Synthesis, spectroscopic characteristic of novel fluorescent dyes of pyrazoline compounds

Article abstract of DOI:10.1016/j.saa.2012.03.040

Four novel fluorescence dyes of the pyrazoline were synthesized and fully characterized by means of ¹H, ¹³C NMR, and HRMS. The optical, electrochemical properties were also investigated. Solvent effect on the fluorescence characteristics of the four compounds indicates that the emission wavelength was red-shifted with the increase of solvent polarity. As we expected, the results indicated that these compounds exhibited high quantum yields. Quantum chemical calculations were used to obtain optimized ground-state geometry, spatial distributions of the HOMO, LUMO levels of the compounds.

Full text of DOI:10.1016/j.saa.2012.03.040

Spectrochimica Acta Part A 93 (2012) 343–347
Contents lists available at SciVerse ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Synthesis, spectroscopic characteristic of novel fluorescent dyes of pyrazoline
compounds
Hai-Ying Wanga,b,∗, Xiao-Xiao Zhanga,b, Jing-Jing Shia,b, Gang Chenc, Xiao-Ping Xuc, Shun-Jun Jic
a Jiangsu Key Laboratory of Green Synthetic Chemistry for Functional Materials, Xuzhou Normal University, Xuzhou 221116, China
b School of Chemistry and Chemical Engineering, Xuzhou Normal University, Xuzhou 221116, China
c Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, China
a r t i c l e i n f o
a b s t r a c t
Four novel fluorescence dyes of the pyrazoline were synthesized and fully characterized by means of 1H,
13C NMR, and HRMS. The optical, electrochemical properties were also investigated. Solvent effect on
the fluorescence characteristics of the four compounds indicates that the emission wavelength was red-
shifted with the increase of solvent polarity. As we expected, the results indicated that these compounds
exhibited high quantum yields. Quantum chemical calculations were used to obtain optimized ground-
state geometry, spatial distributions of the HOMO, LUMO levels of the compounds.
Article history:
Received 19 December 2011
Received in revised form 7 March 2012
Accepted 10 March 2012
Keyword:
Synthesis
Optical
© 2012 Elsevier B.V. All rights reserved.
Electrochemical
Pyrazoline
Naphthalimide
Carbazole
1. Introduction
In our previous work, the photoluminescent (PL) proper-
ties of several dichromophore pyrazoline derivatives containing
Pyrazoline derivatives are fluorescent dyes, which are widely
used for the optical brightening of textile fiber, plastics and paper
[1]. Pyrazoline derivatives have not only excellent hole-transfer
performance but also excellent emitting blueness property [2,3].
The fluorescence properties of these pyrazoline derivatives were
reported by studying the effect of substituents on the absorption
and fluorescence properties [4–8]. In fact, substitution in position
5 is responsible for spiroconjugated charge transfer quenching of
pyrazoline fluorescence, whereas aryl units in positions 1 and 3
are essential to enhance fluorescence properties of the most useful
products [2c].
naphthalimide group were studied and founded to give green
fluorescence [15,16]. Those compounds exhibited strong lumines-
cence in solutions. Carbazole derivatives have been widely used
as hole-transporting materials in the fabrication of the organic
photoconductors, nonlinear optical materials, and photorefractive
materials due to their electron-donating capabilities [17,18]. So if
carbazole radical is linked to pyrazoline molecule, it would bring
an excelsior efficiency. Herein the new optical materials based on
naphthalimide pyrazoline incorporation of carbazole group have
been synthesized (Fig. 1) and the optical, electrochemical proper-
ties of these compounds were discussed.
Naphthalimide usually exhibits strong fluorescent emission on
irradiation, which usually acts as supermolecular moieties for
the study of photo-induced electron transfer [9,10], fluorescence
switcher [11] or liquid crystal displays [12]. Recently, naphthalim-
ide derivatives utilized as EL materials have been reported [13,14],
whose fluorescence emission can be widely tuned (from blue to
yellow, green and even red) with amino and alkoxy-groups at the
4-position of naphthalimide.
2. Experimental
2.1. Chemicals and instruments
All reactants were commercially available and used without fur-
ther purification. Melting points were recorded on Electrothermal
digital melting point apparatus and were uncorrected. 1H and 13
C
NMR spectra were recorded at 295 K on a Varian INOVA 400 MHz
or a Varian NMR System 300 MHz spectrometer using CDCl3 or d6-
DMSO as solvent and TMS as internal standard. UV–vis spectra were
recorded on a Shimadzu UV-2501PC spectrometer; fluorescence
spectra were obtained on an Hitachi FL-2500 spectrofluorimete;
Cyclic voltammetry were carried on a Chi 1200A electrochemical
∗
Corresponding author at: Jiangsu Key Laboratory of Green Synthetic Chemistry
for Functional Materials, Xuzhou Normal University, Xuzhou 221116, China.
Tel.: +86 516 83403163; fax: +86 516 83403163.
E-mail address: haiying11@163.com (H.-Y. Wang).
1386-1425/$ – see front matter © 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2012.03.040

344
H.-Y. Wang et al. / Spectrochimica Acta Part A 93 (2012) 343–347
Fig. 1. Synthetic routines for compounds.
analyzer with three-electrode cell (platinum was used as working
electrode and as counter electrode, and SCE as reference elec-
trode) at room temperature; HRMS data were measured using
TOF-MS(EI+) instrument.
7.80 (d, J = 8.6 Hz, 2H), 7.43–7.55 (m, 4H), 7.31 (d, J = 7.6 Hz, 1H),
4.32 (t, J = 7.0 Hz, 2H), 1.86–1.93 (m, 2H), 1.23–1.40 (m, 6H), 0.87 (t,
J = 7.0 Hz, 3H).
Compound 2d: Yield 94%, yellow. 1H NMR (400 MHz, CDCl3):
ı 8.34 (s, 1H), 8.08–8.16 (m, 2H), 7.92–7.93 (d, J = 3.6 Hz, 1H),
7.78–7.81 (d, J = 8.4 Hz, 1H), 7.67–7.68 (d, J = 4.8 Hz, 1H), 7.41–7.53
(m, 4H), 7.28–7.32 (t, J = 7.4 Hz, 1H), 7.20–7.22 (t, J = 4.2 Hz, 1H),
4.29–4.33 (t, J = 7.2 Hz, 2H), 1.85–1.92 (m, 2H), 1.25–1.40 (m, 6H),
0.85–0.89 (t, J = 6.8 Hz, 3H).
2.2. 9-hexyl-3-carbaldehyde (1)
9-hexyl-3-carbaldehyde was prepared according to the liter-
ature [19]. Phosphorus oxychloride (1.57 mL, 16.82 mmol) was
added dropwise to DMF (1.32 mL, 19.50 mmol) at 0 ◦C, and the
mixture was stirred for 1 h at this temperature. Carbazole (3.35 g,
13.33 mmol) was added and the reaction mixture was stirred at
100 ◦C for 6 h. Then, the mixture was cooled to room tempera-
ture, poured into ice water and carefully neutralized with sodium
hydroxide. The solution was extracted with dichloromethane (3×
150 mL), then, the organic phase was washed with water (2×
100 mL) and dried over anhydrous sodium sulfate. After filtration,
the solvent was removed. The crude product was purified by recrys-
tallization in ethanol.
2.4. General procedure for the synthesis of the compounds (3)
Compound 3 were synthesizsd by 2-hydrazinylnaphthalimide
with chalcones
2 as following procedure: a mixture of 2-
hydrazinylbenzothiazole (1.00 mmol) and chalcones 2 (1.00 mmol)
in EtOH (5.00 mL) and 37% HCl (0.20 mL) was refluxed for 6–12 h.
The resulting mixture was cooled down and the precipitates were
filtered to afford the crude products, which can be purified by
recrystallization in EtOH/THF (v/v = 1:1).
Compound 1: yield 90%, yellow. 1H NMR (CDCl3): ı 10.09 (s, 1H),
8.60 (s, 1H), 8.16 (d, J = 8.0 Hz, 1H), 8.01 (d, J = 8.0 Hz, 6H), 7.44–7.56
(m, 3H), 7.33 (t, J = 7.4 Hz, 1H), 4.32 (t, J = 7.2 Hz, 2H), 1.84–1.92 (m,
2H), 1.27–1.41 (m, 6H), 0.87 (t, J = 7.2 Hz, 3H).
Compound 3a: M.p.: 124–125 ◦C. yield 76%, red powder. 1H
NMR (400 MHz, CDCl3): ı 9.76 (d, J = 9.2 Hz, 1H), 8.63 (d, J = 7.2 Hz,
1H), 8.23 (d, J = 8.4 Hz, 1H), 7.98–8.07 (m, 2H), 7.71–7.83 (m, 3H),
7.28–7.52 (m, 7H), 7.16–7.20 (m, 1H), 6.91 (d, J = 8.4 Hz, 1H),
5.84–5.89 (m, 1H), 4.22 (t, J = 7.2 Hz, 2H), 4.09 (t, J = 7.6 Hz, 2H),
3.60–3.93 (m, 1H), 3.36–3.42 (m, 1H), 1.64–1.82 (m, 4H), 1.21–1.36
(m, 24H), 0.81–0.87 (m, 6H); 13C NMR (75 MHz, CDCl3): ı 165.0,
164.1, 152.1, 146.0, 141.0, 140.3, 134.7, 132.9, 132.6, 132.0, 131.5,
131.1, 130.9, 130.7, 130.0, 129.1, 126.5, 126.3, 124.9, 123.6, 123.5,
123.3, 122.6, 122.4, 120.6, 119.2, 118.0, 113.9, 111.0, 109.7, 109.1,
66.8, 43.3, 40.5, 32.1, 31.7, 29.8, 29.7, 29.6, 29.5, 29.1, 28.4, 27.4,
27.1, 22.9, 22.7, 14.4, 14.2;
2.3. General procedure for the synthesis of the chalcones (2)
The chalcones 2 were prepared according to the literature [20],
as following procedure: 9-hexyl-9H-carbazole-3-carbaldehyde 1
(2.79 g, 10.00 mmol) was dissolved in EtOH (50 mL). 15% NaOH
(2 mL) aqueous solution was added dropwise at 0 ◦C. Substitu-
tional acetophenone (10 mmol) was added and was stirred for 3 h
at ambient temperature. The reaction product was filtrated, dried
and recrystallized in EtOH.
HRMS [Found: m/z 758.4553 (M+), Calcd for C51H58N4O2: M,
758.4560].
Compound 2a: yield 86%, yellow. 1H NMR (CDCl3): ı 8.37 (s, 1H),
8.12–8.15 (m, 1H), 8.03–8.08 (m, 3H), 7.77–7.80 (m, 1H), 7.27–7.61
(m, 8H), 4.30 (t, J = 7.2 Hz, 2H), 1.87 (m, 2H), 1.27–1.39 (m, 6H), 0.86
(t, J = 7.2 Hz, 3H).
Compound 3b: M.p.: 164–165 ◦C. yield 63%, red powder. 1H NMR
(400 MHz, CDCl3): ı 8.62 (d, J = 7.2 Hz, 1H), 8.22 (d, J = 8.4 Hz, 1H),
8.06 (s, 1H), 8.02 (d, J = 7.6 Hz, 1H), 7.70–7.77 (m, 3H), 7.30–7.53
(m, 4H), 7.17–7.20 (m, 1H), 6.99 (d, J = 8.0 Hz, 2H), 6.87 (d, J = 8.8 Hz,
1H), 5.81–5.85 (m, 1H), 4.29–4.32 (m, 1H), 4.23 (t, J = 6.8 Hz, 2H),
4.10 (t, J = 7.0 Hz, 2H), 3.92–3.97 (m, 1H), 3.87 (s, 3H), 3.33–3.39 (m,
Compound 2b: yield 82%, yellow. 1H NMR (CDCl3): ı 8.36 (s, 1H),
8.08–8.14 (m, 3H), 8.04 (d, J = 15.2 Hz, 1H), 7.76–7.78 (m, 1H), 7.59
(d, J = 15.6 Hz, 1H), 7.28–7.51 (m, 4H), 6.99 (d, J = 8.8 Hz, 2H), 4.28
(t, J = 7.2 Hz, 2H), 3.89 (s, 3H), 1.83–1.90 (m, 2H), 1.26–1.38 (m, 6H),
0.86 (t, J = 7.2 Hz, 3H).
1H), 1.65–1.83 (m, 4H), 1.25–1.47 (m, 24H), 0.84–1.00 (m, 6H); 13
C
NMR (75 MHz, CDCl3): ı 160.4, 160.3, 159.5, 156.5, 147.5, 141.5,
136.3, 135.6, 130.3, 128.1, 126.8, 126.3, 126.2, 123.4, 121.6, 112.0,
118.8, 117.9, 117.7, 116.0, 114.5, 113.3, 112.4, 109.8, 108.7, 106.0,
Compound 2c: yield 92%, yellow. 1H NMR (CDCl3): ı 8.40 (s, 1H),
8.37 (d, J = 8.8 Hz, 2H), 8.14–8.20 (m, 3H), 8.09 (d, J = 15.6 Hz, 1H),

H.-Y. Wang et al. / Spectrochimica Acta Part A 93 (2012) 343–347
345
Table 1
Optical and electrochemical properties of the compounds 3.
a
c
d
Compound
Abs. (nm)
Em (nm)
˚
Band gapb
HOMO/LUMOb (eV)
Eg (eV)
Eox (V)
EHOMO/ELUMO (eV)
3a
3b
3c
3d
465
475
476
472
505
516
548
513
0.15
3.18
3.07
2.97
3.09
−5.31/−2.13
−5.12/−2.05
−5.62/−2.65
−5.23/−2.14
3.26
3.23
3.38
3.16
1.45
1.48
1.39
1.40
−5.85/−2.59
−5.88/−2.65
−5.79/−2.41
−5.80/−2.62
0.026
0.021
0.040
a
Quantum yields (˚) in CHCl3 solutions were determined using quinine sulfate (Ф= 0.55) as standard.
b
c
DFT/B3LYP calculated values.
Oxidation potential in DMF (10−3 M) containing 0.1 M (n-C4H9)4NPF6 with a scan rate of 100 mV s−1
EHOMO was calculated by Eox + 4.4 V (vs NHE), and ELUMO = EHOMO − Eg.
.
d
105.1, 104.4, 62.0, 51.0, 38.7, 35.8, 27.5, 27.1, 25.2, 25.0, 24.9, 24.8,
24.7, 24.5, 23.7, 22.8, 22.5, 18.3, 18.1, 9.7, 9.6;
0.20
0.15
0.10
0.05
0.00
3a
3b
3c
3d
HRMS [Found: m/z 788.4654 (M+), Calcd for C52H40N4O3:
M,788.4665].
Compound 3c: M.p.: 98–99 ◦C. yield 52%, red powder. 1H NMR
(400 MHz, CDCl3): ı 9.58 (d, J = 8.8 Hz, 1H), 8.66 (d, J = 7.2 Hz,
1H), 8.31 (d, J = 8.8 Hz, 2H), 8.25–8.28 (m, 1H), 8.00–8.10 (m, 2H),
7.91–7.94 (m, 2H), 7.76–7.80 (m, 1H), 7.32–7.47 (m, 4H), 7.16–7.21
(m, 1H), 7.02 (d, J = 8.4 Hz, 1H), 5.95–6.00 (m, 1H), 4.23 (t, J = 7.2 Hz,
2H), 4.10 (t, J = 7.6 Hz, 2H), 3.95–4.02 (m, 1H), 3.40–3.46 (m, 1H),
1.61–1.86 (m, 4H), 1.22–1.36 (m, 24H), 0.79–0.88 (m, 6H); 13C NMR
(75 MHz, CDCl3): ı 160.1, 159.3, 152.6, 151.8, 144.6, 143.3, 140.5,
136.4, 135.7, 133.6, 129.1, 127.6, 126.9, 126.0, 125.4, 124.7, 122.1,
121.8, 120.8, 119.8, 118.9, 118.2, 117.6, 115.9, 114.6, 113.4, 110.7,
107.5, 105.2, 104.5, 62.9, 38.7, 38.2, 38.1, 35.9, 35.8, 27.5, 27.1, 25.2,
25.1, 25.0, 24.9, 24.5, 23.7, 22.7, 22.5, 18.3, 18.1, 9.7, 9.6;
HRMS [Found: m/z 803.4427 (M+), Calcd for C51H57N5O4: M,
803.4411].
300
350
400
450
500
550
Wavelength / nm
Compound 3d: M.p.: 113–115 ◦C. yield 64%, red powder. 1H NMR
(400 MHz, CDCl3): ı 9.70 (d, J = 8.8 Hz, 1H), 8.62 (d, J = 7.2 Hz, 1H),
8.23 (d, J = 8.4 Hz, 1H), 8.06 (s, 1H), 8.02 (d, J = 7.6 Hz, 1H), 7.71–7.75
(m, 1H), 7.31–7.44 (m, 5H), 7.17–7.23 (m, 2H), 7.09–7.11 (m, 1H),
6.90 (d, J = 8.8 Hz, 1H), 5.85–5.90 (m, 1H), 4.23 (t, J = 7.2 Hz, 2H), 4.10
(t, J = 7.6 Hz, 2H), 3.93–4.00 (m, 1H), 3.36–3.43 (m, 1H), 1.57–1.85
(m, 4H), 1.22–1.36 (m, 24H), 0.82–0.88 (m, 6H); 13C NMR (75 MHz,
CDCl3): ı 160.3, 159.4, 143.2, 141.1, 136.4, 135.6, 134.2, 131.2,
123.0, 128.1, 127.9, 126.8, 126.2, 125.8, 123.6, 123.4, 123.2, 121.7,
120.3, 118.9, 118.8, 118.7, 117.9, 116.0, 114.6, 113.4, 109.2, 106.4,
105.1, 104.4, 62.4, 39.2, 38.7, 35.8, 27.3, 27.1, 25.2, 25.1, 25.0, 24.9,
24.5, 23.7, 22.8, 22.5, 18.3, 18.1, 9.7, 9.6;
Fig. 2. The absorption spectra of Compound 3a–d (1 × 10−5 mol L−1) in CH2Cl3.
may be possibly due to the introduction of naphthalimide unit at
the C-3 position in these compounds. As shown in Fig. 3, the emis-
sion peaks of 3a, 3b and 3d were at 505 nm, 516 nm, and 513 nm,
respectively, which may be possibly due to the different conjuga-
tion degree and different electron effect in these compounds. In the
case of 3c, the NO2 functional group with the electron-accepting
ability is introduced. As a result, the position of the maximum
emission peaks was red-shifted at 530 nm [2c].
The fluorescence quantum yields (Ф) were measured in CHCl3
using quinine sulfate (Ф= 0.55) as standard [22]. The Фvalue of 0.15
is observed for 3a, which is higher than that of other compounds.
The PL quantum yields of the other compounds are in the range of
0.021–0.040. This difference of quantum yields might be due to the
HRMS [Found: m/z 764.4124 (M+), Calcd for C49H56N4O2S: M,
764.4124].
3. Results and discussion
10000
3.1. Absorption and fluorescence spectra
TPP
The UV–vis absorption and photoluminescent (PL) properties of
compounds 3 in dilute solutions are presented in Table 1. As shown
in Fig. 2, these compounds exhibit two prominent bands in the solu-
tion, appearing at 336–352 nm and 464–476 nm, respectively. The
absorption peaks at about 336–352 nm are attributed to the absorp-
tion of the carbazole moiety; the absorption peak at 464–473 nm is
attributed to naphthalimide unit [9c]. The maximum absorption of
3c was located at 476 nm and the others appeared at 465–472 nm.
The red-shift phenomenon of 3c was due to the electron affinity.
There are slightly differences among these compounds, although
they are similar in the structure. Thus, these differences might be
result from different conjugation degree and electron effect in these
compounds [21].
8000
6000
4000
2000
0
3a
3b
3c
3d
Fig. 3 shows the fluorescence spectra for these compounds in
diluted toluene solutions. Compounds 3 present a blue emission
with the peaks varying from 505 nm to 548 nm. The difference in the
fluorescence spectra of 3 and 1,3,5-triphenyl-2-pyrazoline (TPP)
400
450
500
550
600
650
700
Wavelength / nm
Fig. 3. Fluorescence emission spectra of compounds 3a–d (1 × 10−5 mol L−1) in THF.

346
H.-Y. Wang et al. / Spectrochimica Acta Part A 93 (2012) 343–347
0.000015
10000
8000
6000
4000
2000
0
Toluene
0.000010
0.000005
THF
0.000000
-0.000005
-0.000010
-0.000015
DMF
-0.2 0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
500
550
600
650
E/V
Wavelength / nm
Fig. 5. Cyclic voltammetry of the compound 3a in 0.1 mol L−1 Bu4NPF6–CHCl3.
Fig. 4. The emission spectra of compound 3a in different solvents (1 × 10−5 mol L−1).
from −5.88 to −5.79 eV, while the LUMO ranges are from −2.65
to −2.41 eV, which are in agreement with the calculated values
(−5.62 to −5.12 eV for the HOMO, and −2.65 to −2.05 eV for the
LUMO of compounds), which were near the most widely used
hole-transport material 4,4ꢀ-bis(1-naphthylphenylamino)biphenyl
(NPB) (HOMO = −5.5 eV, LUMO = −2.4 eV) and therefore, these com-
pounds might be used as hole-transporting materials in OLEDs [24].
Therefore, these compounds might be used for hole-transporting
and electron-transporting materials for OLEDs [4].
change of the electronic push–pull substitution of the conjugated
part in the molecules [4].
Moreover, the solvent effect on the fluorescence characteristics
of these compounds was studied, which indicated that the emission
wavelength of the compound was red-shifted with the increase of
solvent polarity (Fig. 4) [6,7].
3.2. Electrochemical properties
The electrochemical properties of compounds 3 were analyzed
by cyclic voltammetry in CHCl3 in the presence of tetrabutylammo-
nium hexafluorophosphate (0.10 mol L−1) as supporting electrolyte
(Fig. 5) and the results are listed in Table 1. All CV measurements
were recorded at room temperature with a conventional three
electrode configuration consisting of a platinum wire working elec-
trode, a platinum counter electrode, and a SCE (saturated calomel
electrode) reference electrode under argon. Electrochemical band
gaps were calculated from onset potentials of the anodic and
cathodic waves [23]. The cyclic voltammetry (CV) of compounds
3 exhibit an reversible oxidation process which shift positively
from −1.48 to −1.39 V. As shown in Table 1, the HOMO ranges are
3.3. Theoretical calculation
The ground-state geometry of compounds were optimized by
hybrid densityfunctional theory (B3LYP) with 6-31G* basis set in
the Gaussian 03 program package [25] (Fig. 6). The dihedral angle
of 3 formed between the naphthalimide ring and a benzene ring of
carbazole is about 30 degree and the whole molecule takes a planar
configuration, which helps to impede the ␲–␲* stacking interaction
in solid state to some extent. Fig. 7 illustrates the calculated spatial
distributions of the HOMO (the highest occupied molecular orbital),
LUMO (the lowest unoccupied molecular orbital) levels with
Fig. 6. Optimized ground-state geometry of compounds with B3LYP/6-31G* in gas phase.

H.-Y. Wang et al. / Spectrochimica Acta Part A 93 (2012) 343–347
347
Fig. 7. Calculated spatial distributions of the HOMO, LUMO levels of compound 3a.
˝
compound 3a as sample. The theoretically predicted energy levels
are a little lower. The lower values than those estimated experi-
mentally may be related with various effects such as conformation
and salvation which were not taken into account. The HOMO/LUMO
energy levels and band gaps of the compounds are listed in Table 1.
[6] C. Albayrak, M. Odabasog˘lu, A. Ozek, O. Bu˝ ykgu˝ ngor, Spectrochim. Acta A 85
(2012) 85–91.
[7] Z.Y. Lu, Q. Jiang, W.G. Zhu, M.G. Xie, Y.B. Hong, X.H. Chen, Z.J. Wang, Synth. Met.
111 (2000) 465–468.
[8] X.H. Zhang, S.K. Wu, Z.Q. Gao, C.S. Lee, S.T. Lee, H.L. Kuong, Thin Solid Films 371
(2000) 40–46.
[9] (a) H. Tian, T. Xu, Y.B. Zhao, K.C. Chen, J. Chem. Soc. Perkin Trans. 2 (1999)
545–549;
4. Conclusions
(b) B. Liu, H. Tian, Chem. Commun. (2005) 3156–3158;
(c) P. Du, W.H. Zhu, Y.Q. Xie, F. Zhao, C.F. Ku, Y. Cao, C.P. Chang, H. Tian, Macro-
molecules 37 (2004) 4387–4398.
A series of new organic fluorescent dyes of pyrazoline com-
pounds have been synthesized. Their optical, electrochemical
properties are studied. As believed, these compounds showed
efficient emission from blue to green. Moreover, all of the com-
pounds exhibit suited HOMO ranges (−5.62 to −5.12 eV), which
have promising potential for application in OLEDs.
[10] J.M. Chovelon, I. Grabchev, Spectrochim. Acta A 67 (2007) 87–91.
[11] X. Poteau, A.I. Brown, R.G. Brown, C. Holmes, D. Matthew, Dyes Pigments 47
(2000) 91–105.
[12] I. Grabchev, I. Moneva, V. Bojinov, S.J. Guittonneau, J. Mater. Chem. 10 (2000)
1291–1296.
[13] K. Utsugi, S.J. Takano, J. Electrochem. Soc. 139 (1992) 3610–3620.
[14] Y. Chen, R. Wehrmann, A. Elschner, Ger Offen, DE19505942, 1996.
[15] B. Bing, S.J. Ji, H.B. Shi, Dyes Pigments 76 (2008) 348–352.
[16] G. Chen, H.Y. Wang, Y. Liu, X.P. Xu, S.J. Ji, Dyes Pigments 85 (2010) 194–200.
[17] (a) B. Liu, W. Yu, Y. Lai, W. Huang, Chem. Mater. 13 (2001) 1984–1991;
(b) C. Xia, R.C. Advincula, Macromolecules 34 (2001) 5854–5859;
(c) O. Stephan, J.C. Vial, Synth. Met. 106 (1999) 115–119;
(d) V. Promarak, M. Ichikawa, T. Sudyoadsuk, S. Saengsuwan, S. Jungsuttiwong,
T. Keawin, Synth. Met. 157 (2007) 17–22;
Acknowledgments
We are grateful to Dr. Xiao-peng Chen and Prof. Ping Lu in
Department of Chemistry of Zhejiang University for computational
assistance.
The work was partially supported by the foundation of the “Pri-
ority Academic Program Development of Jiangsu Higher Education
Institutions”, Key Basic Research Project in Jiangsu University (No.
10KJA430050), Nature Science of Jiangsu Province for Higher Edu-
cation (No. 11KJB150017), Natural Science Foundation of Xuzhou
Normal University (No. 10XLR19 and No. 09XLB05).
(e) J. Li, C. Ma, J. Tang, C.S. Lee, S.T. Lee, Chem. Mater. 17 (2005) 615–619;
(f) Q. Zhang, J. Chen, Y. Cheng, L. Wang, D. Ma, X. Jing, F. Wang, J. Mater. Chem.
14 (2004) 895–900;
(g) Z.J. Ning, H. Tian, Chem. Commun. (2009) 5483–5495;
(h) N.D. Mcclenaghan, R. Passalacqua, F. Liseau, S. Campagna, B. Verbeyde, A.
Hameurlaine, J. Am. Chem. Soc. 125 (2003) 5356–5365.
[18] (a) R. Kannan, Chem. Mater. 13 (2001) 1896–1904;
(b) W.R. Dichtel, J.M. Serin, C. Edder, J.M.J. Fréchet, M. Matuszewski, L.S. Tan,
T.Y. Ohulchanskyy, P.N. Prasad, J. Am. Chem. Soc. 126 (2004) 5380–5831;
(c) D.X. Cao, Q. Fang, D. Wang, Z.Q. Liu, G. Xue, G.B. Xu, W.T. Yu, Eur. J. Org.
Chem. (2003) 3628–3636;
References
(d) X.H. Zhang, O.Y. Wong, Z.Q. Gao, C.S. Lee, H.L. Kwong, S.T. Lee, S.K. Wu, Mater.
Sci. Eng. B 85 (2001) 182–185.
[1] (a) A. Wagner, C.W. Schellhammer, P.S. Petersen, Angew. Chem. Int. Ed. 5 (1966)
699–704;
[19] Y.B. Song, C.A. Di, Z.M. Wei, T.Y. Zhao, W. Xu, Y.Q. Liu, D.Q. Zhang, D.B. Zhu,
Chem. Eur. J. 14 (2008) 4731.
(b) F. Wilkinson, G.P. Kelly, C. Michael, D. Oelkrug, J. Photochem. Photobiol. A:
Chem. 52 (1990) 309–320.
[2] (a) B. Yang, Y. Li, C.X. Xu, Chem. Res. Appl. 15 (2003) 11–16;
(b) Y.C. Jiang, S.K. Wu, Acta Phys. Chim. Sinica 14 (1998) 1068–1074;
(c) X. Zhou, A.M. Ren, J.K. Feng, X.J. Liu, G.B. Yang, W.J. Tian, Opt. Mater. 27
(2004) 315–321.
[3] Z.H. Lu, Q. Jing, W.G. Zhu, M.G. Xie, Y.B. Hou, X.H. Chen, Z.J. Wang, D.C. Zou, T.
Tsutsui, Synth. Met. 111 (2000) 425–427.
[4] X.H. Zhang, W.Y. Lai, Z.Q. Gao, T.C. Wong, C.S. Lee, H.L. Kwong, Chem. Phys. Lett.
320 (2000) 77–80.
[20] S. Otto, F. Bertoncin, J.B.F.N. Engberts, J. Am. Chem. Soc. 118 (1996) 7702.
[21] Y.F. Sun, Y.P. Cui, Dyes Pigments 81 (2009) 27–34.
[22] Y. Qian, K. Meng, C.G. Lu, B.P. Lin, W. Huang, Y.P. Cui, Dyes Pigments 80 (2009)
174–180.
[23] Y. Liu, H.Y. Wang, G. Chen, X.P. Xu, S.J. Ji, Aust. J. Chem. 62 (2009) 934–940.
[24] (a) S. Janietz, D.D.C. Bradley, M. Grell, C. Giebeler, M. Inbaselatan, E.P. Woo, Appl.
Phys. Lett. 17 (1998) 2453–2455;
(b) J. Pommerehne, H. Vestweber, W. Guss, R.F. Mahrt, H. Bässler, M. Porsch, J.
Daub, Adv. Mater. 7 (1995) 551–554.
[25] M.J. Frisch, G.W. Trucks, H.B. Schlegel, P.M.W. Gill, B.G. Johnson, M.A. Robb,
Gaussian 03, Revision C, in: 01, Gaussian, Inc., Pittsburgh, PA, 2004.
[5] X.C. Gao, H. Cao, L.Q. Zhang, B.W. Zhang, Y. Cao, C.H. Huang, J. Mater. Chem. 9
(1999) 1077–1080.