Complexation Behavior of 1-Phenyl-2,3-dimethyl-4-(benzylamino) pyrazol-5-one Schiff Base Ligand with Manganese ion
K.O. Eberendu, I.E. Otuokere
Department of Chemistry, Michael Okpara University of Agriculture, Umudike, Nigeria
*Corresponding Author E-mail: ifeanyiotuokere@gmail.com
Abstract:
Complexation behaviour of the Schiff base ligand, 1-phenyl-2,3-dimethyl-4-(benzylamino)pyrazole-5-one with manganese metal ion has been studied. The Schiff base ligand, 1-phenyl-2,3-dimethyl-4-(benzylamino)pyrazol-5-one was synthesized by the condensation reaction of 4-aminoantipyrine and benzaldehyde. The ligand and complex were characterized based on their colour, melting point, solubility, infrared and mass spectral analyses. Spectroscopic analyses suggested the involvement of C=N, C=O and chloride ions in chelation. A tetrahedral geometry was suggested for the manganese complex.
KEY WORDS: 1-phenyl-2,3-dimethyl-4-(benzylamino)pyrazol-5-one, manganese, mass spectra, infrared, Schiff base.
Introduction:
Schiff base ligands have been playing an important part in the development of coordination chemistry. Schiff base metal complexes have been studied extensively because of their attractive chemical, physical properties and their wide range of applications in numerous scientific areas [1]. Paramount to the goals of the present-day inorganic chemists is the discovery and development of chelating agents as well as their applications. Chelating agents have broadly found applications in different fields of industrial, analytical, metal cleaning, scale removal as well as clinical chemistry[2]. In discovery and development of better drugs to fight diseases, this has led to numerous studies on drug metal complexes, various studies have been carried out on complexation of some antibacterial, antifungal, anti-malarial, antioxidant and carcinostatic drugs with metals [3].
In industrial area, for example, EDTA is used for estimation of Ca2+ and Mg3+ ions in hard water. Silver and gold are extracted by treating zinc with their cyanide complexes. Complexes are also used as catalysts for different reactions.
It has been reported that aromatic Schiff bases and their metal complexes catalyzes oxygenation, hydrolysis, decomposition, and electro-reduction reactions[4-8]. Antibacterial activity against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, and Proteus vulgaris were exhibited by Schiff base derived from furylglyoxal and p-toluidene[9]. Effective antifungal activity have been reported in thiazole and benzothiazole Schiff bases[10]. Physiological activity against A. niger have been evaluated in pyrandione Schiff bases [11]. Antifungal activity against Candida albicans, Trichophyton rubrum, T. mentagrophytes, A. niger and Micosporum gypseum were exhibited in some quinazolinones Schiff bases[12]. Helminthosporium gramineum(causing stripe disease in barely), Syncephalostrum racemosus (causing fruit rot in tomato) and C. capsici (causing die back disease in chillies) were inhibited when treated with furan or furylglycoxal derived Schiff bases[13]. High antiviral activity were exhibited by Schiff bases of gossypol[14].
In continuation with the research on Schiff bases, we hereby report complexation behavior of 1-phenyl-2,3-dimethyl-4-(benzylamino pyrazol-5-one Schiff base ligand with manganese ion
MATERIALS AND METHODS:
All the reagents are of analytical grades, these include the following; 4-aminoantipyrine (Kem light laboratory PVT Ltd), benzaldehyde (BDH chemical Ltd. Poole England), manganese chloride, (BDH chemical Ltd. Poole England), methanol, (Fisher Scientific international company), acetone, (BDH chemical Ltd. Poole England) and ether (BDH chemical Ltd. Poole England). Infrared analysis was performed using spectrum BX Perkin Elmer FTIR Spectrophotometer. The vibrational frequencies were obtained between 4400-350 cm-1 while the mass spectra were analysed with GC-MS QP2010 Plus (Shimadzu, Japan) with Thermal Desorption System, TD 20 coupled with mass Spectroscopy (Shimadzu).
Synthesis of 1-phenyl-2, 3-dimethyl-4-(benzylamino) pyrazol-5-one
The ligand, 1-phenyl-2, 3-dimethyl-4-(benzylamino) pyrazol-5-one was synthesized via the following procedures. Methanol solution (10ml) of 4-aminoantipyrine (2.03g, 0.01 mol) was prepared. Benzaldehyde (0.01mol) was added to the solution and stirred gently. The precipitate formed was air-dried. The yield was calculated.
Synthesis of the Mn(II) 1-phenyl-2, 3-dimethyl-4-(benzylamino) pyrazol-5-one complex
The metal salt, Manganese chloride (2.37g, 0.01mol) was prepared by dissolving in 10ml methanol. The solution was then added to the methanol solution of the ligand and stirred gently. No precipitate was formed. The solution was then refluxed using a reflux condenser apparatus for about 2 hours. The precipitate formed was air-dried for few days and carefully placed in desiccators. The yield was calculated.
RESULT AND DISCUSSION:
The physical properties, infrared spectral data and mass spectral data of 1-phenyl-2,3-dimethyl-4-(benzylamino)pyrazol-5-one and its Mn(II) complex are presented in Tables 1, 2, 3 and 4 respectively.
The melting point of the ligand was found to be 1210C while that of the complex is 143.50C (Table 1). The increment in melting point is an indication that complexation has taken place. The ligand and complex were found both to be sparingly soluble in acetone and soluble in ether (Table 1).
Table 1: Physical properties of 1-phenyl-2,3-dimethyl-4-(benzyl amino)pyrazol-5-one and its Mn(II) complex
|
Compound |
Colour |
Melting point(oC) |
Yield (%) |
Solubility test in Acetone |
Solubility test in Ether |
|
L |
Bright Yellow |
121 |
50.47 |
Sparingly soluble |
Soluble |
|
ML |
Reddish Brown |
143.5 |
54.7 |
Sparingly soluble |
Soluble |
Assignment |
Vibrational stretching frequencies and intensities (cm-1) |
Characteristic functional group |
N-H |
3697.14 (weak) |
Amino groups. |
C=N |
1636.54 (weak) |
Amines, amides. |
C-H (aromatic) |
3045.71 (moderate) |
Aromatic rings. |
C-H (aliphatic) |
2925.00(moderate) |
Alkanes and saturated Hydrocarbons. |
C=O |
1716.47 (moderate) |
Carbonyls |
Assignment |
Vibrational stretching frequencies and intensities (cm-1) |
Characteristic functional group |
N-H |
3754.28 (weak) |
Amines |
C-H (aromatic) |
3194.28 (weak) |
Aromatic rings. |
C-H (aliphatic) |
2931.42 (weak) |
Alkanes and saturated hydrocarbons. |
C=N |
1622.53 (sharp) |
Imines (Schiff bases) |
C=O |
1703.44 (moderate) |
Carbonyls |
Mn-N |
503.88(weak) |
-- |
Mn-O |
592.22(weak) |
-- |
Mn-Cl |
686.47(weak) |
-- |
Table 4: Mass spectra data of the ligand and Mn(II) complex
|
Compound |
m/z |
|
1-phenyl-2,3-dimethyl-4-(benzylamino)pyrazol-5-one |
291.34, 277.32, 263.29, 174.20, 105.02, 77.10, 56.11 |
|
Mn(II) 1-phenyl-2,3-dimethyl-4-(benzylamino)pyrazol-5-one |
416.18, 402.15, 388.12, 342.10, 187.21. 111.21, 77.10 |
This suggests that the ligand and complex are mildly polar. In the Infrared spectrum of the ligand (Table 2), a strong N-H vibration occurs in the region of 3697.14 cm-1 which is characteristics of compounds containing the amino group. In the IR spectrum of the ligand, the C=N vibrational frequency appeared at 1636.54 cm-1 while in the complex, the C=N stretching occurred at 1622.53 cm-1 (Table 3). This shift suggested the involvement of C=N in chelation. In the spectra of the ligand and metal complex, the C-H stretching of the aromatic and aliphatic systems appeared at 3045.71, 3194.28 and 2925.00 and 2931.42 cm-1 respectively. In the spectrum of the ligand, the Carbonyl (C=O) stretching appeared at 1716.47 cm-1showing that the compound contains a C=O functional group. The C=O band was shifted in the metal complex suggesting the coordination through this functionality. The appearance of weak bands at 503.88 cm-1, 592.22 cm-1 and 686.47 cm-1 in the spectrum of the complex, which are the bands for M-N, M-O and M-Cl respectively(Table 3). Thses vibrational frequecies are absent in the spectrum of the ligand. This suggests the formation of the manganese metal complex [3]. In the mass spectral data (Table 4), the compound shows a molecular ion at m/e 291 which is the molecular weight of the ligand minus an electron. The peak at m/e 77 is the hallmark of the benzyl cations. This shows the presence of benzene ring in the compound. Other peaks occur due to more complex fragmentations, the base peak at m/e 56 is as a result of loss of molecular ion 235. The fragmentation pattern of the ligand and complex has been illustrated in Scheme 1 and 2 respectively.
Therefore, on the basis of colour, melting point, solubility and spectral information, the synthesis of 1-phenyl-2,3-dimethyl-4-(benzylamino)pyrazol-5-one and its manganese derivative have been illustrated in Scheme 3 and 4 respectively.
REFERENCES:
1. Schiff HA Avaibable at http//www.wikkipedia.com/Schiffbaseligands, retrieved 14/08/16
2. Wasi N and Sing HB. Synthesis of metal complexes of anti-malaria and in-vitro evaluation of their activity against plasmodium falciparium. Inorg. Chim. Acta, 135; 1987: 133-137
3. Obaleye JA, Balogun EA and Adeyemi OG. Synthesis and in-vitro effects of some metal-drug complexes on malaria parasite. Bokemistry. 9 (1); 1999 :23-27
4. Nishinaga A, Yamada T, Fujisawa H and Ishizaki K, Catalysis by cobalt Schiff complexes in the oxygenation of alkenes on the mechanism of ketonization, J Mol Catal, 48; 1988: 249-64
5. Xi Z, Liu W, Cao G, Du W, Huang J, Cai K and Guo H, Catalytic oxidation of naphthol by metalloporphyrins, Cuihau Xuebao, 7; 1986: 357- 363
6. Chakraborty H, Paul N and Rahman M L, Catalytic activities of Schiff bases aquo complexes of Cu(II) in the hydrolysis of aminoacid esters, Trans Met Chem (Lond), 19 (1994)524-526.
7. Zhao YD, Pang DW, Zong Z, Cheng JK, Luo ZF, Feng CJ, Shen HY and Zhung XC, Electochemical studies of antitumor drugs, fundamental electrochemical characteristics of an iron(III) Schiff base complex and its interaction with DNA, Huaxe Xuebao, 56; 1988:178-183
8. Sreekala R, Yusuff K K and Mohammed K, Catalytic activity of mixed ligand five coordinate Co (II) complexes of a polymer bound Schiff base, Catal (Pap Natl Symp);1994: 507-510
9. Saxena CG and Shrivastava SV. Mn(II) ,Co(II) ,Ni(II) and Cu(II) complexes with p-toly-2-furylgloxalimine, J Ind Chem.Soc, 64; 1987: 685-686.
10. Dash B, Mahapatra PK, Panda D and Patnaik JM, Fungicidal activities of Schiff base derived from p-hydroxybenzaldehydes and their derivatives, J Indian Chem Soc, 61; 1984: 1061-1064.
11. Rao NR, Rao P V, Reddy G V and Ganorkar MC, Metal chelates of a physiologically active O:N:S tridentate Schiff base, Indian J Chem, 26A; 1987: 887-890.
12. Mishra P, Gupta P N and Shakya A K.. Synthessis of Schiff base of 3-amino-2-methyl-quinazolin-4(3H)-ones and their antimicrobial activity, J Indian Chem Soc, 68;1991: 539-541.
13. Dhakrey R, and Saxena G, Synthesis of Ni(II) complexes with Heterocylic aldehyde Schiff base, J Indian Chem Soc, 64; 1987: 685-686.
14. Mirzabdullaev AB, Aslanova DK, and Ershov FI. Prep.Induktory Interferona (Imst Biol Org Khim, Tashkent USSR) Chem Abstr, 99; 1984: 22191.
Received on 14.08.2016 Modified on 05.09.2016
Accepted on 13.09.2016 ©A&V Publications All right reserved
Research J. Science and Tech. 2016; 8(4):199-203.
DOI: 10.5958/2349-2988.2016.00029.2