Synthesis and Characterization of Ni(II), Co(II), Cr(III) and Mn(II) complexes of Schiff Base derived from 4-Benzoyl-3-methyl-1-phenylpyrazol-5-one and 4,4’-Oxydianiline

Aarushi Jain¹, Dr. Sheela Valecha²*

¹Department of Chemistry, Kishinchand Chellaram College, Church Gate, Mumbai-20

²Associate Professor, Department of Chemistry, Kishinchand Chellaram College, Church Gate, Mumbai-20

*Corresponding Author E-mail:

ABSTRACT:

Schiff base derived from condensation of (4-Benzoyl-3-methyl-1-phenylpyrazol-5-one and 4,4’-Oxydianiline ). The Schiff base ligand then complexed with Ni(II),Co(II),Cr(III),Mn(II) metal salts. The resultant complexes were characterized by Elemental analysis, IR Spectroscopy, UV-Vis. Spectroscopy, Thermal Stability.

KEYWORDS:

INTRODUCTION:

Schiff Bases are the compounds having (>C=N-) Linkage. The transition metal complexes have a Variety of applications in chemical world.The complexes have many anti-microbial activity over some gram positive or gram negative bacteria also(Bacillus subtilis, Staphylococcus aureus, Salmonella typhi, Eschirichia coli). Schiff base and their metal complexes have huge application in food¹ industry and dyes industry, agriculture, analytical chemistry etc. They play a vital role in metabolic and toxicological functions in biological system^2,3. The present paper describes synthesis, characterization and bacterial studies of Ni(II), Co(II), Cr(III), Mn(II) complexes of Schiff Base derived from 4-benzoyl-3-methyl-1-phenylpyrazol-5-one and 4,4’-Oxydianiline .

EXPERIMENTAL:

All the chemicals used for synthesis were of AR grade. Solvents were double distilled before use. Classical method was used for the preparation of Schiff’s Bases i.e. by refluxing amines like p-anisidine and 4,4’-Oxydianiline with 4-Benzoyl-3-methyl-1-phenylpyrazol-5-one.

Preparation of 4-Benzoyl-3-methyl-1-phenylpyarazol-5-one

It is a benzoyl derivative of 3-Methyl-1-phenylpyrazol-5-one (C₁₀H₁₀N₂O).

Preparation of 3-Methyl-1-phenylpyrazol-5-one:-

In an evaporating dish 50gm (49mL,0.384 mol) of redistilled Ethyl aceto acetate and 40gm (36.5mL,0.37 mol) of Phenyl hydrazine were mixed together. The mixture is heated on a boiling water bath/sand bath for about 2 hrs. With constant stirring. The heavy reddish syrupy liquid obtained was allowed to cool and about 100mL of Ether as added with constant stirring (vigorously) when yellowish solid was obtained within 15mins. This solid is washed with ether to remove colour impurities. It was recrystallized from hot water.

For Benzoyl Derivative:-

The solid obtained (3-Methyl-1-phenylpyrazol-5-one) was taken in a round bottom flask (5.22gm,0.029 mol) and Calcium hydroxide(3.87gm,0.05 mol) and 1,4-Dioxane (55mL) were added and was stirred at 70 ̊C on a magnetic stirrer. To this hot mixture Benzoyl chloride (3.32 mL,0.029 mol) was added drop wise with constant stirring. After completion of addition of benzoyl chloride the mixture was kept at 70⁰C for 30mins. It was then refluxed for 3hrs. at 110-115⁰C. The resulting mixture was added to a beaker containing crushed ice and HCl (5.4mL). The solid obtained was 4-Benzoyl-3-methyl-1-phenylpyrazol-5-one and was filtered, washed several times with water and dried at room temperature and recrystallized from 50% alcohol.

Preparation of Schiff’s base

1:2 mol of 4,4’-Oxydianiline and Benzoyl derivative respectively were mixed in a R.B.F with a few drops of HCl. Absolute alcohol was used as a solvent. Then refluxed this mixture on a boiling water bath for about 24hrs. The reaction was monitored by TLC. Light green Schiff Base was produced when the mixture was poured in crushed ice.

Preparation of metal salts

Equimolar conc. Were taken of both the ligand and salt. The ligand was dissolved in minimum quantity of alcohol and the salt dissolved in min. quantity of water. Both the solutions were mixed with constant stirring. The pH was adjusted with 0.1M NaOH (pH: 7.5-8.5). A coloured complex was formed , it was kept on boiling water bath on magnetic stirrer for 1hr.

RESULTS AND DISCUSSIONS:

As per the analytical data, the Schiff base derived from 4-Benzoyl-3-methyl-1-phenylpyrazol-5-one and 4,4’-Oxydianiline forms ML type of metal complexes. From TGA analysis it is shown there is a weight loss in the range of upto 200⁰C corresponds to two water molecules. All these complexes are quite stable and coloured. The complexes are soluble in organic (non-polar) solvents.

In the Infra-red spectrum of the Schiff base a sharp peak is observed at 1629cm^-1 due to the presence of azomethine group (>C=N-). In the metal complexes this band is slightly shifted in the range of 1630-1697cm^-1 which confirms there is a coordination through nitrogen atom of the azomethine group. Two more sharper bands are observed in all the metal complexes in the range of 690-696cm^-1 and 755-761cm^-1 which is assigned to the bending frequency of Metal-Oxygen and Metal-Nitrogen bond respectively. In all the metal complexes there is a broad band in the range of 3300-3617 cm^-1 which have significantly different characteristic from the band which is arrived due to ν_O-H stretching vibration which is present in the Schiff base at 3392cm^-1. This indicates the involvement of oxygen in coordination to metal ion⁴. There is also a medium intensity band band observed in the range of 827-845cm^-1 assigned to δ_H2O which is present in all the metal complexes. All these values are given in Table no. 1.

Elemental Analysis confirms the molecular formulae of the Schiff base and its metal complexes which were predicted and is shown in Table no. 2.

In the electronic spectrum of the Schiff base in alcohol, an intense absorption is observed at 180nm in the Ultraviolet region which can be assigned to n→σ^* transition which is mainly the intralig and transition. In the spectrum of complexes this absorption showed some shift towards the longer wavelength due to the complex formation.

The green coloured Ni(II) complex showed bands at 12,820cm^-1 (780 nm), 14,705cm^-1 (680nm) and 16,666cm^-1 (600nm) in the visible region due to the transition⁵,

³A_2g(F)→³T_2g(F) ν₁

³A_2g(F)→³T_1g(F) ν₂

³A_2g(F)→³T_1g(P) ν₃

respectively which indicates an octahedral environment for Ni(II) ion.

The brown coloured Co(II) complex showed two d-d transition bands at 17,574cm^-1 (569nm) and 13,458cm^-1 (743nm) which corresponds to the following transitions:

⁴T_1g(F)→⁴T_1g(P) ν₁

⁴T_1g(F)→⁴A_2g(F) ν₂

⁴T_1g(F)→⁴T_2g(F) ν₃

The ν₂ band is not observed here. It has been frequently found in high spin octahedral complexes that ν₃ band involving one electron transfer is stronger than ν₂ band involving two electron transfer. The ν₂ band appears as a shoulder or often does not appear at all.⁶

Mn(II) complex showed absorption at 18,181cm^-1 (550nm) and is assigned to the transition as

⁶A_1g(S)→⁴T_2g(G)

which corresponds to octahedral geometry around Mn(II) ion.

The antimicrobial activity of the Schiff base and all the metal complexes were tested using well established Ditch Plate method⁷. The Schiff base have inhibitory property against only on gram positive bacteria viz. Bacillus subtilis and Staphylococcus aureus.

The Ni(II) and Cr(III) complex showed very low activity against only on S. aureus. The Mn(II) showed some variability against S. aureus and some gram negative bacteria-Escherichia coli and Salmonella typhi (SPB). The most active Co(II) complex inhibited all the bacteria. It is a broad spectrum complex.

Table1: IR spectra of Schiff Base and its Metal complexes

Samples	νOH	νC=N (azo)	νC=N (pyro)	νC-O (phenolic)	νC-H (arom)	νC-H (aliph.)	δOH	δH2O	δM-N	δM-O	νH2O
Schiff Base [(SB)Ni.2H2O] [(SB)Co.2H2O] [(SB)Cr.2H2O] [(SB)Mn.2H2O]	3392 - - - -	1629 1695 1630 1696 1697	1597 1617 1500 1619 1615	1499 1378 1440 1374 1377	2933 3025 3000 2855 2890	2880 2361 2305 2361 2360	1221 1216 1210 1220 1215	- 833 845 827 834	- 761 755 760 760	- 696 690 693 694	3617 3380 3564 3300

Table2:Elemental Analysis of Ligand and Metal Complexes

Samples	Percentage of elements Calculated (found)
	Molecular weight	%C	%H	%N	%O	%M	Colour	Melting point
Schiff Base	720	73.66 (74)	5.0 (4.5)	10.6 (10.7)	5.8 (5.9)		Green
[(SB)Ni.2H₂O]	812.6	67.93 (67.93)	4.67 (5.04)	10.33 (10.26)	9.84 (10.05)	7.21 (7.25)	Dark green	201.3
[(SB)Co.2H₂O]	810.9	68.07 (68.06)	4.68 (5.05)	10.36 (10.37)	9.86 (10.17)	7.02 (7.12)	Green	175
[(SB)Cr.2H₂O]	805.9	68.49 (68.45)	4.72 (4.78)	10.42 (10.43)	9.93 (10.04)	6.44 (6.47)	Dark Brown	185
[(SB)Mn.2H₂O]	808.9	68.24 (67.21)	4.69 (4.66)	10.38 (10.40)	9.88 (10.20)	6.78 (6.80)	Mud Brown	150.7

Table-3: Antibacterial activity of Schiff Bases of Benzoyl derivative and 4,4’-Oxydianiline

Compounds	Test Organisms
	B.subtilis	S.aureus	E.coli	SPB
Benzoyl derivative	_	_	+	+
Schiff Base	_	_	+	+
Metal Complexes Of Schiff Base
Ni(II)	+	-	+	+
Co(II)	-	-	-	-
Cr(III)	+	-	+	+
Mn(II)	+	-	-	-

Note: “+” indicates growth of bacteria and “-” indicates no growth

Table 3: Inhibition of certain bacteria against ligands and complexes of concentration 0.01g/ml.

Samples	Diameter of inhibition zone(in mm)
	Bacillus subtilis	S.aureus
BMPHPZ	8	20
Schiff Base	13	15
Ni(II)	10	9
Co(II)	13	10
Cr(III)	10	0
Mn(II)	8	10

From the above studies the following structure was proposed for Schiff base and its Metal complexes respectively.

M= Ni(II), Co(II), Cr(III) and Mn(II)

Note: For Cr(III) complex it is a cationic structure which is forming a bond with chloride ion.

REFERENCES:

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4. Sheela Valecha, University of Mumbai, Thesis, 149 (2008).

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Received on 07.10.2015 Modified on 16.10.2015

Accepted on 25.10.2015 © AJRC All right reserved

Asian J. Research Chem. 8(10): October 2015; Page 651-654

DOI: 10.5958/0974-4150.2015.00104.2