Disperse dyes based on aminothiophenes: Their dyeing applications on polyester fabrics and their antimicrobial activity

Article abstract of DOI:10.3390/molecules18067081

A series of monoazo disperse dyes derived from arylazothienopyridazines were synthesized. Fastness properties of dyed polyester samples were measured. Most of the dyed fabrics tested displayed excellent washing and perspiration fastness and moderate light

Full text of DOI:10.3390/molecules18067081

Molecules 2013, 18, 7081-7092; doi:10.3390/molecules18067081
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molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Disperse Dyes Based on Aminothiophenes:
Their Dyeing Applications on Polyester Fabrics and
Their Antimicrobial Activity
Saleh Mohammed Al-Mousawi 1,*, Morsy Ahmed El-Apasery 1,2 and Huda M. Mahmoud 3
1
Chemistry Department, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait;
E-Mail: elapaserym@yahoo.com
2
Dyeing, Printing and Textile Auxiliaries Department, Textile Research Division,
National Research Centre, Dokki, Giza 12622, Egypt
3
Department of Biological Sciences, Faculty of Science, Kuwait University, P.O. Box 5969,
Safat 13060, Kuwait; E-Mail: bsm8ham@yahoo.co.uk
* Author to whom correspondence should be addressed; E-Mail: saleh.almousawi@yahoo.com.
Received: 31 May 2013; in revised form: 13 June 2013 / Accepted: 14 June 2013 /
Published: 18 June 2013
Abstract: A series of monoazo disperse dyes derived from arylazothienopyridazines were
synthesized. Fastness properties of dyed polyester samples were measured. Most of the
dyed fabrics tested displayed excellent washing and perspiration fastness and moderate
light fastness. Finally, the biological activity of the synthesized dyes against Gram positive
bacteria, Gram negative bacteria and yeast were evaluated.
Keywords: biological activity; polyester fabrics; disperse dyes; thienopyridazines
1. Introduction
Aminothiophene-based azo dyes are known as disperse dyes with excellent brightness of shade.
This class of dyes was established as an alternative to more expensive anthraquinone dyes [1].
Thiophene-containing azo dyes have many advantages, including a colour deepening effect as an
intrinsic property of the thiophene ring and small molecular structure leading to better dyeability. The
heterocyclic nature of the thiophene ring has also allowed for excellent sublimation fastness on the
dyed fibers [2]. A number of researchers have studied aminothiophene derivatives as azo disperse dyes
in the dyeing of synthetic fibers [3–7] and blended polyester/wool fibers [8], This class of compounds

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also showed semiconducting properties and more recently, uses in optical data storage devices [9]. The
synthesis of arylazothienopyridazines and their benzo-fused derivatives have been recently extensively
studied [10,11]. In spite of a large number of reports on the utility of these compounds in the dye
industry, to our knowledge, their corresponding arylazothienopyridazines have never been reported as
potential monoazo disperse dyes. In continuation of our interest in the synthesis of arylazothieno-
pyridazines and their condensed derivatives [12], this paper reports the synthesis of some arylazo-
thienopyridazines using a conventional method and their application as disperse dyes on polyester
fabrics. In addition the biological activity of the synthesized dyes against Escherichia coli and
Pseudomonas aeruginosa (Gram negative bacteria), Bacillus subtilis and Staphylococcus aureus
(Gram positive bacteria) and Candida albicans (yeast) was also evaluated.
2. Results and Discussion
2.1. Synthesis
Arylazopyridazinone 1 reacted with dimethylformamide dimethyl acetal (DMFDMA) in refluxing
DMF for 6 hours affording dihydropyridazine-4-carbonitrile 2 that was readily converted into the
pyrido[3,4-d]pyridazine-4,5-dione disperse dye 3 in 87% yield on treatment with ammonium acetate
and acetic acid at reflux for 3 h.
Compound 1 readily reacted with elemental sulphur in the presence of few drops of piperidine in
dioxane as reaction medium to yield arylazoaminothienopyridazine disperse dye 4 in 89% yield. An
X-ray crystal structure determination of 4 confirmed with certainly its structure [13] (cf. Scheme 1 and
Figure 1). Typical to the established behavior of thienopyridazines, compound 4 reacted readily with
N-phenylmaleimide in a mixture of acetic acid and dioxane to yield pyrrolo[3,4-g]phthalazine disperse
dye 7 via the intermediary of the [4+2] cycloadduct 6.
Reaction of compound 4 with DMFDMA afforded the corresponding amidine disperse dye 8. The
X-ray crystal structure determination of 8 confirmed with certainly its structure [13] (cf. Scheme 1 and
Figure 2). Compound 8 upon heating with ammonium acetate in the presence of a few drops of acetic
acid afforded the pyridopyridazine disperse dye 11 via the intermediacy of the [4+2] cycloadduct 10.
Hydrolysis of the dimethylamino moiety in the latter product afforded the final product 11. Acylating 4
by refluxing in acetic acid resulted in the formation of the acetylamino disperse dye 9 in 80% yield.
2.2. Dyeing
Disperse dyes 3, 4, 7–9 and 11 were applied to polyester fabrics at 2% (dye shade), using the high
temperature dyeing method (HT) at 130 °C. Yellowish-brown to brown color shades were obtained.
The dyeing properties on the polyester fabrics were evaluated in terms of their fastness properties (e.g.,
fastnesses to washing, perspiration and light). The color of dyeing on polyester fabrics is expressed in
terms of CIELAB values (Table 1), and the following CIELAB coordinates were measured: lightness
(L*); chroma (C*); hue angle (h) from 0 to 360°; a*, whose value represents the degree of redness
(positive) and greenness (negative); and b*, whose value represents the degree of yellowness (positive)
and blueness (negative).

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Scheme 1. Preparation of monoazo disperse dyes.
NMe2
H3C
H3C
H3C
N
H
O
N
O
CN
O
ArN=N
ArN=N
CN
O
ArN=N
NH4OAc / AcOH
N
N
DMFDMA
N
N
N
Ar
2
Ar
Ar
1-11 Ar=4-CH3C6H4
3
S / Pip.
S
Ph
N
H3C
N
O
H3C
S
O
O
ArN=N
N
ArN=N
N
Ph
NH2
NH2
5
O
N
O
N
Ar
4
O
Ar
6
AcOH
-H2S
N
H3C
N
DMFDMA
O
S
CH3
Ph
ArN=N
N
O
H3C
N
CH3
H
S
N
O
H3C
ArN=N
N
O
ArN=N
N
CH3
Ar
NH2
N
Ar
8
O
9
N
N
O
Ar
NH4OAc / AcOH
7
NMe2
N
OH
H3C
N
H3C
N
H
S
N
ArN=N
ArN=N
SH
N
O
N
Ar
O
Ar
10
11

Molecules 2013, 18
Figure 1. ORTEP plot of the X-ray crystallographic structure of 4.
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Figure 2. ORTEP plot of the X-ray crystallographic structure of 8.
For dyeing polyester fabrics, in practical terms only disperse dyes are suitable. Through their
hydrophobic properties, these dyes are capable of penetrating into the similarly hydrophobic polyester
fibre. In general, the positive values of b* (yellow–blue axis) indicated that the color hues of the all
disperse dyes on the polyester fabric shifted to the yellowish directions. The results listed in Table 1
show that the dyeing fabrics have different color strengths. The difference in color strength depends on
the substitutes present and/or the position of the substitutes on the structure of the synthesized dyes. A
chromophore-containing compound is called a “chromogen”: its color depends on the nature, number
and position of the “auxochromes”. Auxochromes may shift the absorption towards higher
wavelengths and thus the color of the dye will deepen. Such groups are called ’bathochromes’ (i.e.,
having electron-donating substituents such as OH, NH2 and CH3); these are said to have a
bathochromic effect. A group having the opposite, hyposochromic, effect is called a ‘hypochrome’
(i.e., having electron-attracting substituents such as CHO, COR and NO2). The results given in Table 1,

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show that the magnitude of color strength K/S of dye 4 (17.78) at λmax 464 is much higher than the
color of dyes 8 and 9 (10.49 and 16.30) at λmax 448 and 431, respectively. The results listed in Table 1,
show also that the heteroaromatic diazo component can provide disperse dyes with bathochromic shifts
due to the stabilization of the excited state.
Table 1. Shade and optical measurements of the azo disperse dyes on the polyester fabrics.
Color on polyester
Dye No.
L*
a*
b*
C*
h*
K/S
(2% shade)
Yellowish-brown 50.77 4.40 20.70 21.17 78.01 13.33
3
4
Brown
Cream
46.06 24.84 29.03 38.21 49.45 17.78
83.98 11.31 42.49 43.97 75.09 6.79
68.84 22.97 39.59 45.77 59.88 10.49
7
8
Light brown
9
Brownish-yellow 66.03 22.50 60.44 64.49 69.58 16.30
Light cream 82.96 9.55 33.54 34.87 74.11 6.76
11
The physical data for the dyed fabrics given in Table 2, shows that the disperse dyeing displayed
moderate fastness levels to light. The light fastness of each of the dyes was measured by employing the
standard method for determination of color fastness of textiles. Several reports [14] suggest that fading
of azo dyes is mainly a consequence of decomposition of the –N=N– moiety either by oxidation,
reduction or photolysis. The rates of these processes should be sensitive to the chemical structure of
the dye, the type of substrate and treatment conditions. Since the dyed substrate employed in this study
is a polyester fabrics (i.e., non-proteinic), the fading process likely occurs by oxidation [15]. The ease
of oxidation of azo linkages should be a function of electron density. Therefore, electron donating
substituents on this moiety should increase the fading rate while electron withdrawing groups should
decrease the rate. This proposal is in agreement with the observed results (Table 2) which demonstrate
that the presence of a hydroxyl group in dye 11 causes decrease of light fastness to 3. On the other
hand, high light fastness of dye 7 to 6, is may be attributed to hydrogen bonding between the amino
group and carbonyl group cause aggregation of this dye sequent, the fading is decreased [16].
In addition the results obtained showed that dyed fabrics have excellent fastness levels to washing
and perspiration fastness properties that may be due to the absence of solubilizing groups, which
affects solubility, and wash ability of the dye-out of the fabrics or to the size of the dye molecule is
considered relatively big.
Table 2. Fastness properties of monoazo disperse dyes on polyester fabrics.
Perspiration fastness
Wash fastness
Dye No.
Light fastness
Alkaline
Acidic
Alt SC SW Alt SC SW Alt SC SW
3
4
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
4–5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
2
2
6
3
3
3
7
5
5
8
4–5
5
4–5
5
4–5
5
9
11
5
5
5
Alt = alteration; SC = staining on cotton; SW = staining on wool.

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2.3. Antimicrobial Activities
The antimicrobial activities of the synthesized disperse dyes were screened against selected bacteria
and fungi by the agar well diffusion method and their inhibition zones diameters, given in Table 3,
reveal that the tested dyes 3 and 9 showed positive antimicrobial activities against at four of the tested
microorganisms. Dye 3 showed strong activities (>10 mm inhibition zone) against E. coli, whereas
dyes 7, 8 and 11 showed no activities against any of the tested microorganisms used in the study. Only
dye 9 showed a significant inhibition zone <10 mm against Candida albicans.
Table 3. Diameter of the zones of inhibition of the tested disperse dyes against Gram
positive, Gram negative bacteria and yeast.
Inhibition zone diameter
G+ve bacteria
B. subtilis S. aureus
Mean ± SD Mean ± SD Mean ± SD
G-ve bacteria
Fungi
Dye No.
E. coli
P. aeruginosa
C. albicans
Mean ± SD
Mean ± SD
3
8.4 ± 0.7
6.6 ± 0.2
11.2 ± 0.2
8.6 ± 1.3
-
7
-
-
-
-
-
8
-
-
-
-
-
9
5.1 ± 0.5
-
5.1 ± 0.2
-
7.4 ± 0.8
-
6 ± 0.3
-
6.4 ± 0.4
-
11
Ampicillin *
10 ± 0.5
3.5 ± 0.2
10.8 ± 0.7
9.5 ± 2.6
Cycloheximide **
-
(-) no inhibition; * Ampicillin: Antibacterial (100 mg·mL−1); ** Cycloheximide: Antifungal (100 mg·mL−1);
SD = Standard Deviation.
In addition, disperse dyes 3 and 9 (Figures 3 and 4) showed cytolytic effect even after six days of
incubation, there were no growth recorded in the inhibited zone for all five tested microbes.
Figure 3. E. coli. treated with 100 mg/mL of dye 3 after 1, 4, and 6 days of incubation.
1 day
4 days
6 days

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Figure 4. E. coli. treated with 100 mg/mL of dye 9 after 1, 4, and 6 days of incubation.
7087
1 day
4 days
6 days
Currently, we are inspecting the biological activity of the polyester fabrics dyed with
aminothiophene dyes against Gram positive bacteria, Gram negative bacteria and yeast.
3. Experimental
3.1. General
Melting points were recorded on a Gallenkamp apparatus. IR spectra were recorded using KBr pellets
on a JASCO FTIR-6300 FT-IR spectrophotometer. 1H- and 13C-NMR spectra were recorded on Bruker
DPX 400 MHz or AvanceII 600 MHz super-conducting NMR spectrometers with proton spectra
measured at 400, 600 MHz and carbon spectra at 100 and 150 MHz, respectively. Mass spectra were
measured on a high resolution GC/MS DFS-Thermo instrument. Microanalyses were performed on an
Elementar-Vario Microcube analyzer. The crystal structure of compounds 4 and 8 were determined by
Bruker AXS X8 Prospector Single Crystal X-Ray Diffractometer at Kuwait University. The dyeing of
polyester fabrics were conducted using LINITEST+Laboratory High Temperature Dyeing and
Fastness System (ATLAS, Lichtenstein, Germany). The colorimetric parameters of the dyed polyester
fabrics were determined on a reflectance spectrophotometer (UltraScan PRO D65, HunterLab,
Virginia, VA, USA).
6-p-Tolyldiazenyl)-5-(1-(dimethylamino)prop-1-en-2-yl)-3-oxo-2-p-tolyl-2,3-dihydropyridazine-4
carbo-nitrile (2). A solution of compound 1 (3.55 g, 10 mmol) and DMFDMA (1.19 g, 10 mmol) was
refluxed for 2 h then allowed to cool to room temperature. The solid product obtained was crystallized
from dioxane to afford compound 2 as a yellow powder (73%), m.p. 292–294 °C; IR (KBr): 2237
(CN), 1655 (CO) cm-1; 1H-NMR (DMSO-d6): δ = 2.08 (s, 3H, CH3), 2.23 (s, 6H, 2(p-tolyl-CH3)), 2.27
(s, 6H, N-(CH3)2), 6.80 (d, 2H, J = 7.7 Hz, p-tolyl-H), 7.01 (d, 2H, J = 6.6 Hz, p-tolyl-H), 7.07–7.13
(m, 2H, p-tolyl-H), 7.21 (d, 2H, J = 8.1 Hz, p-tolyl-H), 7.32 (d, 1H, J = 7.9 Hz, vinylic-H). MS, m/z
(%), 412 ([M]+, 45), UV/Vis at λmax(DMF) = 432 nm. Anal. Calcd. For C24H24N6O: C, 69.88; H, 5.86;
N, 20.37. Found C, 69.91; H, 5.44; N, 19.73.
8-Methyl-3-p-tolyl-1-(p-tolyldiazenyl)pyrido[3,4-d]pyridazine-4,5(3H,6H)-dione(3). A solution of
compound 2 (4.32 g, 10 mmol), acetic acid (15 mL) and ammonium acetate (1.15 g, 15 mmol) was

Molecules 2013, 18
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refluxed for 3 h, then allowed to cool to room temperature. The solid product so formed was collected
by filtration and crystallized from acetic acid. Compound 3 was obtained as a light brown powder
(87%), m.p. 226–228 °C; IR (KBr): 3451 (NH), 1706, 1659 (CO) cm-1; 1H-NMR (DMSO-d6): δ = 2.16
(s, 3H, CH3), 2.31 (s, 6H, 2(p-tolyl-CH3)), 7.10–7.40 (m, 4H, p-tolyl-H), 7.46 (d, 2H, J = 8.4 Hz,
p-tolyl-H), 7.52 (d, 2H, J = 7.2 Hz, p-tolyl-H), 8.79 (s, 1H, pyridyl-H). 9.91 (s, 1H, NH). MS, m/z (%),
383 ([M-2]+, 32), UV/Vis at λmax(DMF) = 590. Anal. Calcd. For C22H19N5O2: C, 68.56; H, 4.97; N,
18.17. Found C, 68.58; H, 4.99; N, 18.26.
7-Amino-5-methyl-2-p-tolyl-4-p-tolylazo-2H-thieno[3,4-d]pyridazin-1-one (4).
A
mixture of
compound 1 (3.55 g, 10 mmol) and elemental sulphur (0.32 g, 10 mmol) and a few drops of piperidine
in dioxane (10 mL) was refluxed for 4 h then allowed to cool to room temperature. The crude product
was poured onto water, the solid product, so formed, was collected by filtration and crystallized from
ethanol. Compound 4 was obtained as wine red crystals (89%), m.p. 209 °C (Lit. [12] m.p.
1
208–209 °C), IR (KBr): 3321, 3278 (NH2), 1642 (CO) cm-1; H-NMR (DMSO-d6): δ = 2.30 (s, 3H,
CH3), 2.37 (s, 3H, p-tolyl-CH3), 2.40 (s, 3H, p-tolyl-CH3), 7.21 (d, 2H, J = 10.2 Hz, p-tolyl-H), 7.32
(d, 2H, J = 9.6 Hz, p-tolyl-H), 7.38 (s, 2H, NH2), 7.39 (d, 2H, J = 7.2 Hz, p-tolyl-H), 7.78 (d, 2H,
J = 7.2 Hz, p-tolyl-H). 13C NMR (DMSO-d6): δ = 160.77 (CO), 159.2, 150.4, 150.1, 144.0, 139.5,
136.9, 130.7, 129.5, 126.3, 123.6, 121.9. 116.7, 104.7, 21.5 (p-tolyl-CH3), 21.0 (p-tolyl-CH3), 14.7
(CH3). MS (EI) m/z = 389 (M]+, 100); UV/Vis at λmax(DMF) = 464 nm. Anal. Calcd for C21H19N5OS:
C, 64.76; H, 4.92; N, 17.98; S, 8.23. Found: C, 65.09; H, 5.08; N, 17.90; S, 8.21.
9-Amino-5-methyl-7-phenyl-2-p-tolyl-4-p-tolylazo-2H-pyrrolo[3,4-g]phthalazine-1,6,8-trione (7). A
solution of compound 4 (3.89 g, 10 mmol), N-phenylmaleimide (1.73 g, 10 mmol) and a few drops of
acetic acid was refluxed in dioxane (15 mL) for 10 h. The solid products, so formed, were collected by
filtration and crystallized from DMF. Compound 7 was obtained as orange crystals (79%), m.p.
302–304 °C) (Lit. [12] m.p. 300–302 °C), IR (KBr): 3435, 3310 (NH2),1752, 1704, 1645 (CO) cm−1;
1H-NMR (DMSO-d6): δ = 2.42 (s, 3H, CH3), 2.48 (s, 3H, p-tolyl-CH3), 2.75 (s, 3H, p-tolyl-CH3), 7.36
(d, 2H, J = 7.8 Hz, p-tolyl-H), 7.50 (d, 4H, J = 8.1 Hz, p-tolyl-H), 7.57–7.64 (m, 5H, phenyl-H), 7.94
(d, 2H, J = 7.7 Hz, p-tolyl-H), 9.47 (s, 2H, NH2). MS (EI) m/z = 528 ([M]+, UV/Vis at λmax(DMF) = 471 nm.
Anal. Calcd for C31H24N66O3: C, 70.44; H, 4.58; N, 15.90. Found: C, 69.99; H, 4.58; N, 15.96.
N,N-Dimethyl-N'-(7-methyl-4-oxo-3-p-tolyl-1-p-tolylazo-3,4-dihydrothieno[3,4-d]pyridazin-5-yl)-
formamidine (8). A mixture of compound 4 (3.89 g, 10 mmol) and DMFDMA (1.19 g, 10 mmol) in
dimethylformamide (15 mL), was refluxed for 1 h. The solvent was evaporated and then the residue
was washed with ethanol. The solid product, so formed, was collected by filtration and crystallized
from dimethylformamide. Compound 8 was obtained as wine red crystals (93%), m.p. 307 °C
1
(Lit. [12] m.p. 203–205 °C), IR (KBr): 1651 (CO) cm-1. H-NMR (DMSO-d6): δ = 2.31 (s, 3H, CH3),
2.39 (s, 3H, p-tolyl-CH3), 2.53 (s, 3H, p-tolyl-CH3), 2.96 (s, 3H, N-CH3), 3.04 (s, 3H, N-CH3), 7.22 (d,
2H, J = 9.0 Hz, p-tolyl-H), 7.30 (d, 2H, J = 9.0 Hz, p-tolyl-H), 7.41 (d, 2H, J = 7.8 Hz, p-tolyl-H), 7.80
(d, 2H, J = 8.4 Hz, p-tolyl-H), 7.92 (s, 1H, amidine-H). 13C NMR (DMSO-d6): δ = 163.7 (CO), 157.5,
157.3, 150.5, 149.9, 144.0, 139.2, 137.1, 130.7, 129.3, 126.8, 125.4, 123.8, 123.7, 112.9, 34.7
(N-CH3), 21.5 (p-tolyl-CH3), 21.0 (p-tolyl-CH3), 15.8 (CH3). MS (EI) m/z = 444 (M]+, 100), UV/Vis at

Molecules 2013, 18
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λ
max(DMF) = 448 nm. Anal. Calcd for C24H24N6OS: C, 64.84; H, 5.44; N, 18.90; S, 7.21. Found: C,
64.58; H, 5.59; N, 18.70; S, 7.16.
N-(7-Methyl-4-oxo-3-p-tolyl-1-p-tolylazo-3,4-dihydrothieno[3,4-d]pyridazin-5-yl)acetamide (9).
A
solution of compound 4 (3.89 g, 10 mmol) in acetic acid (20 mL) was refluxed for 3h. The solvent was
evaporated and then the residue was washed with ethanol. The solid product, so formed, was collected
by filtration and crystallized from dioxane. Compound 9 was obtained as brown crystals (80%), m.p.
209 °C) (Lit. [12] m.p. 207–209 °C), IR (KBr): 3270 (NH), 1673, 1641 (CO) cm-1. 1H-NMR (DMSO-d6):
δ = 2.30 (s, 3H,COCH3), 2.26 (s, 3H, p-tolyl-CH3), 2.33 (s, 3H, p-tolyl-CH3), 2.39 (s, 3H, CH3), 7.27
(d, 2H, J = 9.0 Hz, p-tolyl-H), 7.40–7.44 (m, 4H, p-tolyl-H), 7.83 (d, 2H, J = 7.8 Hz, p-tolyl-H), 11.03
13
(s, 1H, NH). C NMR (DMSO-d6): δ = 167.6 (CO), 158.3, 153.5, 149.9, 144.4, 142.7, 138.3, 137.4,
130.8, 129.5, 126.6, 123.8, 120.8, 119.8, 112.4, 23.1 (p-tolyl-CH3), 21.1 (p-tolyl-CH3), 16.5 (CH3),
14.8 (CH3). MS (EI) m/z = 431 (M]+, 100), UV/Vis at λmax(DMF) = 431 nm. Anal. Calcd for
C23H21N5O2S: C, 64.02; H, 4.91; N, 16.23; S, 7.43. Found: C, 63.88; H, 4.89; N, 16.36; S, 7.34.
7-Hydroxy-8-methyl-5-thioxo-3-p-tolyl-1-p-tolylazo-5,6-dihydro-3H-pyrido[3,4-d]pyridazin-4-one
(11). A mixture of compound 8 (4.44 g, 10 mmol) acetic acid (10 mL) and ammonium acetate (3.45 g,
30 mmol) was refluxed for 3 h. The crude product was poured onto water, the solid product, so
formed, was collected by filtration and crystallized from dioxane/ethanol (3:1). Compound 11 was
obtained as a light violet powder (68%), m.p. 297 °C (Lit. [12] m.p. 295–297 °C), IR (KBr): 3440
1
(OH), 3275 (NH), 1681, 1641 (CO) cm-1. H-NMR (DMSO-d6): δ = 2.37 (s, 3H, CH3), 2.43 (s, 3H,
p-tolyl-CH3), 2.66 (s, 3H, p-tolyl-CH3), 7.29 (d, 2H, J = 7.8 Hz, p-tolyl-H), 7.44 (t, 4H, J = 7.4 Hz,
13
p-tolyl-H), 7.87 (d, 2H, J = 7.8 Hz, p-tolyl-H), 8.61 (s, 1H, NH), 11.7 (s, 1H, OH). C NMR
(DMSO-d6): δ = 157.8, 151.3, 151.0, 144.4, 141.1, 138.4, 138.2, 130.6, 130.2, 130.0, 129.6, 126.4,
125.6, 124.5, 120.2, 22.3 (p-tolyl-CH3), 21.8 (p-tolyl-CH3), 15.7 (CH3). MS (EI) m/z = 417 (M]+, 100),
Anal. Calcd for C22H119N5O2S: C, 63.29; H, 4.59; N, 16.78; S, 7.68. Found: C, 63.26; H, 4.78; N,
16.75; S, 7.56.
3.2. High Temperature Dyeing Method (HT)
3.2.1. Materials
Polyester 100% (150 130 g/m2, 70/2 denier) was used. The fabric was treated before dyeing with a
solution containing non-ionic detergent (Sera Wash M-RK, 5 g/L) and sodium carbonate (2 g/L) in a
ratio of 50:1 at 60 °C for 30 min, then thoroughly washed with water and air dried at room temperature.
3.2.2. Dyeing
The dye baths were prepared from the dye (2% weight of fibre) to a final liquor of 50:1, w/w. The
pH value of the bath was adjusted to 4.5–5 with acetic acid (10%) in the presence of a 1:1 ratio of the
dispersing agent (Sera Gal P-LP). The temperature was raised to 130 °C at the rate of 7 °C/min, and
dyeing continued for 60 min. After dyeing, the fabrics were thoroughly washed and then subjected to a
surface reduction clearing [(2 g NaOH + 2 g sodium hydrosulphite)/L]. The samples were heated in
this solution for 30 min at 80 °C and then thoroughly washed and air-dried.

Molecules 2013, 18
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3.3. Color Measurements and Analyses
3.3.1. Color Measurements
The colorimetric parameters (Table 1) of the dyed polyester fabrics were determined on a
reflectance spectrophotometer. The color yields of the dyed samples were determined by using the
light reflectance technique performed on (UltraScan PRO D65) UV/VIS Spectrophotometer. The color
strengths, expressed as K/S values, were determined by applying the Kubelka-Mink equation
as follows:
K/S = [(1 − R)2/2R] − [(1 − Ro)2/2Ro]
where R = decimal fraction of the reflectance of the dyed fabric; Ro = decimal fraction of the
reflectance of the undyed fabric; K = absorption coefficient; S = scattering coefficient.
3.3.2. Fastness Testing
3.3.2.1. Fastness to Washing
After washing using 2 g/L of the nonionic detergent Hostapal CV at 80 °C for 15 min, the dyed
fabrics were tested by using standard methods [17]. A specimen of dyed polyester fabric was stitched
between two pieces of undyed cotton and wool fabrics, all of equal length, and then washed at 95 °C
for 30 min. The staining on the undyed adjacent fabrics was assessed according to the following gray
scale: 1—poor, 2—fair, 3—moderate, 4—good, 5—excellent.
3.3.2.2. Fastness to Perspiration
The samples were prepared by stitching a piece of dyed polyester fabric between two pieces of
cotton and wool fabrics, all of equal length, and then immersed in the acid or alkaline solution for
30 min. The staining on the undyed adjacent fabrics was assessed according to the following gray
scale: 1—poor, 2—fair, 3—moderate, 4—good, 5—excellent. The acid solution (pH = 4.5) contains
sodium chloride (10 g/L), sodium dihydrogen orthophosphate (1 g/L) and histidine monohydrochloride
(0.25 g/L). The alkaline solution (pH = 9.5) contains sodium chloride (10 g/L), disodium
orthophosphate (1 g/L) and histidine monohydrochloride (0.25 g/L).
3.3.2.3. Fastness to Light
Light fastness was determined by exposing the dyed polyester fabrics on a Xenotest 150 (Original
Hanau, Lichtenstein, Germany). Chamber temperature: 25–30 °C, black panel temperature: 60 °C, relative
humidity: 50%–60%, dark glass UV filter system) for 40 h. The changes in color were assessed
according to the following blue scale: 1—poor, 3—moderate, 4—good, 6—very good, 8—excellent.
3.4. Antimicrobial Activities Test
The antimicrobial activities of different arylazothienopyridazines disperse dyes were tested using
Agar-well diffusion technique [18] against five different microbial cultures. Pure cultures of

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Escherichia coli and pseudomonas aeruginosa (Gram negative bacteria), Bacillus subtilis and
Staphylococcus aureus (Gram positive bacteria) and Candida albicans (yeast) were used in the test. An
aliquot of 0.1 mL of each bacterial strain was inoculated and spread on nutrient agar (NA) while
0.1 mL of the yeast was spread on potato dextrose agar (PDA). The inoculated plates were supplied
with 100 µL of each of the tested dyes with a total final concentration of 10 mg mL−1. The dyes were
included in 4 mm wells produced by sterile cork borer. The NA plates were incubated at 37 °C for 24 h
while PDA plates were incubated at 25 °C for 24–48 h. The zones of inhibition around the wells were
determined and the average based on three replica was recorded. Cycloheximide and ampicillin were
both used as references in the experiment, where cycloheximide known to inhibit eukaryotic organisms
while ampicillin inhibits prokaryote organisms. All plates were kept for six days after inoculation and
the changes in the inhibition zone was monitored and documented by photography in order to
determine on the cytolytic and cytostatic effect of the tested disperse dyes.
4. Conclusions
In summary, a series of monoazo disperse dyes based on arylazothienopyridazines were synthesized.
The dyes produced in this manner were then applied to polyester fabrics by using a high temperature
dyeing method at 130 °C. The dyed polyester fabrics, which display yellowish-brown to brown hues,
displayed excellent washing and perspiration fastness and moderate light fastness. Finally, the
biological activity of the synthesized compounds against Gram positive bacteria, Gram negative
bacteria and yeast was tested.
Acknowledgments
The authors are grateful to M.H. Elnagdi for his help and valuable advices. Support of this work
provided by Kuwait University through a research grant (SC 05/09) and the facilities of GF-S,
supported by research grants (GS03/08), (GS01/01), (GS01/03) and (GS01/05) are highly appreciated.
Conflict of Interest
The authors declare no conflict of interest.
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Sample Availability: Samples of compounds 2–4, 7–9 and 11 are available from the authors.
© 2013 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article
distributed under the terms and conditions of the Creative Commons Attribution license
(http://creativecommons.org/licenses/by/3.0/).