The triazine-based azo-azomethine dyes; synthesis, characterization, spectroscopy, solvatochromism and biological properties of 2,2′-(((6-methoxy-1,3,5-triazine-2,4-diyl)bis(sulfanediyl)bis(2,1-phenylene))bis(azanylylidene)bis(methanylylidene))bis(4-(phen

Article abstract of DOI:10.1016/j.saa.2014.11.048

(Chemical Equation Presented) The macrocyclic azo-azomethine dyes 2,2′-(((6-methoxy-1,3,5-triazine-2,4-diyl)bis(sulfanediyl)bis(2,1-phenylene))bis(azanylylidene)bis(methanylylidene))bis(4-(phenyldiazenyl)phenol) and its derivatives were synthesized and ch

Full text of DOI:10.1016/j.saa.2014.11.048

Accepted Manuscript
The Triazine-based Azo-azomethine Dyes; Synthesis, Characterization, Spec-
troscopy, Solvatochromism and Biological Properties of 2,2’-(((6-me-
thoxy-1,3,5-triazine-2,4-diyl)bis(sulfanediyl)bis(2,1-phenylene))bis(azanylyli-
dene)bis (methanylylidene))bis(4-(phenyldiazenyl)phenol
Motaleb Ghasemian, Ali Kakanejadifard, Farideh Azarbani, Abedin Zabardasti,
Somayeh Shirali, Zeinab Saki, Sahar Kakanejadifard
PII:
S1386-1425(14)01707-7
http://dx.doi.org/10.1016/j.saa.2014.11.048
SAA 12984
DOI:
Reference:
Spectrochimica Acta Part A: Molecular and Biomo-
lecular Spectroscopy
To appear in:
Received Date:
Revised Date:
Accepted Date:
2 August 2014
11 November 2014
20 November 2014
Please cite this article as: M. Ghasemian, A. Kakanejadifard, F. Azarbani, A. Zabardasti, S. Shirali, Z. Saki, S.
Kakanejadifard, The Triazine-based Azo-azomethine Dyes; Synthesis, Characterization, Spectroscopy,
Solvatochromism and Biological Properties of 2,2’-(((6-methoxy-1,3,5-triazine-2,4-diyl)bis(sulfanediyl)bis(2,1-
phenylene))bis(azanylylidene)bis (methanylylidene))bis(4-(phenyldiazenyl)phenol, Spectrochimica Acta Part A:
Molecular and Biomolecular Spectroscopy (2014), doi: http://dx.doi.org/10.1016/j.saa.2014.11.048
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The Triazine-based Azo-azomethine Dyes; Synthesis, Characterization,
Spectroscopy, Solvatochromism and Biological Properties of 2,2'-(((6-methoxy-
1,3,5-triazine-2,4-diyl)bis(sulfanediyl)bis(2,1-phenylene))bis(azanylylidene)bis
(methanylylidene))bis(4-(phenyldiazenyl)phenol
Motaleb Ghasemiana, Ali Kakanejadifarda*, Farideh Azarbanib, Abedin Zabardastia, Somayeh
Shiralia, Zeinab Sakia and Sahar Kakanejadifardb
a) Department of Chemistry, Faculty of Science, Lorestan University, Khorramabad, Iran
b) Department of Biology, Faculty of Science, Lorestan University, Khorramabad, Iran
Abstract
The macrocyclic azo-azomethine dyes 2,2'-((((6-methoxy-1,3,5-triazine-2,4-diyl)bis(sulfanediyl
)bis(2,1-phenylene))bis(azanylylidene)bis(methanylylidene))bis(4-(phenyldiazenyl)phenol) and its
derivatives were synthesized and characterized by elemental analysis, mass, FT-IR, UV-vis and NMR
spectroscopy. The solvatochromism as well as effects of substitutions on the electronic absorption of
these compounds have been studied in the DMSO, DMF, THF, CH3CN, CH3OH and CH3COOH as
solvents. Also they positive solvatochromism behaviors are explained on the basis of intramolecular
hydrogen bonding, enol–keto tautomeric and dipole moment changes. Compounds having electron
donating substituent on the phenyl ring showed good antioxidant activity. However, none of them has a
considerable antibacterial activity.
Keywords: Azo-azomethine, Schiff base, Triazine, Solvatochromism, Enol–keto tautomeric,
Antibacterial activity, Antioxidant activity.
*Corresponding author. kakanejadi.a@lu.ac.ir and alikakanejadifard@Yahoo.com Tel: +98- 661-
6200610; Fax: +98-661-6200612.
1

1. Introduction
The azo dyes are one of the major groups of synthetic organic dyes; which their applications of
high technology have been attracting much attention. They are used in various fields such as paper
printing, electronic photography, color formers, dyeing, bleaching, polymers, liquid crystal displays,
laser technology, data storage and solar energy conversion [1-10]. Recently, there is a rapidly growing
interest in the potential of their biological-medical applications. They are known to have a broad range
of biological activities such as antibacterial, antifungal, antitumor and antioxidant activities [11-14]. In
addition, azo dyes also have an adverse impact in terms of total organic carbon (TOC), biological
oxygen demand (BOD) and chemical oxygen demand (COD) [15]. It is worth to mention that many
synthetic azo dyes and their metabolites are toxic, carcinogenic, and mutagenic [16]. The azo-
azomethine compounds provide the possibility of forming different type of intra- and intermolecular
hydrogen bond and allow the formation of an intramolecular proton transfer with the nitrogen atoms.
This tautomerization can be induced either by light, heat or the solvent [17-22]. We are now interested
on the tautomerization and solvatochromism of azo-azomethine compounds. On the other hand, s-
triazines have found widespread applications in the pharmaceutical, textile, plastic, and rubber
industries, and are used as pesticides, dyestuffs, optical bleaches, explosives, and surface active agents
[23–29]. The azo dyes including s-triazines ring (i.e., Reactive Red 141 (RR141), Reactive Blue 171
(RB 171), Reactive Green 19 (RG19) have appropriate chemical behavior [30-33]. Therefore, the
ultimate scope of our investigation is preparation of azo-azomethine dyes of 3a-d with three objectives:
(i) Synthesis of 1,3,5-triazine-based azo-azomethine dyes, (ii) Study of solvatochromic behavior and
substituent effects of the prepared dyes in various solvents, (iii) Study of antibacterial and antioxidant
properties of synthesized compounds and comparison with similar known compounds.
2

2. Experimental
2.1. Materials and Measurements
All chemical reagents were obtained from the Merck and used without further purification. For
UV–vis measurements solvents with spectroscopic grade (>99.9%) were used, without any further
purification. 2,4-Dichloro-6-methoxy-1,3,5-triazine,2-hydroxy-5-[(aryldiazenyl)]benzaldehydes (1a-d)
and 2-((2-mercaptophenyl imino)methyl)-4-(aryldiazenyl)phenols (2a-d) have been prepared and
purified according to the methods reported in the literature [34, 17-22]. Elemental analyses were
performed on an Elementar Vario EL III elemental analyzer. Mass spectra were recorded on a Agilent
MS Model 5973. Melting points were measured with Electrothermal 9300 apparatus. FT-IR spectra
were recorded on Shimadzu 8400S spectrometer with samples investigated as KBr discs. The electronic
absorption spectra were recorded with a Shimadzu 1650 spectrophotometer. The structure of all
synthesized compounds were confirmed by 1H and 13C NMR spectra, in DMSO-d6 as solvent recorded
on a Bruker AV 300 MHz spectrometer.
2.2. General procedure for synthesis of 2,2'-((((6-methoxy-1,3,5-triazine-2,4-diyl)bis(sulfanediyl)
bis(2,1-phenylene))bis(azanylylidene)bis(methanylylidene))bis(4-(phenyldiazenyl)phenol) (3a-d):
2,4-Dichloro-6-methoxy-1,3,5-triazine [34] (10 mmol) was dissolved in THF (20 ml). K2CO3 (20
mmol) was added and the suspension mixture was cooled to 0-5 °C. Then 2-((2-mercaptophenylimino)
methyl)-4-(aryldiazenyl)phenols (2a-d, 20 mmol) [21] in 30 ml THF was added portionwise to the
mixture. The suspension mixture was allowed to increase to 25 °C and kept for 1 h then heated at 60-70
°C for 6 h. The mixture was filtered and the solvent of the filtrate was removed to give the crude
product. Products are air stable and soluble in DMSO, DMF, CH3OH, CH3COOH and THF. They were
3

purified by recrystallization and their structures were characterized by elemental analysis, mass, FT-IR,
UV-Vis, 1H and 13С NMR spectroscopy.
2.2.1. Compound 3a
The orange product crystallized from CH3CN. Yield, 4.49 g (58%), m.p.239 ºC. Anal. Calcd.
for C42H31N9O3S2: C, 65.18; H, 4.04; N, 16.29; S, 8.29.Found:C, 65.14; H, 3.96; N, 16.12; S, 8.16. The
EI-MS: m/z; 775(M+1)+, 774(M) +, 669, 578, 558, 474, 442, 333, 301, 225, 198, 106. FT-IR (KBr, cm-
1): 3300-3500 v(bs, OH), 3056 v(Ar-H), 2943, 2848 v(CH=N),1612 v(C=N),1581 v(N=N), 1490
1
v(C=C), 1277, 1153 v(C-N), 1217, v(C-S), 1070 v(C-O). H NMR ppm:11.11 (1H, OH, D2O
exchangeable),9.92(s, 1H, CH=N),8.84-6.83(m, 11H, Ar-H), 3.91(s,3H).13C NMR ppm: 190.98,
178.24,163.63, 161.66, 161.58, 160.75, 152.89, 149.92, 144.99, 134.87, 132.99, 131.84, 128.99,119.59,
119.52, 119.49, 118.94,116.84, 116.78 , 54.12.
2.2.2. Compound 3b
The yellow product crystallized from CH3CN. Yield, 4.88 g (61%). m.p. 256 ºC. Anal. Calcd.
for C44H35N9O3S2: C, 65.90; H, 4.40; N, 15.72; S, 8.00. Found: C, 65.78; H, 4.36; N, 15.66; S, 7.92.
The EI-MS: 804(M+2)+, 802(M)+, 746, 685, 652, 626, 582, 559, 399, 239, 196, 92. FT-IR (KBr, cm-1):
3300-3500 v(bs, OH), 3070 v(Ar-H),2972, 2869 v(CH=N),1618v(C=N), 1575 v(N=N),1479 v(C=C),
1286, v(C-N), 1205(C-S), 1174, 1089 v(C-O). 1H NMR ppm: 11.21 (1H, OH, D2O exchangeable),
9.95 (s, 1H, CH=N), 8.64-6.42 (m, 11H, Ar-H), 3.95 ( s,3H), 2.28 (s,3H ). 13C NMR ppm: 191.42,
175.98, 165.59, 154.92, 152.58, 142.26, 135.68, 131.86, 130.73, 128.84, 127.16, 123.09, 123.03,
122.53, 119.52, 119.46 , 119.17, 116.89, 116.62, 53.49, 21.48.
2.2.3. Compound 3c
The yellow product crystallized from a mixture of THF/C2H5OH (1:1). Yield, 4.96 g (59%).
m.p. 271-273 ºC. Anal. Calcd. For C42H29Cl2N9O3S2: C, 59.86; H, 3.47; N, 14.96; S, 7.61. Found: C,
4

59.78; H, 3.40; N, 14.84; S, 7.52. The EI-MS: m/z 845(M+2)+, 843(M)+, 732, 704, 612, 585, 509, 367,
232, 102. FT-IR (KBr, cm-1): 3300-3500 v(bs, OH), 3058 v(Ar-H), 2954, 2864 v(CH=N), 1616 v(C=N),
1
1583 v(N=N), 1490 v(C=C), 1274, 1217 v(C-N), 1217 v(C-S), 1108, 1066 v(C-O), 831(C-Cl). H
NMR ppm: 11.19(1H, OH, D2O exchangeable), 9.83 (s, 1H, CH=N), 8.85-7.30 (m, 11H, Ar-H), 3.90 (
s, 3H) . 13C NMR ppm: 191.87, 178.38, 164.22, 161.83, 161.66, 160.75, 151.21,149.93,144.99,134.87,
132.79, 132.27, 127.99, 119.59, 119.52, 119.49 , 118.82, 116.69, 116.58, 54.46.
2.2.4. Compound 3d
The brown product crystallized from a mixture of THF/CH3CN (1:1). Yield, 4.85 g (56%).
m.p.292-293 ºC. FT-IR (KBr, cm-1): 3300-3500 v(bs, OH), 3068 v(Ar-H), 2966, 2874 v(CH=N), 1610
v(C=N), 1581 v(N=N), 1532 v(N=O, Unsym. Stretching), 1488 v(C=C), 1336 v(N=O, Sym.
1
Stretching), 1263, 1211v(C-N), 1205 v(C-S), 1112 v(C-O), 1076,921v(N-O). H NMR ppm:11.18(1H,
OH, D2O exchangeable), 10.43 (s, 1H, CH=N), 8.87(m, 2H), 8.72(m, 2H), 8.34, 8.18(dd, 8H, J=5.82
Hz), 7.39(m, 2H), 7.35-7.23(m, 8H), 3.93 (s, 3H). Anal. Calcd. For C42H29N11O7S2.: C, 58.39; H, 3.38;
N, 17.84; S, 7.42. Found: C, 58.31; H, 3.34; N, 17.78; S, 7.38.The EI-MS: m/z 865(M+1)+, 864(M)+,
863(M-1)+, 818, 742,714, 622, 595, 519, 487, 378, 346, 270, 243, 151, 123.
2.2.4. Antioxidant activity
Antioxidant activity of compounds was investigated using DPPH method [35]. Briefly, 50 μl of
test samples at a concentration of 100 μg/ ml in DMSO was added to 5 ml of a 0.004 % solution of
diphenyl picryl-hydrazyl (DPPH) in methanol. After incubation for 30 min at room temperature in the
dark, the absorbance at 517nm was measured and the inhibition percentage was calculated using the
following equation:
% Inhibition = [(AControl - ASample) / AControl] × 100
5

Where AControl is the absorbance of DPPH without sample and ASample is the absorbance of DPPH in the
presence of sample.
2.2.5. Antibacterial activity
The synthesized compounds were evaluated for their antibacterial activity against gram positive
(Bacillus cereus PTCC 1556 and Staphylococcus aureus PTCC 1112) and gram negative (Escherichia
coli PTCC 1330 and Klebsella pneumonia PTCC 1053) bacteria using disc diffusion method [36].
Nutrient agar plates were inoculated with the test strains. The compounds were dissolved in DMSO and
at different concentrations were placed on the surface of the inoculated plates. The petri plates were
incubated at 37°C for 24 h and then the antibacterial activity was determined by measuring the
diameter of the zone of growth inhibition.
3. Results and discussion
The condensation reaction of 2-hydroxy-5-(aryldiazenyl)benzaldehydes (1a-d) with 2-
aminothiophenole afforded Schiff base compounds 2-((2-mercaptophenylimino)methyl)-4-
(phenyldiazenyl)phenols (2a-d) in good yields [17, 21]. Then, the azo-azomethine triazine-based dyes
2,2'-(((6-methoxy-1,3,5-triazine-2,4-diyl)bis(sulfanediyl)bis(2,1-phenylene))bis(azanylylidene)bis
(methanylylidene))bis(4-(phenyldiazenyl)phenols (3a-d) were synthesized using 2a-d and 2,4-dichloro-
6-methoxy-1,3,5-triazine (4) in THF (Fig.1).
Fig. 1:
3.2. Infrared spectra
6

In order to clarify the mode of bonding, the IR spectra of prepared compounds 1a-d, 2a-d and
3a-d were studied on careful comparison of the latter with the former [17-22, 37, 38]. Strong bands
observed in the IR spectra of 1a–d in the region of 1665–1668 cm-1 and 1286-1288 cm-1 can be
assigned to the v(C=O) and v(C-O) functions. The total absence of v(C=O) absorption in the IR spectra
of the prepared dyes together with the appearance of new v(C=N) absorption in the range of 1610–1614
cm-1 clearly indicated that new Schiff base compounds (2a-d) had been formed. In the IR spectra of 2a-
d, appearance of absorption bands at 3413-3444 ν(OH), 2944-2868 ν(CH=N), 1610-1614 ν(C=N),
1457-1490 ν(N=N) are in agreement with the structures proposed of 2a-d [19-22, 38]. The N…O-H
bands are located the range of 3300-3600 cm-1 in compounds 3a-d. The bands ν(CH=N), ν(C=N) and
v(N=N) vibrations are in the range of 2869-2948, 1612-1618 , 1575-1583 and 2966-1610 cm-1,
respectively. The v(C-N), v(C-S) and v(C-O) bands were observed in the range of 1274-1286, 1205-
1217, 1070-1108 and 1263-1112 cm-1, respectively. Also, the IR spectrum of 3d showed strong bands
at 1336 and 1532 cm-1 which could be assigned for νs and νas of the NO2 groups and it is in agreement
with results obtained for similar azo-azomethine dyes [17-22, 39].
3.3. The 1H and 13C NMR spectra
The NMR spectral results obtained from compounds 3a-d at ambient temperature in DMSO-d6,
with the hydrogen assignments are presented in experimental section. The NMR analysis appeared to
1
support the synthesis of all compounds. The H NMR spectrum of 3a-d exhibited D2O exchangeable
signals for the OH protons in the range of 11.11-11.21 ppm. The CH=N and Ar-H protons signals
13
appeared in the range of 9.83-10.43 and 6.42-8.87ppm, respectively [17-20]. The C NMR spectra of
3a-c consisted of nineteen carbon peaks; two peak for triazine rings carbons (190.98-191.87 and
175.98-178.38 ppm), one peak for CH=N, two peak for C-O, C-N and thirteen peak for benzene
7

aromatic region. The C-OH carbon peak was appearing at 163.63-165.59 ppm, which indicated more
character of C=O, suggesting compounds (3a-c) exists as a keto-amine tautomer. These chemical shifts
are supported by IR and 1H NMR spectra, as well as it is in agreement with results obtained for similar
Schiff bases dyes [17-22, 38--44].
3.3. The electronic absorption spectra
Electronic spectroscopy is one of the most applicable and successful techniques for
investigating the tautomerism of azo-azomethine compounds. Therefore, the tautomers can be detected
from the absorption spectra in the visible region. The electronic spectra of compounds (1a-d, 2a-d and
3a-d) were measured (in the range of 300–600 nm) in six solvents DMSO, DMF, THF, CH3CN,
CH3OH and CH3COOH at room temperature (Table 1). The absorption curves of 3c are shown in Fig.
2.
Table 1 and Fig. 2
The UV–vis absorption spectra of 2a–d and 3a-d in CH3OH, CH3CN, CH3COOH and THF
solvents show main band at 339-387 nm which can be assigned to the moderate energy transition of the
aromatic ring. However, in the DMSO and DMF solvents mainly two bands are displayed arising from
the π→π* transitions in the backbone. The first band that located at 342-375 nm, similar to other
solvents, is because of transition of the aromatic ring, while the second one which appeared at 440-585
nm can be assigned to an intramolecular charge transfer n→π* transition of azo-aromatic chromophore
[17-22, 38-44].
In all studied solvents, the absorption bands of 2a-c and 3a-c at 342-375 nm and 440-585nm
generally shows bathochromic shift (positive solvatochromism) with polarity change of solvent (Table
8

1). Our study indicates that solvatochromism exhibited by the dyes may be due to the effect of proton
transfer or dipole moment changes in various solvents [19-22].
Absorption spectra of compounds 3a-d in DMF solvent are shown in Fig. 3. It clearly show that
the 310-360 nm bands are in the order, 3b>3d>3a>3c and 410-490 nm bands are in the order,
3d>3c>3a>3b (Table 1). Results are indicating those bands appeared at 410-490 nm (n→π* absorption)
are influenced by the nature of substitutions (Table 1). It shows that solvatochromism is influenced by
the substituents [17-22, 38-44].
Fig. 3
Furthermore, the absorption spectra of 3c at different volume ratios of the applied pair of
solvents DMF/H2O were also recorded (Fig. 4). It was observed that with increasing the volume
content of water the intensity of absorption of the band about 343 nm (probably azo-enol-imine form)
decreased and shifted to 363 nm. Also band at 453 nm for other form (hydrazo-keto-imine or azo-keto-
enamine) shifted to 470 nm. This implies presence of enol–keto equilibrium that its direction depends
on the polarity of solvent. In general, the nature of substitutions, solvent environment, hydrogen bonds,
temperature, pH and changes in the dipole moment of the molecules are the key factors in deciding the
solvatochromism of azo-azomethine dyes [17-22, 38-44].
Fig. 4
3.4. Biological results
DPPH is a stable free radical, which has been widely accepted as a tool for evaluation of
antioxidant activity [45]. In the DPPH assay, compounds 3a-d with ascorbic acid as standard were
evaluated. As are shown in Table 2, compounds 3a and 3b showed good antioxidant activity, while
compounds 3c and 3d did not display remarkable activity. The minimum activity observed in
9

compound 3c containing Cl group on the phenyl ring. In the disc diffusion antimicrobial sensitivity
testing, none of the compounds showed inhibitory effects against all the tested pathogens.
Table 2
4. Conclusion
The synthesized compounds were obtained from condensation reactions of 2-((2-
mercaptophenylimino)methyl)-4-(phenyldiazenyl)phenol and with 2,4-dichloro-6-methoxy-1,3,5-
triazine. The nature of substitutions, solvent environment, hydrogen bonds and dipole moment of the
molecules are the key factors in deciding the solvatochromism of azo-azomethine dyes. The present
results, compared to previous studies (20-22, 40, 46) showed that 2,2'-(((6-methoxy-1,3,5-triazine-2,4-
diyl)bis(sulfanediyl)bis(2,1-phenylene))bis(azanylylidene)bis(methanylylidene))bis(4-(phenyldiazenyl)
phenol and its substituted derivatives (3a-d) have greater antioxidant activity than 2,2′-((2,2′-(6-
methoxy-1,3,5-triazine-2,4-diyl)bis(oxy)bis(2,1-phenylene))bis(azan-1-yl-1-ylidene)bis(methan-1-yl-1-
ylidene))bis(4-phenyldiazenyl)phenol and its substituted derivatives (3e-h). In addition to, the
compounds 3a-d compared to 2a-d exhibited relatively higher antioxidant property, while the
compounds 3e-h showed less activity than 2e-h.
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13

Tables and Figures Captions
Table 1: Summary of the UV-Vis absorption bands for synthesized compounds 1a-d, 2a-d and 3a-d
Table 2: Comparison of antioxidant activity of compounds 2a-d, 3a-d, 2e-h and 3e-f at a concentration
of 100 μg/mL
Fig. 1: The synthesized 3 with azo precursors
Fig. 2: Absorption spectra of 3c in; 1) DMSO, 2) DMF, 3) THF, 4) CH3OH, 5) CH3CN and 6)
CH3COOH solvents.
Fig. 3: Effects of substituent on absorption spectra of the compounds 3a-d in DMF at room temperature
Fig. 4: Absorption spectra of 3c in DMF (C= 4.3×10-5 M) and H2O: (a) 0%; (b) 10% (c) 20% and (d)
30% water.
14

Table 1.
CH3OH
343
Compound DMSO
DMF
THF
341
343
342
CH3CN
341
CH3CO2H
343
340, 441(sh) 340, 450
350, 441(sh) 349, 444
349, 455(sh) 347, 454
1a
1b
1c
1d
2a
2b
2c
2d
3a
345
342
344
341
341
345
377,526(sh)
365,535
361,456(sh) 361,454(sh) 360,454(sh) 364,458(sh)
355, 470(sh) 343, 480
356, 468(sh) 355, 450
357, 463(sh) 355, 497
346
347
348
346
345
347
345
342
343
346
347
346
375,467(sh)
342, 451(sh)
350,585
386,508(sh) 386,506(sh) 385,506(sh) 387,510(sh)
347,
449(sh)
341,452(sh) 341
356,458(sh) 340
340
340
357,
440(sh)
3b
357, 455(sh)
339
335
340
345, 456
370,461
343, 453
348,583
346,435(sh) 339
338,431(sh)
3c
381,503(sh) 384,504
381,503(sh) 386,508(sh)
3d
Table 2.
DPPH Scavenging
(%)
Compounds
Compounds
DPPH Scavenging (%)
41.4h
(X=S)
(X=O)
10.4g
2a
2e
15

48.7g
16g
9.6g
28
45.3h
11.8h
31.1h
14.4m
19.0m
1.0
2b
2c
2d
3a
3b
3c
2f
2g
2h
3e
3f
48.9
11
3g
3h
6.9
-
3d
Ascorbic acid
92.1
g:ref 21 , h; ref 22, m:ref 40
Fig. 1
NH2
HX
OH
XH
OH
CHO
N
N
N
N
N
EtOH
R
1
R
2
OMe
N
OMe
N
THF
N
N
N
Cl
Cl
O
O
H
X
N
X
H
N
N
N
N
N
N
R
R
3
X=S
X=O
a R=H, b R=Me c R=Cl, d R=NO2 e R=H, f R=Me g R=Cl, h R=NO2
Fig. 2
16

1
4
3
0.4
0.2
0
e
2
n
b
5
Absor
6
290
390
490
Wavelength(nm)
Fig. 3
0.4
0.2
0.0
3a
3d
3b
3c
305
405
505
605
705
Wavelength(nm)
Fig. 4
17

0.4
0.2
0.0
b
e
a
n
c
orba
b
A
d
312
412
512
Wavelength(nm)
18

Highlights
► azo-azomethine dyes with triazine based. ► the tautomerism between enol-amine,
enaminone and hydrazone forms in organic solvent was studied. ► the solvatochromism is
dependent on the substitution, solvent, pH and temperature. ►the azo-azomethine dyes has
antioxidant activity, which are dependent on electron releasing of substituents.

The azo-azomethone dyes were prepared via condensation reaction of 2,4-dichloro-6-methoxy -
1,3,5-triazine with azo couled 2-(2-mercaptophenylimino)methyl)-4-(aryldiazenyl)phenol.
The UV-vis spectra indicated positive solvatochromism in synthesized compound are dependent
on the substitution, solvent, pH and temperature. Some compounds exhibited antibacterial,
antioxidant activities.
OMe
N
N
O
O
H
N
H
N
S
N
S
N
N
N
N
R
R