Synthesis, Characterization and Antibacterial Activity of Complexes of Transition Metal Ions with Schiff Base Derived From Salicylaldehyde and p-Methoxy Aniline

 

S. Shanthi* and J. Stella

The Standard Fireworks Rajaratnam College for Women, Sivakasi-626123.

*Corresponding Author E-mail: shansal.8805@yahoo.com

ABSTRACT:

 

 

INTRODUCTION:

Coordination compounds exhibit different characteristic properties which depends on the metal ion to which they are bound. The nature of the metal as well as the type of ligand^1-2 etc. These metal complexes have found extensive application in various fields of human interest. p-methoxy aniline and salicylaldehyde compounds are capable to form complex with transition metal ions in the form of Schiff base. The complex of Fe(II), Hg(II), Zn(II), Co(II), and Cu(II). Schiff base have been synthesized. The M(II) Schiff base complex also have been prepared from Salicylaldehyde and O-aminobenzoic acid. Metal selected for the preparation of complexes was Cu, Ni, Fe and Zn. They showed that the Ni complex of Schiff base showed best antibacterial activity^3-5.

 

Mixed ligand complexes of Ni,Cu,and Zn(II) with 5-chloro(or bromo) salicylaldehyde and hydroxyaromatic aldehydes or ketones have been synthesized and characterized these complexes by conductance, TLC, thermalanalysis, magnetic moments, IR, ¹H NMR and electronic spectral studies^. Synthesis, characterization and antimicrobial activity^6-7 of cobalt(II) and nickel(II) complexes of acetyl derivatives of urea and thiourea metal complexes are monodentate and bind to the central metal atom through the oxygen and sulphur donor atoms^8-10. Homogeneous catalytic hydrogenation of organic compounds using orthometallated schiffbase complexes of palladium(II) have been carried out. Catalytic activites of various dinuclear orthopalladated complexes with differently C, N- substituted Schiff base ligand^11-12 also have been carried. Cobalt complex of a Schiff base(salicylaldehyde with diamine) has excellent light resistance and storage ability and does not degrade even in acidic gases (CO₂). Effect of N-salicyaldehyde amino glucose Schiff base complex with Cu(II) and Zn(II) inhibit synthesis of O₂ markedly inhibitory¹³ effect of Cu was more than that of Zn. Tetradentate Schiff base complexes with Mn(II), Ni(II), Cu(II), and Zn(II) show miscellaneous effect on membrane in amylase productions. Some Schiff bases^14-15 possess simple harmonic generation activity. As all these work suggest that Schiff base complexes have a large number of roles as drugs, catalysts etc.In the present work,complexes of Cu(II), Co(II), Hg(II), Zn(II) and Fe(II) with Schiff base have been synthesized,characterized the chemical structure by Elemental analysis,UV,IR and NMR spectral analysis and to study the antibacterial activity of prepared Schiff base transition metal complexes derived from salicylaldehyde and p- methoxy aniline.

 

MATERIALS AND METHODS:

Metal salts like Copper sulphate, Cobalt chloride, Zinc oxide, Mercury chloride and Ferrous sulphate were purchased from E.merck limited. salicylaldehyde and p- methoxy aniline were purchased from Loba chemie limited. The antibacterial activity of synthesized Schiff base metal complexes was determined by Disc Diffusion Method.

 

EXPERIMENTAL:

For the preparation of Schiff base 20ml of ethanolic solution of salicylaldehyde (1.22 gram; 0.01 M) and the same volume of ethanolic solution of p- methoxy aniline (1.23 gram; 0.01 M) were mixed. The mixture was stirred for 4-5 hours. This solution was evaporated and dried in vaccum to remove the solvent. The product after filtration was washed several times with ethanol and recrystallized from hot ethanol and dried. The reaction can be represented as follows

 

The product Schiff base formed in this way was used as a ligand (L) for the preparation of transition metal complexes.

For each metal complex, different metal salt solution were prepared. The compounds used for the synthesis of the Cu, Co, Fe, Hg and Zn complexes were copper sulphate, cobalt chloride,ferrous sulphate,mercury chloride and zinc oxide respectively.A mixture of the Schiff base under investigation (0.01M; 2.27 gram) in 20 ml of ethanol and the same volume of aqueous solution of M(II) salt (0.01M; ) refluxed for 4-5 hours in a water bath. A coloured precipitate was obtained. The precipitate was filtered and washed several times with ethanol to remove excess metal ions. The precipitate was dried and stored in a desiccators over anhydrous CaCl₂ under vaccum.

 

RESULTS AND DISCUSSIONS:

Metal ions play a vital role in a number of different biological process through co-enzymatic system. The interaction of these ion with biologically active ligand, for instance in drugs, is subject of great interest. Some biologically active compounds act via chelation, but for most of them little is known about how metal coordination influences their activity. The colour and melting point of the Schiff base transition metal complexes are given in the Table 1.

 

Table 1: Colour and Melting point of Schiff base ligand their Metal complexes.

Compound	% of Yield	colour	Melting point (0C)
Ligand Copper complex Iron complex Zinc complex Mercury complex Cobalt  complex	95 90 92 90 95 91	Light green Brown Dark brown Yellowish brown Orange pink	194 206 218 230 237 244

 

The percentage of C, H and N obtained from the elemental analyzer are compared with the percentages calculated using the assumed structure of 1:1 (M:L) complex. The proximity of the values suggests that the ligand forms 1:1 complex with the metal ions. The results are tabulated in Table 2.

 

Table 2: Analytical data of (CHN) of divalent Cu,Co,Zn,Fe and Hg Schiff base complexes

S.NO.	Complexes	Elements	C %	H%	N%
1.	Copper	Calculated Found	11.54 11.57	83.14 83.16	0.96 0.98
2.	Ferrous	Calculated Found	11.60 11.61	83.58 83.61	0.97 0.99
3.	Zinc	Calculated Found	11.52 11.64	83.03 82.99	0.96 0.97
4.	Mercury	Calculated Found	10.55 10.56	75.99 76.09	0.88 0.93
5.	Cobalt	Calculated Found	11.58 11.59                             10.56	83.40 83.49	0.46 0.52

 

From the above FT-IR spectral studies,we observed that the schiff base shows at 3392 cm^-1 which is due to the intramolecular bonding involving hydrogen of the phenolic group and nitrogen atom of amine group .The band arising due to –OH stretching of the ligand at 3336 cm^-1 is shifted in all the metal complxes showing that the oxygen is involved in bonding with metal ion. The V_C=N band appears at 1500-1610  cm^-1  in the metal complexes as compared to that at 1718 cm^-1  in schiff base. This decrease indicate the coordination of nitrogen of azomethine group with the metal ion. The strong ligand band at 1280 cm^-1  appears at 1285-1360 cm^-1 in the complexes. This band is characteristic of v_C-O in the ligand. This shift arises due to the formation of M-O bond. From this we confirm that both the oxygen and nitrogen atom in the ligand are coordinated toi metal ion. The results of the IR spectra of the complexes are collectively given in Table 3.

 

Table 3. Analytical data of metal complexes in IR KBR discs.

Complexes	Free -OH	ν-OH	νC=N	νM-N	νM-O
Cu(II) Complex	3291	1280	1611	417	527
Fe(II) Complex	3159	1341	1508	657	512
Zn (II) Complex	3356	1304	1645	478	572
Hg(II)  Complex	3329	1281	1701	457	563
Co (II) Complex	3401	1283	1618	459	544
Ligand	3336	1284	1718	--	--

 

Comparison of the UV spectra of the ligand with the complexes reveal that, the bond at 400nm in the ligand corresponding to the INCT bond, is shift to higher region of wave length in all the complexes. Thus confirms that the chromophoric group of the ligand is involved in bonding with the metal ions in all the complexes. Comparing the spectral data of metal complex and ligand,we can say that a shift the signal of azomethine proton is due to the bonding with the metal ion. The analysis of antibiotic activity of the complexes against the different types of bacterias, Pseudomonas sp, Klebsiella sp, Bacillus sp, Staphylococcus sp, E.coli, Micrococcus, Proteus sp,Pseudomonas fluorescence and Salomonella enterica. The results are tabulated in Table 4. Comparsion of antibacterial activity of the different metal complexes against various bacteria can be obtained from the graph given in Fig 1.From this analysis, we find that some of the metal complexes are possessing antibacterial activity.

From the above spectral studies, we can propose the following structure for the transition metal complexes.

 

From the above results, it can be concluded that we have observed that higher antimicrobial activity of 8mm in mercury complex against bacillus sp. So, these transition metal complexes can be used in medicinal field.

 

SUMMARY:

The  FT-IR spectra of Schiff base and their metal complexes were obtained in the range of 400-4000cm^-1.The electronic absorption spectra of Schiff base and metal complexes in the range of 200nm-800nm.The 300 MHz ¹H-NMR spectra of the Schiff base  and Zinc complex were recorded.

 

FIG 1:COMPARSION OF ANTIBACTERIAL ACTIVITY OF FIVE DIFFERENT  SCHIFF BASE METAL COMPLEXES

 

 

Table  4 : Antimicrobial activity of Schiff base transition metal complexes

Microorganisms	Zone of inhibition (in mm)
	Copper complex	Ferrous complex	Zinc complex	Mercury complex	Copper complex
Pseudomonas sp	-- -	2	---	7	---
Klebsiella sp	---	---	---	---	---
Bacillus sp	---	---	---	8	---
Staphylococcus sp	---	1	4	---	1
E.coli	---	---	---	---	---
Micrococcus	---	---	---	6	---
Proteus sp	---	--	---	---	---
Pseudomonas fluorescence	---	4	4	---	---
Salomonella enterica	---	---	----	---	---

 

 

Schiff base transition metal complexes plays an important role in medical field. So, we have prepared the transition metal complexes of the metal ions Fe(II), Cu(II), Hg(II),Co(II) and Zn(II) using the Schiff base derived from salicylaldehyde and p- methoxy aniline. The Schiff base was first prepared by condensing salicylaldehyde and p- methoxy aniline using this as the ligand, the Schiff base metal complexes we prepared with Fe(II), Cu(II), Hg(II),Co(II) and Zn(II) as metal ions. The structure of the ligand was confirmed by IR, UV-Visible and ¹H- NMR spectra. The shift in the spectral bands of the ligands up on complexation was also confirmed by taking the spectra of complexes using this we have proposed the possible common structure for the complex. To access the antibacterial ability of the metal complexes, we determined from the anti bacterial activity of Schiff base transition metal complexes against the bacteria Pseudomonas sp, Klebsiella sp, Bacillus sp, Staphylococcus sp, E.coli, Micrococcus,Proteus sp, Pseudomonasfluorescence and Salomonella enterica by finding out their zone of inhibition using disc diffusion method. We have observed that higher antimicrobial activity of 8mm in mercury complex against bacillus sp. So, these transition metal complexes can be used in medicinal field.

 

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Received on 23.07.2010    Modified on 02.08.2010

Accepted on 11.08.2010    © AJRC All right reserved