SHORT COMMUNICATION:
UV-SPECTROSCOPIC CHARACTERIZATION OF THE SCHIFF’S BASE N,N BISSALICILDENE-O-PHENYLENEDIIMINE AND IT’S COMPLEXES WITH SOME METAL
IONS
By:
Naser Eltaher Eltayeb Taha 1 and Taj Elsir A. Ahmed 2
1- International University of Africa, College of Science, Department of Chemistry, E-mail: Nasertaha90@hotmail.com,
2-University of Khartoum, Faculty of Science, Department of Chemistry.
KEY WORDS:
Schiff's base, Analytical reagent, o-phenylenediamine.
ABSTRACT
The synthesis and characterization of N, N bis-salicildene -ophenylenediimine was described, using infra red, ultra violet spectroscopy, melting
point, and elemental analysis for nitrogen.
The behavior towards some metal ions Fe(II), V(V), Co(II) is studied and its
possibility as analytical reagent evaluated. V(V)-NNSP absorbance increased by 17%
in the presence of 0.064 M hydrochloric acid, while Co(II)-NNSP and Fe(II)-NNSP
absorbances increased by 116.27% and 225.2% respectively in the presence of 0.25
M and 0.15 M ammonia.
This reagent can be used quantitatively to determine trace concentr-ation of
metal ions Fe(II), V(V), Co(II) in optimum conditions as described in this paper.
‫ كذلك‬،‫ فينايلين ثنائي أمين‬-‫ثنائي ساليسدين – أورثو‬- ‫ ن‬،‫ ن‬،‫في هذا البحث تم تحضير قاعدة شيف‬
:‫الملخص‬
‫ ودراسة األساس‬،‫تم التعرف على هذا المركب من دراسة طيفه بواسطة األشعة الحمراء واألشعة فوق البنفسجية‬
.‫للنتروجين ودرجة االنصهار‬
، Co(II)،V(V) ،Fe(II) ‫درست أيضاً مقدرة هذا المركب على تكوين معقدات مع األيونات الفلزية‬
.ً‫وامكانية استخدامه في التحليل لتقدير هذه األيونات الفلزية كميا‬
‫ من حامض الهيدروكلوريك بينما زادت‬0.064 M ‫ في وجود‬%17 ‫ زادت‬V(V)-NNSP ‫امتصاصية المعقد‬
‫ في وجود هيدروكسيد‬%225.2‫ و‬%116.2 ‫ بنسبة‬Fe(II)-NNSP‫ و‬Co(II)-NNSP ‫امتصاصية كل من‬
.‫ على التوالي‬0.15 M ‫ و‬0.25 M ‫االمونيوم بتركيز‬
INTRODUCTION
Schiff bases derived from o-phenylenediimine and salicylaldehyde have
already been synthesized and studied from several point of views[1]. Complexes of
Schiff base ligands have been studied for their dioxygen uptake[2] and oxidative
catalysis[3]. In addition, complexes of transition metals (II) which involve derivatives
of salicylaldehyde and diamine have considerable attention. This is because of their
potential as catalysts for the insertion of oxygen into an organic substrate[4-7].
The most interesting applications are related for their capacity to form stable
chelates with metal ions and their usefulness as analytical reagents.
MATERIALS AND METHODS
Experimental: All chemicals and solvents are obtained from Merck, England;
deionized water is obtained from Balsam Factory, Khartoum. Infra red spectra (I.R) were
recorded on Perkin Elmer I.R-1330 spectrophotometer. Ultra Violet (U.V) spectra
were run on Perkin Elmer UV/Vis 550 spectrophotometer.
General Procedure for Preparation of the Ligand: The ligand was prepared by the
modification of Abd-Elzaher method[1]. A typical procedure for the synthesis of Schiff
base is as follow:
A solution of 0.1 mole o-phenylenediamine (in 50 ml ethanol) was slowly
added to a solution of 0.2 mole of salicylaldehyde (in 50 ml ethanol). The mixture was
heated under reflux for 30min. On cooling to room temperature, yellow-orange crystals
were formed. The product was recrystall-ized from methanol, melting point. (m.p.)
163.3ºC (literature 164ºC)[8], N% 7.284 (Calculated. 8.8506).
RESULTS
Identification of Reagent:
The Infrared Spectra: The spectra were measured at room temperature (KBr disk) and
the results are shown in (Table 1).
Table (1): IR Spectra of NNSP
Group
O-H
C=N
O…H
Wave Number (cm-1)
Found
Literature (1,9)
3400
2500-3500
1600
1500-1600
1270
1276
OH
OH
CHO
NH 2
NH 2
+
2
HC
HO
N
N
Ethanol
CH
+ 2H2O
Analytical Parameters for NNSP Complexes with Some Metal Ions Scanning of
the Wavelengths of Maximum Absorption for Metal Ions Complexes:
The wavelengths of maximum absorbance, solutions of 4.0x10-4 M of reagent
and 16.0ppm of each of the metal ions were scanned. The wavelengths of maximum
absorption (λmax) are shown in (Table 2).
Table (2): Wavelengths of Maximum Absorption for Metal Ion Complexes
Metal ion
Fe(II)
Fe(III)
V(V)
Co(II)
Ni(II)
Zn(II)
Wavelength (nm)
420
541
419
448
402
342
Absorbance
0.816
0.045
1.021
0.870
0.316
0.101
Three sets of mixtures were prepared by keeping the
concentration of the metal ion and ligand at 16.0ppm and 4x10-4M respectively, to the
first mixture three drops of 1.0M hydrochloric acid were added and to the second three
drops of 1.0M ammonium hydroxide were added, while the third was taken as
Effect of pH on the Absorbance:
reference. For each metal ion, λmax was measured and the results are summarized in
(Table 3).
Table (3): Effect of HCl and NH4OH on the Absorbance
Metal
Reference
1.021
0.045
0.816
0.316
0.870
0.101
V(V)
Fe(III)
Fe(II)
Ni(II)
Co(II)
Zn(II)
HCl
1.089
0.079
1.727
0.266
1.313
0.080
NH4OH
0.105
0.045
2.282
0.303
1.351
0.064
Analytical Parameters for Fe(ii)-NNSP Complex:
A series of Fe(II)-NNSP solutions were prepared of
16.0ppm of Fe(II) ion and 4.0X10-4 M NNSP in different ammonia concentrations. The
absorbance was measured at 420nm and the results are shown in (Fig.1).
Effect of NH4OH Concentration:
2.8
Absorbance
2.4
2.0
1.6
1.2
0.8
0.4
0.00
0.05
0.10
0.15
0.20
Ammonia concentration (M)
Fig. (1):
Effect of Ammonia Concentration on Fe(II)-NNSP Absorption
The effect of NNSP concentration on the absorbance was
studied by preparing solutions of 16.0 ppm of Fe(II) and 0.15 M of ammonia in
different NNSP concentrations. The absorbance was measured at 420nm and the
results are shown in (Fig. 2).
Effect of Reagent Concentration:
Absorbance
2.6
2.1
1.6
1.1
0.6
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Reagent concentration (M)
Fig. (2): Effect of Reagent Concentration on Fe(II)-NNSP Absorption
Calibration Curve for Fe (II)-NNSP Complex: The calibration curve for Fe(II)-NNSP
complex was constructed using 0.15M of ammonia, 4.0 x 10-4 M of NNSP and different
concentrations of the metal ion. The absorbance was measured at 420nm and the
results are shown in (Fig. 3).
Absorbance
1.5
1.0
0.5
0.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
Fe(II) concentration (ppm)
Fig. (3): Calibration Curve for Fe (II)-NNSP Complex
Analytical Parameters for V (v)-NNSP Complex:
Effect of HCl Concentration: A series of V(V)-NNSP solutions were prepared of 16.0ppm
of V(V) ion and 4.0X10-4 M NNSP in different hydrochloric acid concentrations. The
absorbance was measured at 419nm and the results are shown in (Fig.4).
Absorbance
1.20
1.10
1.00
0.90
0.000
0.010
0.020
0.030
0.040
0.050
0.060
0.070
0.080
HCl concentration (M )
Fig. (4): Effect of HCl Concentration on V (V)-NNSP Complex
Effect of Reagent Concentration: The effect of NNSP concentration on the absorbance was
studied by preparing solutions of 16.0 ppm of V(V) and 0.064M of hydrochloric acid in
different NNSP concentrations. The absorbance was measured at 419nm and the
results are shown in (Fig.5).
Absorbance
1.5
1.3
1.1
0.9
0.7
0.5
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
10.0
Reagent concentration (M)
Fig. (5): Effect of Reagent Concentration on V(V)-NNSP Complex
Calibration Curve for V (V)-NNSP Complex: The calibration curve for V(V)-NNSP complex
was constructed using 0.064M of hydrochloric acid, 8.0 x 10-4 M of NNSP and different
concentrations of the metal ion. The absorbance was measured at 419nm and the
results are shown in (Fig. 6).
1.2
Absorbance
1.0
0.8
0.6
0.4
0.2
0.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
V (V) concentration (ppm)
Fig. (6): Calibration Curve for V(V)-NNSP Complex
Analytical Parameters for Co (II)-NNSP Complex:
Effect of NH4OH Concentration: A series of Co(II)-NNSP solutions were prepared of
16.0ppm of Co(II) ion and 4.0X10-4 M NNSP in different ammonia concentrations. The
absorbance was measured at 448nm and the results are shown in (Fig.7).
Absorbance
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.0
0.1
0.1
0.2
0.2
0.3
Ammonia concentration (M)
Fig. (7): Effect of Ammonia Concentration on Co(II)-NNSP Complex
0.3
of NNSP concentration on the absorbance was
studied by preparing solutions of 16.0ppm of Co(II) and 0.25M of ammonia in
different NNSP concentrations. The absorbance was measured at 448nm and the
results are shown in (Fig.8).
Absorbance
Effect of Reagent Concentration: The effect
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
2.0
4.0
6.0
8.0
10.0
Reagent concentration (M)
Fig. (8): Effect of Reagent Concentration on Co(II)-NNSP Complex
Calibration Curve for Co (II)-NNSP Complex: The calibration curve for Co(II)-NNSP
complex was constructed using 0.25M ammonia, 8.0 x 10-4 M NNSP and different
Absorbance
concentrations of metal ion. The absorbance was measured at 448nm and the results
are shown in (Fig. 9).
1,4
1,2
1,0
0,8
0,6
0,4
0,2
0,0
0,0
1,0
2,0
3,0
4,0
5,0
6,0
7,0
8,0
Co (II) concentration (ppm)
Fig. (9): Calibration Curve for Co(II)-NNSP Complex
DISCUSSION
The Schiff’s base NNSP was identified by I.R, nitrogen content, and melting
point, and its application as analytical reagent was investigated by UV studies. NNSP
gave a relatively better absorbance with V(V), Fe(II), and Co(II).
The optimum conditions of the practical analytical application of the Schiff’s
base NNSP with these metal ions, showed a relatively better absorbance.
The complexes of Fe(II) and Co(II) with NNSP gave a higher absorbance in
basic medium, while V(V) gave a higher absorbance in acidic medium, whereas Ni(II)
complex was not affected by either.
V(V)-NNSP absorbance increased by 17%
in the presence of 0.064 M
hydrochloric acid, while Co(II)-NNSP and Fe(II)-NNSP absorbances increased by
116.27% and 225.2% respectively in the presence of 0.25 M and 0.15 M ammonia.
The increase in the absorption of V(V)-NNSP complex in the acidic medium may be
attributed to the formation of ionic oxyvanadates [V4O9]-2.[10] Increase of absorption
in presence of ammonia can explained by the ability of ammonia to increase the
splitting of d orbitals of the central metal ion and thus increasing the energy required
to bring about excitation.[11]
ACKNOWLEDGMENT
The Author acknowledges the financial support International University of
Africa.
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