>50%, the PL intensity
became obviously quenched at the stage from fw¼50% to fw¼70%,
while which become increased from fw¼70% to fw¼90%. Appar-
ently, the emission of T1 was induced by aggregation, thus verifying
its AIEE attribute. The rotation of diphenylamine units against the
dihydroindolo [3, 2-b] carbazole core may effectively deactivate its
excited state to non-radiative, so the dye exhibited weak emission.
From fw¼40% to fw¼70%, the intramolecular rotation of the dye in
the aggregate condition was restricted, so the non-radiative decay
path was blocked, while the radiative decay path was activated,
thus making the dye to be a strong emitter.9
2.2. One-photon absorption
The one-photon absorption of T1 and T2 in THF was shown in
Fig. 2, the absorption maxima (lmax) of which were located at
398 nm, 397 nm, respectively. The lmax of both compounds was
similar, which can be reasoned that the electron-donating ability of
the central donor was stronger than that of the peripheral donor. So
the whole electron-donating ability of both compounds was
similar.
2.3. AIEE properties
The compounds T1 and T2 could dissolve in common organic
solvents such as dichloromethane and THF, except water. Anhy-
drous THF and water were used to compose the mixture solution
and to explore the AIEE attributes of T1 and T2. The method to

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G. Tian et al. / Tetrahedron 72 (2016) 298e303
A similar phenomenon was observed for T2. The weakest PL
intensity was at fw¼20%, the PL intensity was changed similarly
with T1, which reached its maximum with a 200-fold increase in
the I/I0 ratio when the fw¼90%. Both the compounds exhibited AIEE
feature with their strongly enhanced yellow and deep yellow
fluorescence emissions.15
2.4. Optical properties of the solids
To quantitatively evaluate the AIEE effect of the fluorescent
materials, the emission spectra and quantum efficiencies (VF) of
the solid powders were measured. Both dyes exhibited intense
emission peaks at 575 nm and 588 nm, respectively. The VF values
were determined to be 3.2% and 5.8% for T1 and T2. The AIEE at-
tribute was also confirmed by the vivid images of the solid powers
(Fig. 5).16
Fig. 3. (a, d) The PL spectra of T1 and T2, in different water fractions (fw); Exci-
tation wavelength: 403 nm(T1), 402 nm(T2). (b, e) Plots of (I/I0) values versus
water content of the solvent mixture for T1 and T2, where I0 is the PL intensity in
fw¼0% and fw¼20%, respectively. (c, f) Absorptions of T1 and T2 in THF and water
where fw¼0%, fw¼50% and fw¼20%, fw¼90% at
a
concentration of 1.0ꢀ10ꢁ5 M,
respectively.
Fig. 5. The solid powder emission spectra of T1 and T2; Excitation wavelength:
403 nm(T1), 402 nm(T2). Insert images were T1 and T2 as solid powders under 365 nm
light illumination.
Moreover, the emission of the aggregation was blue-shifted
compared with that of the dye in the solution due to the dye
crystallization in the solid film.13 Fig. 3c showed the absorption of
T1 when fw¼0% and fw¼50%. Compared with the fluorescence
intensity, the absorption spectra of T1 were red-shifted and
2.5. Two-photon absorption properties
widened due to the nano-aggregated state of the molecule.14
A
According to previously described method, the 2PA cross
sections of T1 and T2 were determined by using femtosecond
open-aperture Z-scan technique.9 Fig. 6 (a and c) showed the
quantitative graph of the AIEE attribute could be work out by
measuring the change of the PL spectra with different fw. As for
T1, the fluorescence reached its maximum when the fw was 50%,
while the weakest fluorescence was 0% with a 142-fold reduction
in the I/I0 ratio (Fig. 3b). Fig. 4(b, T1) showed the scanning
electron microscopy (SEM) image of T1. It showed that a nano-
aggregated structure has formed in the mixture with high wa-
ter content.
data fitting of the open-aperture Z-scan. The 2PA cross section (
s)
can be calculated by the equation of
s
¼hnb/N0, in which N0¼NAC
is the number density of the absorption centers, NA is the Avo-
gadro constant and C represents the solute molar concentra-
tion.17 The values of the 2PA at the wavelength of 800 nm for T1
and T2 were 867 GM and 1300 GM in chloroform, respectively. In
view of the solvent effect exerting an influence on the 2PA cross
section, the values of the 2PA for T1 and T2 were further tested in
dichloromethane, which were 570 GM and 739 GM in Fig. S1
(ESIy), respectively. The value in chloroform was bigger than
that in dichloromethane and which confirmed the significant
influence of the solvent effect on the 2PA cross section.18 With
the increase of the solvent polarity and the more pronounced ICT
effect in the excited state, larger changes were generated by
solvent stabilization. The correlation between the solvent effect
and the 2PA cross section value may be related to the solute-
solvent interactions, solubility and the solvent polarity.19 When
introducing the substituted dihydroindolo [3, 2-b] carbazole into
the molecule as the core donor to make a D-A-D-A-D type mol-
ecule structure, the electron-donating ability of the molecule
Fig. 4. (a, c) The one-photon fluorescence (OPF) emission photos of 1.0ꢀ10ꢁ5 M of T1
and T2, respectively, in different ratios of water and THF; Excitation wavelength:
365 nm; (b, d) The SEM images of T1 and T2 nano-aggregates prepared in fw¼50% (T1)
and fw¼90% (T2) at a concentration of 1.0ꢀ10ꢁ5 M.
became strong and the
p-conjugated system became extended,
so the values of the 2PA for T1 and T2 were bigger than that of
reported molecules.9a,d,e

G. Tian et al. / Tetrahedron 72 (2016) 298e303
301
2.6. Electrochemical properties
The electrochemical properties of both compounds were in-
vestigated by cyclic voltammetry. The energy level parameters of T1
and T2 were listed in Table 1. The cyclic voltammograms of T1 and
T2 was showed in Fig. S2 (ESIy) with measured in CH2Cl2 (0.1 M
TBAPF6 as supporting electrolyte), an SCE reference electrode (the
ferrocene/ferrocenium (Fc/FþC ) redox couple as external standard),
platinum-button working electrodes, and a platinum-wire counter
electrode. Onset oxidation potentials of T1 and T2 could be calcu-
lated from Fig. S2 (ESIy) to be 1.16 and 0.82 eV, respectively, and the
corresponding HOMO values were ꢁ5.86 and ꢁ5.52 eV.23 The band
gaps of T1 and T2 could be determined from their onset absorption
wavelengths and their values could be calculated to be 2.55 and
2.66 eV, respectively.
Table 1
Electrochemical and optical properties of T1 and T2a
Compound Eonset-ox (V) HOMO (eV) lonset (nm) Eg (eV) LUMO (eV)
T1
T2
1.16
0.82
ꢁ5.86
ꢁ5.52
486
467
2.55
2.66
ꢁ3.31
ꢁ2.86
a
Abbreviation: Eonset-ox¼onset oxidation potential measured by cyclic
voltammetry, HOMO¼highest occupied molecular orbital derived by the equation:
HOMO¼-e(Eonset-oxþ4.7) (eV), lonset¼onset absorption wavelength, Eg¼energy band
Fig. 6. (a, c) The open-aperture Z-scan trace of T1 and T2 (scattered cir-
cles¼experimental data, straight line¼theoretical fitted data) in CHCl3. (b, d) At
800 nm excited, the TPF emission spectra of T1 and T2 in the solution 0%: 50% (v/v
gap
determined
form
lonset
,
LUMO¼lowest
unoccupied
molecular
water/THF) (T1) and 20%: 90% (v/v water/THF) (T2) at
a concentration of
orbital¼EgþHOMO.
1.0ꢀ10ꢁ5 M.
3. Conclusions
As the electron-donating ability of diphenylamine was stron-
ger than that of carbazole, while the value of the 2PA for T2 was
bigger than that of T1, which seems to be contrary to the general
conclusion that the 2PA cross section of the dye increased with its
electron-donating ability.20 This phenomenon was possibly re-
lated to the interaction of the central donor based on the
substituted dihydroindolo [3, 2-b] carbazole and the peripheral
donor based on diphenylamine and carbazole, the other reason
may be the effect of its measured wavelength on the 2PA cross
section. Due to the limit of our laser apparatus and just measured
at 800 nm, more experiments need to be conducted to see if the
2PA cross section of T1 was larger than that of T2 at other wave-
In summary, we have synthesized two novel D-A-D-A-D type
molecules T1 and T2 based on substituted dihydroindolo [3, 2-b]
carbazole with large 2PA cross sections and excellent AIEE prop-
erties. The values of 2PA cross section at 800 nm are 867 GM and
1300 GM, respectively. Their one- and two-photon absorption
properties, aggregation-induced enhanced emission effect and
electrochemical properties have been investigated. The in-
troduction of the central donor enhances the electron-donating
ability and facilitates the intramolecular charge transfer effect,
resulting in a considerable increase in the value of 2PA cross sec-
tion. The study on molecule structure-property relationships will
be helpful in designing novel chromophores with AIEE and 2PA
properties.
lengths. This suggested that the strategy of extending
p-conju-
gated system and increasing the ICT between the donor and the
acceptor was an effective approach for enhancing the 2PA cross
section of the molecules.21 Thus, we could control the value of 2PA
cross section to some degree by simply introducing different do-
nors or acceptors.
4. Experimental
4.1. Instruments
To examine the aggregation effect of the dye on the two-
photon activity, the two-photon fluorescence (TPF) was
employed to investigate the TPF intensity in different aggrega-
tions. Under the excitation of an 80 fs, 800 nm pulse, T1 and T2
emit deep yellow and yellow fluorescence with peaks located at
619 nm and 616 nm, respectively (Fig. 6b and d), in a mixture of
THF and water (T1, fw¼0% and fw¼50%; T2, fw¼20% and fw¼90%).
Compared with the one- and two-photon excitation fluorescence,
the good overlap between them indicated that the emissions
resulted from the same excited state, regardless of the different
mode of excitation.22 The two-photon emission images in dif-
ferent water fractions (fw) of solution were showed in Fig. 6 (b
and d). For T1, no emission was observed at fw¼0%, while the
dyes irradiated deep yellow emission at fw¼50% at 800 nm. This
phenomenon was also observed for T2, weak emission at fw¼20%
and strong yellow emission at fw¼90%. The same phenomenon
had also been seen in the one-photon emission images (Fig. 3a
and d).
The UV/Vis spectra were recorded on a Nicolet CARY 100 spec-
trophotometer. The PL spectra were taken on a Varian-Cary fluo-
rescence spectrophotometer. Elemental analyses were measured
by German elementar vario EL III. The cyclic voltammograms of
dyes were obtained from a Versastat II electrochemical workstation
(Princeton applied research) with the conventional three electrode
configuration as working electrode, a Pt wire counter electrode, and
a regular calomel reference electrode in saturated KCl solution. The
supporting electrolyte was 0.1 M TBAPF6 in CH2Cl2. The scan rate
was 100 mV sꢁ1. The quantum yields of the solid powders were
measured using a Quanta-4 F-3029 Integrating Sphere. 1H and 13
C
NMR spectra were measured on a Bruker AM-400 spectrometer
using d-chloroform as a solvent and tetramethylsilane (TMS,
d
¼0 ppm) as an internal standard. The 2PA cross section was
measured by femtosecond openaperture Z-scan technique
a
according to a previously described method. The TPF was achieved
using femtosecond pulses with different intensities at a wavelength

302
G. Tian et al. / Tetrahedron 72 (2016) 298e303
of 800 nm. The repetition rate of the laser pulses was 250 kHz and
the pulse duration was 80 fs.
using compound 2b and bis(pinacolato)diboron. 1H NMR (CDCl3,
400 MHz, TMS)
d
: 8.15 (dd, J¼11.2, 6.0 Hz, 4H), 7.82 (t, J¼6.0 Hz, 2H),
7.76 (m, 4H), 7.57 (t, J¼7.2 Hz, 2H), 7.45 (m, 10H), 7.31 (m, 6H), 1.35
4.2. Materials
(m, 12H).
2,2’-((5,11-dihexyl-6,12-diphenyl-5,11-dihydroindolo
[3,2-b]
All reagents that we have used in the process were obtained
from J&K Chemical Co., which were received without further pu-
rification. The solvent THF and DMF were disposed by primary
procedures before use. The key intermediate compound was syn-
thesized according to the previous literature.12
carbazole-2,8-diyl)bis(4,1-phenylene))bis(3,3-bis(4-(diphenyla-
mino)phenyl)acrylonitrile) (T1): In a one-neck flask, compound 3a
(208 mg, 0.3 mmol), compound D-Br (73 mg, 0.1 mmol) were dis-
solved in 20 mL THF, then put 6 mL saturated sodium bicarbonate
solution and 5 mg Pd(dppf)Cl2 into the mixture. The mixture was
refluxed and stirred for 8 h under N2 atmosphere, upon cooling
down to r.t., poured the mixture into water and extracted with
CH2Cl2 (15 mLꢀ3), dried the combined organic layer over anhy-
drous MgSO4 and concentrated using a rotary evaporator. The
residue was purified by column chromatography on silica (petro-
leum ether/CH2Cl2¼2: 1 v/v) to give an orange solid (155 mg).
4.3. Synthesis
Bis(4-(diphenylamino)phenyl)methanone(1a): In a three-neck
flask, diphenylamine (3.4 g, 20 mmol) and potassium tertbut-
oxide (3.4 g, 30 mmol) were dissolved in 100 mL anhydrous DMF,
the bis(4-fluorophenyl)-methanone (2.2 g, 10 mmol) was slowly
dropped into 30 mL anhydrous DMF solution. The reaction mixture
was refluxed for 10 h under N2 atmosphere, when the mixture was
cooled and then poured into 200 mL ice water, then a deep yellow
solid precipitate was filtered off and washed with ethanol. Re-
crystallization from ethanol could to obtain a 3.6 g yellow solid.
Yield: 68.2%. 1H NMR (DMSO-d6, 400 MHz, TMS)
d: 7.66 (d,
J¼8.0 Hz, 4H), 7.39 (t, J¼8.0 Hz, 16H), 7.32 (s, 4H), 7.29 (d, J¼3.2 Hz,
4H), 7.26 (d, J¼7.8 Hz, 6H), 7.15 (d, J¼8.0 Hz, 16H), 7.09 (s, 2H), 7.06
(d, J¼8.0 Hz, 4H), 7.01 (d, J¼7.8 Hz, 8H), 6.97 (s, 2H), 6.95e6.91 (m,
8H), 6.75 (d, J¼8.6 Hz, 4H), 6.66 (d, J¼8.4 Hz, 2H), 3.45 (s, 1H), 3.44
(d, J¼2.0 Hz, 2H), 3.42 (s, 1H), 1.24 (m, 8H), 1.07e1.04 (m, 10H),
Yield: 79.0%. 1H NMR (CDCl3, 400 MHz, TMS)
d
: 7.74 (m, 4H), 7.35
0.87e0.84 (m, 4H). 13C NMR (CDCl3, 100 MHz, TMS)
d: 146.97,
(m, 8H), 7.22 (m, 8H), 7.14 (m, 4H), 7.02 (d, J¼8.8 Hz, 4H).
146.88, 132.36, 131.50, 130.17, 129.49, 129.41, 126.74, 125.60, 125.30,
124.00, 123.91, 123.88, 120.88, 120.74, 120.64, 114.38, 108.81, 108.49,
107.19, 30.64, 29.63, 28.50, 19.55, 19.08, 15.82. MALDI-TOF: [M]
calcd for C132H106N8: 1802.8540, found: 1802.8486. Anal. Calcd for
Bis(4-(9H-carbazol-9-yl)phenyl)methanone(1b): Compound 1b
was synthesized by the same procedure as described above for 1a
using bis(4-fluorophenyl)methanone and carbazole. 1H NMR
(CDCl3, 400 MHz, TMS)
d
: 8.18 (dd, J¼8.0, 3.2 Hz, 8H), 7.80 (d,
C
132H106N8: C, 87.87; H, 5.92; N, 6.21. Found: C, 87.63; H, 5.85; N,
6.15%.
2,2’-((5,11-dihexyl-6,12-diphenyl-5,11-dihydroindolo
J¼8.4 Hz, 4H), 7.57 (d, J¼8.2 Hz, 4H), 7.48 (m, 4H), 7.37 (m, 4H).
2-(4-Bromophenyl)-3,3-bis(4-(diphenylamino)phenyl)acryloni-
trile (2a): Compound 1a (2.0 g, 3.9 mmol), 60% NaH (0.6 g,
15.5 mmol) were put into a three-neck flask and dissolved into
50 mL dry toluene, dropped slowly 2-(4-bromophenyl) acetonitrile
(0.8 g, 3.9 mmol) in 50 mL dry toluene into the mixture over 1 h.
The mixture was refluxed for 10 h under N2 atmosphere, upon
cooling down to r.t., poured the mixture into water and extracted
with CH2Cl2 (50 mLꢀ3), dried the combined organic layer over
anhydrous MgSO4 and concentrated using a rotary evaporator. The
residue was purified by column chromatography on silica (petro-
leum ether/CH2Cl2¼4: 1 v/v) to give a yellow solid (1.8 g). Yield:
[3,2-b]
carbazole-2,8-diyl)bis(4,1-phenylene))bis(3,3-bis(4-(9H-carbazol-
9-yl)phenyl)acrylonitrile) (T2): Compound T2 was synthesized by
the same procedure as described above for T1 using compound 3b
and compound D-Br. 1H NMR (CDCl3, 400 MHz, TMS)
d: 8.16 (dd,
J¼13.6, 7.8 Hz, 8H), 7.85 (d, J¼8.4 Hz, 4H), 7.76 (d, J¼8.4 Hz, 4H), 7.69
(d, J¼6.0 Hz, 6H), 7.65 (d, J¼2.4 Hz, 4H), 7.62 (s, 2H), 7.60e7.55 (m,
8H), 7.48 (m, 6H), 7.44 (d, J¼7.8 Hz, 8H), 7.38 (s, 4H), 7.32 (t,
J¼8.2 Hz, 12H), 6.85e6.80 (m, 2H), 6.76 (s, 2H), 6.53 (d, J¼8.2 Hz,
2H), 3.85e3.80 (m, 4H), 1.31 (m, 8H), 1.12e1.09 (m, 10H), 0.86e0.88
(m, 4H). 13C NMR (CDCl3, 100 MHz, TMS)
d: 140.44, 140.33, 132.52,
80.1%. 1H NMR (DMSO-d6, 400 MHz, TMS)
d
: 7.52 (d, J¼8.6 Hz, 2H),
132.36,131.77,130.52,130.06,129.08,129.00,128.85,126.73,126.58,
126.38, 126.16, 126.13, 126.10, 123.72, 122.88, 120.48, 120.43, 118.23,
109.97, 109.72, 31.47, 31.44, 28.79, 26.34, 22.56, 14.04. MALDI-TOF:
[M] calcd for C132H98N8: 1794.7914, found: 1794.7905. Anal. Calcd
for C132H98N8: C, 88.26; H, 5.50; N, 6.24. Found: C, 88.12; H, 5.41; N,
6.19%.
7.36 (dd, J¼15.2, 8.0 Hz, 10H), 7.21 (m, 10H), 7.05 (d, J¼8.0 Hz, 4H),
6.92 (d, J¼8.8 Hz, 2H), 6.88 (d, J¼8.6 Hz, 2H), 6.75 (d, J¼8.8 Hz, 2H).
3,3-Bis(4-(9H-carbazol-9-yl)phenyl)-2-(4-bromophenyl)acrylo-
nitrile (2b): Compound 2b was synthesized by the same procedure
as described above for 2a using compound 1b and 2-(4-
bromophenyl)acetonitrile. 1H NMR (CDCl3, 400 MHz, TMS)
d: 8.16
(t, J¼7.2 Hz, 4H), 7.82 (d, J¼8.4 Hz, 2H), 7.73 (d, J¼8.6 Hz, 2H), 7.55
Acknowledgements
(dd, J¼13.2, 8.4 Hz, 4H), 7.46 (m, 8H), 7.31 (m, 8H).
3,3-Bis(4-(diphenylamino)phenyl)-2-(4-(4,4,5,5-tetramethyl-
1,3,2-dioxaborolan-2-yl)phenyl)acrylonitrile (3a): In a one-neck
flask, compound 2a (2.0 g, 2.9 mmol), bis(pinacolato)diboron
(1.1 g, 4.3 mmol), KAc (0.9 g, 8.6 mmol) and Pd(dppf)Cl2 (10 mg)
were dissolved into 50 mL anhydrous dioxane. The mixture were
heated to 80 ꢂC and stirred for 10 h under N2 atmosphere, upon
cooling down to r.t., poured the mixture into water and extracted
with CH2Cl2 (30 mLꢀ3), dried the combined organic layer over
anhydrous MgSO4 and concentrated using a rotary evaporator. The
residue was purified by column chromatography on silica (petro-
leum ether/CH2Cl2¼3: 1 v/v) to give a yellow solid (1.6 g). Yield:
This work was supported by National Natural Science Founda-
tion of China (20772031), the National Basic Research 973 Program
(2006CB806200).
Supplementary data
Supplementary data associated with this article can be found in
the online version, at http://dx.doi.org/10.1016/j.tet.2015.11.047.
References and notes
71.2%. 1H NMR (CDCl3, 400 MHz, TMS)
d: 7.65 (d, J¼8.4 Hz, 2H), 7.29
(m, 12H), 7.16 (d, J¼7.6 Hz, 4H), 7.06 (dd, J¼17.2, 8.4 Hz, 10H), 6.80
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