Synthesis, characterization of novel bisheteroaryl bisazo dyes, and their dyeing and solvatochromic behavior

Article abstract of DOI:10.1002/hc.21085

4-Phenyl-2-aminothaizole was diazotized and coupled with N-(alkyl)-2-oxo-3-cyano-4-methyl-6-hydroxypyridine (2-pyridone). The resultant dyes were named as N-(alkyl)-6-hydroxy-4-methyl-2-oxo-5-((4-phenylthiazole-2-yl) diazenyl)-1,2-dihydro pyridine-3-carbonitrite and duly characterized. The diazotized aryl amines were then coupled to a moiety of above-mentioned dyes at 5-position of thiazole. The obtained bisheteroaryl azo dyes were characterized by elemental analysis and spectral studies. Solvent effects on the visible absorption spectra of the dyes were evaluated. The color of the dyes is discussed with respect to the nature of the heterocyclic ring, aromatic amines, and substituents present therein. All these dyes were applied as disperse dyes on to polyester fabrics, and their fastness properties were evaluated.

Full text of DOI:10.1002/hc.21085

Heteroatom Chemistry
Volume 24, Number 3, 2013
Synthesis, Characterization of Novel
Bisheteroaryl Bisazo Dyes, and Their Dyeing
and Solvatochromic Behavior
Visha P. Modi and Hasmukh S. Patel
Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar 388 120, India
Received 2 November 2012; revised 6 February 2013; accepted 7 February 2013
fibers, coloring of different materials, colored plas-
ABSTRACT: 4-Phenyl-2-aminothaizole was diazo-
tics and polymers, biological-medical studies, and
tized and coupled with N-(alkyl)-2-oxo-3-cyano-4-
advanced applications in organic synthesis [2–4].
methyl-6-hydroxypyridine (2-pyridone). The resultant
The heterocyclic compounds such as pyra-
dyes were named as N-(alkyl)-6-hydroxy-4-methyl-
zole, thaizole, oxadiazole, and thiadiazole and their
2-oxo-5-((4-phenylthiazole-2-yl)diazenyl)-1,2-dihydro
derivatives have shown a wide spectrum of biologi-
pyridine-3-carbonitrite and duly characterized. The
cal activities as well as formation of some dyes. The
diazotized aryl amines were then coupled to a moiety
hetroaryl moieties like 2-aminothiazole derivatives
of above-mentioned dyes at 5-position of thiazole. The
were also reported with dyes characteristics.
obtained bisheteroaryl azo dyes were characterized
For the synthesis of biologically active mole-
by elemental analysis and spectral studies. Solvent
cules, 2-aminothiazole derivatives have been used
effects on the visible absorption spectra of the dyes
as precursors since long time [5–8]. A large num-
were evaluated. The color of the dyes is discussed with
ber of 2-aminothiazoles substituted with different
respect to the nature of the heterocyclic ring, aromatic
aryl and hetroaryl groups are already being prepared
amines, and substituents present therein. All these
for pharmaceutical purposes (e.g., antispasmodic or
dyes were applied as disperse dyes on to polyester
antihistaminic activity [7]). Regarding this, the syn-
fabrics, and their fastness properties were evalu-
thesis of disperse dyes based on 5-arylazothiazole
ꢀC
ated.
2013 Wiley Periodicals, Inc. Heteroatom
derivatives and their applications as disperse dyes
for dyeing polyester fabrics has been reported re-
cently [9, 10]. It has also been reported that dyes
made using 2-aminothiazole compounds, which pos-
sess different substituents in the 4-position of ana-
logues derivatives as diazo components, tend to
show bathochromic shifts when compared to anal-
ogous dyes derived from a benzenoid compound
[11–14]. Thus, it was of great interest in several thi-
azolyl azo dyes substituted at the 4-position with
phenyl and pyridones club molecules. The dyes hav-
ing thiazole and pyridone heterocyclic moieties have
received little interest academically as well as tech-
nically.
Chem 24:208–220, 2013; View this article online at
wileyonlinelibrary.com. DOI 10.1002/hc.21085
INTRODUCTION
The synthetic azo compounds are very important in
the fields of dyes, pigments, and advanced materi-
als [1]. It has been known that azo compounds are
widely used a class of dyes because of their adaptable
application in various fields such as dyeing of textile
Although pyridones are widely used in textile
industry for the preparation of azo and azame-
thine dyes [15–19], in the present study some new
Correspondence to: Hasmukh S. Patel; e-mail: drhspatel786
@yahoo.com.
2013 Wiley Periodicals, Inc.
ꢀC
208

Synthesis, Characterization of Novel Bisheteroaryl Bisazo Dyes, and Its Dyeing and Solvatochromic Behavior 209
SCHEME 1 Proposed synthetic route for the synthesis of bisheteroaryl bisazo dyes: 5a–h, 6a–h, 7a–h.
bishetroaryl azopyridone dyes are coupled with var-
ious diazotized aromatic amines at the 5-position of
2-amino-4-phenylthaizole and their solvatochromic
behavior and fastness properties are studied and
these dyes are applied to disperse dyes for dyeing
of polyester fabrics.
that these compounds dominantly exist in the solid
state in the hydrazone tautomeric form and was also
confirmed by H NMR. The infrared spectra of all
synthesized dyes showed two intense carbonyl bands
at about 1635 and 1695 cm−1, which were assigned
to the diketohydrazone form. The other νmax val-
ues at 3095–3044 cm−1 (aromatic CH) were also
recorded.
1
RESULTS AND DISCUSSION
The synthetic route of these dyes is presented in
Scheme 1.
1H NMR and 13C NMR Spectral Data
The 1H NMR spectrum analysis of the tris
(heteroaryl) bisazo dyes 5a–h, 6a–h and 7a–h are
summarized in the Experimental section, which re-
veals that the diazo coupling of the intermediates
3a–c causes the CH of dyes 5a–h, 6a–h and 7a–
Physical Properties of Dyes
All the dyes were obtained as an amorphous pow-
ders ranging in color from yellow to maroon to
brown. The thin-layer chromatography (TLC) results
showed that only a single spot was observed for each
dye.
1
h to be replaced by an azo heteroaryl ring. The H
NMR spectra of all the dyes exhibited a signal near
δ 14.13–14.19 ppm. This signal corresponds to the
imine N–H proton resonance of the hydrazone form.
These results are in agreement with the data ob-
tained for the hydrazone form with N–H peaks in
the range of δ 15.1–15.6 ppm [21]. The tautomerism
is shown in Scheme 2. All of the aromatic protons
are observed around δ 7.75 ppm, and aliphatic pro-
tons are observed around δ 1.2–3.5 ppm. The 13C
NMR spectral data of all the dyes are also summa-
rized in the Experimental section, which are also in
good agreement with their structures.
Structural Characterization
The produced bisheteroaryl bis-azo dyes 3a–c have
been prepared, which are shown in Scheme 1 fol-
lowed by a reported method for 2-pyridone-based
azo dyes [15,20].
The elemental analysis is also in good agree-
ment with the structural data. The physicochemical
parameters and elemental analysis of bishetroaryl
bisazo dyes 3a–c, 5a–h, 6a–h and 7a–h are described
in the Experimental section.
Mass Spectral Data
IR Spectral Data
Besides, the structure of the compound was well con-
firmed by its mass spectral studies. The recorded
direct analysis in real time-mass spectrometry
All the spectra exhibited a broad N–H hydrazone
band in the region 3439–3457 cm−1, which suggests
Heteroatom Chemistry DOI 10.1002/hc

210 Modi and Patel
SCHEME 2 Enole–ketone–hydroazo tautomerism.
(DART-MS) (Fig. 1) and the molecular ion peak for
the dye compound 5a was used to confirm the molec-
ular formula. The proposed fragmentation pattern
for compound 5a is shown in Scheme 3. DART-MS
mass spectra of compound 5a gave a molecular ion
peak with five decimal points at m/z 469.51387, cor-
responding to a molecular formula C24H19N7O2S.
Scheme 3 demonstrates the possible degradation
FIGURE 1 DART mass spectrum of compound 5a.
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization of Novel Bisheteroaryl Bisazo Dyes, and Its Dyeing and Solvatochromic Behavior 211
SCHEME 3 Proposed fragmentation pattern for compound 5a according to DAR-T mass spectrum.
pathway for the investigated dye molecule 5a. The
primary fragmentation of the dye molecule takes
place due to the loss of one N2 molecule from the
species a to give species b, c, d, and e with the molec-
ular ion peak at 264.32870, 177.17996, 364.40188
and 77.10295, respectively. Further degradation of
species b and d takes place with the loss of one
more N2 molecule and yields species f, e, and c
with the molecular ion peak 159.20838, 77.10295
and 177.17996, respectively. The species c further
degrades with the loss of the ethyl group to give a
species cꢀ with molecular ion peak at 148.11886 and
species cꢀ also degrades with the loss of the CH3
group to give species cꢀꢀ with the molecular ion peak
at 133.08434 and finally we get cꢀꢀꢀ from cꢀꢀ with the
loss of the C3N2O moiety with the molecular ion
peak at 54.03838. Meanwhile, we can see that more
degradation in species f and e also occurred. From
species f, we get species fꢀ with the loss of one phenyl
ring with the molecular ion peak at 82.10543 and
from fꢀ we get fꢀꢀ with the loss of C2 with the molecu-
lar ion peak at 58.09302. Species e further degrades
with the loss of the C2H2 moiety with the molecu-
lar ion peak at 51.06562. The mass spectrum of com-
pound 5a is shown in Fig. 1. The measured molec-
ular weights for all the suggested degradation steps
were consistent with expected values.
The visible absorption spectra of all the synthe-
sized compounds were recorded in different solvent
systems as shown in Figs. 2–4 such as dimethyl for-
mamide (DMF), methanol, acetone, and chloroform,
and their data are shown in Table 1. The solva-
tochromic properties of these dyes in different sol-
vents with different polarities were systematically
Heteroatom Chemistry DOI 10.1002/hc

212 Modi and Patel
may be possible with dye molecules but from results
as shown in Table 1 we can see that there is no signif-
icant effect of H bonding on the electronic spectra.
The ꢀλmax values of these dyes shifted in the range
of 3–27 nm in solvents with different polarities.
The effect of substitution in the phenyl ring of
the diazo component and azo group of coupling
component on the visible absorption spectrum and
the color intensity was also investigated. The wave-
length of maximum absorption (λmax) of the dyes
ranges from 441 to 476 nm in chloroform. A change
in the λmax value can be brought about by vary-
ing the substituent in the phenyl ring of the di-
azo component. As expected, the incorporation of
an electron-withdrawing group at any carbon of the
phenyl diazo component moiety was found to give
rise in the bathochromic shift. Thus, the introduc-
tion of another azo group resulted in a shift of
λmax to a longer wavelength. As expected from the
magnitude of the appropriate field and resonance
components of the substituent effect [24, 25], other
dyes followed a similar pattern. The introduction
of another azo group at the 5-position of thiazole
with a strong electron-withdrawing group provided
the much more bathochromic effect; thus the most
bathochromic dyes were prepared. The dyes 5b, 6b,
and 7b have a NO2 group, which is strongly an
electron-withdrawing group, and it shows the good
bathochromic shift. In the dye, 7f has two methoxy
FIGURE 2 Absorption spectra of compound 5b in different
solvents.
FIGURE 3 Absorption spectra of compound 6b in different
solvents.
(
OCH3) group and the methoxy group is highly po-
lar. So it shows the good bathochromic shift than 7a,
7d, and 7e dyes. Dyes 5g, 6g, 7g and 5h, 6h, 7h also
show the good bathochromic shift because Cl and
Br are present in these dyes. So we can say that to
bring the bathochromic shift, either an electroposi-
tive or -negative group is strategically to be placed
in the diazo compound, which allows a greater elec-
tronic displacement. It has been suggested [26] that
the increased diene character of the ring may be
responsible for the observed large color shift. The
bathochromicity of thiazolyl dyes is not attributed
to the contribution of the 3d atomic orbital of the
sulfur atom of the ring [27].
FIGURE 4 Absorption spectra of compound 7b in different
solvents.
Dyeing Characterization on Polyester Fabric
investigated [22]. The visible absorption maxima of
these dyes very clearly depends on the properties of
solvents and increases with an increase in polarities
of solvents in the following order: chloroform < ace-
tone < methanol < DMF. The replacement of DMF
by solvents of lower polarities, which are methanol
(32.60), acetone (20.56), and chloroform (4.18) [23],
led to a hypsochromic shift of absorption maxima.
In methanol solvent system, the hydrogen bonding
All the dyes were applied on polyester fabric at 2%
(w/w) shade as dispersed dyes. Their dyeing prop-
erties are summarized in Table 2. These dyes gave
a wide range of shades varying from yellow to ma-
roon to brown with excellent brightness, levelness,
and depth of fabrics. Variation in the shades of the
dyed fabric results from both the nature and position
of the substituent present on the diazo component.
The dyed fabrics have good to excellent sublimation
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization of Novel Bisheteroaryl Bisazo Dyes, and Its Dyeing and Solvatochromic Behavior 213
TABLE 1 Visible Absorption Spectra and Spectra Shifts in Various Solvents for Dyes 5a–h, 6a–h and 7a–h
DMF (36.71)
MeOH (32.66)
Acetone (20.56)
Chloroform (4.81)
a
Dyes
Color on Polyester
λmax
λmax
ꢀλmax
λmax
ꢀλmax
λmax
ꢀλmax
5a
5b
5c
5d
5e
5f
5g
5h
6a
6b
6c
6d
6e
6f
6g
6h
7a
7b
7c
7d
7e
7f
Yellow
Reddish maroon
Yellow
Yellow
Yellow
460
496
463
462
459
473
480
476
465
498
470
468
466
480
487
484
470
503
477
475
472
488
494
491
451
482
458
452
454
464
473
468
458
486
463
459
462
470
476
473
465
491
468
466
469
476
480
478
−09
−14
−05
−10
−05
−09
−07
−08
−07
−12
−07
−09
−04
−10
−11
−11
−05
−12
−09
−09
−03
−12
−14
−13
443
476
454
448
451
460
468
465
448
479
457
453
455
462
470
467
454
482
457
460
460
464
472
468
−17
−20
−09
−14
−08
−13
−12
−11
−17
−19
−13
−15
−11
−18
−17
−17
−16
−21
−20
−15
−12
−24
−22
−23
441
473
447
445
450
458
465
462
447
475
451
452
454
61
468
465
452
476
455
459
458
463
470
467
−19
−23
−16
−17
−09
−15
−15
−14
−18
−23
−19
−16
−12
−19
−19
−19
−18
−27
−22
−16
−14
−25
−24
−24
Orange
Light red
Dark orange
Turmeric
Reddish Maroon
Orange
Turmeric
Turmeric
Light red
Red
Reddish orange
Orange
Maroon
Dark orange
Dark orange
Orange
Red
Bright red
Red
7g
7h
aꢀλ
= λ
– λmax(MeOH/acetone/chloroform).
max
max(DMF)
fastness. A remarkable degree of levelness and
brightness after washing indicates good penetration
and excellent affinity of these dyes to the fabric.
duction clearing is important for these dyeing. As
these dyes are characteristically hydroscopic and
high fastness ratings.
Although in all the cases, light fastness was good
as shown in Table 2, the dyes containing the strongly
electron-withdrawing and highly polar group were
marginally superior to the other, again emphasizing
the importance of appropriate substituent. Attempts
are in progress to improve the light fastness proper-
ties of these dyes.
The dry heat fastness property and rubbing fast-
ness were determined and are shown in Table 2;
generally fastness to heat was moderate to good,
consistent with the presence of polar groups on the
chromophores.
Color Properties of the Dyes on Polyester Fabric
The dyes when applied to polyester fabric under the
high-temperature dyeing condition furnished yellow
to maroon to brown shades. There appears to be a
general correlation between the hues of dyeing on
polyester with the absorption characteristics in so-
lution. Dyeing on the fabric is also affected by substi-
tution of the phenyl ring. In contrast to the negligi-
ble effect of 4-substituents on the color than the azo
group with the substituted phenyl ring at 5-position
of the thaizole ring. These dyes have two azo groups
with the strongly electron-withdrawing polar group.
Therefore, it shows deep yellow to maroon to brown
shades.
CONCLUSIONS
This article describes the synthesis of some novel
heterocycle-based bisazo disperse dyes by using var-
ious aromatic amine derivatives as diazo compo-
nents and 2-azopyridone-4-phenyl thaizole as a cou-
pling component. The solvatochromic behavior and
substituent effect in various solvents were evalu-
ated. The results indicated that these dyes were
strongly dependent on solvents and show generally
bathochromic shifts as the polarity of solvents was
Fastness Properties of the Dyed Polyester Fabric
The fastness ratings are summarized in Table 2.
They are good to excellent for fabrics that had been
subjected to the reduction clearing stage. However
when the reduction clearing was omitted, marginally
worse staining was observed. This indicates that re-
Heteroatom Chemistry DOI 10.1002/hc

214 Modi and Patel
TABLE 2 Fastness Properties of the Dyes derivatives 5a–h, 6a–h and 7a–h
Sublimation Fastness
Staining
Perspiration
Rubbing
Dye
Washing
Acid
Alkali
Dry
Wet
Change in Tone
180◦C
210◦C
Light (40 h)
5a
5b
5c
5d
5e
5f
5g
5h
6a
6b
6c
6d
6e
6f
6g
6h
7a
7b
7c
7d
7e
7f
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4
4–5
4–5
4–5
4
4–5
4–5
4–5
3
4–5
4–5
4–5
4
4–5
4–5
4–5
4
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
3–4
4–5
4–5
4–5
4
3
4–5
4
4–5
4–5
4
4–5
4–5
4–5
4–5
3–4
4–5
4
4–5
4
4
4
4
4
4–5
4
4–5
4–5
4
4
4
4
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4
4–5
4–5
4–5
4
4–5
3–4
4–5
4–5
4
4
4–5
4
4–5
3–4
3–4
4–5
4
3–4
4
3
4–5
4
5
5
5
4
4–5
4–5
4
4–5
5
4–5
5
5
4
3–4
4–5
4
4–5
4
4–5
4
3
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4–5
4
4–5
4–5
4–5
4
4–5
4–5
4–5
4–5
4–5
4
4
4–5
4–5
4
4–5
3–4
4–5
4–5
3
4–5
4–5
4
5
4–5
4
4–5
4–5
4–5
3–4
4–5
4–5
4–5
3–4
3–4
3–4
4–5
4
3–4
4–5
4–5
4–5
4–5
7g
7h
4–5
4
Grading: 1, poor; 2, fair; 3, moderate; 4, good; 5, very good to Excellent.
increased. The absorption maxima of dyes shifts
bathochromically in the following sequence: DMF
> methanol > acetone > chloroform. The washing
fastness is good, whereas the light fastness prop-
erty is poor, although in most cases incorporation of
electron-withdrawing substituents results obtained
in all samples in a correlation between the color
strength of the dyes in solution and on polyester
fabric.
spectrometer in DMSO-d6 (Department of Chem-
istry, Sardar Patel University, Vallabh Vidyana-
gar, India). Absorption spectra were recorded on
a Shimadzu UV-1601 spectrophotometer (Depart-
ment of Chemistry, Sardar Patel University, Val-
labh Vidyanagar, India) in various solvents. DART-
MS of samples was carried out on a JEOL-AccuTOF
JMC T100LC mass spectrometer instrument (CDRI,
Lucknow, India).
EXPERIMENTAL
Preparation of Bishetroaryl Monoazo Dyes 3a–c
All the chemicals used throughout were of labora-
tory grade. The thiazole and pyridones were pro-
cured from Merck India(Mumbai, India).
General Procedure: Diazotization and Coupling.
4-Phenyl-2-aminothiazole (1.76 g, 0.01 mol) 1 was
dissolved in freshly prepared cool nitrosyl sulfuric
acid (0.01) as per the reported method [27, 28] and
was rapidly cooled in an ice bath to 0–5◦C. Before
the diazotization ends, sulfamic acid (0.5 mg) was
added to the solution of the diazonium salt solution
to remove excess nitrite ion.
In the beaker, 2-pyridone derivatives (0.01 mol)
2a–c as a coupling component were dissolved in
water and added solid sodium acetate until solu-
tion became clear. It was cooled at 0–5◦C, and then
the above-mentioned diazonium salt solution was
added into the 2-pyridone solution by dropwise with
Microanalysis data (C, H, N, and S) were
recorded on a Perkin-Elmer 2400 CHN elemental
analyzer (SICART, Vallabh Vidyanagar, India), and
the results were within the accepted range ( 0.50)
of the calculated values. All melting points were de-
termined on an electro-thermal IA 9100 apparatus
(SICART, Vallabh Vidyanagar, India) and are un-
corrected. IR spectra were recorded in KBr pellets
on a Nicolet 760D spectrophotometer (Vaibhav Lab-
oratory, Ahmedabad, India). 1H NMR and 13C NMR
spectra were recorded on a Bruker Avance DPX 400
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization of Novel Bisheteroaryl Bisazo Dyes, and Its Dyeing and Solvatochromic Behavior 215
constant stirring under the 0–5◦C temperature. The
δ (Ar-C): 74.16, 110.76, 115.46, 127.58 (2C), 128.49,
129.34 (2C), 133.2, 152.43, 156.70, 163.26, 163.8,
166.32. Anal. Calcd. for C20H19N5O3S (FW 409): C,
58.67; H, 4.64; N, 17.11; S, 7.82. Found: C, 58.69; H,
4.65; N, 17.12; S, 7.83.
pH of the mixture was adjusted around 6–7 by
adding 40% aqueous sodium hydroxide. The resul-
tant dyes 3a–c were filtered, washed with water, and
air-dried.
Analytical and Spectral Data of the Bishetroaryl
Monoazo Dyes 3a–c.
Synthesis of Bisheteroaryl Bisazo Dyes 5a–h,
6a–h and 7a–h
(E)-1-Ethyl-6-hydroxy-4-methyl-2-oxo-5-((4-
phenylthiazol-2-yl)diazenyl)-1,2-dihydropyridine-3-
carbonotrile (3a). Yield: 85%. mp: 212◦C. IR (KBr,
cm−1): 1619 ( C C), 2217 ( CN), 1652 and 1682
General Procedure: Diazotization and Coupling.
Various aromatic amines 4a–h were taken and
diazotized by the conventional method. All the
diazo salts were coupled with above-mentioned
bishetroaryl dyes 3a–c by the following process.
Bishetroaryl monoazo dyes were dissolved in
aqueous sodium hydroxide (aq. NaOH) (0.01 M) and
cooled at 0–5◦C. The previously prepared diazonium
solution was then added into it dropwise with con-
stant stirring. After completion of the coupling reac-
tion, the resultant solution was made neutral by ad-
dition of aqueous ammonium solution and the pre-
cipitate of dye was obtained. The precipitated dye
5a–h, 6a–h and 7a–h were filtered, washed with wa-
ter, and air-dried. The progress of the reaction was
monitored by TLC using a DMSO:water mixture (5:2
by volume) as a developing solvent and silica gel TLC
plates as the stationary phase.
(
CO), 3441 ( NH-hydrazo), 1621 ( N N), 1542
(thiazole). 1H NMR (400 MHz, DMSO-d6, δ/ppm):
1.11 (t, J = 7.2 Hz, 3H, CH3), 2.52 (s, H, CH3), 3.79
(q, J = 7.2 Hz, 2H, CH2), 6.10 (s, 1H, thiazole),
7.58–7.87 (m, 5H, Ar-H), 15.13 (s, 1H, N H hy-
drazone). 13C NMR: 9.20 ( CH3), 13.34 ( CH2),
35.70 ( CH3), 117.76 ( CN), δ (Ar-C): 74.0, 110.4,
115.52, 127.43 (2C), 128.91 (2C), 128.70, 133.14,
146.72, 156.24, 159.37, 163.3, 166.4. Anal. Calcd. for
C18H15N5O2S (FW 365): C, 59.17; H, 4.54; N, 19.17;
S, 8.76. Found: C, 59.18; H, 4.55; N, 19.18; S, 8.77.
(E)-1-Butyl-6-hydroxy-4-methyl-2-oxo-5-((4-
phenylthiazol-2-yl)diazenyl)-1,2-dihydropyridine-3-
carbonotrile (3b). Yield: 82%. mp: 211◦C. IR (KBr,
cm−1): 1617 ( C C), 2221 ( CN), 1650 and 1676
Analytical and Spectral Data of the Bisheteroaryl
(
CO), 3452 ( NH-hydrazo), 1611 ( N N), 1540
Bisazo Dyes 5a–h, 6a–h and 7a–h.
(thiazole). 1H NMR (400 MHz, DMSO-d6, δ/ppm):
1.13 (t, J = 7.1 Hz, 3H, CH3), 3.74 (t, J = 7.1 Hz,
2H, CH2), 1.62 (m, 2H, CH2), 1.35 (m, 2H, CH2),
2.56 (s, H, CH3), 6.12 (s, 1H, thiazole), 7.27–7.49 (m,
5H, Ar-H), 15.14 (s, 1H, N-H hydrazone). 13C NMR:
9.18 ( CH3), 13.37 ( CH3), 20.23 ( CH2), 30.63
1-Ethyl-6-hydroxy-4-methyl-2-oxo-((E)-(4-phenyl-
5-((E)-phenyldiazenyl)thiazol-2-yl)diazenyl)-1,2-di-
hydropyridine-3-carbonitrile (5a). Yield: 76%. mp:
226◦C. IR (KBr, cm−1): 1612 ( C C), 2230 ( CN),
1648 and 1689 ( CO), 3447 ( NH-hydrazo), 1638
1
(
CH2), 41.52 ( CH2), 117.84 ( CN), δ (Ar-C):
(
N N), 3057 (
C
H), 843 (p-sub. Ph). H NMR
73.82, 111.03, 115.54, 127.53 (2C), 128.62, 129.20
(2C), 133.17, 152.5, 156.42, 163.17, 163.62, 166.24.
Anal. Calcd. for C20H19N5O2S (FW 393): C, 61.06;
H, 4.83; N, 17.81; S, 8.14. Found: C, 61.08; H, 4.82;
N, 17.82; S, 8.16.
(400 MHz, DMSO-d6, δ/ppm): 1.09 (t, J = 7.4 Hz,
3H, CH3), 2.56 (s, 3H, CH3), 3.95 (q, J = 7.2 Hz,
2H, CH2), 7.37–8.28 (m, 10H, Ar-H), 15.15 (s, 1H,
N
(
H hydrazone). 13C NMR: 9.25 ( CH3), 13.38
CH2), 35.73 ( CH3), 117.79 ( CN), δ (Ar-C):
74.08, 115.50, 127.48 (2C), 127.97 (3C), 128.38 (2C),
128.72 (2C), 128.97, 129.0, 133.18, 146.76, 156.27,
159.33, 163.16, 163.38, 166.48. Anal. Calcd. for
C24H19N7O2S (FW 469): C, 60.88; H, 4.01; N, 20.71;
S, 6.76. Found: C, 60.85; H, 4.02; N, 20.69; S, 6.74.
(E)-6-Hydroxy-1-(methoxymethyl)-4-methyl-2-oxo-
5-((4-phenylthiazol-2-yl)diazenyl)-1,2-dihydropyridine-
3-carbonotrile (3C). Yield: 86%. mp: 222◦C. IR
(KBr, cm−1): 1615 ( C C), 2213 ( CN), 1648 and
1677 ( CO), 3451 ( NH-hydrazo), 1613 ( N N),
1539 (thiazole). 1H NMR (400 MHz, DMSO-d6,
δ/ppm): 2.08 (m, 2H, CH2), 3.77 (t, J = 7.0 Hz,
2H, CH2), 4.89 (t, J = 7.0 Hz, 2H, CH3), 3.42 (s,
3H, OCH3), 2.57 (s, H, CH3), 6.10 (s, 1H, thiazole),
7.33–7.57 (m, 5H, Ar-H), 15.11 (s, 1H, N H hy-
drazone). 13C NMR: 9.23 ( CH3), 56.31 ( OCH3),
74.53 ( CH3), 117.76 ( CN), 123.40 (2C, CH2),
1-Ethyl-6-hydroxy-4-methyl-5-((E)-(5-((E)-(4-
nitrophenyl) diazenyl)-4-phenyl thiazol-2-yl)diazenyl)-
2-oxo-1,2-dihydropyridine-3-carbonitrile (5b). Yield:
83%. mp: 225◦C. IR (KBr, cm−1): 1616 ( C C), 2217
(
CN), 1652 and 1693 ( CO), 3449 ( NH-hydrazo),
1646 ( N N), 3060 ( H), 842 (p-sub.Ph), 1565
(s, NO2). H NMR (400 MHz, DMSO-d6, δ/ppm):
C
1
Heteroatom Chemistry DOI 10.1002/hc

216 Modi and Patel
1.08 (t, J = 7.4 Hz, 3H, CH3), 2.60 (s, H, CH3),
3.98 (q, J = 7.2 Hz, 2H, CH2), 7.33–8.10 (m, 9H,
Ar-H), 15.17 (s, 1H, N H hydrazone). 13C NMR:
9.20 ( CH3), 13.39 ( CH2), 35.78 ( CH3), 117.79
1.12 (t, J = 7.4 Hz, 3H, CH3), 2.57 (s, H, CH3),
3.93 (q, J = 7.2 Hz, 2H, CH2), 7.28–8.02 (m, 9H,
Ar-H), 15.17 (s, 1H, N H hydrazone), 2.27 (s, 3H,
CH3). 13C NMR: 9.23 ( CH3), 13.39 ( CH2), 21.32
(
CN), δ (Ar-C): 74.00, 115.53, 123.81 (2C), 126.35
( CH3), 35.71 ( CH3), 117.73 ( CN), δ (Ar-C):
(2C), 127.47 (2C), 128.70, 128.93 (2C), 133.19,
134.62, 146.74, 147.61, 156.28, 159.37, 163.19,
163.70, 166.43. Anal. Calcd. for C24H18N8O4S (FW
514): C, 56.03; H, 3.50; N, 21.78; S, 6.22. Found: C,
56.04; H, 3.49; N, 21.80; S, 6.20.
74.02, 115.52, 125.62, 127.46 (2C), 128.51 (2C),
128.90 (2C), 129.07, 129.36 (2C), 133.16, 138.50,
146.74, 156.25, 159.33, 163.18, 163.37, 166.87. Anal.
Calcd. for C25H21N7O2S (FW 483): C, 62.11; H, 4.34;
N, 20.28; S, 6.62. Found: C, 62.10; H, 4.35; N, 20.30;
S, 6.60.
4-((E)-(2-((E)-(5-Cyano-1-ethyl-2-hydroxy-4-meth-
yl-6-oxo-1,6-dihydro pyridin-3-yl)diazenyl)-4-phenyl-
thiazol-5-yl)diazenyl) benzoic acid (5c). Yield: 87%.
mp: 228◦C. IR (KBr, cm−1): 1614 ( C C), 2215
1-Ethyl-6-hydroxy-5-((E)-(4-methoxyphenyl)dia-
zenyl)-4-phenylthiazol-2-yl)diazenyl)-4-methyl-2-oxo-
1,2-dihydropyridine-3-carbonitrile (5f). Yield: 79%.
mp: 227◦C. IR (KBr, cm−1): 1615 ( C C), 2220
(
CN), 1656 and 1685 ( CO), 3452 ( NH-hydrazo),
1640 ( N N), 3058 ( H), 848 (p-sub.Ph), 1697
C
(
CN), 1644 and 1687 ( CO), 3443 ( NH-hydrazo),
1633 ( N N), 3059 ( H), 839 (p-sub.Ph), 1253
OCH3). 1H NMR (400 MHz, DMSO-d6, δ/ppm):
(s, COOH). 1H NMR (400 MHz, DMSO-d6, δ/ppm):
1.10 (t, J = 7.4 Hz, 3H, CH3), 2.59 (s, H, CH3),
3.96 (q, J = 7.4 Hz, 2H, CH2), 7.32–7.96 (m, 9H,
Ar-H), 15.15 (s, 1H, N-H hydrazone), 11.78 (1H, s,
COOH). 13C NMR: 9.24 ( CH3), 13.37 ( CH2),
35.74 ( CH3), 117.78 ( CN), δ (Ar-C): 74.09, 115.52,
127.49 (2C), 128.60 (2C), 128.91 (2C), 128.76, 130.42
(2C), 130.62, 133.17, 133.83, 146.78, 156.29, 159.32,
163.17, 163.39, 166.44, 166.98. Anal. Calcd. for
C25H19N7O4S (FW 513): C, 58.47; H, 3.70; N, 19.10;
S, 6.23. Found: C, 58.46; H, 3.71; N, 19.08; S, 6.24.
C
(
1.13 (t, J = 7.4 Hz, 3H, CH3), 2.60 (s, H, CH3),
3.94 (q, J = 7.2 Hz, 2H, CH2), 7.40–8.04 (m, 9H,
Ar-H), 15.15 (1H, s, N H hydrazone), 3.85 (s, 3H,
OCH3). 13C NMR: 9.26 ( CH3), 13.36 ( CH2), 35.72
(
CH3), 55.54 ( OCH3), 117.70 ( CN), δ (Ar-C):
74.08, 114.36 (2C), 115.52, 121.09, 127.42 (2C),
128.91 (2C), 128.76, 129.79 (2C), 133.17, 146.70,
156.25, 159.36, 160.31, 163.17, 163.37, 166.58. Anal.
Calcd. for C25H21N7O3S (FW 499): C, 60.12; H, 4.20;
N, 19.63; S, 6.41. Found: C, 60.13; H, 4.21; N, 19.61;
S, 6.42.
1-Ethyl-6-hydroxy-5-((E)-(5-((E)-(4-hydroxyphen-
yl)diazenyl)-4-phenyl thiazol-2-yl) daizenyl)-4-methyl-
2-oxo-1,2-dihydropyridine-3-carbonitrile (5d). Yield:
77%. mp: 247◦C. IR (KBr, cm−1): 1617 ( C C), 2212
5-((E)-(5-((E)-(4-Chlorophenyl)diazenyl)-4-phen-
ylthiazol-2-yl)diazenyl)-1-ethyl-6-hydroxy-4-methyl-2-
oxo-1,2-dihydropyridine-3-carbonitrile (5g). Yield:
86%. mp: 232◦C. IR (KBr, cm−1): 1617 ( C C),
2216 ( CN), 1652 and 1687 ( CO), 3440 ( NH-
(
CN), 1650 and 1687 ( CO), 3450 ( NH-hydrazo),
1648 ( N N), 3055 ( H), 838 (p-sub.Ph), 3452–
C
3460 (br, OH). 1H NMR (400 MHz, DMSO-d6,
δ/ppm): 1.12 (t, J = 7.4 Hz, 3H, CH3), 2.58 (s, H,
CH3), 3.97 (q, J = 7.2 Hz, 2H, CH2), 7.35–8.13
(m, 9H, Ar-H), 15.16 (s, 1H, N H hydrazone),
10.58 (s, 1H, OH). 13C NMR: 9.27 ( CH3), 13.36
hydrazo), 1642
( N N), 3061 ( C H), 835
(p-sub.Ph), 1086 (s, C Cl stre.). 1H NMR (400 MHz,
DMSO-d6, δ/ppm): 1.10 (t, J = 7.4 Hz, 3H, CH3), 2.61
(s, H, CH3), 3.97 (q, J = 7.2 Hz, 2H, CH2), 7.23–8.99
(m, 9H, Ar-H), 15.18 (s, 1H, N H hydrazone). 13C
NMR: 9.20 ( CH3), 13.32 ( CH2), 35.78 ( CH3),
117.72 ( CN), δ (Ar-C): 74.09, 115.57, 126.71,
127.46 (2C), 128.14 (2C), 128.93 (2C), 128.76, 130.20
(2C), 133.19, 134.38, 146.70, 156.23, 159.30, 163.17,
163.32, 166.92. Anal. Calcd. for C24H18ClN7O2S (FW
503.5): C, 57.20; H, 3.57; N, 19.46; S, 6.35. Found:
C, 57.23; H, 3.55; N, 19.48; S, 6.32.
(
CH2), 35.76 ( CH3), 117.77 ( CN), δ (Ar-C):
74.04, 115.54, 116.12 (2C), 121.48, 127.46 (2C),
128.93 (2C), 128.73, 130.14 (2C), 133.14, 146.72,
156.30, 158.60, 159.35, 163.14, 163.34, 166.42. Anal.
Calcd. for C24H19N7O3S (FW 485): C, 59.38; H, 3.91;
N, 20.02; S, 6.59. Found: C, 59.41; H, 3.92; N, 20.04;
S, 6.60.
1-Ethyl-6-hydroxy-4-methyl-2-oxo-5-((E)-(4-phen-
yl-5-((E)-p-totyldiazenyl)thiazol-2-yl)diazenyl)-1,2-di-
hydropyridine-3-carbonitrile (5e). Yield: 90%. mp:
225◦C. IR (KBr, cm−1): 1608 ( C C), 2211 ( CN),
1646 and 1683 ( CO), 3442 ( NH-hydrazo), 1636
5-((E)-(5-((E)-(4-Bromophenyl)diazenyl)-4-phen-
ylthiazol-2-yl)diazenyl)-1-ethyl-6-hydroxy-4-methyl-2-
oxo-1,2-dihydropyridine-3-carbonitrile (5h). Yield:
81%. mp: 228◦C. IR (KBr, cm−1): 1613 ( C C), 2217
(
(
N N), 3057 (
C
H), 842 (p-sub.Ph), 1465
(
CN), 1642 and 1687 ( CO), 3446 ( NH-hydrazo),
CH3). 1H NMR (400 MHz, DMSO-d6, δ/ppm):
1637 ( N N), 3066 ( H), 840 (p-sub.Ph), 1075
C
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization of Novel Bisheteroaryl Bisazo Dyes, and Its Dyeing and Solvatochromic Behavior 217
(s, C-Br stre.). 1H NMR (400 MHz, DMSO-d6,
mp: 229◦C. IR (KBr, cm−1): 1614 ( C C), 2218
CN), 1646 and 1690 ( CO), 3447 ( NH-hydrazo),
δ/ppm): 1.12 (t, J = 7.4 Hz, 3H, CH3), 2.54 (s, H,
CH3), 3.95 (q, J = 7.2 Hz, 2H, CH2), 7.34–8.16 (m,
9H, Ar-H), 15.14 (s, 1H, N H hydrazone). 13C NMR:
9.21 ( CH3), 13.33 ( CH3), 35.77 ( CH3), 117.73
(
1642 ( N N), 3055 (
C H), 850 (p-sub.Ph), 1699
(s, COOH). 1H NMR (400 MHz, DMSO-d6, δ/ppm):
1.12 (t, J = 7.2 Hz, 3H, CH3), 3.81 (t, J = 7.2 Hz, 2H,
CH2), 1.62 (m, 2H, CH2), 1.36 (m, 2H, CH2), 2.56
(s, H, CH3), 7.33–8.05 (m, 9H, Ar-H), 15.13 (s, 1H,
(
CN), δ (Ar-C): 74.07, 115.56, 123.10, 127.05,
127.46 (2C), 128.90 (2C), 128.73, 131.12 (2C), 131.84
(2C), 133.16, 146.72, 156.26, 159.38, 163.14, 163.39,
166.64. Anal. Calcd. for C24H18BrN7O2S (FW 548):
C, 52.55; H, 3.28; N, 17.88; S, 5.83. Found: C, 52.56;
H, 3.27; N, 17.90; S, 5.84.
N
H hydrazone), 11.74 (s, 1H, COOH). 13C NMR:
9.23 ( CH3), 13.71 ( CH2), 20.14 ( CH2), 30.80
CH2), 41.54 ( CH3), 117.93 ( CN), δ (Ar-C):
(
73.83, 115.54, 127.53 (2C), 128.32 (2C), 128.57,
129.12 (2C), 130.12 (2C), 130.40, 133.22, 133.78,
146.47, 156.44, 159.37, 163.33, 163.80, 166.86,
166.95. Anal. Calcd. for C27H23N7O4S (Fw 541): C,
59.88; H, 4.25; N, 18.11; S, 5.91. Found: C, 59.89; H,
4.23; N, 18.12; S, 5.92.
1-Butyl-6-hydroxy-4-methyl-2-oxo-5-((E)-(4-phen-
yl-5-((E)-phenyldiazenyl)thiazol-2-yl)diazenyl)-1,2-di-
hydropyridine-3-carbonitrile (6a). Yield: 82%. mp:
227◦C. IR (KBr, cm−1): 1612 ( C C), 2220 ( CN),
1638 and 1686 ( CO), 3439 ( NH-hydrazo), 1646
(
N N), 3069 ( C
H), 828 (p-sub.Ph). 1H NMR
1-Butyl-6-hydroxy-5-((E)-(5-((E)-(4-hydroxyphen-
yl)diazenyl)-4-phenylthiazol-2-yl)diazenyl)-4-methyl-2-
oxo-1,2-dihydropyridine-3-carbonitrile (6d). Yield:
84%. mp: 250◦C. IR (KBr, cm−1): 1615 ( C C), 2219
(400 MHz, DMSO-d6, δ/ppm): 1.09 (t, J = 7.2 Hz,
3H, CH3), 3.73 (t, J = 7.2 Hz, 2H, CH2), 1.65 (m, 2H,
CH2), 1.38 (m, 2H, CH2), 2.60 (s, H, CH3), 7.42–8.12
(m, 10H, Ar-H), 15.16 (s, 1H, N H hydrazone). 13C
NMR: 9.19 ( CH3), 13.64 ( CH2), 20.13 ( CH2),
30.81 ( CH2), 41.52 ( CH3), 117.87 ( CN), δ
(Ar-C): 73.80, 115.54, 127.50 (2C), 128.59, 128.73
(3C), 128.89 (2C), 128.97, 129.13 (2C), 133.20,
146.49, 156.40, 159.42, 163.32, 163.84, 166.92. Anal.
Calcd. for C26H23N7O2S (Fw 497): C, 62.27; H, 4.62;
N, 19.71; S, 6.43. Found: C, 62.28; H, 4.64; N, 19.72;
S, 6.45.
(
CN), 1653 and 1694 ( CO), 3443 ( NH-hydrazo),
1647 ( N N), 3053 ( H), 839 (p-sub.Ph), 3451–
C
3456 (br, OH). 1H NMR (400 MHz, DMSO-d6,
δ/ppm): 1.10 (t, J = 7.2 Hz, 3H, CH3), 3.79 (t, J = 7.2
Hz, 2H, CH2), 1.64 (m, 2H, CH2), 1.37 (m, 2H, CH2),
2.53 (s, H, CH3), 7.39–8.13 (m, 9H, Ar-H), 15.12
(s, 1H, N H hydrazone), 10.65 (s, 1H, OH). 13C
NMR: 9.24 ( CH3), 13.72 ( CH2), 20.12 ( CH2),
30.83 ( CH2), 41.51 ( CH3), 117.92 ( CN), δ (Ar-
C): 73.84, 115.56, 116.19 (2C), 121.44, 127.54 (2C),
128.58, 129.14 (2C), 130.51 (2C), 133.21, 146.49,
156.43, 158.38, 159.38, 163.18, 163.84, 166.58. Anal.
Calcd. for C26H23N7O3S (Fw 513): C, 60.81; H, 4.48;
N, 19.10; S, 6.23. Found: C, 60.83; H, 4.50; N, 19.11;
S, 6.25.
1-Butyl-6-hydroxy-4-methyl-5-((E)-(5-((E)-(4-ni-
trophenyl)diazenyl)-4-phenylthiazol-2-yl)diazenyl)-2-
oxo-1,2-dihydropyridine-3-carbonitrile (6b). Yield:
78%. mp: 224◦C. IR (KBr, cm−1): 1607 ( C C),
2212 ( CN), 1645 and 1682 ( CO), 3440 ( NH-
Hydrazo), 1637
( N N), 3062 ( C H), 840
(p-sub.Ph), 1563 (s, NO2). 1H NMR (400 MHz,
DMSO-d6, δ/ppm): 1.11 (t, J = 7.2 Hz, 3H, CH3), 3.76
(t, J = 7.2 Hz, 2H, CH2), 1.67 (m, 2H, CH2), 1.34
(m, 2H, CH2), 2.57 (s, H, CH3), 7.63–8.10 (m, 9H,
Ar-H), 15.17 (s, 1H, N H hydrazone). 13C NMR:
9.21 ( CH3), 13.70 ( CH2), 20.15 ( CH2), 30.82
1-Butyl-6-hydroxy-4-methyl-2-oxo-5-((E)-(4-phen-
yl-5-((E)-p-totyldiazenyl)thiazol-2-yl)diazenyl)-1,2-di-
hydropyridine-3-carbonitrile (6e). Yield: 77%. mp:
235◦C. IR (KBr, cm−1): 1609 ( C C), 2212 ( CN),
1642 and 1689
(
CO), 3442
( NH-hydrazo),
1639 ( N N), 3059 (
C
H), 840 (p-sub.Ph),
(
CH2), 41.53 ( CH3), 117.90 ( CN), δ (Ar-C):
1467( CH3). 1H NMR (400 MHz, DMSO-d6,
δ/ppm): 1.08 (t, J = 7.2 Hz, 3H, CH3), 3.75 (t, J =
7.2 Hz, 2H, CH2), 1.60 (m, 2H, CH2), 1.33 (m, 2H,
CH2), 2.59 (s, H, CH3), 2.23 (s, 3H, CH3), 7.28–7.96
(m, 9H, Ar-H), 15.16 (s, 1H, N H hydrazone). 13C
NMR: 9.22 ( CH3), 13.70 ( CH2), 20.15 ( CH2),
21.43 ( CH3), 30.83 ( CH2), 41.55 ( CH3), 117.93
73.82, 115.52, 123.72 (2C), 126.63 (2C), 127.52 (2C),
128.58, 129.10 (2C), 133.21, 134.82, 146.48, 147.82,
156.42, 159.39, 163.34, 163.82, 166.87. Anal. Calcd.
for C26H22N8O4S (Fw 542): C, 57.56; H, 4.05; N,
20.66; S, 5.90. Found: C, 57.57; H, 4.08; N, 20.67; S,
5.92.
(
CN), δ (Ar-C): 73.82, 115.51, 125.36, 127.56
4-((E)-(2-((E)-(1-Butyl-5-cyano-2-hydroxy-4-meth-
yl-6-oxo-1,6-dihydropyridine-3-yl)diazenyl)-4-phenyl-
thiazol-5-yl)diazenyl) benzoic acid (6c). Yield: 76%.
(2C), 128.54, 128.92 (2C), 129.16 (2C), 129.72 (2C),
133.26, 138.76, 146.46, 156.43, 159.38, 163.32,
163.83, 166.87. Anal. Calcd. for C27H25N7O2S (Fw
Heteroatom Chemistry DOI 10.1002/hc

218 Modi and Patel
511): C, 63.40; H, 4.89; N, 19.17; S, 6.26. Found: C,
63.42; H, 4.87; N, 19.19; S, 6.25.
( CH3), 117.91 ( CN), δ (Ar-C): 73.82, 115.51,
123.33, 127.09, 127.52 (2C), 128.54, 129.17 (2C),
131.07 (2C), 131.63 (2C), 133.26, 146.44, 156.45,
159.34, 163.37, 163.81, 166.82. Anal. Calcd. for
C26H22BrN7O2S (Fw 576): C, 54.16; H, 3.81; N,
17.01; S, 5.55. Found: C, 54.18; H, 3.79; N, 17.00; S,
5.56.
1-Butyl-6-hydroxy-5-((E)-(5-((E)-(4-methoxyphen-
yl)diazenyl)-4-phenylthiazol-2-yl)diazenyl)-4-methyl-2-
oxo-1,2-dihydropyridine-3-carbonitrile (6f). Yield:
86%. mp: 225◦C. IR (KBr, cm−1): 1615 ( C C),
2218 ( CN), 1639 and 1687 ( CO), 3448 ( NH-
hydrazo), 1643
(
N N), 3057
(
C
H), 838
6-Hydroxy-1-(methoxymethyl)-4-methyl-2-oxo-5-
((E)-(4-phenyl-5-((E)-phenyldiazenyl)thiazol-2-yl)dia-
zenyl)-1,2-dihydropyridine-3-carbonitrile (7a). Yield:
84%. mp: 228◦C. IR (KBr, cm−1): 1612 ( C C),
2213 ( CN), 1637 and 1685 ( CO), 3439 ( NH-
(p-sub.Ph), 1256 ( OCH3). 1H NMR (400 MHz,
DMSO-d6, δ/ppm): 1.10 (t, J = 7.2 Hz, 3H, CH3),
3.79 (t, J = 7.2 Hz, 2H, CH2), 1.67 (m, 2H, CH2),
1.40 (m, 2H, CH2), 2.57 (s, H, CH3), 3.85 (s, 3H,
OCH3), 7.48–8.17 (m, 9H, Ar-H), 15.19 (s, 1H, N
H
hydrazo), 1642 ( N N), 3068 ( C H), 830
1
hydrazone). 13C NMR: 9.21 ( CH3), 13.73 ( CH2),
20.13 ( CH2), 30.81 ( CH2), 41.52 ( CH3), 55.74
(p-sub.Ph). H NMR (400 MHz, DMSO-d6, δ/ppm):
3.76 (t, J = 7.3 Hz, 2H, CH2), 2.07 (m, 2H, CH2),
4.87 (t, J = 7.3 Hz, 2H, CH2), 3.48 (s, 3H, OCH3),
2.56 (s, 3H, CH3), 7.31–7.93 (m, 10H, Ar-H), 15.15
(s, 1H, N H hydrazone form). 13C NMR: 9.33
(
OCH3), 117.91 ( CN), δ (Ar-C): 73.80, 114.43
(2C), 115.53, 121.23, 127.53 (2C), 128.51, 129.15
(2C), 129.82 (2C), 133.36, 146.46, 156.40, 159.38,
160.55, 163.34, 163.84, 166.62. Anal. Calcd. for
C27H25N7O3S (Fw 527): C, 61.48; H, 4.74; N, 18.59;
S, 6.07. Found: C, 61.47; H, 4.75; N, 18.57; S, 6.05.
(
(
CH3), 56.37 ( OCH3), 74.52 ( CH2), 117.54
CN), 123.43 ( CH2, 2C), δ (Ar-C): 74.19, 115.34,
127.60 (2C), 128.38, 128.72 (4C), 128.93 (2C), 129.32
(2C), 133.28, 146.52, 156.76, 159.28, 163.24, 163.82,
166.64. Anal. Calcd. for C26H23N7O3S (Fw 513): C,
60.18; H, 4.48; N, 19.01; S, 6.23. Found: C, 60.19; H,
4.50; N, 19.03; S, 6.24.
1-Butyl-5-((E)-(5-((E)-(4-chlorophenyl)diazenyl)-
4-phenylthiazol-2-yl)diazenyl)-6-hydroxy-4-methyl-2-
oxo-1,2-dihydropyridine-3-carbonitrile (6g). Yield:
89%. mp: 230◦C. IR (KBr, cm−1): 1611 ( C C), 2213
(
CN), 1650 and 1686 ( CO), 3450 ( NH-hydrazo),
1642 ( N N), 3063 ( ), 834 (p-sub.Ph), 1081 (s,
Cl strc.). H NMR (400 MHz, DMSO-d6, δ/ppm):
6-Hydroxy-1-(methoxymethyl)-4-methyl-5-((E)-
(5-((E)-(4-nitrophenyl)diazenyl)-4-phenylthiazol-2-yl)
diazenyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (7b).
Yield: 85%. mp: 229◦C. IR (KBr, cm−1): 1613
C
1
C
1.11 (t, J = 7.2 Hz, 3H, CH3), 3.81 (t, J = 7.2 Hz,
2H, CH2), 1.65 (m, 2H, CH2), 1.38 (m, 2H, CH2),
2.54 (s, H, CH3), 7.35–8.00 (m, 9H, Ar-H), 15.16
(s, 1H, N H hydrazone). 13C NMR: 9.23 ( CH3),
13.71 ( CH2), 20.15 ( CH2), 30.63 ( CH2), 41.56
(
(
C C), 2217 ( CN), 1642 and 1686 ( CO), 3440
NH-hydrazo), 1638 ( N N), 3060 ( H), 837
C
(p-sub.Ph), 1566 (s, NO2). 1H NMR (400 MHz,
DMSO-d6, δ/ppm): 2.52 (s, 3H, CH3), 3.79 (t, J =
7.3 Hz, 2H, CH2), 2.12 (m, 2H, CH2), 4.89 (t, J =
7.3 Hz, 2H, CH2), 3.45 (s, 3H, OCH3), 7.45–8.10 (m,
9H, Ar-H), 15.17 (s, 1H, N H hydrazone form).
13C NMR: 9.31 ( CH3), 56.36 ( OCH3), 74.53
(
CH3), 117.09 ( CN), δ (Ar-C): 73.84, 115.54,
126.34, 127.51 (2C), 128.55, 128.90 (2C), 129.14
(2C), 130.53 (2C), 133.24, 134.56, 146.47, 156.42,
159.34, 163.35, 163.82, 166.92. Anal. Calcd. for
C26H22ClN7O2S (Fw 531.5): C, 58.70; H, 4.13; N,
18.43; S, 6.02. Found: C, 58.72; H, 4.14; N, 18.45; S,
6.03.
(
CH2), 117.54 ( CN), 123.42 ( CH2, 2C), δ (Ar-C):
74.17, 115.36, 124.13 (2C), 126.52 (2C), 127.62 (2C),
128.40, 129.30 (2C), 133.32, 135.08, 146.53, 148.07,
156.76, 159.27, 163.25, 163.83, 166.82. Anal. Calcd.
for C26H22N8O5S (Fw 558): C, 55.91; H, 3.94; N,
20.07; S, 5.73. Found: C, 55.92; H, 3.93; N, 20.09; S,
5.75.
5-((E)-(5-((E)-(4-Bromophenyl)diazenyl)-4-phen-
ylthiazol-2-yl)diazenyl)-1-butyl-6-hydroxy-4-methyl-2-
oxo-1,2-dihydropyridine-3-carbonitrile (6h). Yield:
79%. mp: 233◦C. IR (KBr, cm−1): 1619 ( C C), 2212
(
CN), 1646 and 1696 ( CO), 3446 ( NH-hydrazo),
4-((E)-(2-((E)-(5-Cyano-2-hydroxy-1-(methoxyme-
thyl)-4-methyl-6-oxo-1,6-dihydro pyridine-3-yl)diazen-
yl)-4-phenylthiazol-5-yl) diazenyl) benzoic acid (7c).
Yield: 88%. mp: 230◦C. IR (KBr, cm−1): 1619
1644 ( N N), 3064 ( H), 842 (p-sub.Ph), 1078
C
(s, C Br strc.). 1H NMR (400 MHz, DMSO-d6,
δ/ppm): 1.09 (t, J = 7.2 Hz, 3H, CH3), 3.80 (t, J = 7.2
Hz, 2H, CH2), 1.64 (m, 2H, CH2), 1.37 (m, 2H, CH2),
2.58 (s, H, CH3), 7.36–8.08 (m, 9H, Ar-H), 15.14
(s, 1H, N H hydrazone). 13C NMR: 9.22 ( CH3),
13.74 ( CH2), 20.16 ( CH2), 30.62 ( CH2), 41.53
(
(
C C), 2217 ( CN), 1651 and 1691 ( CO), 3439
NH-hydrazo), 1643 ( N N), 3059 ( H), 848
C
1
(p-sub.Ph), 1697 (s, COOH). H NMR (400 MHz,
DMSO-d6, δ/ppm): 2.57 (s, 3H, CH3), 3.72 (t, J =
Heteroatom Chemistry DOI 10.1002/hc

Synthesis, Characterization of Novel Bisheteroaryl Bisazo Dyes, and Its Dyeing and Solvatochromic Behavior 219
Yield: 78%. mp: 226◦C. IR (KBr, cm−1): 1609
7.3 Hz, 2H, CH2), 2.09 (m, 2H, CH2), 4.86 (t, J =
7.3 Hz, 2H, CH2), 3.43 (s, 3H, OCH3), 7.40–8.15
(m, 9H, Ar-H), 11.82 (s, 1H, COOH), 15.17 (s, 1H,
(
(
C C), 2215 ( CN), 1647 and 1693 ( CO), 3444
NH-hydrazo), 1640 ( N N), 3058 ( H), 836
C
N
H hydrazone form). 13C NMR: 9.32 ( CH3),
1
(p-sub.Ph), 1255 (s, OCH3). H NMR (400 MHz,
DMSO-d6, δ/ppm): 2.52 (s, 3H, CH3), 3.80 (t, J =
7.3 Hz, 2H, CH2), 2.09 (m, 2H, CH2), 4.77 (t, J =
7.3 Hz, 2H, CH2), 3.42 (s, 3H, OCH3), 3.85 (s, 3H,
56.35 ( OCH3), 74.52 ( CH2), 117.53 ( CN),
123.43 ( CH2, 2C), δ (Ar-C): 74.18, 115.37, 127.63
(2C), 128.42, 128.60 (2C), 129.32 (2C), 130.30 (2C),
130.82, 133.38, 134.08, 146.54, 156.77, 159.28,
163.28, 163.82, 166.32, 169.98. Anal. Calcd. for
C27H23N7O5S (Fw 557): C, 58.16; H, 4.12; N, 17.59;
S, 5.74. Found: C, 58.18; H, 4.11; N, 17.60; S, 5.76.
OCH3), 7.39–8.12 (m, 9H, Ar-H), 15.16 (s, 1H, N
H
hydrazone form). 13C NMR: 9.32 ( CH3), 55.88
(
(
OCH3), 56.3 ( OCH3), 74.56 ( CH2), 117.50
CN), 123.42 ( CH2, 2C), δ (Ar-C): 74.18, 114.28
(2C), 115.34, 121.37, 127.62 (2C), 128.43, 129.32
(2C), 129.72 (2C), 133.29, 146.53, 156.70, 159.24,
160.32, 163.24, 163.83, 166.78. Anal. Calcd. for
C27H25N7O4S (Fw 543): C, 59.66; H, 4.60; N, 18.03;
S, 5.89. Found: C, 59.68; H, 4.58; N, 18.01; S, 5.86.
6-Hydroxy-5-((E)-(5-((E)-(4-hydroxyphenyl)diaze-
nyl)-4-phenylthiazol-2-yl)diazenyl)-1-(methoxymeth-
yl)-4-methyl-2-oxo-1,2-dihydropyridine-3-carbonitrile
(7d). Yield: 89%. mp: 243◦C. IR (KBr, cm−1): 1613
(
(
C C), 2223 ( CN), 1649 and 1694 ( CO), 3446
NH-hydrazo), 1637 ( N N), 3056 (
C H), 841
5-((E)-(5-((E)-(4-Chlorophenyl)diazenyl)-4-phen-
ylthiazol-2-yl)diazenyl)-6-hydroxy-1-(methoxymethyl)-
4-methyl-2-oxo-1,2-dihydropyridine-3-carbonitrile(7g).
Yield: 79%. mp: 231◦C. IR (KBr, cm−1): 1610
(p-sub.Ph), 3455–3458 (br, OH). 1H NMR (400
MHz, DMSO-d6, δ/ppm): 2.59 (s, 3H, CH3), 3.73 (t,
J = 7.3 Hz, 2H, CH2), 2.07 (m, 2H, CH2), 4.78 (t,
J = 7.3 Hz, 2H, CH2), 3.41 (s, 3H, OCH3), 7.38–8.03
(
(
C C), 2214 ( CN), 1637 and 1687 ( CO), 3449
(m, 9H, Ar-H), 10.72 (s, 1H, OH), 15.17 (1H, s, N
H
NH-hydrazo), 1643 ( N N), 3064 (
C H), 838
hydrazone form). 13C NMR: 9.34 ( CH3), 56.37
(p-sub.Ph), 1080 (s, C Cl strc.). 1H NMR (400 MHz,
DMSO-d6, δ/ppm): 2.56 (s, 3H, CH3), 3.81 (t, J =
7.3 Hz, 2H, CH2), 2.10 (m, 2H, CH2), 4.81 (t, J =
7.3 Hz, 2H, CH2), 3.44 (s, 3H, OCH3), 7.40–8.06 (m,
(
(
OCH3), 74.53 ( CH2), 117.52 ( CN), 123.44
CH2, 2C), δ (Ar-C): 74.19, 115.36, 115.60 (2C),
121.18, 127.62 (2C), 128.44, 129.33 (2C), 130.32
(2C), 133.27, 146.55, 156.76, 158.38, 159.29, 163.29,
163.84, 166.34. Anal. Calcd. for C26H23N7O4S (Fw
529): C, 58.97; H, 4.34; N, 18.52; S, 6.04. Found: C,
58.95; H, 4.35; N, 18.51; S, 6.02.
9H, Ar-H), 15.19 (s, 1H, N H hydrazone form). 13
C
NMR: 9.35 ( CH3), 56.37 ( OCH3), 74.52 ( CH2),
117.52 ( CN), 123.46 ( CH2, 2C), δ (Ar-C): 74.18,
115.34, 126.82, 127.64 (2C), 128.46, 129.08 (2C),
129.32 (2C), 130.37 (2C), 133.32, 134.52, 146.59,
156.71, 159.27, 163.22, 163.80, 166.32. Anal. Calcd.
for C26H22ClN7O3S (Fw 547.5): C, 56.98; H, 4.01; N,
17.89; S, 5.84. Found: C, 56.97; H, 4.03; N, 17.90; S,
5.85.
6-Hydroxy-1-(methoxymethyl)-4-methyl-2-oxo-
5-((E)-(4-phenyl-5-((E)-p-totyldiazenyl)thiazol-2-yl)
diazenyl)-1,2-dihydropyridine-3-carbonitrile
(7e).
Yield: 78%. mp: 235◦C. IR (KBr, cm−1): 1614
(
(
C C), 2221 ( CN), 1639 and 1686 ( CO), 3442
NH-hydrazo), 1648 ( N N), 3060 (
C H), 834
(p-sub.Ph), 1461 (s, CH3). 1H NMR (400 MHz,
DMSO-d6, δ/ppm): 2.53 (s, 3H, CH3), 3.76 (t, J =
7.3 Hz, 2H, CH2), 2.06 (m, 2H, CH2), 4.74 (t, J =
7.3 Hz, 2H, CH2), 3.40 (s, 3H, OCH3), 2.26 (s, 3H,
5-((E)-(5-((E)-(4-Bromophenyl)diazenyl)-4-phen-
ylthiazol-2-yl)diazenyl)-6-hydroxy-1-(methoxymethyl)-
4-methyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (7h).
Yield: 84%. mp: 234◦C. IR (KBr, cm−1): 1616
CH3) 7.28–8.10 (m, 9H, Ar-H), 15.13 (s, 1H, N
H
(
(
C C), 2217 ( CN), 1640 and 1691 ( CO), 3440
hydrazone form). 13C NMR: 9.30 ( CH3), 21.24
NH-hydrazo), 1649 ( N N), 3069 (
C H), 838
(
(
CH3), 56.38 ( OCH3), 74.55 ( CH2), 117.53
CN), 123.45 ( CH2, 2C), δ (Ar-C): 74.17, 115.37,
(p-sub.Ph), 1074 (s, C Br strc.). 1H NMR (400
MHz, DMSO-d6, δ/ppm): 2.60 (s, 3H, CH3), 3.79 (t,
J = 7.3 Hz, 2H, CH2), 2.09 (m, 2H, CH2), 4.83 (t, J =
7.3 Hz, 2H, CH2), 3.45 (s, 3H, OCH3), 7.42–8.04 (m,
125.58, 127.63 (2C), 128.42, 128.82 (2C), 129.19
(2C), 129.34 (2C), 133.36, 138.40, 146.53, 156.74,
159.28, 163.28, 163.83, 166.97. Anal. Calcd. for
C27H25N7O3S (Fw 527): C, 61.48; H, 4.74; N, 18.59;
S, 6.07. Found: C, 61.49; H, 4.75; N, 18.60; S, 6.09.
9H, Ar-H), 15.15 (s, 1H, N H hydrazone form). 13
C
NMR: 9.31 ( CH3), 56.38 ( OCH3), 74.53 ( CH2),
117.50 ( CN), 123.42 ( CH2, 2C), δ (Ar-C): 74.17,
115.32, 122.98, 127.03, 127.62 (2C), 128.44, 129.34
(2C), 131.34 (2C), 131.98 (2C), 133.27, 146.56,
156.70, 159.28, 163.23, 163.82, 166.78. Anal. Calcd.
for C26H22BrN7O3S (Fw 592): C, 52.70; H, 3.71; N,
6-Hydroxy-1-(methoxymethyl)-5-((E)-(4-methoxy-
phenyl)diazenyl)-4-phenylthiazol-2-yl)diazenyl)-4-met-
hyl-2-oxo-1,2-dihydropyridine-3-carbonitrile
(7f).
Heteroatom Chemistry DOI 10.1002/hc

220 Modi and Patel
[3] Bahatti, H. S.; Seshadri, S. Col Technol 2004, 120,
151–155.
[4] El-Sonbati, A. Z.; Belal, A. A. M.; El-Wakeel, S. I.;
Hussien, M. A. Spectrochem Acta, Part A 2004, 60,
965–972.
[5] Amishiro, N.; Nagamuro, S.; Kobayashi, E.; Gomi,
K.; Saito, H. J Med Chem 1999, 42, 669–676.
[6] Kaupp, G.; Amer, F. A.; Metwally, M. A.; Abdel-Latif,
E. J Heterocyclic Chem 2003, 40, 963–971.
[7] Metwally, M. A.; Abdel-latifa, E.; Amera, F. A.; Kaupp,
G. Dyes Pigm 2004, 60, 249–264.
[8] Yamaguchi, K.; Yada, M.; Tsuji, T.; Hatanaka, Y.;
Goda, K.; Kobori, T. Bioorg Med Chem Lett 1999,
9, 957–960.
16.55; S, 5.40. Found: C, 52.69; H, 3.69; N, 16.56; S,
5.42.
Dyeing of Polyester Fabric and Dying Properties
Dyeing Procedure. 1% (Avolan IS; Atul Ltd.,
Vapi, India) dispersing agent was kept at a liquor
ratio of 20:1. The process was started at 60◦C; the
temperature was then raised to 130◦C over 30 min
and maintained for 1 h. Fabric was taken out af-
ter cooling, and treated with 2% sodium bisulfate,
2% sodium hydroxide, and 0.1% dispersing agent
(Avolan IS) at 70◦C for 30 min. Finally, the fabric
was rinsed and dried at 60◦C.
[9] Metwally, M. A.; Abdel-Latif, E.; Amer, F. A. J Text
Asso 2002, 63, 149–154.
[10] Metwally, M. A.; Abdel-Latif, E.; Amer, F. A. J Text
Asso 2001, 62, 155–159.
[11] Rangnekar, D. W.; Chaudkari, M. B. Dyes Pigm 1989,
10, 173–181.
[12] Deligeorgiev, T. G. Dyes Pigm 1990, 12, 243–248.
[13] Penchev, A.; Simov, D.; Gadjev, N. Dyes Pigm 1991,
16, 77–81.
[14] Peters, A. T.; Gbadamosi, N. M. A. Dyes Pigm 1992,
18, 115–123.
[15] Chen, C. C.; Wang, I. J. Dyes Pigm 1991, 15, 69–82.
[16] Adiba, H.; Nadia, S. I.; Sherif, M. S.; Hoda, Z. S.;
Rafat, M. M. Heterocycles 1986, 24, 2463–2466.
[17] ICI PLC. Br. Patent 1969, 129, 2454.
[18] Nermin, E.; Fatih, E. Dyes Pigm 1995, 27, 313–320.
[19] Krapcho J.; Turk, C. T.; GP 252, 1299, 1975.
Fastness Properties. The fastness to light, subli-
mation and perspiration was assessed in accordance
with BS: 1006-1978. The rubbing fastness test was
carried out using a crockmeter (Atlas) in accordance
with AATCC-1961 and the wash fastness test in ac-
cordance with IS:765-1979. The details of various
fastness tests are mentioned in the literature [29].
The fastness test and dyeing facilities was provided
by Atul Ltd. (India).
[20] Ertan, N.; Seferog*lu, Z.; Yılmazb, E.; Urazb, G. Col
ACKNOWLEDGMENTS
Technol 2008, 124, 27–35.
[21] Saylam, A.; Seferoglu, Z.; Ertan, N. Russ J Org Chem
2008, 44, 587–594.
[22] Golob V.; Tusek, L. Dyes Pigm 1999, 40, 211–217.
[23] Reichardt, C. Solvent and Solvent Effects in Organic
Chemistry; Wiley-VCH: New York, 1990; pp. 40, 213.
[24] Yazdanbakhsh, M. R.; Mohammadi, A.; Abbasnia, M.
Spectrochim Acta, Part A 2010, 77, 1084–1087.
[25] Fozooni, S.; Tikdari, A.; Hamidian, H.; Khabaz-
zadeha, H. Arkivoc 2008, 2008, 115–123.
We are grateful to Dr. Pradip K. Bhowmik, Univer-
sity of Nevada, Las Vegas, NV, USA, for providing
library facility for the literature survey to carry out
this research work.
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Applications; Wiley-VCH: Weinheim, Germany,
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[29] Maradiya, H. R. Turk J Chem 2001, 25, 441–450.
[2] Zollinger, H. Synthesis, Properties and Applications
of Organic Dyes and Pigments Color Chemistry, third
revised ed; Wiley-VCH: Weinheim, Germany, 2003.
Heteroatom Chemistry DOI 10.1002/hc