Synthesis and Serviceability of New Symmetric Bis-pyrazolone Metal Complex Acid Dyes

Article abstract of DOI:10.1134/S1070363219120272

Synthesis of new symmetric bis-pyrazolone acid dye and its 3d transition metal complexes is studied. Bis-pyrazolone is synthesized from (E)-6,6’-(ethene-1,2-diyl)bis(3-hydrazinylbenzenesulfonic acid) and ethyl ace-toacetate. The synthesized bis-pyrazolone is coupled with diazonium salt of 4-sulpho-2-aminophenol in alkaline medium targeting bis-pyrazolone ligand acid dye. Various metal complexes are obtained by treating a methanolic solution of metal salts with ligand acid dye in basic media. Structures of the synthesized ligand dye and its metal complexes are confirmed by UV-Vis, FTIR, and NMR spectra. The ligand acid dye and metal complex dyes demonstrate absorption in UV-Vis in the range of 400–600 nm. Ligand acid dye and its metal complexes demonstrate good to high value of light speed, washing fastness and rubbing fastness on leather.

Full text of DOI:10.1134/S1070363219120272

ISSN 1070-3632, Russian Journal of General Chemistry, 2019, Vol. 89, No. 12, pp. 2498–2503. © Pleiades Publishing, Ltd., 2019.
Synthesis and Serviceability of New Symmetric Bis-pyrazolone
Metal Complex Acid Dyes
M. Ayaza, F. Alia,*, A. Saeedb, N. Abbasb, M. Khanc, G. Shabirb,
A. Saleemd, S. A. Raza Kazmid, and Khanzadad
a Department of Chemistry, Hazara University, Mansehra, KPK, 21300 Pakistan
b Department of Chemistry, Quaid-I-Azam University, Islamabad, 45320 Pakistan
c Department of Chemistry, Abdul Wali Khan University, Mardan, 23200 Pakistan
d Department of Chemistry, Govt. Gordon College Rawalpindi, Punjab, 46000 Pakistan
*e-mail: ayazanwar239@gmail.com
Received April 15, 2019; revised July 15, 2019; accepted December 10, 2019
Abstract―Synthesis of new symmetric bis-pyrazolone acid dye and its 3d transition metal complexes is studied.
Bis-pyrazolone is synthesized from (E)-6,6'-(ethene-1,2-diyl)bis(3-hydrazinylbenzenesulfonic acid) and ethyl ace-
toacetate. The synthesized bis-pyrazolone is coupled with diazonium salt of 4-sulpho-2-aminophenol in alkaline
medium targeting bis-pyrazolone ligand acid dye. Various metal complexes are obtained by treating a methanolic
solution of metal salts with ligand acid dye in basic media. Structures of the synthesized ligand dye and its metal
complexes are confirmed by UV-Vis, FTIR, and NMR spectra. The ligand acid dye and metal complex dyes dem-
onstrate absorption in UV-Vis in the range of 400–600 nm. Ligand acid dye and its metal complexes demonstrate
good to high value of light speed, washing fastness and rubbing fastness on leather.
Keywords: bis-pyrazolone, acid dyes, spectroscopic techniques, light fastness, rubbing fastness
DOI: 10.1134/S1070363219120272
INTRODUCTION
capillary tubes. FTIR (KBr) spectra were recorded on a
Single beam Nicolet, IR 100 spectrophotometer. UV-Vis
spectra were recorded by a Genesys spectrophotometer
for water solutions. 1H and 13C NMR spectra were mea-
sured on a Bruker DPX 400 spectrometer using D2O as a
solvent and TMS as an internal standard. CHNS analysis
was carried out on a Flash EA 1112 analyzer. TLC was
carried out on Silica Gel G plates using petroleum ether:
chloroform (6 : 4, v/v), chloroform: ethanol (9 : 1, v/v),
and petroleum ether: chloroform (9 : 1, v/v) as eluents
and UV lamp for visualization. Fastness to light was as-
sessed by a BS 1006-1978. Rubbing fastness was checked
by an Atlas crock meter in accordance with AATCC TM
8-1961. Wash fastness was determined according to ISO:
765-1975 [8,9].
Pyrazolones based azo dyes have been widely studied
in oil-soluble light fast dyes and in optical recording
medium toner ink inject printing due to their excellent
thermal stability and optical characteristics [1, 2]. Ease
of use and enhanced strong and clear colors stimulated
their wide use in dyeing textile fibers like wool, viscose,
silk, synthetic fibers, and particularly cotton [3, 4]. De-
pending upon structure of a medium and pH, azo dyes
demonstrate a variety of colors [5, 6], and are also used
on a broad scale in organic photoconductors, non-linear
optical elements and molecular memory storages [7].
The objective of our study is synthesis of new bis-
pyrazolone and its metal complexes for creating mol-
ecules with desired washing, light and rubbing fastness,
and dyeing properties.
Synthesis of bis-hydrazine from 4,4ꞌ-diamino-
stilbene-2,2ꞌ-disulfonic acid. Symmetric bridged bis-
pyrazolone reactive acid dyes were synthesis from a
common bis-azo component, reactive system and coupler
but a different bridging system.
EXPERIMENTAL
All commercial materials were purchased from
Sigma Aldrich. Analytical grade solvents were purified
and dried by the standard methods. Melting points were
determined on a Stuart melting point apparatus in open
4,4ꞌ-Diaminostilbene-2,2ꞌ-disulfonic acid (DASDA)
was treated with concentrated HCl and stirred at 0–5°C.A
2498

SYNTHESIS AND SERVICEABILITY OF NEW SYMMETRIC BIS-PYRAZOLONE METAL COMPLEX 2499
solution of NaNO2 was added within 30 min to the cooled
solution of DASDAupon stirring which was continued for
1 h more. The diazonium salt was filtered off and slowly
added to Na2SO3 solution at 0–5°C upon stirring within
1 h. The mixture was removed from an ice jacket and
heated up to 100°C. Hydrochloric acid was added upon
stirring drop wise within 1 h at 100°C. The mixture was
cooled down to room temperature and a small portion of
Zn dust was added for completing reduction. The reac-
tion mixture was stored overnight at room temperature.
The precipitate of hydrazinium hydrochloride was col-
lected and dried. The synthesized hydrazine 3 (4.0 g,
0.01 mol) was dissolved in H2O (30 mL) and Na2CO3
(2 g) was added to the mixture to make a clear solution.
The residue was filtered off. Few drops of HCl were
added to neutralize the hydrazine solution, which was
then refluxed at 100°C with ethyl acetoacetate (0.02 mol)
for 1 h upon constant stirring and heating till completion
of the process (TLC, methanol–chloroform, 9 : 1). The
reaction mixture was cooled down. Following addition
of HCl (10 mL) resulted in precipitation of pyrazolone 4
which was filtered off and dried in an oven at 70°C. Thus
synthesized pyrazolone (5.32 g, 0.01 mol) was coupled
with diazonium salt of 4-sulpho-2-aminophenol (3.78 g,
0.02 mol) prepared at 0–5°C in alkaline medium (pH =
9.0). The synthesized ligand dye 7 was precipitated from
aqueous solution by adding HCl (15mL), filtered off
and dried at 70°C in an oven. Dry ligand dye 7 (0.932 g,
0.001 mol) was dissolved in methanol and treated with
CuSO4·5H2O (8a, 0.002 mol), mole ratio 1 : 2, upon
refluxing. The reaction mixture was then made basic by
adding TEA (pH = 9.5–10) and stirred for 4 h till com-
plex formation was completed. Methanol was evaporated
slowly at temperature, and precipitates of metal complex
dyes were obtained. All metal complex dyes 9a–9h were
synthesized similarly by treating ligand 7 with different
metal salts 8a–8h.
(1H), 8.29 s (1H), 8.45 s (1H), 11.06 br (2H, SO3H), 13.69
br (1H, O–H), 14.33 br (1H, O–H). 13C NMR (DMSO-
d6) spectrum, δ, ppm: 157.45, 148.95, 146.25, 145.53,
136.34, 131.97, 130.44, 129.30, 127.32, 126.72, 125.86,
124.40, 118.35, 117.61, 117.11, 114.05, 12.05. Found,
%: C 43.65; H 3.08; N 11.90; S 13.88. C34H28N8O16S4.
Calculated, %: C 43.77; H 3.03; N 12.01; S 13.75.
C40H48Cu2N8O30S6 (9a). Reddish brown complex,
yield 73%. FTIR spectrum, νmax, cm–1: 3344 (OH), 1534
(C=C benzene), 1387 (CH2 bend), 1115 (C–N), 1031
(C–O), 840 (Ar-H), 532 (N–Cu). Found, %: C 33.30; H
3.40; N 7.65; S 13.43. C40H48Cu2N8O30S6. Calculated,
%: C 33.36; H 3.36; N 7.78; S 13.36.
C40H48Fe2N8O30S6 (9b). Brown complex, yield 77%.
FTIR spectrum, νmax, cm–1: 3325 (OH), 2876 (C–H),
1645 (C=C benzene), 1439 (CH2), 1357 (CH2 bend),
1039 (C=O), 871 (Ar-H). Found, %: C 39.15; H 2.40;
N 10.65; S 12.41. C40H48Fe2N8O30S6. Calculated, %: C
39.25; H 2.32; N 10.77; S 12.32.
C40H48Ni2N8O30S6 (9c). Greyish brown complex,
yield 74%. FTIR spectrum, νmax, cm–1: 3345 (OH),
2880 (C–H), 1660 (C=C benzene), 1374 (CH2 bend),
1177 (C–N), 1082 (C–O), 1027 (C–O), 841 (Ar-H),
598 (Ni). Found, %: C 39.08; H 2.38; N 10.58; S 12.43.
C40H48Ni2N8O30S6. Calculated, %: C 39.03; H 2.31; N
10.71; S 12.26.
C40H48Co2N8O30S6 (9d). Greyish brown complex,
yield 75%. FTIR spectrum, ν, cm–1: 3456 (OH), 1665
(C=C aromatic), 1559 (C=C benzene), 1409 (CH2), 1180
(C–N amines aromatic), 1029 (C–O), 973, 845 (C=C
bend), 587 (N–Co). Found, %: C 39.06; H 2.36; N 10.53;
S 12.33. C40H48Co2N8O30S6. Calculated, %: C 39.02; H
2.31; N 10.71; S 12.25.
C40H48Cr2N8O30S6 (9e). Violet brown complex, yield
77%. FTIR spectrum, ν, cm–1: 3341 (OH), 1647 (C=C
benzene), 1433 (OH), 1355 (CH2 bend), 1044 (C=O), 874
(Ar-H), 585 (Cr). Found, %: C 39.58; H 2.38; N 10.76;
S 12.52. C40H48Cr2N8O30S6. Calculated, %: C 39.54; H
2.34; N 10.85; S 12.42.
2-[(E)-4-{5-hydroxy-4-[(E)-(2-hydroxy-5-sul-
fophenyl)diazenyl]-3-methyl-1H-pyrazol-1-yl}-2-
sulfostyryl)-5-{5-hydroxy-4-[(E)-(2-hydroxyphenyl)-
diazenyl]-3-methyl-1H-pyrazol-1-yl}benzenesulfonic
acid] [ligand acid dye, C34H28N8O16S4 (7)]. Brown
compound, yield 75%. FTIR spectrum, ν, cm–1: 3338
br (OH, NH), 1548 (C=C aromatic), 1388 (S=O), 1120
(C–O), 1029 (C–O), 839 (C=C bend). 1H NMR (DMSO-
d6) spectrum, δ, ppm: 2.24 s (6H, CH3), 6.67 s (1H), 6.96
d (1H), 7.34 d (1H), 7.71 d (1H), 7.84 s (1H), 7.907 s
(1H), 7.95 d (2H, J = 7.5), 8.98 s (1H), 8.08 s (1H), 8.12 d
C40H48Zn2N8O30S6 (9f). Greyish brown complex,
yield 73%. FTIR spectrum, ν, cm–1: 3375 (OH), 1557
(C=C aromatic), 1407 (N=N), 1182 (C–N), 1083, 1028
(C–O), 838 (C=C bending). Found, %: C 38.63; H 2.33;
N 10.47; S 12.22. C40H48Zn2N8O30S6. Calculated, %: C
38.54; H 2.28; N 10.58; S 12.10.
C40H48Cd2N8O30S6 (9g). Yellowish brown complex,
yield 76%. FTIR spectrum, ν, cm–1: 3371 (OH str), 1386
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

2500
AYAZ et al.
6.5 by adding 1.0 mL of 10% w/v acetic acid solution.
The total amount of the solution was adjusted to 100 mL
by water. The leather fabric was introduced into the dye
bath at 45–50°C. The dye bath solution was stirred for
1 h while rising temperature gradually up to 80°C which
was maintained for 3 h more. pH of the dye-bath solution
was adjusted to 2.0 by adding 2.0 mL of formic acid. The
dye liquor was separated and the dyed fabric was washed
with cold water. The dye liquor solution combined with
washing was then further diluted with 250 mL of water.
1 mL Of the dye was further diluted by water to 50 mL.
For determining the exhaustion of dye on the fabric, the
characteristic absorbance of this solution was measured.
The dyed fabric was then dried and mounted on a shade
card. The percent of fixation of this solution was deduced
from the absorbance when a weighed amount of leather
fabrics was stirred in boiling acidified pyridine, which
was able to remove the unfixed dye from the fabric.
Fig. 1. Combined UV-Vis spectra of the ligand acid dye 7
and its complexes 9a–9h.
(C–H bend), 1175 (C–N), 1026 (C–O), 854 (C=C bend),
599 (O-Cd). Found, %: C 35.46; H 2.16; N 9.62; S 11.19.
C40H48Cd2N8O30S6. Calculated, %: C 35.40; H 2.10; N
9.71; S 11.12.
RESULTS AND DISCUSSION
C40H48Mn2N8O30S6 (9h). Greyish brown complex,
yield 72%. FTIR spectrum, ν, cm–1: 3456 (OH str), 1445
(N=N str), 1380 (C–H bend), 1178 (C–N), 1027 (C–O),
845 (C=C bending), 505 (O-Mn). Found, %: C 39.37; H
2.38; N 10.63; S 12.43. C40H48Mn2N8O30S6. Calculated,
%: C 39.32; H 2.33; N 10.79; S 12.35.
Synthesis of acid dyes and their metal complexes
10a–10h. Diazotization of 4,4ꞌ-diaminostilbene-2,2ꞌ-
disulfonic acid (DASDA) by NaNO2 and HCl at 0–5°C
.
was followed by reduction with Na2SO3 7H2O which gave
hydrazine 3 (Scheme 1). The synthesized hydrazine 3 was
condensed with ethyl acetoacetate upon refluxing form-
ing pyrazolones nucleus on both sides of the hydrazine.
The symmetric bis-pyrazolone 4 was precipitated upon
acidification of the reaction mixture by HCl. The prepared
diazonium salt of 4-sulpho-2-aminophenol 6 was coupled
with bis-pyrazolone derivative 4 upon stirring for ca 3 h
Dyeing process. A dye solution (10 mL, 0.4 % w/v)
was prepared and charged in a dye bath. The content of
the dye bath was stirred throughout the following pro-
cesses. A NaNO2 (7 mL, 20% w/v) solution was added
to the dye solution maintaining pH in the dye bath at
Table 1. Exhaustion and fixation data for the dye 7 and its metal complexes 9a–9h
Dye
Shade on leather
Brown
λ
max, nm (in ethanol)
log ε
6.0
Exhaustion, % (C)
70.31
Fixation, % (C)
75.32
7
408
455
490
432
438
473
437
440
430
9a
9b
9c
9d
9e
9f
Reddish brown
Violet brown
Greyish brown
Greyish brown
Violet brown
Greyish brown
Yellowish brown
Greyish brown
6.10
6.20
6.10
6.20
6.25
6.25
6.05
6.27
77.78
80.67
73.46
82.23
73.42
90.35
75.77
78.63
75.45
80.23
77.28
86.25
9g
9h
75.47
80.54
75.30
87.18
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

SYNTHESIS AND SERVICEABILITY OF NEW SYMMETRIC BIS-PYRAZOLONE METAL COMPLEX 2501
Scheme 1. Synthesis of acid dye 7 and its metal complexes 9a–9h.
SO3H
NH2
SO3H
NaNO2 + HCl
Cl
N N
0ꢀ5oC
Cl
N N
SO3H
H2N
HO3S
2
1
Na2SO3·7H2O
Zn (dust)
HCl
CH3
H
O
O
N NH2
N
N
SO3H
(1)
O
SO3H
Reflux
(2) HCl
OH
SO3H
H2N N
H
HO
3
SO3H
N
N
4
OH
H3C
OH
NH2
N
NCl
NaNO2 + HCl
0ꢀ5oC
SO3H
SO3H
6
CH3
5
N
N
SO3H
N
N
SO3H
OH
OH
HO
HO
N
SO3H
N
N
N
HO3S
7
H3C
M(salts)
8aꢀ8h
CH3
HOCH3
HOCH3
Methanol
reflux
N
N
H
SO3
HOCH3
SO3H
N
M+2
N
O
O
O
O
N
M+2
SO3H
N
N
N
H
O
HO3S
C
HOCH3
HOCH3
H
3
H3C
9aꢀ9h
Metal salts = CuSO4·5H2O (8a), FeSO4·7H2O (8b), Ni(CH3COO)2·4H2O (8c), Co(NO3)2·6H2O (8d), Cr2(CH3CO2)4(H2O) (8e),
ZnCl2 (8f), CdCl2·2.5H2O (8g), MnCl2·4H2O (8h); M = Cu+2 (9a), Fe+2 (9b), Ni+2 (9c), Co+2 (9d), Cr+3 (9e), Zn+2 (9f), Cd+2
(9g), Mn+2 (9h).
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

2502
AYAZ et al.
Fig. 2. FTIR spectrum of the ligand acid dye 7.
Fig. 3. FTIR spectrum of Cr(II) complex 9e of the acid dye 7.
at 0–5°C in an alkaline medium to give the ligand acid
dye 7. The coupling was achieved at active methylene
center of bis-pyrazolone. The dye 7 was precipitated upon
addition of HCl to adjust pH 4.0 of the mixture. The dye
7 was dried and recrystallization from ethanol.
was recorded in the visible range due to π–π*of the N=N
linkage. The metal complex dyes 9a–9h exhibited λmax
in the range of 430–473 nm (Fig. 1). The iron complex
9h was characterized by the largest bathochromic shift
as compared to the ligand dye 7.
FTIR spectra of the acid dye 7 and all its metal com-
plexes 9a–9h exhibited a broad band in the range of
3000–3500 cm–1 which evidenced formation of the strong
H-bond (Figs. 2, 3).
Metal complexes of the dye 7 (Scheme 1). Upon
continuous stirring at 70-80°C one of metal salts 8a–8h
was added to the solution of dye 7 in TEA at pH 9–10.
Completion of the reaction was monitored by TLC using
9 : 1 chloroform - methanol solution. Upon following
addition of HCl the corresponding dye 9a–9h was pre-
cipitated, filtered off and dried in an oven at 70°C. The
dyes were re-crystallized from ethanol.
Because of paramagnetic nature of the metals involved
in the synthesized complexes, 1H and 13C NMR spectra
were not measured.
Spectroscopic study of bis-pyrazolones based acid
dye 7 and its metal complexes 9a–9h. The synthesized
dyes were characterized by UV-Vis, FTIR and NMR spec-
tra. The ligand dye 7 demonstrated λmax at 408 nm, π–π*
transition of C=C (Fig. 1). The second absorption maxima
7
9a
9b 9c
9d
9e
9f
9g
9h
Fig. 4. 2 % Shade of dye 7 and its metal complexes 9a–9h
on leather.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019

SYNTHESIS AND SERVICEABILITY OF NEW SYMMETRIC BIS-PYRAZOLONE METAL COMPLEX 2503
Table 2. Fastness data for the dye 7 and its metal complexes
9a–9h
gas formed from the azo fragments. The loss of gases
CO, CO2, and SO2 occurred in the range of 400–800°C.
Iron metal complex was more stable than other metal
complexes.
Rubbing fastness
Light
fastness
Wash
fastness
Dye
dry
4
wet
4
CONCLUSIONS
7
5–6
6–7
6–7
5–6
6–7
6–7
6–7
5–6
5–6
4
9a
9b
9c
9d
9e
9f
6–7
4–5
4–5
4–5
6–7
4–5
4–5
5
4
3
A new series of bis-pyrazolone metal complex acid
dyes 9a–9h has been synthesized in high yield from bis-
pyrazolone 4. As compared to other metal complexes of
acid dyes, iron and chromium metal complexes 9a and
9e exhibit higher bathochromic shift in UV-Vis spectra.
The synthesized dyes applied on leather and show high
wash fastness, light fastness and rubbing fastness. As
compared to ligand dye, all metal complexes demonstrate
high quality of exhaustion and fixation on leather. Due
to strong metal binding with nitrogen and oxygen, metal
complexes dyes exhibit thermal stability higher than the
ligand dye.
4
4
4–5
4–5
4
3–4
3–4
3–4
3–4
3–4
3–4
4–5
4–5
4–5
9g
9h
Exhaustion and fixation study. Fixation exhaustion
values were determined for application of dyes on cotton
fibers at 2% (Table 1). Symmetric bis-pyrazolones were
used as reagents towards cellulose fibers. In alkaline
media the electron deficient carbon atoms attached to
the sulphonic group could interact efficiently with cotton
fibers. Percent of fixation of 2% dyeing and the percent
of exhaustion [9] on cotton ranged within 70–90 and
65–72% (Table 1). Due to polar groups, physical and
chemical interactions of dyes with fibers could lead to
good exhaustion and fixation effects.
CONFLICT OF INTEREST
No conflict of interest was declared by the authors.
REFERENCES
1. Gup, R., Giziroglu, E., and Kirkan, B., Dyes Pigm.,
2007, vol. 73, no. 1, p. 40.
https://doi.org/10.1016/j.dyepig.2005.10.005
2. Biannic, B., Bozell, J.J., and Elder, T., Green Chem., 2014
vol. 16, p. 3635
https://doi.org/10.1039/C4GC00709C
3. Biannic, B. and Bozell, J.J., Org. Lett., 2013, vol. 15,
p. 2730.
Fastness properties. The synthesized dyes fastness
properties were also assessed (Table 2). The degree at
which a dye resists fading is called light fastness, which
is different for different dyes. For all sort of dyes, light
fastness in the range of 4–5 is considered to be high. The
resistance of dye fibers to retain colors when washed by
detergents and soaps is called wash fastness.
https://doi.org/10.1021/ol401065r
4. Shukla, H.M., Solanki, Y.K., Shad, A.R., D.S., Shah, A.I.,
and Shah, P.J., Chem. Sci., 2013, vol. 2, no. 1, p. 301.
https://doi.org/10.7598/cst2013.240
5. Rahat, K., Imam, U., Alam, M., and Sultan, D., Bangladesh
J. Pharmacol., 2008, vol. 3, p. 27.
https://doi.org/10.1007/s13659-017-0143-9
6. Anitha, K.R., Venugopala, R., and Rao, V.K.S., J. Chem.
Pharm. Res, 2011, vol. 3, no. 3, p. 511.
7. Girish, B.V. and Raksha, V.Z., Int. J. Chem. Sci., 2011,
vol. 9, p. 87.
Light fastness of the ligand acid dye 7 was in the
range of 5–6 while its metal complexes exhibited high
light fastness 6–7. Ligand dye 7 and its metal complexes
exhibited high rubbing fastness 4–5. Improved properties
like wash fastness can be easily tested by rubbing fastness.
According to rubbing fastness values all synthesized dyes
had high fixation on leather fabrics (Fig. 4).
8. Saeed, A., and Shabir, G., Arabian J. Chem., 2018, vol. 11,
p. 111.
Thermogravimetric analysis of acid dyes 7 and
metal complexes 9a–9h. TGAwas carried out for ligand
7 and its metal complexes 9a–9h. Water molecules loss
(12–13%) occurred in the range of 0–100°C. In the range
of 100–400°C 9% weight loss could be attributed to N2
https://doi.org/10.1080/17415993.2018.1551488
9. Hussain, G., Ather, M., Khan, M.A., Saeed, A., Saleem, R.,
Shabir, G., and Channar, P.A., Dyes Pigm., 2016, vol. 130,
p. 90.
https://doi.org/10.1016/j.dyepig.2016.02.014
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 89 No. 12 2019