Synthesis and optical properties of novel fluorescence-traced benzimidazolium bromides

Article abstract of DOI:10.1002/jhet.1819

Seven novel fluorescence-traced 1-aryl-2-substituted-3-allyl-1H- benzimidazolium bromides (5a, 5b, 5c, 5d, 5e, 5f, 5g) were synthesized by alkylation and quaternization of compounds 1-aryl-2-substituted-1H- benzimidazoles (4a, 4b, 4c, 4d, 4e, 4f, 4g) with excess allyl bromide in acetonitrile at refluxing temperature. Their structures were characterized by ¹H-NMR, MS, and elemental analysis. They emit violet-blue light (λ^Em_max = 386-438 nm) with fluorescence quantum yields of 0.54 to 0.75 in aqueous solution.

Full text of DOI:10.1002/jhet.1819

August 2014
Synthesis and Optical Properties of Novel Fluorescence-Traced
Benzimidazolium Bromides
E71
Hong Shi,a,b Tao Wu,a Peng Jiang,a Xiaodong Jin,a and Hongjun Zhua,c
*
aDepartment of Applied Chemistry, College of Science, Nanjing University of Technology, Nanjing 210009, People’s
Republic of China
bTeaching and Research Department, Jiangsu College of Information Technology, Wuxi 214153, People’s Republic of
China
cJiangsu Key Laboratory of Industrial Water-Conservation and Emission Reduction, Nanjing 210009, People’s Republic
of China
*
E-mail: zhuhjnjut@hotmail.com
Received March 23, 2012
DOI 10.1002/jhet.1819
Published online 17 April 2014 in Wiley Online Library (wileyonlinelibrary.com).
Seven novel fluorescence-traced 1-aryl-2-substituted-3-allyl-1H-benzimidazolium bromides (5a–g) were
synthesized by alkylation and quaternization of compounds 1-aryl-2-substituted-1H-benzimidazoles
(4a–g) with excess allyl bromide in acetonitrile at refluxing temperature. Their structures were characterized
by 1H-NMR, MS, and elemental analysis. They emit violet-blue light (lEmmax = 386–438nm) with fluorescence
quantum yields of 0.54 to 0.75 in aqueous solution.
J. Heterocyclic Chem., 51, E71 (2014).
INTRODUCTION
received much attention in the past few decades for their
intense luminescence and high fluorescence quantum effi-
ciency. They are widely used as fluorescent probes [8,9],
fluorescent brightening agents [10], and nonlinear optical
materials [11,12]. They also bear electron withdrawing
imine nitrogen (C═N) moieties, which behave as electron-
accepting molecules that can facilitate electrochemical
reduction, a feature that renders them suitable electron
carriers [13].
As we know, phenyl rings, triphenyl amino, and carbazole
can increase the conjugated degree of the molecule. Also,
triphenyl amino and carbazole are famous organic light-
emitting diode (OLED) materials because of their high
fluorescence quantum efficiency [14] and good hole-
transporting abilities [15]. In this study, a series of novel
fluorescence-traced benzimidazolium bromides (5a–g)
containing the substituted groups previously mentioned was
designed and synthesized (Scheme 1). The photophysical
properties of these compounds were also investigated.
The fluorescent tracer technique is an effective means to
detect the residual quantity of water treatment agent [1].
Compared with other techniques of measurement, it has
the advantages of high sensitivity, low detection limit,
and multiple spectroscopy parameters [2,3]. Nowadays,
synthesis and application of fluorescent water treatment
agents are the front line of water treatment field, and the
key to this technique is to synthesize the water treatment
agent with improved fluorescence properties.
Previous studies indicate that various heterocyclic
compounds could be used as fluorescent tracer, such as
naphthazine [4], acridine [5], pyrazoline [6], and benzoxazine
[7]. The common characteristics of these compounds are the
strong absorptions in both near ultraviolet and far infrared
regions, as well as their relatively high fluorescence
quantum efficiencies. Benzimidazole-based compounds
are such kinds of heterocyclic compounds that have
© 2014 HeteroCorporation

E72
H. Shi, T. Wu, P. Jiang, X. Jin, and H. Zhu
Vol 51
Scheme 1. The molecular structures and synthetic route of 5a–g.
RESULTS AND DISCUSSION
The UV–vis absorption spectra of compounds 5a–g in
aqueous solution (10À5 M) are displayed in Figure 1. Their
photophysical properties are summarized in Table 2.
The lowest energy absorption bands are from the p–p*
transitions by virtue of their large molar extinction
coefficients (e ꢁ 104 MÀ1 cmÀ1). All seven compounds
showed strong absorptions, with maximum wavelengths
in the range of 280–343 nm (lAmbaxs). The increase in
conjugation length and the increased electron density
associated with carbazolyl groups in 5f and triphenylamine
groups in 5g lead to a large bathochromic shift of absorp-
tion maximum. Ethyl and n-butyl had almost no influence
on absorption maxima.
The emission spectra of 5a–g in aqueous solution
(10À8 M) are shown in Figure 2. The fluorescence properties
of the compounds are also summarized in Table 2. All the
compounds emitted violet-blue light with a maximum
emission in the 386–438-nm range. The variation of N-alkyl
side chains did not have any significant effects on the emission
maximum, indicating that fluorescence emission originate from
the benzimidazolium backbone and 2-substituted groups.
Compared with 5c and 5e, 5c was blue-shifted by 5 nm,
whereas 5e was red-shifted by 8 nm. This observation may
be due to the electron-withdrawing effect of the bromine
atom substituted in phenyl ring [19,20].
The synthesis of compounds 5a–g is outlined in Scheme 1.
Compounds 3a, 3c, and 3e were synthesized by the conden-
sation of 1a–c with o-phenylenediamine (OPDA) using air
as oxidizing agent, and compounds 3b and 3d were synthe-
sized by the condensation of 2d and 2e with OPDA using
phosphoric acid and polyphosphoric acid as activator; the
synthetic route is outlined in Scheme 2. By alkylation reac-
tions of the 2-substituted benzimidazoles (3a–e) with ethyl
bromide or n-butyl bromide as electrophilic reagent [16],
compounds 4a–g were obtained. The yields were all 90%
above. Compounds 5a–g were synthesized by alkylation
and quaternization of compounds 4a–g with excess allyl
bromide in acetonitrile at refluxing temperature [17,18]. The
1H-NMR spectra, MS spectra, and elemental analysis
confirmed the proposed structures.
Compounds 5a–g are found to have melting points
higher than 310ꢀC. In order to seek a better reacting
condition, the effect of solvents on the yields was studied
for comparison, and the results are listed in Table 1. For
acetone, methanol, and ethyl acetate as solvent, the yields
were lower. This is because the boiling points of the three
solvents are not high to meet the needs of the reaction.
Because compounds of 5a–g are soluble in ethylene
glycol monomethyl ether and DMF, the yields are still
unsatisfactory. Compared with all of these solvents,
acetonitrile is the best one.
The fluorescence quantum yields (ΦF) of these com-
pounds in aqueous solution were determined by the standard
method (using quinine sulfate as the standard) [21]. The
fluorescence quantum yields were in the range from 0.54 to
0.75, as can be seen from Table 2. Comparing 5b with 5c
and 5d with 5e, it is noted that their fluorescence quantum
Because the fluorescent tracer technique is used widely in
water treatment fields, it is important to study and discuss the
optical properties of these compounds in aqueous solution.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

August 2014
Synthesis and Optical Properties on Novel Fluorescence-Traced Benzimidazolium Bromides
E73
Scheme 2. The synthetic route of 3a–e.
Table 1
Effect of solvent on the yields.
Solvent
Acetone
22.7
Ethyl acetate
20.5
Ethylene glycol monomethyl ether
67.1
Acetonitrile
93.0
DMF
77.4
Methanol
23.9
Yield (%)
yields increase with the extension of the N-alkyl side chains.
These results indicated that large side chains provide the
benzimidazolium backbone better protection from the
effect of the solvent molecules or other benzimidazolium
molecules [22].
CONCLUSION
In summary, a new series of fluorescence-traced
benzimidazolium bromides were synthesized and character-
ized. Acetonitrile is the best solvent that could lead to higher
yields while synthesizing. The optical properties studied on
UV–vis absorption and fluorescence emission spectroscopy
showed that N-alkyl side chains did not have any significant
effects on the absorption maxima as well as emission
maximum. These compounds emitted violet-blue light
(lEmmax = 386–438 nm) with fluorescence quantum yields of
0.54–0.75 when diluted in water. Thus, these new
Figure 1. UV–vis absorption spectra of 5a–g in aqueous solution
(10À5 M). [Color figure can be viewed in the online issue, which is
available at wileyonlinelibrary.com.]
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

E74
H. Shi, T. Wu, P. Jiang, X. Jin, and H. Zhu
Vol 51
Table 2
Photophysical properties of 5a–g in aqueous solution.
Abs
max
Em
a
Compounds
e (104 molÀ1 cmÀ1
)
l
(nm)
l
(nm)
max
Stokes shift (nm)
ФF
5a
5b
5c
5d
5e
5f
5.02
5.43
5.56
5.29
5.41
6.17
6.24
280
391
111
100
105
100
118
145
95
0.67
0.54
0.58
0.71
0.73
0.70
0.75
281
281
281
281
281
343
391
386
391
399
426
438
5g
aDetermined in aqueous solution (A < 0.05) at room temperature using quinine sulfate (ΦF = 0.55 in 0.1 M H2SO4) as standard.
All the chemicals not recalling for synthesis were purchased either
from the Sinopharm Chemical Reagent Co. Ltd. or the Shanghai
Lingfeng Chemical Company, and the solvents were purified
according to standard procedures. 4-(Carbazole-9-yl)benzonitrile
(2d) was synthesized from carbazole and 4-bromobenzonitrile
according to methods described in the literature [23]. 4-(N,N-
Diphenylamino)benzaldehyde (2e) was synthesized by formylation
of triphenyl amine using DMF and POCl3 according to the reported
method [24]. 2-Substituted-1H-benzimidazoles (3a–e) were synthe-
sized by condensation of o-phenylenediamine with aromatic
carboxylic aldehydes (2a–e) in the presence of DMF or in the
presence of phosphoric acid and polyphosphoric acid according to
the reported methods [25–27].
The synthesis of 1-ethyl-2-phenylbenzimidazole (4a). 2-
Phenyl-1H-benzimidazole (3a) (1.94 g, 10mmol) and DMF
(30 mL) were put into a 50-mL four-necked flask equipped with a
temperature probe and magnetic stirrer and stirred to dissolve. The
whole mixture was cooled to 0ꢀC using ice bath. After adding
NaH (1.44 g, 60mmol), the mixture was warmed to room
temperature and stirred for 1.5h. Then, ethyl bromide (1.31 g,
12mmol) was added, and the mixture was heated to 45ꢀC. After
reacting for 6–10 h at that temperature, saturated salt water
(10 mL) was added dropwise, and the reaction stopped. The
mixture was extracted with ethyl acetate (3 Â 10 mL), washed with
saturated salt water, and separated. The organic layer was dried
over MgSO4, filtered, and concentrated under reduced pressure to
give 4a with the following properties: white crystal; mp 89–91ꢀC
(reference [28]: 88–88.5ꢀC); yield: 93.1%. 1H-NMR (CDCl3,
300 MHz, ppm): d 1.46 (t, J= 7.6 Hz, 3H, CH3), 4.26 (q, J=7.6Hz,
2H, CH2), 7.42–7.48 (m, 3H, Ar-H), 7.50–7.56 (m, 3H, Ar-H),
7.71–7.81 (m, 3H, Ar-H). Anal. Calcd for C15H14N2: C, 81.05; H,
6.35; N, 12.60. Found: C, 81.09; H, 6.33; N, 12.58.
Figure 2. PL spectra of 5a–g in aqueous solution (10À8 M). [Color figure
can be viewed in the online issue, which is available at wileyonlinelibrary.
com.]
compounds have potential applications as fluorescence-
traced materials. Further studies of their copolymers’
application are underway in our laboratory.
EXPERIMENTAL
Melting points were measured on an X-4 microscope electro-
thermal apparatus (Taike, Beijing Taike Instrument Company,
Beijing, China) and remained uncorrected. 1H-NMR spectra were
recorded on either a Bruker AV-500 spectrometer at 500 MHz or
a Bruker AV-300 spectrometer at 300 MHz (Bruker AXS Inc.,
Madison, WI), using CD3OD, D2O, and CDCl3 as the solvents,
with TMS as the internal standard. Electrospray ionization mass
spectroscopy measurements were carried out with an Agilent
1100 series LC/MSD Trap SL mass spectrometer (Agilent Inc.,
Santa Clara, CA). Elemental analyses were performed with a
Vario EL III elemental analyzer (Elementar Analysensysteme
GmbH, Hanau, Germany). Optical absorption spectra were
obtained using an HP-8453 UV/vis/near-IR spectrophotometer
(Agilent Inc., Santa Clara, CA). Photoluminescence spectra were
carried out on an LS-55 spectrofluorometer (PerkinElmer Inc.,
Fremont, CA).
1-Ethyl-2-(4-methylphenyl)benzimidazole (4b). Following
the same procedure described for the synthesis of 4a. 2-(4-
Methylphenyl)-1H-benzimidazole (3b) and ethyl bromide were
used to obtain product 4b. White crystal; mp 104–106ꢀC; yield:
1
92.0%. H-NMR (CDCl3, 500MHz, ppm): d 1.46 (t, J = 7.25Hz,
3H, CH3), 2.44 (s, 3H, CH3), 4.28 (q, J = 7.25Hz, 2H, CH2),
7.33–7.29 (m, 4H, Ar-H), 7.43–7.40 (m, 1H, Ar-H), 7.62
(d, J = 8.05 Hz, 2H, Ar-H), 7.84–7.81 (m, 1H, Ar-H); MS: m/z
237.1 (M+ H+), 238.1 (M+ 2H+), 359.1 (M + Na+). Anal. Calcd
for C16H16N2: C, 81.32; H, 6.82; N, 11.85. Found: C, 81.35; H,
6.78; N, 11.87.
1-Butyl-2-(4-methylphenyl)benzimidazole (4c). Compound
4c was obtained from 2-(4-methylphenyl)-1H-benzimidazole (3b)
and n-butyl bromide. White crystal; mp 62–63ꢀC; yield: 91.4%.
1H-NMR (CDCl3, 500MHz, ppm): d 0.87 (t, J = 7.35 Hz, 3H,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

August 2014
Synthesis and Optical Properties on Novel Fluorescence-Traced Benzimidazolium Bromides
E75
CH3), 1.31–1.25 (m, 2H, CH2), 1.83–1.77 (m, 2H, CH2), 2.44
(s, 3H, CH3), 4.22 (t, J = 7.65Hz, 2H, CH2), 7.30–7.27 (m, 4H,
Ar-H), 7.41–7.39 (m, 1H, Ar-H), 7.61 (d, J = 8.1Hz, 2H, Ar-H),
7.83–7.81 (m, 1H, Ar-H); MS: m/z 265.2 (M + H+), 266.2
(M+ 2H+). Anal. Calcd for C18H20N2: C, 81.78; H, 7.63; N,
10.60. Found: C, 81.75; H, 7.61; N, 10.63.
J = 15.39Hz, 1H, CH2═), 5.34 (d, J = 10.38Hz, 1H, CH2═),
6.03–5.98 (m, 1H, -CH═), 7.74–7.41 (m, 6H, Ar-H), 7.93–7.84
(m, 2H, Ar-H), 8.00 (d, J = 7.47 Hz, 1H, Ar-H); MS: m/z: 261.3
[MÀ Br]+. Anal. Calcd for C18H19BrN2: C, 62.98; H, 5.58; N,
8.16. Found: C, 62.96; H, 5.60; N, 8.19.
1-Ethyl-2-(4-methylphenyl)-3-allyl-1H-benzimidazolium bromide
1
(5b). Yield: 92.4%; white crystals; mp >310ꢀC; H-NMR (D2O,
1-Ethyl-2-(4-bromophenyl)benzimidazole (4d). Compound
4d was obtained from 2-(4-bromophenyl)-1H-benzimidazole
(3c) and ethyl bromide. Yellow crystal; mp 137–138ꢀC; yield:
500 MHz, ppm): d 1.47 (t, J= 7.15 Hz, 3H, CH3), 2.54 (s, 3H, CH3),
4.43–4.39 (q, J=7.15Hz, 2H, CH2), 4.95 (d, J= 3.95 Hz, 2H, CH2),
5.12 (d, J=17.25Hz, 1H, CH2═), 5.34 (d, J= 10.5 Hz, 1H, CH2═),
6.06–6.00 (m, 1H, -CH═), 7.67–7.62 (m, 4H, Ar-H), 7.79–7.74
(m, 2H, Ar-H), 7.91 (d, J= 7.75 Hz, 1H, Ar-H), 8.00 (d, J=7.85Hz,
1H, Ar-H); MS: m/z: 277.3 [MÀ Br]+. Anal. Calcd for C19H21BrN2:
C, 63.87; H, 5.92; N, 7.84. Found: C, 63.84; H, 5.93; N, 8.21.
1-Butyl-2-(4-methylphenyl)-3-allyl-1H-benzimidazolium bromide
(5c). Yield: 90.3%; yellow crystals; mp >310ꢀC; 1H-NMR (CDCl3,
300 MHz, ppm): d 0.84 (t, J=7.35Hz, 3H, CH3), 1.33–1.28
(m, 2H, CH2), 1.89–1.83 (m, 2H, CH2), 2.52 (s, 3H, CH3),
4.47–4.42 (t, J=7.47Hz, 2H, CH2), 5.06 (d, J=4.14Hz, 2H, CH2),
5.17 (d, J= 17.13 Hz, 1H, CH2═), 5.35 (d, J= 10.17 Hz, 1H,
CH2═), 6.07–5.94 (m, 1H, -CH═), 7.52–7.49 (m, 2H, Ar-H), 7.69–
7.61 (m, 2H, Ar-H), 7.86–7.81 (m, 4H, Ar-H); MS: m/z: 305.1
[M À Br]+. Anal. Calcd for C21H25BrN2: C, 65.46; H, 6.54; N, 7.27.
1
94.8%. H-NMR (CDCl3, 500 MHz, ppm): d 1.44 (t, J = 7.2 Hz,
3H, CH3), 4.25 (q, J = 7.2 Hz, 2H, CH2), 7.33–7.29
(m, 2H, Ar-H), 7.42–7.40 (m, 1H, Ar-H), 7.59 (d, J = 8.15 Hz,
2H, Ar-H), 7.65 (d, J = 8.4 Hz, 2H, Ar-H), 7.83–7.81 (m, 1H,
Ar-H); MS: m/z 301.0 (M + H+), 304.0 (M + 4H+), 323.0
(M + Na+). Anal. Calcd for C15H13BrN2: C, 59.82; H, 4.35; N,
9.30. Found: C, 59.86; H, 4.31; N, 9.35.
1-Butyl-2-(4-bromophenyl)benzimidazole (4e). Compound
4e was obtained from 2-(4-bromophenyl)-1H-benzimidazole (3c)
and n-butyl bromide. Yellow crystal; mp 81–83ꢀC; yield: 93.3%.
1H-NMR (CDCl3, 500 MHz, ppm): d 0.88 (t, J = 7.35Hz, 3H,
CH3), 1.31–1.24 (m, 2H, CH2), 1.82–1.76 (m, 2H, CH2), 4.21
(t, J = 7.65 Hz, 2H, CH2), 7.33–7.29 (m, 2H, Ar-H), 7.47–7.40
(m, 1H, Ar-H), 7.58 (d, J = 8.3 Hz, 2H, Ar-H), 7.65 (d, J = 8.2 Hz,
2H, Ar-H), 7.82–7.80 (m, 1H, Ar-H); MS: m/z 329.1 (M + H+),
332.1 (M+ 4H+), 351.0 (M+ Na+). Anal. Calcd for C17H17BrN2:
C, 62.02; H, 5.20; N, 8.51. Found: C, 62.04; H, 5.19; Br, 24.23;
N, 8.54.
1-Ethyl-2-{4-(9H-carbazole-9-yl)phenyl}benzimidazole (4f).
Compound 4f was obtained from 2-{4-(9H-carbazole-9-yl)
phenyl}-1H-benzimidazole (3d) and ethyl bromide. Yellow
crystal; mp 166–168ꢀC; yield: 88.7%. 1H-NMR (CDCl3,
500 MHz, ppm): d 1.58 (t, J = 7.25 Hz, 3H, CH3), 4.45–4.40
(q, J = 7.25 Hz, 2H, CH2), 7.38–7.30 (m, 4H, Ar-H), 7.51–7.43
(m, 5H, Ar-H), 7.76 (d, J = 8.35 Hz, 2H, Ar-H), 7.89–7.87
(m, 1H, Ar-H), 8.00 (d, J = 8.35 Hz, 2H, Ar-H), 8.16
(d, J = 7.7 Hz, 2H, Ar-H); MS: m/z 388.2 (M + H+), 389.2
(M + 2H+), 410.2 (M + Na+). Anal. Calcd for C27H21N3: C,
83.69; H, 5.46; N, 10.84. Found: C, 83.72; H, 5.44; N, 10.84.
4-(1-Ethyl-1H-benzimidazol-2-yl)-N,N-diaphenylbenzenamine
(4g). Compound 4g was obtained from 4-(N,N-diphenylaminophenyl)-
1H-benzimidazole (3e) and ethyl bromide. Light yellow crystal; mp
170–172ꢀC; yield: 90.2%. 1H-NMR (CDCl3, 300 MHz, ppm):
d 1.48 (t, J=7.17Hz, 3H, CH3), 4.30 (q, J=7.17Hz, 2H, CH2),
7.10–7.05 (m, 2H, Ar-H), 7.24–7.15 (m, 6H, Ar-H), 7.32–7.26
(m, 6H, Ar-H), 7.41–7.38 (m, 1H, Ar-H), 7.59 (d, J=8.46Hz, 2H,
Ar-H), 7.81–7.78 (m, 1H, Ar-H); MS: m/z 390.3 (M + H+), 391.3
(M + 2H+), 412.3 (M + Na+). Anal. Calcd for C27H23N3: C, 83.26;
H, 5.95; N, 10.79. Found: C, 83.28; H, 5.90; N, 10.82.
Procedure for the synthesis of 5a–5g. 1-Alkyl-2-aryl-1H-
benzimidazole (4a–g) (5 mmol) and acetonitrile (20 mL) were
put into a 50-mL four-necked flask and stirred to dissolve. After
heated to 60ꢀC, the mixed liquid of allyl bromide (0.6 g,
5 mmol) and acetonitrile (20 mL) was added dropwise, and the
mixture was heated at refluxing temperature for 24 h. After the
reaction, the mixture was washed with acetonitrile (20 mL)
and then concentrated under reduced pressure to give crude
products. The crude products were purified by recrystallization
from acetonitrile to give pure 5a–g with the following properties:
Found: C, 65.43; H, 6.58; N, 8.20.
1-Ethyl-2-(4-bromophenyl)-3-allyl-1H-benzimidazolium bromide
(5d). Yield: 87.2%; yellow crystals; mp >310ꢀC; 1H-NMR (D2O,
500 MHz, ppm): d 1.43 (t, J= 7.5 Hz, 3H, CH3), 4.40–4.36
(q, J= 7.5 Hz, 2H, CH2), 4.93 (d, J= 4.0 Hz, 2H, CH2), 5.08
(d, J= 16.5 Hz, 1H, CH2═), 5.31 (d, J= 10.5 Hz, 1H, CH2═),
6.02–5.95 (m, 1H, -CH═), 7.65 (d, J= 8.5 Hz, 2H, Ar-H), 7.77–
7.71 (m, 2H, Ar-H), 7.90–7.88 (m, 1H, Ar-H), 7.99–7.94 (m, 3H,
Ar-H); MS: m/z: 341.0 [M À Br]+. Anal. Calcd for C18H18Br2N2: C,
51.21; H, 4.30; N, 6.64. Found: C, 51.25; H, 4.29; N, 6.61.
1-Butyl-2-(4-bromophenyl)-3-allyl-1H-benzimidazolium
bromide (5e).
Yield: 86.3%; yellow crystals; mp >310ꢀC;
1H-NMR (CDCl3, 500 MHz, ppm): d 0.87 (t, J = 7.4 Hz, 3H,
CH3), 1.32–1.23 (m, 2H, CH2), 1.89–1.83 (m, 2H, CH2), 4.39
(t, J = 7.75Hz, 2H, CH2), 5.00 (d, J = 3.45Hz, 2H, CH2), 5.20
(d, J = 17.15 Hz, 1H, CH2═), 5.37 (d, J = 10.45 Hz, 1H, CH2═),
6.05–5.98 (m, 1H, -CH═), 7.68–7.64 (m, 2H, Ar-H), 7.80–7.76
(m, 2H, Ar-H), 7.85 (t, J = 4.20Hz, 2H, Ar-H), 8.04
(d, J = 8.45 Hz, 2H, Ar-H); MS: m/z: 369.0 [MÀ Br]+. Anal.
Calcd for C20H22Br2N2: C, 53.36; H, 4.93; N, 6.22. Found: C,
53.39; H, 4.89; N, 8.22.
1-Ethyl-2-{4-(9H-carbazole-9-yl)phenyl}-3-allyl-1H-
benzimidazolium bromide (5f). Yield: 64.1%; brown crystals;
mp >310ꢀC; 1H-NMR (CD3OD, 500MHz, ppm): d 1.60
(t, J = 7.35Hz, 3H, CH3), 4.57 (q, J = 7.35 Hz, 2H, CH2),
5.12–5.10 (m, 2H, CH2), 8.21–8.20 (m, 2H, Ar-H), 8.14–8.13
(m, 1H, Ar-H), 8.10–8.08 (m, 4H, Ar-H), 5.28 (d, J = 16.95Hz,
1H, CH2═), 5.41 (d, J = 10.5Hz, 1H, CH2═), 6.15–6.09 (m, 1H,
-CH═), 7.37–7.34 (m, 2H, Ar-H), 7.50–7.47 (m, 2H, Ar-H), 7.62
(d, J = 8.25 Hz, 2H, Ar-H), 7.84–7.78 (m, 2H, Ar-H), 8.03–8.02
(m, 1H, Ar-H); MS: m/z: 428.3 [M À Br]+. Anal. Calcd for
C30H26BrN3: C, 70.87; H, 5.15; N, 8.26. Found: C, 70.91; H,
5.16; N, 8.21.
1-Ethyl-2-{(4-N,N-diphenyl)aminophenyl}-3-allyl-1H-
benzimidazolium bromide (5g). Yield: 64.1%; brown crystals;
mp >310ꢀC; 1H-NMR (CD3OD, 500MHz, ppm): d 1.51
(t, J = 7.3 Hz, 3H, CH3), 4.48–4.44 (q, J = 7.3 Hz, 2H, CH2),
5.01–4.99 (m, 2H, CH2), 5.19 (d, J = 17.2Hz, 1H, CH2═), 5.36
(d, J = 10.45Hz, 1H, CH2═), 6.06–6.01 (m, 1H, -CH═),
7.18–7.16 (m, 2H, Ar-H), 7.27–7.23 (m, 6H, Ar-H), 7.44–7.40
1-Ethyl-2-phenyl-3-allyl-1H-benzimidazolium bromide (5a).
Yield: 93.0%; white crystals; mp >310ꢀC; 1H-NMR (D2O,
300 MHz, ppm):
d 1.47 (t, J = 7.05Hz, 3H, CH3), 4.40
(q, J = 7.05 Hz, 2H, CH2), 4.96 (d, J = 3.95Hz, 2H, CH2), 5.12 (d,
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

E76
H. Shi, T. Wu, P. Jiang, X. Jin, and H. Zhu
Vol 51
[12] Carella, A.; Centore, R.; Fort, A.; Peluso, A.; Sirigu, A.; Tuzi,
A. Eur J Org Chem 2004,12, 2620.
[13] Nomura, M.; Shibasaki, Y.; Ueda, M.; Tugita, K.; Ichikawa,
M.; Taniguchi, Y. Synth Met 2005, 151, 261.
[14] Chen, C. T.; Chiang, C. L.; Lin, Y. C.; Chan, L. H.; Huang,
C. H.; Tsai, Z. W. Org Lett 2003, 5(8),1261.
(m, 4H, Ar-H), 7.54–7.52 (m, 2H, Ar-H), 7.76–7.70 (m, 2H,
Ar-H), 7.93–7.91 (m, 1H, Ar-H), 8.04–8.02 (m, 1H, Ar-H); MS:
m/z: 430.5 [M À Br]+. Anal. Calcd for C30H28BrN3: C, 70.59; H,
5.53; N, 8.23. Found: C, 70.62; H, 5.54; N, 8.19.
[15] Guan, Y. T.; Bian, Z. Q.; Zhou, Y. F.; Li, F. Y.; Li, Z. J.;
Huang, C. H. Chem Commun 2003, 21, 2708.
[16] Vindodkumar, R.; Vaidya, S. D.; Kumar, B. V. S.; Bhise,
U. N.; Bhirud, S. B.; Mashelkar, U. C. Arkivoc 2008 (xiv), 37.
[17] Lee, I. S.; Kil, H. J.; Ji, Y. R. J Phys Org Chem 2007, 20, 487.
[18] Shi, Z.; Gu, H.; Xu, L. L. Synthetic Comm 1996, 26, 3175.
[19] Krebs, F. C.; Spanggaard, H. J Org Chem 2002, 67(21),
7185.
[20] Kang, I. N.; Shim, H. K.; Zyung, T. Chem Mater 1997, 9(3),
746.
[21] Eaton, D. F. Pure Appl Chem 1988, 60(7), 1107.
[22] Liu, X. M.; He, C. B.; Huang, J. C. Tetrahedron Lett 2004,
45, 6137.
[23] Samanta, A.; Saha, S.; Fessenden, R. W. J Phys Chem A 2001,
105, 5438.
[24] Zhang, Z. G.; Zhang, K. L.; Liu, G.; Zhu, C. X.; Neoh, K. G.;
Kang, E. T. Macromolecules 2009, 42, 3104.
[25] Knǒdler, A.; Hǔbler, K.; Kaim, W. Inorg Chem Comm 2000,
3, 182.
[26] Hein, D. W.; Alheim, R. J.; Leavitt, J. J. J Am Chem Soc 1957,
79, 427.
REFERENCES
[1] Cai, C.; Wu, D. C.; Guo, R. W. Industrial Water Treatment
2003, 23, 5.
[2] Ping, C. X.; Wang, Y. Y.; Xia, M. Z.; Lei, W.; Zhou, Z. G.;
Wang, F. Y. Industrial Water Treatment 2004, 24, 48.
[3] Hoots, J. E.; Hunt, B. E. US Patent 4,783,314 (A), 1988; Chem
Abstr 1989, 110, 41309.
[4] Jiao, C. L.; Hou, C. Y.;Wu, Y. F.; Wang, H. Z. Industrial
Water Treatment 2008, 28, 33.
[5] Antonio, L. R.; JoséA, A. J Neurosci Methods 1995, 60, 39.
[6] Aicolina, L. E.; Leaver, I. H.; Stapleton, I. W. Dyes and
Pigments 1989, 11, 213.
[7] Declemy, A.; Rulliere, C.; Kottis, P. Chem Phys Let
1983,101, 401.
[8] Jung, H. J.; Singh, N.; Jang, D. O. Tetrahedron Lett 2008,
49, 2960.
[9] Mukherjee, T. K.; Lahiri, P.; Datta, A. Chem Phys Let 2007,
438, 218.
[10] Josef, B.; Bernhard, W. German Patent 2,920,948, 1980;
Chem Abstr 1981, 94,141209.
[27] Ferreiro, J. J.; Campa, J. G. de la; Lozano, A. E.; Abajo J. de;
Preston, J. J Polymer Sci A Polymer Phys 2008, 46, 7566.
[28] Weidenhagen; T. Chem Ber 1942, 75, 1936.
[11] Batista, R. M. F.; Costa, S. P. G.; Belsley, M.; Raposo,
M. M. M. Tetrahedron 2000, 63, 9842.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet