Synthesis and color properties of novel polymeric dyes based on grafting of anthraquinone derivatives onto O-carboxymethyl chitosan

Article abstract of DOI:10.1039/c7ra04024e

Four polymeric dyes were prepared by grafting brominated anthraquinone derivatives onto O-carboxymethyl chitosan through Ullmann condensation. The chemical structure of the prepared polymeric dyes was determined by Fourier transform infrared spectroscopy (FT-IR), elemental analysis and differential scanning calorimetry (DSC), and the results showed that the anthraquinone derivatives were successfully grafted onto O-carboxymethyl chitosan. The grafting degrees of the four polymeric dyes were 0.66, 1.14, 0.93 and 1.01 mmol g^-1 respectively. The color performance of brominated anthraquinone derivatives and prepared polymeric dyes was determined and compared using digital photographs and UV-Vis adsorption spectra, and it was found that the electronic properties and planarity of the substituent group in the anthraquinone derivatives obviously affected the adsorption wavelength of the prepared polymeric dyes. In addition, the polymeric dyes with an electron donating group and higher planarity showed longer adsorption wavelengths and more deep color. The cytotoxicity of prepared polymeric dyes was tested, and their IC₅₀ values on human liver cell lines LO2 were 7.666, 8.557, 8.186 and 8.934 g L^-1 respectively, suggesting low cytotoxicity of the prepared polymeric dyes.

Full text of DOI:10.1039/c7ra04024e

RSC Advances
View Article Online
View Journal | View Issue
PAPER
Synthesis and color properties of novel polymeric
dyes based on grafting of anthraquinone
derivatives onto O-carboxymethyl chitosan
a
Cite this: RSC Adv., 2017, 7, 33494
Dongjun Lv,ac Jin Cui,b Yufang Wang,d Guohua Zhu,a Mingjie Zhang
*
and Xiujing Lic
Four polymeric dyes were prepared by grafting brominated anthraquinone derivatives onto O-
carboxymethyl chitosan through Ullmann condensation. The chemical structure of the prepared
polymeric dyes was determined by Fourier transform infrared spectroscopy (FT-IR), elemental analysis
and differential scanning calorimetry (DSC), and the results showed that the anthraquinone derivatives
were successfully grafted onto O-carboxymethyl chitosan. The grafting degrees of the four polymeric
dyes were 0.66, 1.14, 0.93 and 1.01 mmol gꢀ1 respectively. The color performance of brominated
anthraquinone derivatives and prepared polymeric dyes was determined and compared using digital
photographs and UV-Vis adsorption spectra, and it was found that the electronic properties and planarity
of the substituent group in the anthraquinone derivatives obviously affected the adsorption wavelength
of the prepared polymeric dyes. In addition, the polymeric dyes with an electron donating group and
higher planarity showed longer adsorption wavelengths and more deep color. The cytotoxicity of
prepared polymeric dyes was tested, and their IC50 values on human liver cell lines LO2 were 7.666,
8.557, 8.186 and 8.934 g Lꢀ1 respectively, suggesting low cytotoxicity of the prepared polymeric dyes.
Received 9th April 2017
Accepted 20th June 2017
DOI: 10.1039/c7ra04024e
rsc.li/rsc-advances
activities and pharmacological effects, such as antiviral,11 anti-
oxidant,12,13 antibacterial,14,15 anti-cancer16,17 and anti-inam-
matory,18,19 and to prevent osteoporosis and hypoglycemic
Introduction
Polymeric dyes are a new type of dye with organic dyes intro-
duced into the main or side chains of polymers by chemical
reactions. Polymeric dyes integrate characteristics of both dyes
and polymers, and also offer excellent solvent resistance,
thermal and chemical stability, biocompatibility and good color
fastness.1–3 In addition, they are non-absorbable by the gastro-
intestinal tract, which obviously improves their safety in the
human body.4
Generally, most synthetic food dyes are azo compounds.
However, due to their harm to human health, particularly when
they are excessively consumed, the edible azo dyes have been
gradually banned and their usage seriously restricted.5 Thus, it
is necessary to nd some new species of edible colorants for the
replacement of presently used azo food dyes. Anthraquinone
dyes and their derivatives are species of colorants with excellent
color properties, and they are widely used as dyes and
pigments,6,7 and colorants in cosmetics, drugs and foods.8–10
Furthermore, they have a variety of interesting biological
activity.20,21
Based on the advantages of anthraquinone derivatives, we
intend to gra them to high molecular materials to fabricate
polymeric dyes. As reported in our previous work,22 the O-car-
boxymethyl chitosan is an optimal carrier due to their good
water solubility and biological compatibility.23–25 In this paper,
anthraquinone derivatives were rstly brominated, and then
graed onto the O-carboxymethyl chitosan by Ullmann
condensation to obtain polymeric dyes. The chemical structure
of prepared polymeric dyes was determined by Fourier trans-
form infrared spectroscopy (FT-IR), elemental analysis and
differential scanning calorimetry (DSC), and the color perfor-
mance and adsorption properties of anthraquinone derivatives
and prepared polymeric dyes were determined and compared
by digital photographs and UV-Vis adsorption spectra. Eventu-
ally, the toxicity of prepared polymeric dyes was tested by
a cytotoxicity experiment on normal human liver cell lines LO2.
Results and discussion
Characterization of prepared polymer dyes
aDepartment of Chemistry, School of Science, Tianjin University, Tianjin 300354,
China. E-mail: mjzhangtju@163.com
bNational Foodstuff Inspection Center, Tianjin Product Quality Inspection Technology
FT-IR spectral analysis. FT-IR spectra of polymeric dyes 1–4
are shown in Fig. 1. The characteristic absorption peaks at
1621–1637 and 1384–1420 cmꢀ1 were corresponded to carbonyl
Research Institute, Tianjin 300384, China
cShandong Yu Hong New Pigment Co., Ltd., Dezhou 253000, China
dShi Jia Zhuang University of Applied Technology, Shijiazhuang 050081, China
33494 | RSC Adv., 2017, 7, 33494–33501
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
determined by elemental analysis, and the results were listed in
Table 1. For polymeric dye-1, according to the change in the S
content, the graing degree could be calculated as S%/MS/1 g ¼
0.66 mmol gꢀ1. Similarly, for the polymeric dye-2, dye-3 and dye-
Table 1 Elemental analysis results of the prepared polymeric dyes
Elemental content/%
Sample
C
N
S
H
OMCS
39.5
34.0
45.1
45.4
49.9
5.8
4.2
4.7
4.0
4.1
6.0
4.1
3.8
3.4
4.2
Polymeric dye-1
Polymeric dye-2
Polymeric dye-3
Polymeric dye-4
2.1
3.3
3.2
2.9
Fig. 1 FT-IR spectra of polymeric dye-1 (a), dye-2 (b), dye-3 (c) and
dye-4 (d).
group absorption in anthraquinone structure26 and C]C
absorption peak in aromatic ring respectively. The absorption
peak at 701–827 cmꢀ1 revealed ]C–H bending vibration
absorption outside the plane. From the chemical structure of
the four prepared polymeric dyes, it could be found that the
anthraquinone derivatives graed onto the O-carboxymethyl
chitosan through C–N bond, and its stretching vibration at
1257–1275 cmꢀ1 was observed. In addition, there was a sulfo-
nate group in the four prepared polymeric dyes, and the char-
acteristic peak at 1050–1065 cmꢀ1 corresponded to –SO3
stretching vibration was also observed. From the analysis
results mentioned above, it was concluded that anthraquinone
derivatives were successfully graed onto OMCS through Ull-
mann condensation.
Fig. 2 DSC analysis of OMCS, physical mixture of anthraquinone
intermediates and OMCS, anthraquinone intermediates and prepared
Elemental analysis. The graing degree of anthraquinone
derivatives onto OMCS in the four prepared polymeric dyes were polymeric dyes.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 33494–33501 | 33495

View Article Online
RSC Advances
Paper
4, according to the change in S and N content, the graing
degrees could be calculated as (N%/MN ꢀ S%/MS)/2/1 g, it was
calculated that the graing degrees were 1.14, 0.93 and
Color performance and UV-Vis spectra of prepared polymeric
dyes
Color performance of anthraquinone intermediate and
polymeric dyes. As shown in synthetic route of polymeric dyes,
the anthraquinone intermediates graed onto OMCS through
an Ullmann condensation reaction and formed an n–p conju-
gate electronic structure, which would affect the adsorption
properties and color performance of polymeric dyes. Table 2
presented the digital photographs of anthraquinone interme-
diates and prepared polymeric dyes. It was obvious that the
anthraquinone intermediates and prepared polymeric dyes
showed different colors, and the color change illustrated that
the chemical reaction between anthraquinone intermediates
and OMCS did have happened, which was in accordance with
the FT-IR and DSC analysis results.
UV-Vis spectra of anthraquinone intermediates and poly-
meric dye. The adsorption properties of the anthraquinone
intermediates and the prepared polymeric dyes were deter-
mined by UV-Vis spectra, and the results were shown in Fig. 3.
It could be found that aer graing onto OMCS, there was an
obvious red-shi on the adsorption wavelength of anthraqui-
none intermediates, and the maximum adsorption wavelength
of intermediates I–IV red-shied from 489, 505, 405 and 414 nm
to 574, 582, 530 and 535 nm respectively (Table 3). As
mentioned above that the anthraquinone intermediates formed
n–p conjugate electronic structure with OMCS, and the elec-
tronic property and planarity of substituent group in anthra-
quinone intermediates affected the adsorption wavelength of
1.01 mmol gꢀ1
.
DSC analysis. The DSC analysis results of OMCS, physical
mixture of intermediate and OMCS, anthraquinone intermedi-
ates and the prepared polymer dyes were presented in Fig. 2. For
all the samples, the endothermic peaks at 59.2–65.9 ꢁC were
assignꢁed to the evaporation of free water. The exothermic peak at
ꢁ
ꢁ
ꢁ
363.1 C, 257.7 C, 316.2 C and 336.8 C was the degradation
peak of anthraquinone intermediate I–IV. As shown in Fig. 2a,
for polymeric dye-1 there were two exothermic peaks at 224.8 ꢁC
ꢁ
and 272.4 C. However, for the physical mixture of anthraqui-
none intermediate I and OMCS, only one exothermic peak at
273.6 ꢁC was observed, suggesting that the anthraquinone
intermediate I formed a chemical bond with OMCS rather than
a physical mixture. As shown in Fig. 2b, in the curve of physical
mixture of anthraquinone intermediate II and OMCS, an
exothermic peak at 273.9 ꢁC was observed, which was similar to
that of OMCS. And in the curve of polymeric dye-2, the
exothermic peak was shied to 277.4 ꢁC, illustrating the
formation of a chemical bond between anthraquinone inter-
mediate II and OMCS. Similarly, it could be seen form Fig. 2c
and d that in the curve of polymeric dye-3 two higher exothermic
ꢁ
peaks at 364.5 and 434.8 C were observed, and in the curve of
ꢁ
polymeric dye-4 a higher exothermic peak at 385.2 C was also
observed, the mentioned results illustrated that in polymeric
dye-3 and dye-4 the intermediate III and IV formed a chemical
bond rather than a physical mixture with OMCS.22
Table 2 Digital photographs of intermediate and polymer dyes solution
Intermediate
Digital photographs
Product
Digital photographs
Polymeric dye-1
Polymeric dye-2
Polymeric dye-3
Polymeric dye-4
33496 | RSC Adv., 2017, 7, 33494–33501
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
the prepared polymeric dyes. For polymeric dye-1 and dye-2, the
electron donating property of –NH2 and –NHCH3 in the
anthraquinone intermediates I and II enhanced the n–p inter-
action, increased the conjugation and thus decreased the
energy gaps of p orbit, which lead to red-shi of maximum
adsorption wavelength of polymeric dyes. In addition, the –CH3
in anthraquinone intermediates II increased the molecular
polarity of polymeric dyes and p electronic liquidity, decreased
the activation energy DE, which made the adsorption wave-
length shied to longer wavelength. Thus, the polymeric dye-2
showed a larger adsorption wavelength and more dark color
than polymeric dye-1.
As reported that the molecular planarity also affected the
adsorption wavelength, and when the entire atom in conjuga-
tion system were in the same plane, the maximum conjugative
effect and largest overlap degree of p electron cloud were ob-
tained. The planarity of anthrapyridone group in polymeric dye-
3 and dye-4 was lower than that in polymeric dye-1 and dye-2,
which lead to an increase in the activation energy DE and the
blue-shi to the short adsorption wavelength. Thus, the poly-
meric dye-3 and dye-4 showed a shorter adsorption wavelength
than the polymeric dye-1 and dye-2. Additionally, the benzene
ring anthrapyridone group in polymeric dye-4 increased the
conjugated system and the overlap degree of electronic orbit,
which decreased the activation energy DE. Thus, the polymeric
dye-4 showed a longer adsorption wavelength than the poly-
meric dye-3.27,28
Cytotoxicity studies
The cytotoxicity of the anthraquinone intermediates and the
prepared polymeric dyes were assessed by the in vitro cell
cytotoxicity test against normal human liver cell lines LO2.
The concentration required for 50% inhibition of cell
viability IC50 was calculated and listed in Table 4. The IC50
values of intermediates I–IV on LO2 were 1.018, 1.167, 1.218
and 1.204 g Lꢀ1 respectively. IC50 values for polymeric dye 1–4
on human liver cell lines LO2 was 7.666, 8.557, 8.186 and
8.934 g Lꢀ1 respectively. Obviously, the high IC50 values
(>7.6 g Lꢀ1) suggested that the prepared polymeric dyes
exhibited slight cytotoxicity and they could be safely applied
in vivo as food additive.29
Cytotoxicity of polymeric dye 1–4 was studied using the MTT
assay, and the results were shown in Fig. 4. The MTT assay
showed a dose dependent response in normal human liver cell
lines LO2, and the LO2 exposed to polymeric dye 1–4 showed
high cell viability, which indicated lower toxicity of the prepared
polymeric dye 1–4 towards normal cells.
Fig. 3 The UV-Vis spectra of anthraquinone intermediates and poly-
meric dyes: (a) intermediate I and polymeric dye-1; (b) intermediate II
and polymeric dye-2; (c) intermediate III and polymeric dye-3; (d)
intermediate IV and polymeric dye-4.
Table 3 The maximum absorption wavelength of anthraquinone
intermediates and polymeric dyes
Anthraquinone
intermediates
lmax/nm Polymeric dyes lmax/nm Red shi/nm
I
489
505
405
414
Polymeric dye-1 574
Polymeric dye-2 582
Polymeric dye-3 530
Polymeric dye-4 535
85
77
125
121
II
III
IV
Table 4 IC50 values of the anthraquinone intermediates and the prepared polymeric dyes on human liver cell lines (LO2)
Compounds
IC50 g Lꢀ1
Intermediate I
1.018
Polymeric
dye-1
7.666
Intermediate
II
1.167
Polymeric
dye-2
8.557
Intermediate
III
1.218
Polymeric
dye-3
8.186
Intermediate
IV
1.204
Polymeric
dye-4
8.934
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 33494–33501 | 33497

View Article Online
RSC Advances
Paper
Fig. 4 Cell viability of normal cells (LO2) treated with: (a) intermediate I (b) polymeric dye-1; (c) intermediate II (d) polymeric dye-2; (e) inter-
mediate III (f) polymeric dye-3; (g) intermediate IV (h) polymeric dye-4.
a time interval of 1 h. The mixture was reuxed for 8 h. Aer
ltration, the reaction mixture was distilled in reduced pressure
at 50 ꢁC to give concentrated solution, which was then puried
Conclusions
Four polymeric dyes were prepared by an Ullmann condensa-
by a dialysis experiment in distilled water to remove impurities
with low molecular-weight using a benzoylated cellulose
membrane (MWCO 3500 g molꢀ1). The mixture in the
meꢁmbrane was condensed under reduced pressure and dried at
60 C to give the nal product polymeric dye-1 (0.76 g).
Synthesis of polymeric dye-2
tion reaction between brominated anthraquinone derivatives
and O-carboxymethyl chitosan. The FT-IR, DSC and elemental
analysis results showed that the anthraquinone derivatives were
successfully graed onto O-carboxymethyl chitosan, and the
graing degree of the four polymeric dyes were 0.66, 1.14, 0.93
and 1.01 mmol gꢀ1 respectively.
(1) Preparation of 1-methylamino-4-bromoanthraquinone. In
a 100 mL three-necked ask, 1-methylamino anthraquinone
(3.57 g) and glacial acetic acid (45 mL) were mixed and stirred
for 30 min. Then the mixture was cooled down to 15 ꢁC, and the
bromine (1.50 g) was dropwise added ꢁinto reaction mixture
during 20 minutes. Aer reaction at 35 C for 15 h, additional
bromine (0.30 g) was added. And then the mixture was heated to
50 ꢁC and reacted for another 4 h. Aer the reaction was
completed, the reaction mixture was cooled to room tempera-
ture, ltered and washed with glacial acetic acid (120 mL) and
deionized water, and then the obtained cake was added into 150
mL deionized water. Under stirring the sodium hydrogen sulte
The color performance and UV-Vis spectra analysis results
showed that the electronic property and planarity of substituent
group in anthraquinone derivatives affected the adsorption
wavelength of prepared polymeric dyes obviously, and the
polymeric dyes with electron donating group and higher
planarity showed longer adsorption wavelength and more dark
color. The cytotoxicity test results revealed that IC50 values for
the four prepared polymeric dyes on human liver cell lines LO2
were all higher than 7.6 g Lꢀ1, suggesting low cytotoxicity of
prepared polymeric dyes.
Experimental section
Materials
ꢁ
(9 g) was added, and the mixture was heated and kept at 80 C
for 1 h. Again, the reaction mixture was ltered, washed with
deionized water and dried to obtain 1-methylamino-4-
bromoanthraquinone (intermediate II, 4.27 g).
Bromaminic acid (Industrial grade), Jiangsu Yabang Dyestuff
Co., Ltd. 1-Methyl amino anthraquinone (Industrial grade),
Jiangsu Aolunda High-tech Industry Co., Ltd. 1-Amino-2-methyl
HPLC purity was 96.5%; IR (KBr) 3434, 1665, 1596, 1551,
1514, 1433, 1357, 1265, 1194, 1118, 997, 718, 610, 550 cmꢀ1
;
anthraquinone (AR) and O-carboxymethyl chitosan (Mw
¼
HRESIMS m/z 315.9958 [M + H]+ (calcd for C15H11BrNO2,
315.9973).
200 000 g molꢀ1), Shanghai Yuanye Bio-technology Co., Ltd. All
the other reagents are analytical grade.
(2) Synthesis of polymeric dye-2. The synthesis process of
polymeric dye-2 was similar to that of polymeric dye-1. The
difference was that when the reaction mixture was heated to
Synthesis of polymeric dyes
Synthesis of polymeric dye-1. Under magnetic stirring, O-
carboxymethyl chitosan (0.66 g) was added into 25 mL water,
and the solution pH was adjusted to 10–10.5 by sodium
ꢁ
90 C, 10 mL DMF was added, and the intermediate II (0.32 g)
was dissolved in 15 mL DMF. The mixture was reuxed for 8 h.
Aer ltration, trimethylamine–sulphur trioxide complex (1.26
g) was added into the ltrate, the pH was kept at 10 by the
addition of sodium carbonate solution (10%) as necessary. Aer
ꢁ
carbonate solution (10%, w/w). Then under 90 C, the broma-
minic acid aqueous solution (0.41 g intermediate I dissolved in
10 mL water) was added to the reaction mixture and heated to
ꢁ
stirring at 70 C for 24 h the reaction mixture was distilled in
ꢁ
100 C. Another 10 mL aqueous solution containing pentahy-
reduced pressure at 50 ꢁC to obtain the concentrated solution of
polymeric dye. All the other reaction conditions were the same
drate copper sulphate (0.15 g) and stannous chloride dihydrate
(0.06 g) was added into the reaction mixture by three portions at
33498 | RSC Adv., 2017, 7, 33494–33501
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
as that shown in the synthesis process of polymeric dye-1, and carbethoxy-2-methyl-4-bromo-1,9-anthrapyridone
(interme-
the yield of polymeric dye-2 was 0.78 g.
diate III, 1.1 g).
HPLC purity was 98.4%; IR (KBr) 2976, 1744, 1727, 1640,
Synthesis of polymeric dye-3
(1) Preparation of 1-amino-2-methyl-4-bromoanthraquinone. 1590, 1461, 1447, 1364, 1338, 1257, 1195, 1113, 927, 717, 648,
The 1-amino-2-methyl-4-bromoanthraquinone was synthesized 583 cmꢀ1; 1H NMR (400 MHz, DMSO) d 8.35 (d, J ¼ 6.7 Hz, 1H),
using the 1-amino-2-methyl-anthraquinone as original material 8.01 (dd, J ¼ 13.3, 7.9 Hz, 2H), 7.89 (t, J ¼ 7.1 Hz, 1H), 7.81 (d, J ¼
and the synthesis process was the same as that shown in 7.2 Hz, 1H), 7.67 (d, J ¼ 7.7 Hz, 1H), 4.48 (q, J ¼ 7.1 Hz, 2H), 2.57
synthesis process of intermediate II. The dosage of 1-amino-2- (s, 3H), 1.34 (t, J ¼ 7.1 Hz, 3H). HRMS m/z 409.9975 [M ꢀ H]ꢀ
methyl anthraquinone and the yield were 2.42 and 2.71 g (calcd for C20H13BrNO4, 410.0028).
respectively.
(3) Synthesis of polymeric dye-3. The synthesis process of
1-Amino-2-methyl-4-bromoanthraquinone: HPLC purity was polymeric dye-3 was the same as that shown in the preparation
98.5%; IR (KBr) 3410, 1665, 1607, 1552, 1536, 1458, 1375, 1268, process of polymeric dye-2. The dosage of 30-carbethoxy-2-
1205, 1003, 973, 718, 620, 583 cmꢀ1; HRESIMS m/z 314.9903 methyl-4-bromo-1,9-anthrapyridone and yield of polymeric
[M]+ (calcd for C15H9BrNO2, 314.9895).
dyes-3 were 0.41 and 0.82 g respectively.
Preparation of polymeric dye-4
(1) Synthesis of 6-bromo-4-methyl-1-phenylanthrapyridone. In
(2) Preparation
anthrapyridone.
of
30-carbethoxy-2-methyl-4-bromo-1,9-
mixture of 1-amino-2-methyl-4-
The
bromoanthraquinone (0.95 g), diethyl malonate (1.9 g), argon atmosphere, 1-amino-2-methyl-4-bromoanthraquinone
ꢁ
Na2CO3 (0.08 g) and xylene (15 mL) was stirred at 140 C for synthesized earlier (4.74 g) and toluene (36 mL) was added
8 h, and the volatiles were removed with argon stream. Aer into a ask with magnetic stirring and condenser to obtain red
cooling, the product was ltered, washed with ethanol, hot slurry, and then the phenylacetyl chloride (2.94 g) was added.
water and ethanol again, and dried at 70 ꢁC to give 30- The mixture was heated to reux for 6 h, and then it was cooled
Fig. 5 Synthetic route of polymeric dyes 1–4.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 33494–33501 | 33499

View Article Online
RSC Advances
Paper
down to 60 ꢁC and ltered. The obtained dark yellow ltrate
was concentrated with a rotary evaporator, cooled to form
a large amount of dark solid, which was separated, washed with
ethyl acetate and dried in oven at 70 ꢁC to give 3.94 g
intermediate.
Acknowledgements
This work was nancially supported by the National Natural
Science Foundation of China (31201426).
Under stirring, in a 50 mL three-necked ask equipped with
water-cooled condenser and Ar inlet, the synthesized interme-
diate (3.2 g) and ethylene glycol monomethyl ether (22 mL) was
heated to 120 ꢁC, and then potassium hydroxide solution
(0.32 g KOH dissolved in 0.4 mL H2O) was added into the
reaction system during 1 min. Aer reaction for 3 h, the reac-
Notes and references
1 B. Tang, S. Zhang, J. Yang and F. Liu, Dyes Pigm., 2006, 68,
69–73.
2 H. Mao, Y. Wang, D. Yao, C. Wang and S. Sun, RSC Adv.,
2016, 6, 56831–56838.
ꢁ
tion mixture was cooled down to 5 C, ltrated, washed with
water and dried to obtain the yellow solid product (1.22 g). In
addition, the ltrate was condensed by rotary evaporation to
further recycle the solid product, which was recrystallized in
120 mL acetic acid, ltered and washed with water and dried to
yield 1.30 g product. Thus, the total amount of the product 6-
bromo-4-methyl-1-phenylanthrapyridone (intermediate IV) was
2.52 g.
3 H. Mao, F. Yang, C. Wang, Y. Wang, D. Yao and Y. Yin, RSC
Adv., 2015, 5, 30631–30639.
4 L. A. Bunes, Polymeric aminoanthrapyridine orange colors,
US 4206240 A, 1980.
5 P.
Mpountoukas,
A.
Pantazaki,
E.
Kostareli,
P. Christodoulou, D. Kareli, S. Poliliou, C. Mourelatos,
V. Lambropoulou and T. Lialiaris, Food Chem. Toxicol.,
2010, 48, 2934–2944.
HPLC purity was 96.3%; IR (KBr): 3154, 3019, 1661, 1637,
1597, 1459, 1444, 1336, 1272, 1064, 925, 709, 628, 569 cmꢀ1
;
6 E. M. Malik, M. Rashed, L. Wingen, Y. Baqi and C. E. Muller,
¨
HRMS m/z: 414.0099 [M ꢀ H]ꢀ (calcd for C23H13BrNO2,
414.0130). 1H NMR (400 MHz, CDCl3) d 8.21 (s, 1H), 7.76 (s, 1H),
7.37 (m, 7H), 7.12 (m, 1H), 2.56 (s, 3H).
Dyes Pigm., 2016, 131, 33–40.
7 H. Matsumoto and N. Kajiura, Anthrapyridone compound,
magenta ink composition and colored matter, US 7727320,
2010.
8 Y. Caro, L. Anamale, M. Fouillaud, P. Laurent and T. Petit,
Nat. Prod. Bioprospect., 2012, 2, 174–193.
9 J. S. Al-Otaibi and T. M. E. L. Gogary, J. Mol. Struct., 2017,
1130, 799–809.
10 The Council of Europe's Committee of Experts on Cosmetics
products, Active ingredients used in cosmetics: safety survey,
Council of Europe Publishing, 2008.
(2) Synthesis of polymeric dye-4. Polymeric dye-4 was
synthesized following the same procedure of polymeric dye-2 as
mentioned earlier. The dosage of intermediate IV was 0.42 g,
and the yield of resulted polymeric dye-4 was 0.81 g. Based on
what mentioned above, the synthesis routes of the prepared
polymeric dyes were illustrated in Fig. 5.
Characterization of prepared polymer dyes
11 J. Wang, X. Qin, Z. Chen, Z. Ju, W. He, Y. Tan, X. Zhou, Z. Tu,
F. Lu and Y. Liu, Phytochem. Lett., 2016, 15, 13–15.
12 Y. Cai, M. Sun, J. Xing and H. Corke, J. Agric. Food Chem.,
2004, 52, 7884–7890.
13 G. Zengin, M. Locatelli, R. Ceylan and A. Aktumsek, J.
Enzyme Inhib. Med. Chem., 2016, 31, 754–759.
14 G. Meazza, F. E. Dayan and D. E. Wedge, J. Agric. Food Chem.,
2003, 51, 3824–3828.
15 M. Wuthi-udomlert, P. Kupittayanant and W. Gritsanapan, J.
Health Res., 2010, 24, 117–122.
16 Q. Huang, G. Lu, H. M. Shen, M. Chung and C. N. Ong, Med.
Res. Rev., 2007, 27, 609–630.
The chemical structure of the prepared polymeric dyes was
characterized by FT-IR spectrum (Nicolet i5, America). The UV-
Vis spectra of the prepared polymeric dyes and anthraquinone
intermediates were determined by a UV-Vis spectrophotometer
(T9, Beijing Purkinje General Instrument Co., Ltd, China), and
their thermal behavior was analyzed using differential scanning
calorimetry (DSCꢀ, 1EV02, Rigaku Company, Japan) at a heating
rate of 10 ꢁC min from 30 ꢁC to 450 ꢁC. The graing degree of
the polymer dyes was analyzed by the elemental (C, H, N, S)
analysis on a Vario EL III Elemental analyzer (Elementar,
Germany).
17 J. S. Al-Otaibi, P. T. Spittle and T. M. E. l. Gogary, J. Mol.
Struct., 2017, 1127, 751–760.
Cytotoxicity test of the prepared polymeric dyes
Human normal liver cells (LO2) were purchased from the Cell 18 T. Akihisa, K. Matsumoto, H. Tokuda, K. Yasukawa,
Bank of Chinese Academy of Sciences (Shanghai, China).
K.-i. Seino, K. Nakamoto, H. Kuninaga, T. Suzuki and
Conuent human normal liver cells (LO2) in good state were
Y. Kimura, J. Nat. Prod., 2007, 70, 754–757.
cultured in 96-well plates (5–6 ꢂ 103 cells per well) and treated 19 K. Khan, R. Karodi, A. Siddiqui and S. Thube, Int. J. Appl. Res.
ꢁ
with various concentrations of regents at 37 C for 24 h. Then
Nat. Prod., 2011, 4, 875–889.
the cells were incubated with 10 mL of 5 mg mLꢀ1 MTT reagent 20 L. N. Sun, T. Han, L. Jiao, Q. Y. Zhang and J. Z. Wu, Molecules,
for 4 h at 37 ꢁC and dissolved in 150 mL dimethyl sulfoxide and
2009, 14, 573–583.
shaken for 5 min. Finally, the light absorption (OD) of the 21 J. M. Zheng, J. M. Zhu, L. S. Li and Z. H. Liu, Br. J. Pharmacol.,
dissolved cells in reagent group and blank group was 2008, 153, 1456–1464.
measured at 490 nm with so Graphpad prism 5, then the IC50 22 D. Lv, M. Zhang, J. Cui, J. Lu and W. Li, New J. Chem., 2016,
values for the samples was calculated.
40, 3363–3369.
33500 | RSC Adv., 2017, 7, 33494–33501
This journal is © The Royal Society of Chemistry 2017

View Article Online
Paper
RSC Advances
23 N. N. Inamdar and V. K. Mourya, Adv. Mater. Lett., 2010, 1, 26 X. Hu, X. Zhang, J. Liu and J. Dai, J. Lumin., 2013, 142, 23–27.
11–33. 27 A. S. Abd-El-Aziz and T. H. A, Dyes Pigm., 2006, 70, 8–17.
24 X. G. Chen, Z. Wang, W. S. Liu and H. J. Park, Biomaterials, 28 D. Liu and J. Liu, J. Mater. Cycles Waste Manage., 2014, 16,
2002, 23, 4609–4614. 557–565.
25 L. Upadhyaya, J. Singh, V. Agarwal and R. P. Tewari, 29 D. Lv, M. Zhang, J. Cui, W. Li and G. Zhu, Materials, 2017, 10,
Carbohydr. Polym., 2013, 91, 452–466.
219.
This journal is © The Royal Society of Chemistry 2017
RSC Adv., 2017, 7, 33494–33501 | 33501