Synthesis and photophysical processes of an anthracene derivative containing hole transfer groups

Article abstract of DOI:10.1016/j.saa.2010.10.009

A novel luminescent compound 9,10-di-(N-carbazovinylene)anthracene (DCVA) was synthesized by Heck reaction of 9,10-dibromoanthracene and N-vinylcarbazole. The structure was characterized by MS, ¹H NMR and Elemental analysis. The photoluminescent properties of DCVA have been carefully investigated by UV-vis absorption and fluorescence emission spectra. The results showed that the luminescent quantum yield of DCVA was 0.73 in THF and it emitted blue-light with the band gap of 3.60 eV estimated from the onset absorption. In addition, the light-emission of DCVA can be quenched by electron acceptor (dimethyl terephthalate), however, the fluorescent intensities of DCVA were slowly increased with the addition of electron donor (N,N-dimethylaniline). Furthermore, the molecular interactions of DCVA with fullerene (C₆₀) and carbon nanotubes (CNTs) were also investigated, which indicated the organic luminescent compound can be used as new fluorescent probe.

Full text of DOI:10.1016/j.saa.2010.10.009

Spectrochimica Acta Part A 78 (2011) 294–297
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis and photophysical processes of an anthracene derivative containing
hole transfer groups
a
b,∗
Haipeng Diao , Liheng Feng
a
Department of Chemistry, Shanxi Medical University,Taiyuan 030001, PR China
School of Chemistry and Chemical Engineering, Shanxi University, Taiyuan 030006, Shanxi, PR China
b
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 8 July 2010
Received in revised form
A novel luminescent compound 9,10-di-(N-carbazovinylene)anthracene (DCVA) was synthesized by
Heck reaction of 9,10-dibromoanthracene and N-vinylcarbazole. The structure was characterized by MS,
H NMR and Elemental analysis. The photoluminescent properties of DCVA have been carefully investi-
gated by UV–vis absorption and fluorescence emission spectra. The results showed that the luminescent
quantum yield of DCVA was 0.73 in THF and it emitted blue-light with the band gap of 3.60 eV estimated
from the onset absorption. In addition, the light-emission of DCVA can be quenched by electron accep-
tor (dimethyl terephthalate), however, the fluorescent intensities of DCVA were slowly increased with
the addition of electron donor (N,N-dimethylaniline). Furthermore, the molecular interactions of DCVA
with fullerene (C60) and carbon nanotubes (CNTs) were also investigated, which indicated the organic
luminescent compound can be used as new fluorescent probe.
1
2
0 September 2010
Accepted 1 October 2010
Key words:
Synthesis
Anthracene
Photophysics
Carbazole
©
2010 Elsevier B.V. All rights reserved.
1
. Introduction
interactions of DCVA with electron donor or electron acceptor have
been carefully studied. Moreover, the molecular interactions of
DCVA with excellent semiconductor materials such as fullerene
(C60) and carbon nanotubes (CNTs) were also carefully investigated.
The results showed that the photo-functional molecule DCVA was
blue-light emission material for organic light emitting diodes.
Organic light emitting diodes (OLEDs) have intrigued many
researchers owing to their handing color turning and potential
for application in display devices than inorganic semiconductors
[
1–3]. To date, although a great number of luminescent compounds
which can be used for the OLEDs have been synthesized and inves-
tigated, the search for new compounds that possess the combined
desirable properties, such as high brightness and luminescent effi-
ciency, good film-forming properties, remains a big challenge in
this area [4,5]. It is still urgent to design and synthesis lumines-
cent organic compounds with high photoluminescence efficiency,
excellent charge transport ability and film-forming property [6–8].
Anthracene has a blue emission and high fluorescence quantum
yield and has been wildly applied as a photoluminescent com-
pound in the fields of diode and battery [9]. Carbazole is not only an
excellent hole-transfer molecule but also a blue-emission material
with high luminescent efficiency. Introduced carbazole group to
the compound consisting anthracene can give a well luminescent
moiety which can contribute to the luminescent material [10,11].
Herein, our job combined anthracene and carbazole in one
molecular and synthesis the following compound, DCVA, with
blue emission and high fluorescence quantum yield unit and hole-
transfer unit. The optical properties were investigated by UV–vis
absorption and fluorescence emission spectra. Additionally, the
2
. Experimental
2.1. Materials and measurements
All the solvents were of analytic grade. Melting point was
determined on a Sanyo Gallenkamp MPD350 melting point appa-
ratus and melting point was uncorrected. 1H NMR was measured
on a Bruker ARX300 spectrometer with chemical shifts reported
as ppm (in DMSO, TMS as an internal standard). Mass spectra
were measured on a JEOL GC-MS D300 spectrometer. Elemental
analyses were performed on a Vario EL elemental analysis instru-
ment (Elementar Co.). Absorption and fluorescence spectra were
recorded on a Varian Cary 300 absorption spectrophotometer and
a Hitachi F-4500 fluorescence spectrophotometer. Both excitation
and emission bands were set at 10 nm. All the experiments were
carried out at room temperature. The synthetic routes used are
shown in Scheme 1.
2
2
.2. Synthesis
.2.1. Synthesis of 9,10-dibromoanthracene
9
,10-Dibromoanthracene was synthesized according to the
∗ Corresponding author. Tel.: +86 3517011600; fax: +86 3517011688.
E-mail addresses: lhfeng@sxu.edu.cn, zbchen@sxu.edu.cn (L. Feng).
method previously reported [12].
1
386-1425/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2010.10.009

H. Diao, L. Feng / Spectrochimica Acta Part A 78 (2011) 294–297
295
H O
r.t
Bu NBr
4
+
V O
2
2
Bu NBr
2
5
4
3
TBATB
Br
Br
Bu NBr
4
3
CH COOH/r.t 30min
3
Br
Br
Pd(PPh ) Cl
3
2
2
N
+
2
CH COONa
3
N
N
[
BMIM]BF4
Scheme 1. The synthetic route of DCVA.
2
(
.2.2. Synthesis of 9,10-di-(N-carbazovinylene)anthracene
DCVA)
The solution of Pd(OAc)2 0.056 g (0.25 mmol) and PPh3 0.262 g
3.3. Quantum yield of photoluminescence and the band gap
The photoluminescent quantum yield of DCVA was measured
by relative method using the quinine sulfate as the standard (0.546
in 0.5 mol/L H SO ) [13]. The quantum yield was calculated from
◦
(
3
1.0 mmol) as catalyst in 20 mL [BMIM]BF4 was stirred at 80 C for
0 min under nitrogen atmosphere and then cooled to room tem-
2
4
perature. A mixture of 9,10-dibromoanthracene 0.84 g (2.5 mmol),
N-vinylcarbazole 1.05 g (5 mmol), and anhydrous sodium carbon-
ate 0.4 g (5 mmol) was added. After stirred at 110 C for 24 h, the
mixture solution was extracted by 50 mL ether for 5 times. The
organic solution was washed with water saturated solution of NaCl
the following equation:
ꢀ
ꢁ
2
◦
Fs Ar nr
˚ = ˚
s
r
Fr As ns
In the above expression, ˚ is the fluorescent quantum yield, F is
s
and dried over MgSO . Removal of the solvent in vacuo to give
the integration of the emission intensities, n is the index of refrac-
4
a yellow solid and purified by column chromatography on silica
gel with petroleum ether:ethyl acetate (4:1) as the elutant to give
slightly yellow crystals of 9,10-di-(N-carbazovinylene)anthracene
tion of the solution, and A is the absorbance of the solution at the
exciting wavelength. The subscripts r and s denote the reference
and unknown samples, respectively. The value of quantum yield of
◦
1
opt
(
7
DCVA) in 58.8% yield, m.p. 167–168 C. H NMR(d-DMSO, ppm) ı:
.26–8.10 (m, 28H); MS (EI, m/z): 560 (M ), 368 (C14H16N); Ele-
DCVA in THF was 0.73. The band gap (Eg ) of the complex can be
+
opt
estimated from the onset absorption (UVonset) with E
(eV) = hc/ꢀ
g
mental analysis: Calcd (%) for C42H28N2 (560.69) C, 89.97; H, 5.03.
Found: C, 89.12; H, 4.86.
−34
J s, c = 3 × 10 nm/s, 1 eV = 1.602 × 10−19 J). The
17
(h = 6.626 × 10
band gap of DCVA was 3.60 eV.
3
.4. The interactions of DCVA with dimethyl terephthalate
3
. Results and discussion
(
DMTP) and N,N-dimethylaniline (DMA)
3.1. The synthesis of DCVA
The fluorescence quenching technique was a helpful method
for the study of the mechanism of molecular interaction, energy
transfer or charge transfer. Dimethyl terephthalate (DMTP) was
a typical electron acceptor and N,N-dimethylaniline (DMA) was a
typical electron donor. As seen in Fig. 2, when DMTP was added to
a solution of DCVA in THF, the fluorescence of DCVA was efficiently
The luminescent compound DCVA was synthesized by Heck
reaction of 9,10-dibromoanthracene and N-vinylcarbazole.
Although this is a well-established method for C–C bond for-
mation, but the contents of catalyst, reaction temperature and
reaction medium have a significant influence on the Heck reaction.
It has been found by experiment that the appropriate ratio of
Pd(OAc)2 to PPh3 is 1:4 (mol), which can successfully form the
◦
400
reactive catalyst. The suitable reaction temperature is 110–120 C.
ab
em
Noticeably, the reaction yield is more two times in [BMIM]BF4
than in common solvents such as DMF, DMSO, etc.
3
2
1
00
00
00
0
3
.2. UV–vis absorption and fluorescence emission spectrum
Fig. 1 shows the UV–Vis absorption spectra of DCVA in dilute
THF solution. The maximum UV–Vis absorption peak of DCVA was
75 nm with shoulder peak 240 nm, which was similar with the
2
absorption spectra of N-vinylcarbazole and it should mainly come
from N-vinylcarbazole unit absorption. Meantime, the fluorescence
emission peak of DCVA was 433 nm with shoulder peak 410 nm that
also rooted in the emission peak of N-vinylcarbazole. Based on the
fluorescent emission wavelength, the DCVA was a potential blue
emission material compound.
250
300
350
400
450
500
Wavelength/nm
Fig. 1. UV–vis absorption and fluorescence emission spectra of DCVA
1.68 × 10−5 M) in THF.
(

2
96
H. Diao, L. Feng / Spectrochimica Acta Part A 78 (2011) 294–297
4
3
2
1
00
00
00
00
0
900
7
6
50
00
4
0
0
7
450
3
1
00
50
0
400
420
440
460
480
500
520
400
420
440
460
480
500
Wavelength/nm
Wavelength/nm
Fig. 2. Fluorescence spectra of DCVA at different concentrations of DMTP. Con-
Fig. 4. Fluorescence spectra of DCVA at different concentrations of DMA. Concentra-
tion of DCVA, 1.80 × 10−5 M; concentration of DMA (mol/L, M), 0, 0.00; 1, 5.12 × 10−6;
−5
centration of DCVA, 1.50 × 10 M; concentration of DMTP (mol/L, M): 0, 0.00;
, 7.14 × 10 ; 2, 2.13 × 10−6; 3, 4.96 × 10−6; 4, 8.97 × 10 ; 5, 2.65 × 10 ; 6,
−
7
−6
−5
2, 1.58 × 10−6; 3, 9.24 × 10−6; 4, 1.22 × 10−5.
1
8
.16 × 10− ; 7, 1.27 × 10
5
−4
.
C60 related to electron transfer phenomena is that it can efficiently
induce a rapid charge separation and a further slow charge recom-
bination [14]. In the experiment, the interactions of DCVA with C60
were examined. The results were shown in Fig. 5. As we have seen
quenched and the quenching process followed the Stern–Volmer
equation: F /F = 1 + Ksv[Q], where F0 is the initial unquenched fluo-
0
rescence, F is the fluorescence in the presence of quencher, Ksv is the
static quenching coefficient, and [Q] is the quencher concentration
−5
in Fig. 5, ‘0’ was DCVA in concentration (1.68 × 10 M) without
(
1
as shown in Fig. 2). The apparent quenching coefficient, Ksv, was
.13 × 104 M (as shown in Fig. 3). The quenching process of DCVA
C
6
, ‘1–7’ were DCVA in the present with different concentrations
0
−1
of C60. With the gradual increasing of concentration of C60, the flu-
orescence of DCVA was quenched efficiently and the process was
also following the Stern–Volmer equation (Fig. 6). The apparent
with DMA was also examined and shown in Fig. 4. It can be seen
that the fluorescence emission intensity of DCVA was increased
with gradual adding of DMA in THF, which was obviously differ-
ent phenomenon with DMTP adding to DCVA solution. From the
experimental facts and references, an explanation is possible rea-
sonable: N,N-dimethylaniline (DMA) is a rich electron group, while
carbazole group is an hole transfer body, so the strong interac-
tion between DMA and carbazole happens when DMA is gradually
added into the solution of DCVA. The DMA molecule is associated
by carbazole unit and the charge of DMA may then be transferred
to DCVA, which would lead to increasing of fluorescence intensity
of DCVA that are released from the actions of intramolecular or
intermolecular carbazole units.
4
−1
quenching constant was 1.85 × 10 M , which suggests that the
strong interactions between DCVA and C60 happen in the excited
state. This can be explained by two reasons. Firstly, both DCVA
and C60 have a large ␲-conjugated system in which ␲–␲ inter-
action may change the configuration of DCVA [15]. Secondly, the
photo-induced charge transfer from excited DCVA to C60 was rapid.
Upon this charge transfer the conjugated system may be dramati-
cally modified and distorted because of the strong electron–lattice
interaction in the one-dimensional system [16].
3.6. Interaction between DCVA and carbon nanotubes (CNTs)
3.5. Interaction between DCVA and fullerene (C60)
The investigation on the interaction between DCVA and carbon
nanotubes (CNTs) was helpful to understand the optical property
of DCVA and apply it to LEDs. The interaction between them in
diluted solutions was examined by fluorescence spectrophotome-
Many researches show C60 bears many unusual electrochemical
and electronic properties. One of the most remarkable properties of
3
2
2
2
1
1
.2
.8
.4
.0
.6
.2
4
3
00
00
0
200
7
1
00
0
400
420
440
460
480
500
520
0
2
4
6
8
10
12
14
Wavelength/nm
-
5
Concentration of DMTP (10 M)
Fig. 5. Fluorescence spectra of DCVA at different concentrations of C60. Concentra-
−
5
−5
−6
;
Fig. 3. Dependence of F0/F on the concentration of DMTP. [DCVA]: 1.50 × 10 M;
F0 is fluorescent intensity of DCVA without DMTP and F is fluorescent intensity of
DCVA in the present with different concentrations of DMTP.
tion of DCVA, 1.68 × 10 M; concentration of C (mol/L, M), 0, 0.00; 1, 2.36 × 10
6
0
2, 1.31 × 10−5; 3, 2.85 × 10−5; 4, 3.44 × 10−5; 5, 6.21 × 10−5; 6, 1.42 × 10−4; 7,
2.16 × 10−4.

H. Diao, L. Feng / Spectrochimica Acta Part A 78 (2011) 294–297
297
cated that the intense interaction of DCVA and CNTs in excited state
was happened [17]. Due to the different space structures and opti-
cal properties of CNTs and C60, the quenching interaction of C60 to
DCVA was stronger than CNTs in dilute solution. Further research
towardabetter understandingofthis actionis currently inprogress.
5
4
3
2
1
4. Conclusions
A novel luminescent compound DCVA containing anthracene
blue-emitting photoluminescent group and carbazole hole trans-
port group was designed and synthesized. The optical research
showed the absorption had two absorptions peaks (275 nm,
240 nm) and the emission was located at 433 nm and 410 nm in
THF. The luminescence quantum yield was 0.73 in THF. The light-
emitting can be quenched by electron acceptor and the quenched
processes followed the Stern–Volmer equation. The molecular
interactions of DCVA with fullerene (C60) and carbon nanotubes
both happened in the excited state. It can be anticipated that DCVA
will have a potential application as an emitting blue-light material.
0
5
10
15
20
25
-5
Concentration of C60 (10 M)
−
5
Fig. 6. Dependence of F0/F on the concentration of C60. [DCVA]: 1.50 × 10 M; F0 is
fluorescent intensity of DCVA without C60 and F is fluorescent intensity of DCVA in
the present with different concentrations of C60.
Acknowledgements
500
400
300
200
100
0
The present work is supported by Natural Science Foundation of
China (20802042) and Shanxi Province Natural Science Foundation
of China (2009021006-1).
0
7
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