Volume 03 Issue 03-2023
18
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
ABSTRACT
This article discusses spectrophotometric study of cobalt(II) complex formation with qinazolone-4.
KEYWORDS
Methanol, qinazolone-4, spectrophotometric study.
INTRODUCTION
Methanol solutions of sulfate, nitrate and chloride of
cobalt(II) in the region of 400-700 nm have one
absorption band at about 515 nm with a molar
absorption coefficient
Ɛ
=8 (Fig. 1). The light absorption
law is observed for solutions at least up to a cobalt
concentration of 0.12 M. In the visible region of the
spectrum, methanol solutions of quinazolone-4 and its
potassium salt do not absorb.
THE MAIN RESULTS AND FINDINGS
When KHz solutions and cobalt salts are mixed, an
intense violet color of the solutions appears, the
absorption spectra of which have a maximum at 560
nm (Fig. 1), which indicates the complex formation of
cobalt ions with quinazolone.
Research Article
SPECTROPHOTOMETRIC STUDY OF COBALT(II) COMPLEX FORMATION
WITH QINAZOLONE-4
Submission Date:
March 12, 2023,
Accepted Date:
March 17, 2023,
Published Date:
March 22, 2023
Crossref doi:
https://doi.org/10.37547/ajast/Volume03Issue03-04
Erkin Sh. Yakubov
Candidate Of Chemical Sciences, Dosent Karshi State University, Uzbekistan
Nilufar Sh. Boykabilova
Master's Degree 1st Year Chemistry (Inorganic, Analytical And Rare Metals Chemistry) Karshi State University,
Uzbekistan
Journal
Website:
https://theusajournals.
com/index.php/ajast
Copyright:
Original
content from this work
may be used under the
terms of the creative
commons
attributes
4.0 licence.
Volume 03 Issue 03-2023
19
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
Рис. 1. ЭСП CoCl2.6H2O (a) и в присутствии KHz (b
-
e) в метаноле.
ССo=10
-
3 M, CKHz=0 (a); 0,02 M (b); 0,035 M (c); 0,05 M (d) и 0,15 M (e).
To determine the composition and stability of the
complex, the dependence of the optical density of the
absorption band maximum of the complex on the
ligand concentration at a constant metal concentration
was studied. With an increase in the Hz content in the
solution, the optical density of the complex increases
and reaches its maximum at a 100-fold excess of the
ligand, regardless of the chosen metal salt (Fig. 2).
Obviously, in this case, the entire cobalt ion is bound
into a complex and its concentration will be equal to
the concentration of the initial metal. Therefore, the
molar absorption coefficient of the complex is
Ɛ
ком
=D0/CM.L. In all three cases, close values are
calculated
Ɛ
ком
=(1,1±0,1).103. This value is more than
100 times higher than the values of the extinction of
solutions of the initial cobalt salts.
Volume 03 Issue 03-2023
20
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
Rice. 2. Absorption saturation curve (λ=560 nm).
The above experiment makes it possible to determine
the composition and stability of the complex by the
methods of equilibrium shift, Babko and Foster [1]. In
table. Tables 1-3 show the spectrophotometric
parameters of the complex formation of quinazolone-
4 with chloride, sulfate, and cobalt(II) nitrate,
necessary for calculating the composition and stability
by these three methods.
According to the equilibrium shift method (Fig. 3), the
dependence of the optical density of the complex on
the concentration of the ligand at a constant metal
concentration coordinates lgD/D0
–
D и lg[C]
represents parallel straight lines with an angle of
inclination tgα=2,
which indicates the formation of a
complex of composition Me:L=1:2.
Volume 03 Issue 03-2023
21
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
Рис. 3. Dependency Plots lgD/D0
-
D от lg [CL].
This composition is also confirmed by the Foster
method. Dependencies D/CLn from D only in case n=2
(composition of the complex) are straigh
t lines (рис.
4), т.е. two independent methods confirm the
formation of a composition complex 1:2.
Since, regardless of the chosen cobalt salt, one
complex is formed, which has an absorption band at
560 nm, it becomes obvious that the complex does not
include
anions
SO42-,
Cl-,
NO3-.
Therefore,
quinazolone-4 enters complex formation in the form of
a monobasic anion.
For the potassium salt Hz, it was found that the metal
replaces the nitrogen proton in position 3 [2]. On this
basis, for the cobalt complex with quinazolone-4, one
can assume the formation of an ionic bond with
nitrogen and a coordination bond with carbonyl
oxygen to form a four-membered metallocycle.
Volume 03 Issue 03-2023
22
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
Рис. 4. Dependency Plots D/CLn от D. –
о –
CoSO4.7H2O + KHz,
–
.
–
Co(NO3)2.6H2O + KHz,
–
x
–
CoCl2.6H2O + KHz.
Table 1.
Spectrophotometric parameters of complexation
CoCl2.6H2O+nKHz в метаноле. Co=10
-
3M, λмак=560 нм, L=1см.
Volume 03 Issue 03-2023
23
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
C
L
, 10
-2
M
D
[C
k
], 10
-4
M
[C
L
], 10
-2
Lg[C
L
]
lgD
i
/(D
0
-D
i
)
(lg
[C
L
])
2
lgD
i
/D
0
-D
i
.
lg[C
L
]
C
L
2
, 10
-4
M
2
C
L
3
, 10
-6
M
2
D/C
L
, M
-1
D/C
L
2
, 10
2
M
2
D/C
L
3
, 10
3
M
3
15,0 1,10 6,00 14,940
7,5 0,93 5,07 7,399 -1,131 0,74 1,29 -0,84 56,25 421,9 12,40 1,65 2,20
6,0 0,86 4,69 5,90 -1,229 0,54 1,52 -0,67 36,00 216,0 14,33 2,39 3,98
4,5 0,74 4,04 4,42 -1,355 0,31 1,85 -0,42 20,25 91,13 16,44 3,65 8,12
3,5 0,59 3,22 3,43 -1,464 0,06 2,15 -0,09 12,25 42,88 16,86 4,82 13,76
2,5 0,40 2,18 2,45 -1,610 -0,24 2,60 0,39 6,25 15,63 16,00 6,40 25,59
1,5 0,20 1,09 1,48 -1,830 -0,65 3,36 1,19 2,25 3,38 13,33 8,89 59,17
3,32 25,09 -8,620 0,76 12,77 -0,437 89,36 27,80 112,82
C
L
, 10
-2
M
D
i
[C
k
], 10
-4
M
[C
L
], 10
-2
lg[C
L
]
lgD
i
/D
0
-D
i
(lg
[C
L
])
2
lgD
i
/D
0
-D
i
.
lg[C
L
]
C
L
2
, 10
-4
M
2
C
L
3
, 10
-6
M
2
D/C
L
, M
-1
D/C
L
2
,10
2
M
2
D/C
L
3
,10
3
M
3
15,0 0,92 6,00 14,880 -0,827
8,0 0,77 5,02 7,900 -1,102 0,71 1,22 -0,78 64,00 512,0 9,63 1,20 1,50
Volume 03 Issue 03-2023
24
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
6,0 0,68 4,43 5,911 -1,278 0,45 1,51 -0,55 36,00 216,0 11,33 1.89 3,15
5,0 0,62 4,04 4,920 -1,307 0,32 1,71 -0,42 25,00 125,0 12,40 2,48 4,96
3,0 0,40 2,61 2,948 -1,530 -0,11 2,34 0,17 9,00 27,0 13,33 4,44 14,81
1,5 0,15 0,98 1,480 -1,830 -0,71 3,35 1,30 2,25 3,4 10,00 6,67 44,12
2,62 23,16 -6,99 0,66 10,13 -0,29 56,69 16,68 68,54
Table 3
Spectrophotometric parameters of complexation
CoSO
4
.
7H
2
O+nKHz
в
метаноле
. Co=10
-3
M,
λ
мак
=560
нм
, L=1
см
.
C
L
, 10
-2
M
D
i
[C
k
], 10
-4
M
[C
L
], 10
-2
lg[C
L
]
lgD
i
/D
0
-D
i
(lg
[C
L
])
2
lgD
i
/D
0
-D
i
.
lg[C
L
]
C
L
2
, 10
-4
M
2
C
L
3
, 10
-6
M
2
D/C
L
, M
-1
D/C
L
2
,10
2
M
2
D/C
L
3
,10
3
M
3
11,0 0,63 6,00 8,880 -1,052
6,0 0,57 5,40 5,892 -1,230 0,98 1,51 -1,20 36,00 216,0 9,50 1,58 2,64
4,0 0,50 4,76 3,905 -1,408 0,58 1,98 -0,82 16,00 64,0 12,50 3,13 7,81
3,0 0,44 4,19 2,916 -1,535 0,38 2,36 -0,58 9,00 27,0 14,67 4,89 16,29
2,0 0,31 3,00 1,940 -1,712 0,00 2,93 0,00 4,00 8,0 15,75 7,88 39,37
1,5 0,23 2,19 1,456 -1,837 -0,24 3,37 0,44 2,25 3,4 15,33 10,22 67,65
1,0 0,12 1,14 0,977 -2,010 -0,63 4,04 1,27 1,00 1,0 12,00 12,00 120,0
---------------------------------------------------------------------------------------------------------------------
2,80 23,97 -10,774 1,07 16,19 -0,89 79,75 39,70 253,76
Volume 03 Issue 03-2023
25
American Journal Of Applied Science And Technology
(ISSN
–
2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
Oscar Publishing Services
Servi
The most probable octahedral structure in solution is formed due to the coordination of two solvent molecules to the
axial positions of the square planar complex.
CH
3
OH
CH
3
OH
N
N
O
N
N
O
Co
The observed band at 560 nm corresponds to the most intense transition
4
T
1g
(F)
→
4
A
2g
(F) octahedral cobalt complex
[3]. The remaining two weak transition bands
4
T
1g
(F)
→
4
T
2g
(F)
и
4
T
1g
→
4
T
1g
(F) in the region of 1250 and 500 nm, we did
not detect them due to the impossibility of recording the spectrum with this device, as well as due to overlapping by
a strong band at 560 nm.
As expected, the instability constant of the complex, determined by the three methods, gives close values
corresponding to low-stability complexes.
Table 4
Logarithm of the instability constant (lgK) of the complex Co(Hz)2.2CH3OH
Комплексообразование
хиназолона
-
4 с
По Фостеру
По Бабко
По сдвигу
равновесия
CoSO
4
.
7H
2
O
CoCl
2
.
6H
2
O
Co(NO
3
)
2
.
6H
2
O
-3,38
-2,97
-2,92
-3,41
-3,02
-2,94
-3,42
-3,00
-2,92
CONCLUSION
Thus, based on the study of the complexation of the
potassium salt of quinazolone-4 with sulfate, chloride
and cobalt nitrate by the photometric method, the
formation of an unstable complex Co(Hz)2.2CH3OH.
The maximum light absorption of the methanol
solution of the complex is observed at 560 nm, the
molar light absorption coefficient
–
1,1.103. An
octahedral structure of the complex with two
molecules of the quinazolone-4 anion in the equatorial
plane and two molecules of methanol in the axial
Volume 03 Issue 03-2023
26
American Journal Of Applied Science And Technology
(ISSN
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2771-2745)
VOLUME
03
I
SSUE
03
Pages:
18-26
SJIF
I
MPACT
FACTOR
(2021:
5.
705
)
(2022:
5.
705
)
(2023:
7.063
)
OCLC
–
1121105677
Publisher:
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Servi
positions of the complex is proposed. The ligand is
bidentately coordinated through oxygen and nitrogen
atoms, forming a four-membered metallocycle [4].
REFERENCES
1.
Бабко А.К. Физико
-
химический анализ
комплексных соединений в растворах. –
Киев: АН УССР.,
- 1955.
–
С. 139.
2.
Якубов Э.Ш., Назаров Ф.Ф., Назаров Ф.С.
Смещалигандные комплексы
меди(II) с
хиназолоном
-
4
и
его
производными.
UNIVERSUM:
ХИМИЯ
И
БИОЛОГИЯ
Учредитель и издатель: ООО «МЦНО»
Выпуск: 3(96) март. Москва 2022. Стр. 32
-37.
3.
Якубов Э.Ш., Гулбоева Д., Сафарова М.,
Чориев А.У.
4.
Комплексные
соединения
кобальта(II),
меди(II)
и
цинка
с
хиназолоном
-4.
UNIVERSUM:
ХИМИЯ
И
БИОЛОГИЯ
Учредитель и издатель: ООО МЦНО» Выпуск:
3(57) Июль Москва. 2019. Стр.72
-76.
