SYNTHESIS, CHARACTERISATION AND ANTIMICROBIAL STUDIES OF MANGANESE(II), COBALT(II) AND CADMIUM(II) COMPLEXES CONTAINING OXINE AND 2 – PICOLINE

www.wjpr.net Vol 7, Issue 8, 2018. ₂₃₄

SYNTHESIS, CHARACTERISATION AND ANTIMICROBIAL

STUDIES OF MANGANESE(II), COBALT(II) AND CADMIUM(II)

COMPLEXES CONTAINING OXINE AND 2 – PICOLINE

R. Bharathiand Dr. M. Nagarathinam*

PG & Research Department of Chemistry, D.K. M. College for Women (Autonomous),

Vellore District, Tamil Nadu.

ABSTRACT

The complexes of transition metal ions Mn(II), Co(II) and Cd(II) with

oxine (8-hydroxy quinoline) and mixed ligand complexes with oxine

and 2-picoline have been synthesized. The structural, spectroscopic

and thermal properties have been studied on the basis of Infrared

spectra, TGA-DTA analysis, X-ray diffraction analysis and Molar

conductivity measurements. From the results obtained the following

general formula has been given for the complexes [M(oxine)2] and

[M(oxine)2(2-pic)2]. The oxine complexes exhibit antiseptic,

disinfectant and pesticide properties. So the metal complexes have

been tested against microorganisms using Agar well diffusion method

in order to assess their antimicrobial properties. The metal complexes

were screened for antibacterial activity against gram negative (Escherichia coli) and gram

positive bacteria (Bacillus subtilis) and the fungal activity against Aspergillus niger and

Penicillium chrysogenum.

KEYWORDS: Transition metal complexes, oxine, 2-picoline, Thermal Analysis,

Antimicrobial studies.

INTRODUCTION

Transition metals have varying utility and interesting chemistry. Coordination compounds are

important due to their role in biological and chemical systems in various ways. It has been

observed that metal complexes with appropriate ligands are chemically more significant and

specific than the metal ions in original. The mixed ligand complexes are biologically active

Volume 7, Issue 8, 234-242. Conference Article ISSN 2277–7105

*Corresponding Author

Dr. M. Nagarathinam

PG & Research Department of Chemistry, D.K. M. College for Women (Autonomous), Vellore District, Tamil Nadu. Article Received on 05 March 2018,

Revised on 25 March 2018, Accepted on 15 April 2018

www.wjpr.net Vol 7, Issue 8, 2018. ₂₃₅ against pathogenic microorganisms. Oxine is a monoprotic bidentate chelating agent. Oxine

and its metalloquinolates have attracted great interest because of their higher thermal

stability. Oxine is the only one, among seven isomeric monohydroxyl quinolines, capable of

forming complexes with divalent metal ions through chelation.[1] Most bioactivities of oxine

and its derivatives originate from their chelating ability.[2] 2-Picoline was the

first pyridine compound reported to be isolated in pure form. The complexation of metallic

elements with biologically inactive compounds renders them active and in case the compound

is already active, it makes them more active. In this paper, we have investigated the

preparation, properties and antimicrobial studies of some metal ions with oxine and

2-picoline.

MATERIALS AND METHODS

Reagents and solvents: All the chemicals (MnSO4, CoCO3 and CdSO4) and reagents used for

the preparation of complexes were commercial products (E Merck Ltd, India) and used

without further purification. DMF and DMSO were purchased from SRL chem.

Melting points of the synthesised compounds were measured using a melting point apparatus

obtained from Guna Enterprises, Chennai.

The IR spectra of the synthesised compounds were recorded using SHIMADZU

spectrophotometer in 4000 – 400 cm-1 range, using KBr pellet.

The X – ray diffraction patterns of the samples were tested by an X – ray scattering

SHIMADUZ XD – DI diffractometer using in filter Cu Kα radiation source (LAMDA =

0.154 nm ), set a scan rate = 10 / min, using a voltage of 40 Kv and a current of 30 Ma.

The complexes were tested in a SDT Q600 V8.0 build 95 instrument at Anna University,

Chennai. The temperature range was varied from room temperature to 800 °C with heating

rate of 20 °C/min in oxygen atmosphere.

The molar conductivities were measured with the conductivity meter of model DCM 900

using the freshly prepared solution of the complexes (10-3 M) in DMSO.

The effect of various metal complexes on the several bacterial strains and fungal strains were

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Preparation of metal complexes

Complexes of the type [M(oxine)2]

5 ml of DMF was added to an aqueous solution of the metal salt in 25 ml water. 5.8 g of

oxine was dissolved in 5 ml of DMF, 10 ml of ethanol and 20 ml of 2 M NaOH. Both the

solutions were mixed well and heated in a boiling water bath for about three and a half hour.

The precipitate formed was filtered using Whatmann no.1 filter paper in hot condition,

washed with ether and dried.

Complexes of the type [M(oxine)2(2-pic)2]

5.8 g of oxine was dissolved in 10 ml ethanol and 20 ml of 2 M NaOH. The mixture was

added to an aqueous solution of metal salt and stirred for half an hour using a magnetic

stirrer. A dense yellow precipitate was formed. To this solution 2 ml of 2-picoline was added

slowly and heated in a boiling water bath for half an hour. The precipitate formed was filtered

with Whatmann no.1 filter paper, washed with ether and dried.

RESULTS AND DISCUSSION

The metal complexes obtained were solid and coloured. They were insoluble in water and

soluble in solvents like dimethyl sulphoxide and dimethyl formamide.

Table 1: Analytical data of synthesized transition metal complexes.

Compound Molecular

Formula

Molecular

weight Colour

Melting Point (°C)

[Mn(oxine)2] MnC18H12O2N2 343.26 Yellow >350

[Co(oxine)2] CoC18H12O2N2 347.25 Dark Brown >340

[Cd(oxine)2] CdC18H12O2N2 400.72 Bright yellow >360

[Mn(oxine)2(2-pic)2] MnC30H26O4N2 529.52 Yellow >320

[Co(oxine)2(2-pic)2] CoC18H12O2N2 533.51 Brown >350

[Cd(oxine)2(2-pic)2] CdC18H12O2N2 586.98 Bright yellow >340

1. Infrared spectra

The IR spectra provide valuable information regarding the nature of the functional groups

attached to the metal ion. The transition metal complexes show characterized functional

bands such as C-O, C-N, O-H, and C=N groups. Formation of nitrogen and

metal-oxygen bonds were further confirmed by the presence of the stretching vibration of ʋ(M-N)

www.wjpr.net Vol 7, Issue 8, 2018. ₂₃₇ 500 1000 1500 2000 3000 4000 1/cm 40 60 80 100 %T 3 1 2 4 .6 8 3 0 6 6 .8 2 3 0 4 7 .5 3 3 0 2 6 .3 12 9 3 1 .8 0 2 8 5 4 .6 5 1 5 7 7 .7 7 1 5 0 0 .6

214

7 3 .6 2 1 4 3 3 .1 1 1 4 0 9 .9 6 1 3 8 1 .0 3 1 2 8 6 .5 2 1 2 7 4 .9 5 1 2 2 2 .8 7 1 2 0 5 .5

111

6 5 .0 0 1 1 3 8 .0 0 1 0 9 3 .6 4 8 1 7 .8 2 7 8 1 .1 7 7 4 0 .6 7 7 0 9 .8 0 6 3 6 .5 1 L1 500 1000 1500 2000 3000 4000 1/cm 40 60 80 100 %T 3 4 6 4 .1 5 3 4 1 4 .0

0 31

6 3 .2 6 3 0 5 9 .1 0 1 6 2 0 .2 1 1 5 7 3 .9 1 1 4 9 8 .6 9 1 4 6 5 .9 0 1 3 8 6 .8 2 1 3 2 3 .1 7 1 2 8 0 .7

3 12

3 8 .3 0 1 1 3 6 .0 7 1 1 0 7 .1 4 1 0 6 8 .5 6 1 0 3 3 .8

5 90

4 .6 1 8 5 6 .3 9 8 1 9 .7 5 7 9 0 .8 1 7 4 2 .5 9 6 4 4 .2 2 4 9 9 .5 6 B1

Wavenumber (cm-1) Wavenumber (cm-1)

Fig.1: IR Spectrum of oxine Fig. 2: IR spectrum of [Mn(oxine)2]

The IR spectrum of the ligand is shown in Fig.1. The spectrum shows the characteristic

frequencies of υ(O-H) at 3157.47 cm-1_{, υ(C-O) at 1278.81 cm}-1

and υ(C-N) at 1101.35 cm-1.

The IR spectrum of [Mn(oxine)2] exhibited a strong band at 1107.14 cm-1 and this could be

due to υ (C-O) where as other strong bands at 3464.15 cm-1

, 1323.17 cm-1, 819.75 cm-1,

742.59 cm-1 and 1165.00 cm-1 are due to υ(O-H), υ(C-N) respectively. Metal-nitrogen and

metal-oxygen bands are further confirmed by the presence of stretching vibration of υ(Mn-N)

and υ(Mn-O) are at 499.56 cm-1

and 644.22 cm-1 respectively.

The IR spectrum of 2-picoline and its complexes

500 1000 1500 2000 3000 4000 1/cm 45 60 75 90 %T 3 4 4 6 .7 9 3 1 3 4 .3 3 3 0 8 8 .0 3 3 0 1 4 .7

4 29

2 6 .0 1 2 8 5 6 .5 8 1 5 9 5 .1 3 1 5 7 7 .7 7 1 4 7 7 .4 7 1 4 0 0 .3 2 1 2 9 6 .1 6 1 2 3 8 .3 0 1 1 4 9 .5 7 1 0 5 1 .2

0 99

9 .1 3 7 4 8 .3 8 7 3 1 .0 2 6 3 0 .7 2 5 4 7 .7 8 4 7 0 .6 3 4 0 1 .1 9 L2 500 1000 1500 2000 3000 4000 1/cm 0 25 50 75 100 %T 3 3 8 3 .1 4 3 1 6 1 .3 3 3 1 4 3 .9 7 3 0 6 4 .8 9 2 9 2 7 .9 4 2 8 5 2 .7 2 2 3 1 4 .5 8 1 6 3 5 .6 4 1 5 7 5 .8 4 1 4 9 8 .6 9 1 4 6 5 .9 0 1 3 8 8 .7 5 1 3 7 3 .3 2 1 3 2 5 .1 0 1 2 8 2 .6 6 1 1 5 3 .4 3 1 1 0 9 .0 7 1 0 6 8 .5 6 8 2 1 .6 8 7 4 4 .5 2 B5

Wavenumber (cm-1) Wavenumber (cm-1)

Fig. 3: IR Spectrum of 2-picoline Fig. 4: IR spectrum of [Co(oxine)2(2-pic)2]

The band appeared at1587.42 cm-1 in Fig.3 indicate the presence of C=N linkage. Bands

www.wjpr.net Vol 7, Issue 8, 2018. ₂₃₈ spectrum of the sample is shown in Fig.4. The spectra exhibited strong bands at 1109.7 cm-1

and 1282.66 cm-1 and this could be due to υ(C-O). Vibrations due to aromatic ring appear at

3064.89 cm-1, 1575.84 cm-1 and 1465.90 cm-1. Metal-nitrogen and metal-oxygen bands were

further confirmed by the presence of stretching vibration of υ(Co-N) and υ(Co-O) at 503.14

cm-1 and 642.30 cm-1 respectively.[4]

2. X-Ray Diffraction Analysis

XRD analysis is used to determine the percentage of crystallinity present in the material. The

crystal size has been calculated using Debye-Scherrer’s equation.[5]

Table 2:X-Ray Diffraction of the Complexes.

Complexes FWHM (deg) 2θ (deg) Crystal size (nm)

[Mn(oxine)2] 0.3053 8.654 26.0987

[Co(oxine)2] 0.4594 8.713 17.3449

[Cd(oxine)2] 0.2593 8.529 30.7261

Mn(oxine)2(2-pic)2] 0.3748 8.653 21.2591

[Co(oxine)2(2-pic)2] 0.3354 23.471 24.1943

[Cd(oxine)2(2-pic)2] 0.2959 22.558 27.3796

Fig. 5: X-Ray Diffraction of [Co(oxine)2] Fig. 6: X-Ray Diffraction of [Cd(oxine)2(2-pic)2]

3. Thermal Data

The thermal properties for metal oxine complexes and metal oxine and 2-picoline complexes

have been investigated. All the stages of decomposition follow one after the other without

any stable compound in between.[6] The exothermic peaks are due to oxidative degradation of

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14.38% (0.6489mg)

48.82°C

70.71°C 63.28°C

7.833% (0.3534mg) 143.66°C

170.34°C 158.84°C

11.77% (0.5311mg) 439.87°C

465.93°C 455.44°C

335.54°C368.90°C 5.920% (0.2671mg) 499.24°C

524.20°C

514.95°C 602.39°C

741.23°C

34.47% (1.555mg)

592.24°C

676.26°C Residue: 11.32% (0.5106mg)

0.0 0.1 0.2 0.3 0.4 0.5

Deriv. Weight

(%/°

C)

0 10 20 30 40 50 60 70 80 90 100 110 120

Weight (%)

0 100 200 300 400 500 600 700 800

Temperature (°C)

Sample: Govin B2 Jan 27 2014 Size: 4.5120 mg Method: Test Comment: Test

DSC-TGA File: C:...\govin B2 Jan 27 2012.001Operator: TA Run Date: 2014-01-27 08:58 Instrument: SDT Q600 V8.0 Build 95

Universal V4.1D TA Instruments

10.90% (0.2579mg) 119.14°C

138.11°C 130.89°C

28.29% (0.6694mg)

400.40°C

462.64°C 444.63°C

17.67% (0.4182mg) 677.96°C

740.23°C 713.28°C

Residue: 30.10% (0.7123mg)

258.01°C

0.0 0.2 0.4 0.6

Deriv. Weight

(%/°

C)

10 20 30 40 50 60 70 80 90 100 110 120

Weight (%)

0 100 200 300 400 500 600 700 800

Temperature (°C)

Sample: Govin B4 Jan 23 2014 Size: 2.3660 mg Method: Test Comment: Test

DSC-TGA File: C:...\Govin B4 Jan 23 2012.001Operator: TA Run Date: 2014-01-23 08:55 Instrument: SDT Q600 V8.0 Build 95

Universal V4.1D TA Instruments

Fig. 5: Thermal data of [Co(oxine)2] Fig. 5: Thermal data of [Mn(oxine)2(2-pic)2]

4. Molar Conductance

The synthesized transition metal complexes were dissolved in DMSO and the molar

conductivities of 10-3 M solution at 25±2 °C were measured. The molar conductivity values

of the complexes are given in table-3.

Table 3: Molar Conductance data of the complexes.

Compound Specific Conductance

ohm-1 cm2

Molar Conductance

ohm-1 cm-2 mol-1

[Mn(oxine)2] 0.04 × 10-6 0.04

[Co(oxine)2] 0.04 × 10-6 0.04

[Cd(oxine)2] 0.04 × 10-6 0.04

[Mn(oxine)2(2-pic)2] 0.04 × 10-6 0.04

[Co(oxine)2(2-pic)2] 0.04 × 10-6 0.04

[Cd(oxine)2(2-pic)2] 0.04 × 10-6 0.04

The measured molar conductance of all synthesized transition metal complexes were of 0.04

ohm-1 cm-2mol-1. The lower molar conductivity values showed the non-electrolytic nature of

the complexes.[7]

5. Antimicrobial Studies

Bioeffiency of the transition metal complexes were tested against bacteria such as Bacillus

species, E. coli and fungi like, Aspergillus niger and Pencillium chrysogenum using well

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Antibacterial Activity of Metal Complexes

The antibacterial activities of complexes were studied using Agar well diffusion method. The

bacterial species used in the screening were Bacillus species (gram positive) and E. coli

(gram negative).

The diameter of zone of inhibition was calculated in millimeters. The well diameter was

detected from the zone diameter to get the actual zone of inhibition and the values have been

tabulated. The results indicate that most of the test compounds exhibit very good antibacterial

and antifungal activity.[8]

IMAGES OF ANTIBACTERIAL ACTIVITY

ESCHERICHIA COLI BACILLUS SPECIES

[M(oxine)2] [M(oxine)2(2-pic)2] [M(oxine)2] [M(oxine)2(2-pic)2]

Table 4: Antifungal Activity of Metal Complexes.

Complexes Concentration

Zone of inhibition( in diameter)

E. coli Bacillus

species

Ampicilln (standard)

[Mn(oxine)2] 1 mg/ml 13 17 16

[Co(oxine)2] 1 mg/ml 15 14 16

[Cd(oxine)2] 1 mg/ml 13 15 16

[Mn(oxine)2(2-pic)2] 1 mg/ml 19 18 16

[Co(oxine)2(2-pic)2] 1 mg/ml 10 14 16

[Cd(oxine)2(2-pic)2] 1 mg/ml 12 24 16

Antifungal Activity of Metal Complexes

The Antifungal activity of standard fungicide (polymyxin) and complexes were tested for

their effects on the growth of microbial cultures and studied for their interaction with

Aspergillus niger and Penicillium chrysogenum. The zone of inhibition measured for standard

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IMAGES OF ANTIFUNGAL ACTIVITY

ASPERGILLUS NIGER PENICILLIUM CHRYSOGENUM

[M(oxine)2] [M(oxine)2(2-pic)2] [M(oxine)2] [M(oxine)2(2-pic)2]

Table 5: Antifungal Activity of the Metal Complexes.

Complexes Concentration

Zone of inhibition(in diameter)

Aspergillusniger Penicilliumchrysogenum polymyxin

(standard)

[Mn(oxine)2] 1 mg/ml 12 31 11

[Co(oxine)2] 1 mg/ml - 16 11

[Cd(oxine)2] 1 mg/ml 15 24 11

[Mn(oxine)2(2-pic)2] 1 mg/ml 5 27 11

[Co(oxine)2(2-pic)2] 1 mg/ml 5 20 11

[Cd(oxine)2(2-pic)2] 1 mg/ml 16 23 11

The results are corroborated with the findings of other researchers (3). The proposed structure

of the complexes is given below.

where M = Mn2+, Co2+ and Cd2+.

CONCLUSIONS

The complexes of Mn(II), Co(II) and Cd(II) were synthesised using oxine as ligand and also

with mixed ligands oxine and 2-picoline. The complexes were coloured and they are

insoluble in water and soluble in DMF and DMSO. The Complexes were characterized by

www.wjpr.net Vol 7, Issue 8, 2018. ₂₄₂ The metal oxine complexes and metal oxine, 2-picoline complexes exhibit good activity

aganist bacterial strains Gram positive (Bacillus species) and Gram negative(Escherichia

coli), fungal strains such as (Aspergillus niger, Penicillium chrysogenum) compared with the

standard drugs. The increase in antimicrobial activity may be due to metal chelation.

Manganese and cadmium chelates are highly active due to the combined effect of Mn(II) and

Cd(II) and its functional groups present in the ligands.

The lower conductivity values indicated the non-electrolytic nature of the complexes. The

melting points of metal chelates are higher which suggests their thermal stability. The thermal

degradation steps were identified and are mainly due to the direct decomposition of oxine and

2-picoline from metal complex leaving the corresponding metal oxide. The exothermic peaks

are due to oxidative degradation of the complexes. The XRD of the complexes were studied.

The complexes [Co(oxine)2(2-pic)2] and [Cd(oxine)2(2-pic)2] are found to be crystalline and

the other complexes are found to be semicrystalline. The structure assignment cannot be

considered final in the absence of X-ray crystal studies.

REFERENCES

1. Abeer Abdul Jaleel Ibrahim. Synthesis and Characterization of Mixed Ligand Complexes

of Some Metal Chlorides with 8-Hydroxyquinoline and Amino Acid (L-Lysine). Diyala

Journal for Pure Sciences, 2011; 7: No. 4.

2. Patel KB, Kharadi GJ and Nimavat KS. Synthesis and Description of Transition Metal

Complexes ond Antimicrobial Studies. www.jocpr.com, 2012; 5: 2422- 2428.

3. Alia Salman Kindeel, Ibtisam Jameel Dawood, Manhel Remon Aziz. J. Baghdad for Sci,

2013; 10: 396 – 403.

4. Gopalan R, Subramanian PS, Rengarajan K. Elements of Analytical Chemistry.

5. Mishra A. J. Phy. Conference Series, 2012; 012010, 365.

6. Mackenzie RC. Thermochim. Acta, 1979; 28: 1.

7. Robert K Bogges. J. Chem. Edu, 1975; 52: 649-665.