SHORT COMMUNICATION:

UV-SPECTROSCOPIC CHARACTERIZATION OF THE SCHIFF’S BASE N,N BIS-SALICILDENE-O-PHENYLENEDIIMINE AND IT’S COMPLEXES WITH SOME METAL IONS

By:

Naser Eltaher Eltayeb Taha and Taj Elsir A. Ahmed

1- International University of Africa, College of Science, Department of Chemistry, E-mail: ,

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 -o- phenylenediimine 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.

الملخص:

في هذا البحث تم تحضير قاعدة شيف، ن، -ثنائي ساليسدين – أورثو- فينايلين ثنائي أمين، كذلك تم التعرف على هذا المركب من دراسة طيفه بواسطة الأشعة الحمراء والأشعة فوق البنفسجية، ودراسة الأساس للنتروجين ودرجة الانصهار.

درست أيضاً مقدرة هذا المركب على تكوين معقدات مع الأيونات الفلزية Fe(II)، V(V)، Co(II)، وإمكانية استخدامه في التحليل لتقدير هذه الأيونات الفلزية كمياً.

امتصاصية المعقد V(V)-NNSP زادت 17% في وجود 0.064 M من حامض الهيدروكلوريك بينما زادت امتصاصية كل من Co(II)-NNSP وFe(II)-NNSP بنسبة 116.2% و225.2% في وجود هيدروكسيد الامونيوم بتركيز 0.25 M و0.15 M على التوالي.

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; de-ionized 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
/ Wave Number (cm-1)
Found
/ Literature (1,9)
O - H
/ 3400 / 2500-3500
C = N
/ 1600 / 1500-1600
O…H
/ 1270 / 1276

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
/ Wavelength (nm) /
Absorbance
Fe(II) / 420 / 0.816
Fe(III) / 541 / 0.045
V(V) / 419 / 1.021
Co(II) / 448 / 0.870
Ni(II) / 402 / 0.316
Zn(II) / 342 / 0.101

Effect of pH on the Absorbance: 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 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 / HCl / NH4OH
V(V) / 1.021 / 1.089 / 0.105
Fe(III) / 0.045 / 0.079 / 0.045
Fe(II) / 0.816 / 1.727 / 2.282
Ni(II) / 0.316 / 0.266 / 0.303
Co(II) / 0.870 / 1.313 / 1.351
Zn(II) / 0.101 / 0.080 / 0.064

Analytical Parameters for Fe(ii)-NNSP Complex:

Effect of NH4OH Concentration: 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).

Fig. (1): Effect of Ammonia Concentration on Fe(II)-NNSP Absorption

Effect of Reagent Concentration: 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).

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).

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).

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).

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).

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).

Fig. (7): Effect of Ammonia Concentration on Co(II)-NNSP Complex

Effect of Reagent Concentration: The effect 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).

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 concentrations of metal ion. The absorbance was measured at 448nm and the results are shown in (Fig. 9).

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.

REFERENCES

1-  Abd-Elzaher, M. M. (2001). Spectroscopic Characterization of Some Tetradentate Schiff Bases and Their Complexes with Nickel, Copper, and Zinc, J. Chin. Chem. Soc., 48, PP: [153 -158].

2-  Tovrog, B. S., Kitko, D. J., Drago, R. S. (1976). Nature of the bound oxygen in a series of cobalt dioxygen adducts. J. Am. Chem. Soc, 98, PP: [5144 -5153].

3-  Dixit, P. S., Srinivaso, K., (1988). The effect of clay-support on the catalytic epoxidation activity of a manganese (III)-Schiff base complex Inorg. Chem., 27, PP: [4507- 4509].

4-  Tojo, N. M., Matsura, T., (1974). A model catalytic oxygenation for the reaction of quercetinase. J. Chem. Soc., Chem. Commun., (21), PP: [896-897].

5-  Kessel, S. L., Emberson, R. M., Debunner, P.G., Hendrickson, D. N. (1980). Iron (III), manganese (III), and cobalt (III) complexes with single chelating o-semiquinone ligands. Inorg. Chem., 19, PP: [1170-1178].

6-  Bailey, N. A., Higson, B. M., Mekenzie, E. D. (1972). Crystal and molecular structure of benzoylacetonato-[NN-ethylene bis (salicylideneiminato)] cobalt (III)–1·5 water, J. Chem. Soc., Dalton Tran.,(6), PP: [503-508].

7-  Cummins, D., McKenzie, E. d., Milburn, H. (1976).Steric strain in cobalt (III) compounds. Crystal and molecular structure of dibenzoylmethanato -O,O-[NN-o-phenylenebis(salicylideneiminato)] cobalt (III). J. Chem. Soc., Dalton Tran., (2), PP: [130-135].

8-  Aggett, J., Richardson, R. A. (1980). Bissalicylidene-o-phenylenediimine as a solvent extraction-spectrophotometric reagent for nickel (II). Analyst, 105, PP: [1118-1120].

9-  Neely,W. B., “Advance Carbohydrates Chemistry”, eds. Wilform M. L., and Tipson R. S., Vol. 12, Acadimic Press, New York.

10-  Akhmetov, N., (1987). “General and Inorganic Chemistry” third printing, Mir Publishers, Moscow, PP: [540-548].

11-  Kask, U., and David R. J. (1993). "General Chemistry" WCB Publishers, USA, PP: [810-840].