Synthesis and Thermal Studies of Chalcone Ligand Complexes of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) with 4-Dimethylamino benzaldehyde and Dehydroacetic Acid

Synthesis and Thermal Studies of Chalcone Ligand Complexes of Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) with 4-Dimethylamino benzaldehyde and Dehydroacetic Acid

Dr. Balaji H. Jawale

Department of Chemistry,

B.S.S. Arts Science & Commerce College, Makni Tq. Lohara Dist. Osmanabad Pin. 413604

Abstract:- Some novel transition metal [Cu(II), Ni(II), Co(II), Mn(II) and Fe(III)] complexes of substituted Dehydroacetic acid Chalcone have been prepared and characterized by physical, spectral and analytical data. The synthesized Chalcone act as bidentate for the complexation reaction with Cu(II), Ni(II), Co(II), Mn(II) and Fe(III) ions. In order to evaluate the effect of metal ions upon chelation, the Chalcone and their complexes have been screened for antibacterial activity against the strains such as Shigella Boydii, Bacillus Cereus, Bacillus Megaterium and Escherichia Coli and antifungal activity against the strains such as Saccharomyces Cerevisiae, Penicillium Natatum and Aspergillus Oryzae. The complexed Chalcone have shown to be more antimicrobial against species as compared to uncomplexed Chalcone.

Keywords :- Dehydroacetic acid, metal complexes, chalcone, antimicrobial activity,

INTRODUCTION

The field of coordination chemistry is one of the most scholarly, attractive and experimentally demanding frontiers in modern chemical sciences. It has grown in a half century from a readily defined and limited area into the most active research field of inorganic chemistry. Coordination compounds brought about a synthetic revolution in inorganic chemistry which leads to new products of equally novel applications in wide range of areas such as pharmaceuticals, fungicidal, bactericidal, herbicidal & insecticidal activities. Complexation reactions are used in qualitative as well as quantitative analysis of metals. There are some extremely sensitive and selective organic reagents for the determination of metal ions. Coordination chemistry, by its very nature, deals with metals and ligands. Metal coordination occurs when lone pair electrons from a ligand are donated to an empty orbital in a metal ion. There are many broad classes of ligands such as classical, organo-metallic, cluster and bioinorganic. A classical ligand, also called a Werner complex after coordination chemistrys founder Alfred Werner, is a ligand that binds through the lone pairs of the main group atom of the ligand. Many metal-ligand interactions seen in nature are classical ligands. Metals are known to have first choice for certain ligands and for certain geometries. Classical

cases are the so-called chalcone couplings; in other cases rather unique ligands can be formed only when the metal is present.

Chalcones are the condensation product of acetophenone with aromatic aldehydes in the presence of strong base. Chalcones and their metal complexes play a prominent role in modern coordination chemistry. These compounds possessing novel structural features, interesting spectral and magnetic properties, have been the subject of intensive research due to their importance in medical, agriculture, analytical, biological and industrial fields, In recent years a number of -dicarbonyl compounds in which the carbonyl function(s) bonded to olefinic linkage(s) have gained considerable importance1-2 mainly because of the fact that such compounds are structurally related to the active chemical constituents of several traditional medicinal plants. For instant, curcuminoids, the active chemical component present in Indian medicinal plant turmeric (curcuma longa, linn, zingiberacea family) contain three -dicarbonyl compounds in which the diketo function is directly linked to olefinic group2. Such unsaturated -dicarbonyl compounds and their metal complexes possess interesting biochemical properties such as antitumour, antioxidant, antifungal and antimicrobial activities1-14. A search of the literature revealed that no work has been done on transition metal complexes of the chalcone derived from dehydroaceticacid and 4- Dimethylaminobenzaldehyde. The complexes of Ni(II), Cu(II),Mn(II), Co(II) and Fe(III)with this ligand were also prepared in the solid state and characterized by different physico-chemical methods, investigate antimicrobial activities.

EXPERIMENTAL

Dehydroacetic acid (purity 99%) for synthesis was obtained from Merck, Germany & used as supplied. 4- Dimethylamino benzaldehyde of A.R. grade obtained from AVRA chemicals were used for the synthesis of the ligands. A.R. grade hydrated metal chlorides from Thomas Baker were used for the preparation of the complexes. The carbon, hydrogen & nitrogen content in each sample were measured on a Perkin Elmer(2400) CHNS analyzer. The IR spectra (KBr), in the range of 4000-450 cm-1 were recorded

on a Perkin Elmer (C-75430) IR spectrometer. The 1H- NMR spectrum of the ligand was measured in CDCL3 on Bruker instrument. The mass spectrum of the ligand was measured in Qc-01 DAD Mas-spectrometer, thermogravimetric analysis differential thermal analysis (TGA-DTA) were realised on a METTLER-TOLEDODB V13.00 instruments. The UV-VIS spectra of the complexes were recorded on a Shimadzu UV-2202 Spectrophotometer. Magnetic susceptibility measurements of the complexes were performed using a Gouy balance at room temperature using Hg [Co (SCN)4] as the calibrant.

SYNTHESIS OF THE LIGAND (HL) :-

A solution of 0.01mol of dehydroacetic acid, 10 drops of piperidine & 0.01 mol of 4- Dimethylaminobenzaldehyde in 25 ml chloroform were refluxed for 8-10 hrs, 10 ml of the chloroform-water azeotrope mixture way separated by distillation. Crystal of product separated on slow evaporation of the remaining chloroform. The resulting precipitate was filtered, washed several times with ethanol & recrystallized from chloroform15-16.

Scheme : Synthesis of Ligand

SYNTHESIS OF METAL COMPLEXES :-

To a chloroform solution (30ml) of the ligand (2mmol), methanolic solution (20ml) of metal chlorides was added with constant stirring. The PH of the reaction mixture was maintained around 7.5 by adding 10% methanolic solution of ammonia. It was then refluxed for 2hr. the resulting metal complex was filtered in hot condition & washed with ethyl acetate methanol, pet- ether & dried over calcium chloride in vaccum desicator.

Scheme : Preparation of Metal Complex

ANTIMICROBIAL ACTIVITY :-

The ligand and its metal complexes were screened for in vitro antibacterial activity against Gram-positive i.e. Bacillus Cereus, Bacillus Megaterium and Gram-negative

i.e. Shigella boydii, Escherichia Coli by the paper disc plate method17. The compound were tested at concentrations of 1.0 mg ml-1 in DMF (0.1ml) was placed on a paper disk ( 6mm in diameter) with the help of micropipette and compared with a known antibiotic, viz. Ciprofloxacin at the same concentrations. To evaluate the fungicidal activity of the ligands and the metal complexes, their effects on the growth of Saccharomyces Cerevisiae, Aspergillus Oryzae and Penicillium notatum were studied. The ligand and their corresponding metal chelates in DMF were screened in vitro by the disc diffusion method18. The ligands and complexes were dissolved separately in DMF to obtain concentration 500 µg disc-1. The linear growth of

the fungus was recorded by measuring the diameter of the colony after 96 hr. The diameters of the zone of inhibition produced by the complexes were compared with Griseofulvin, an antifungal drug.

RESULTS AND DISCUSSION

The elemental analyses showed 1:2 ( metal : ligand ) stoichiometry for all the complexes ( Fig. II ) . The analytical data ofthe ligand and its metal complexes corresponded well with the general formula [ M(L)2(X)2], where M=Mn (II), Co(II), Ni(II), Cu (II), and M=Fe(III),

L=C17H17NO4. The absence of chlorine in the complex was evident from the Vol-hard test. The complexes were coloured, stable in air, insoluble in water and common solvents, except for DMF and DMSO. Since a single crystal of the complexes could not be isolated from any common solvent, the possible structure was predicted based on analytical, spectroscopic, magnetic and thermal data.

Table I : Physical Characterization and Analytical data of ligand and its metal complexes.

1H-NMR Spectra of ligand :-

The 1H NMR spectra of free ligand in CDCL3 at room temperature shows the following signals. 2.27 (s, 3H, -CH3), 3.09 ( s, 6H, two N(CH3)2 gr), 5.92 (s,1H, C5-hydrogen of DHA moiety),6.71( dd, 2H, Ar-H), 7.64( dd, 2H, Ar-H), 8.04(d,1H,

olefinic proton), 8.16 (d,1H, olefinic proton) and 14.50 (s,1H, enolic OH of DHA moiety). The NMR spectra giving in the

following fig.III.

Massspectra of ligand :-

Fig.III :- NMR Spectra of Chalcone Ligand

of coordination water was observed in the region 3570-

Mass spectroscopy regard as clear and strong evidence to prove the formation of molecules via the observation of the mother ion at molecular weight equivalent value and this observed in the mass fragmentation spectra of ligand , that the mother ion appear clear band at ( 299 m/e ) , this was a good agreement for the formation of the new ligand.

IR Spectra of ligand :-

The FTIR spectrum of free ligand shows characteristic bands at 3081, 1725, 1648, 1456, 1242cm-1 assignable to (OH) of the intramolecular phenolic group of the dehydroacetic acid moiety, (C=O) (lactone carbonyl), (C=O) (acetyl carbonyl), (C-N) (P-substituted emine gr) & (C-O) (phenolic ) stretching mode, respectively19. In the IR spectra of all the metal chelates, no band was observed in the region of 3200-3000cm-1. Instead, in its place, a broad band characteristic of (OH)

3200cm-1. The absence of (OH) (Phenolic) at 3100cm-1 suggests subsequent deprotonation of the phenolic group and coordination of phenolic oxygen to the metal ion. This was supported by an upward shift in (C-O) (phenolic) 20 by 10-45cm-1. The (C=O) (acetyl carbonyl) was shifted to lower energy with respect to the free ligand, suggesting the participation of the acetyl carbonyl in the coordination 19-21. The IR spectra of all the compounds showed a prominent band at 1377 & 970cm-1, typical of (C-O-C) and trans

CH=CH- absorption. The presence of new bonds in the region 600-450cm-1 can be assigned to (M-O) vibration22. Important spectral bands for the ligand and its metal complexes are presented in Table II.

Hence, the ligands coordinated with the metal ions as mono-deprotonated bi-dentate and the coordination occurs via the acetyl & phenolic oxygen of dehydroacetic acid moiety, as shown in Fig. II.

TABLE II. Characteristic IR frequencies (cm-1) of the ligand and its metal complexes

THERMAL ANALYSIS:-

The simultaneous TG/DT analysis of the Cu(II), Co(II), Ni(II), Mn(II) and Fe(III) metal complexes was studied from ambient temperature to 10000C under a nitrogen atmosphere using -Al2O3 as the reference. In the TG curve of Cu(II) complex of ligand, the mass loss starts from 50oC and an inclined slope from 160- 185oC with a mass loss of 6.0% (calcd.6.10%), indicates the removal of two molecules of coordinated water, an endothermic peak in the range 150- 200oC(Tmin=175oC) in DTA corresponds to dehydration step. The rate controlling process of dehydration is found to be random nucleation with one nucleus on each particle (F1). The mass loss continues in TG curve upto 325oC with a mass loss 26.5 % (calcd., 27.1%), an exothermic peak Tmax = 280oC in DTA may be attributed to the removal of non-coordinated part of the ligand. The third step corresponds to decomposition of coordinated part of the ligand in the range of 350-900oC with a mass loss 54.5 % ( calcd., 53.22%). A broad endotherm is observed for this step. The mass of the final residue corresponds to stable CuO, 13.0 % (calcd.,13.48%).

The thermal decomposition profile of Ni(II) complex of ligand show weight loss 3% (calcd., 2.98%) in the range 30-100oC indicates the removal of one physically adsorbed water molecule. An endothermic peak between 30-55oC (Tmin= 35oC), correspond to dehydration. The mass loss of 6.0% (calcd., 5.95%) is observed in the range 100-180oC. An endothermic peak between 120-180oC (Tmin = 157.5oC), correspond to loss of two coordinated water molecules. The third step decomposition is in between 250 and 425oC with 27% mass loss (calcd., 26.52%). A broad exothermic peak between 200-450oC (Tmax = 315.7oC) in DTA, attributed to the removal of non-coordinating part of the ligand.

he thermal decomposition profile of Co(II) complex of ligand show no weight loss up to 150oC. The mass loss of 6.5% (calcd. 6.14%) is observed in the range 150-200oC. An endothermic peak between 140-210oC (Tmin = 180oC), correspond to the loss of two molecules of water. The second step decomposition is in between temperature 235 and 375oC with 28.5% mass loss (calcd. 27.33%). A broad exothermic peak between 225-375oC (Tmax = 320oC) in DTA, attributed to the

removal of non-coordinating part of the ligand. The mass loss continues and follows slow decomposition of remaining part of the ligand 53.5% (calcd., 53.64). The mass of the final residue corresponds to CoO, 11.5% (calcd. 12.8%).

In the TG curve of Mn(II) complex of ligand, the first step shows a steep slope between 150-200oC with a mass loss of 6.0% (calcd., 6.2%), indicates the removal of two molecules of coordinated water, an endothermic peak in the range 150-200oC (Tmin=165oC) in DTA corresponds to dehydration step. The anhydrous compound in second step decomposes within a short temperature range from 220- 330oC with a 27.0 % mass loss (calcd, 27.52 %), an exotherm between 240 and 400oC with Tmax = 280oC in DTA. This step may be attributed to the removal of non-coordinated part of the ligand. The third step corresponds to decomposition of coordinated part of the ligand and in the range of 400-750oC with a mass loss 55.5

% (calcd., 54.01 %). The mass of the final residue corresponds to stable MnO, 11.5 % (calcd., 12.21%).

In the thermal study of Fe(III) complex of ligand show slow weight loss upto 225oC and an inclined slope from 230o-260oC in TG curve with mass loss 10.0% (calcd., 8.92 %) indicates the removal of one molecule of water and one chloride ion, an endothermic peak in the range 180-240oC is observed in DTA (Tmin = 213oC). The decomposition of complex continues in between temperature 270 and 500oC with 27% mass loss (calcd. 26.67%). An exothermic peak between 250-270oC (Tmax = 260oC) in DTA, attributed to the removal of non-coordinating part of the ligand.

MAGNETIC MEASUREMENT AND ELECTRONIC ABSORPTION SPECTRA :-

The electronic spectra of all the complexes were recorded in DMF solution. The magnetic and electronic spectral data are given in table III. The electronic spectrum of the Mn(II) complex exhibited three bands at 18248 cm 1(= 26 dm3mol1cm1), 20492 cm1(= 16 dm3mol1cm1) and 33113 cm1(= 28 dm3mol1cm1), which are assigned to 6A1g 4T1g(G), 6A1g 4T2g(G) and 6A1g 4A1g, 4E1g(4G) transitions, respectively, indicating an octahedral configuration23,24 around the Mn(II) ion. The octahedral geometry of Mn(II) was further confirmed by the value of

the magnetic moment (5.84 B).

Three electronic transitions were observed in the electronic spectrum of the Fe(III) complex, at 14472 cm 1(= 22 dm3mol1cm1), 21322 cm1(= 26 dm3mol1cm1) and 24272 cm1(= 32 dm3mol1cm1), which are assigned

to 6A1g 4T1g(G), 6A1g 4T2g(G) and 6A1g 4Eg(G), respectively, suggesting an octahedral complex of Fe(III),which was confirmed by the value of magnetic moment (5.69B) 23.

TABLE III. Magnetic And electronic absorption spectral data ( in DMSO) of the compounds.

The electronic spectrum of the Co(II) complex exhibited three bands at 9794 cm1(= 17 dm3mol1cm1), 18726 cm1(= 59 dm3mol1cm1) and 23923 cm1(= 98 dm3mol1cm1), which are assigned to 4T1g(F) 4T2g(F), 4T1g(F) 4A2g(F) and 4T1g(F)4T1g(P), respectively, indicating octahedral configuration around the Co(II) ion. The magnetic moment of the Co(II) complex was 4.92 B. The calculated spectral parameters 2/1, 10Dq, B, and the ligand field stabilizing energy (LFSE) have the values 1.96, 9169 cm1, 783.1 cm1, 0.81 and 26.20 kcal mol1, respectively, which are in good agreement with the reported values of an octahedral Co(II) complex 23.

The electronic spectrum of the Ni(II) complex exhibited three bands at 9671 cm1(= 34 dm3mol1cm1), 14880 cm1(= 67 dm3mol1cm1) and 25125 cm1(= 188 dm3mol1cm1), which are assigned to 3A2g 3T2g(F), 3A2g

3T1g(F) and 3A2g 3T1g(P), respectively. The ligand field parameters 2/1, 10Dq, B, and the LFSE have the values 1.68, 9345 cm1, 675.6 cm1, 0.65 and

1. 1. kcalmol1, respectively. These values, as well as the magnetic moment value (2.99 B), support an octahedral geometry of the Ni(II) complex 23.

      The spectrum of the Cu(II) complex consisted of a broad band at 15083 cm1(= 94 dm3mol1cm1), assigned to the 2Eg 2T2gtransition of a distorted octahedral geometry 24. In addition to this band, the band observed at 24937 cm1 (= 1143 dm3mol1cm1) arises from intra ligand charge transfer. The LFSE value of the Cu(II) complex is 42.64 kcal mol1. The obtained values of LFSE determine the stability of the complexes and follows the order in terms of metal ions Cu(II)>Ni(II)>Co(II).

      POWDER X-RAY DIFFRACTION ANALYSIS :-

      The Cu(II), Ni(II) and Co(II) complexes of ligand were subjected to X-ray powder diffraction studies. The X-ray powder diffractograms of Cu(II)

      complex are presented in (Fig. IV). X-ray powder data of all the main peaks having relative intensity greater then 10% have been indexed by using computer software independently by trial and error method. The indexed powder diffraction data, the unit cell data and crystal lattice parameters of complex are presented in following Table. The diffractogram of Cu(II) complex had ten reflection with maximum reflection at 2 = 7.562o corresponding to the value of d = 11.6810Ã…. The crystal volume is obtained from indexing of the diffraction pattern. The Z (number of molecules per unit cell) values were calculated and rounded up to the nearest whole number. The porosity percentage was calculated from the observed and calculated densities. The density calculated from diffraction data and the observed density was found to be very close to each other indicating the perfection in indexing. Such refined parameters were also used for finding out probable space group. All this values are given in Table.

      The crystallographic data of the complexes fit perfectly in orthorhombic for Cu-complex with 2 molecules each per unit cell.

      The Ni(II) complexes of diffractogram of Ni(II) complex of Ligand had eleven reflection with maximum reflection at 2 = 25.7o corresponding to the value of d = 3.4636Ã…. The crystallographic data of the complexes fit perfectly in monoclinic system for Ni complex 2 molecule per unit cell of ligand. The probable space group is P 2/m for all the Ni(II) complex under investigation.

      Where as the diffractogram of Co(II) had eleven reflection with maximum reflection at 2 = 13.510o corresponding to the value of d = 6.548 Ã…. The crystallographic data of the Co complexes fit perfectly in monoclinic system for Co complex with 4molecules per unit cell. The probable space group is P 2/m for Co(II) complexes under investigation.

      Figure IV : X-ray Diffractogram of Cu-Complex
      	180
      	160
      	140
      intensity(count)	120
      	100
      	80
      	60
      	40
      	20
      	0
      	5	10	15	20	25	30	35	40	45	50	55	60	65	70	75	80

      Table:XRD data of Cu- Complex

      H	K	L sin2-OBS sin2-CALC DELTA				2-OBS 2-CALC d-OBS			RI%
      0	1	0	0.004349	0.004337	0.000012	7.562	7.552	11.6810	100
      0	1	1	0.014937	0.014930	0.000007	14.040	14.037	6.3027	79.9
      0	2	0	0.017197	0.017349	-0.000152	15.070	15.137	5.8741	78.1
      2	2	0	0.025756	0.025761	-0.000005	18.470	18.472	4.7998	27.7
      3	0	1	0.029415	0.029521	-0.000106	19.751	19.787	4.4914	18.8
      0	3	0	0.039138	0.039034	0.000104	22.821	22.790	3.8937	14.7
      4	0	1	0.044283	0.044243	0.000040	24.296	24.285	3.6605	19.6
      1	3	1	0.051603	0.051730	-0.000127	26.260	26.293	3.3909	30.6
      2	1	2	0.055112	0.055121	-0.000009	27.155	27.157	3.2812	39.7
      3	2	2	0.078703	0.078648	0.000055	32.585	32.573	2.7458	45.8

      Crystal System: Orthorhombic
      a = 16.7968 ± 0.02166 Å	= 90.00 ± 0.000 DEG
      b = 11.6965 ± 0.00936 Å	= 90.00 ± 0.000 DEG
      c = 7.4843 ± 0.00708 Å	= 90.00 ± 0.000 DEG
      Density (obs) = 1.3853 g cm-3	Z = 2
      Density (cal) = 1.3922 g cm-3	Space group = P mmm
      Porosity % = 0.4935	Volume = 1470.41 Ã…3
      Particle size = 87.81 Ã…

      ANTIMICROBIAL ACTIVITY :-

      The synthesized Ligand and their complexes were screened for antibacterial activity against four pathogenic organisms: Shigella Boydii, Bacillus Cereus, Bacillus Megaterium and Escherichia Coli and antifungal activity against three organisms: Saccharomyces Cerevisiae, Penicillium Natatum and AspergillusOryzae (Table 2). The paper disc diffusion method25 and mycelia dry weight method26 with glucose nitrate media were used for antibacterial and antifungal activities respectively. The tested compounds were dissolved in N,Ndimethylformamide (DMF) to get a solution of 1 mg ml-1. The inhibition zones were measured in millimeters at the end of an incubation period of 48 hrs at (35±2)oC. DMF

      alone showed no inhibition. Commercial antibacterial Ciprofloxacin and antifungal Griseofulvin were also tested under similar conditions for comparison.

      It is observed that the metal complexes show enhanced antimicrobial activity as compared to the ligand. This is because of chelation, which reduces the polarity of metal ion due to partial sharing of its positive charge with donor groups and also due to delocalization of pi electrons over whole chelate ring. Thus chelation increase lipophilic character in the complexes and results in the enhancement of activity. The inhibition by metal complexes has been increased by 30-65% and 40-70% for 125 and 250ppm concentration respectively.

      Table 4 : Antimicrobial Activity of HL and its metal complexes

      td>Grysofulvin

      Compound	Inhibition zone of bacterial & fungal growth in mm
      	Antimicrobial activity				Antifungal activity
      	Bacillus Megaterium	Bacillus Cereus	Escherichia Coli	Shigellaboydii	Penicillium notatum	Saccharomyc es Cerevisiae	Aspergillus Oryzae
      	Concn,1mg/ ml	Concn,1mg/ ml	Concn,1mg/ ml	Concn,1mg/ ml	Concn,0.5mg/ ml	Concn,0.5mg/ ml	Concn,0.5mg/ ml
      Ligand HL C17H17NO4	12	10	13	11	06	09	07
      C34H32FeN2O8	18	11	19	15	11	10	10
      C34H32CuN2O8	26	22	22	25	13	15	12
      C34H32CoN2O8	21	20	19	14	11	13	11
      C34H32MnN2O8	24	21	17	19	10	12	16
      C34H32NiN2O8	20	19	19	21	12	–	15
      Ciprofloxacin	36	54	32	30	–	–	–
      –	–	–	–	34	40	42

      CONCLUSION :-

      On the basis of present investigation metal complexes are biologically active and show enhanced antimicrobial activities compared to free ligand. Based on the physicochemical and spectral data discussed above, a distorted octahedral geometry for the Cu(II) complex and an octahedral geometry for the Mn(II), Fe(III), Co(II) and Ni(II) complexes are proposed.

      A thermal study revealed that the complexes are thermally stable. An XRD study suggested

      the monoclinic crystal system for the Co(II), Ni(II) and Orthorhombic crystal system for the Cu(II) complexes.

      ACKNOWLEDGEMENTS :-

      Financial assistance in the form of Minor Research Project [File No :- 47-646/13 ] from UGC (WRO) Pune, is gratefully acknowledged. The authors are also thankful to the Head of chemical Science, Solapur University, Solapur and Vishnu chemicals Hydrabad for providing spectral data.

      REFERENCES :-

      1. K.Krishanankutty, V.D.John,

         Synth.React.Inorg.Metal-Org.Chem, 33 (2003) 343.

      2. V.D.John, G.Kuttan and K.Krishanakutty,

         J.Exp.Clin.Caner.Res, 21 (2002) 219.

      3. K.Krishanakutty and P.Vanugopalan,

         Synth.React.Inorg.Metal.Org.Chem, 28 (1998) 1313.

      4. H.J.J.Pabon, Reac.Trans.Chim, 83 (1964) 237.
      5. V.S.Govindrajan, CRC Critical review in food science and nutrition, 12 (1980) 199.
      6. R.J.Anto, K.N.Dinesh Babu, K.N.Rajasekharan and R.Kutton, Cancer.Lett, 94 (1995) 74.
      7. M.T.Haung, Z.Y.Wang, C.A.Geogiadis, J.D.Lasken and A.H.Canney, Carcinogensis, 13 (1992) 2183.
      8. S.M.Khopde, K.Indira Priyadarsini, P.Venteketesan and M.N.A.Rao, Biophys.Chem, 80 (1999) 85.
      9. R.Kuttan, P.C.Sudheeran and C.D.Joseph, Tumori 73 (1987) 29.
      10. M.Nagabushan and S.V.Bhide, J.Am.Coll.Nutr, 11 (1992) 192.
      11. T.S.Roa, N.Basu and H.H.Siddique, Indian.J.Med.Res, 75 (1982) 574.
      12. O.P.Sharma, BioChem,Pharmacol, 25 (1976) 1811.
      13. K.K.Soudamini and R.Kuttan, Ethnopharmacol, 27 (1989) 227.
      14. R.C.Srimal and B.N.Dhawan, J.Pharm.Pharmacol, 25 (1973) 447.
      15. A.S. Munde, A.N. Jagdale, S.M. Jadhav, T.K. Chondhekar,

          J.Korean Chem. Soc. 2009 (53), 4.

      16. Vaibhav N. Patange, R.K. Pardeshi., B.R. Arbad, J. Serb. Chem. Soc. 2008 (1073-1082) 73 .
      17. H.H. Thornberry, Phytopathology 1950 (40), 419.
      18. A.W. Bauer, W.M.M. Kirby, J.C. Shesies, M. Turck, Am. J. Clin. Pathol.1966 (44), 93.
      19. N. Ramarao, V.P. Rao, V.J. TyagaRaju, M.C. Ganorkar,

          Indian J.Chem.A 1985 (24), 877.

      20. P.V. Rao, A.V. Narasaiah, Indian J. chem. A 2003 (42), 1896.
      21. O.Carugo, C.B. Castellani, M.Rizzi, Polyhedron 1990 (9), 2061.
      22. K. Nakamoto, Infrared spectra of inorganic & coordination compounds, Wiley, New York, 1970, pp. 159,167,214.
      23. K. A. H. Afkar, Indian J. Chem., A 1994(33), 879.
      24. A. B. P. Lever, Inorganic electronic spectroscopy, Elsevier, Amsterdam, 1968 (55), 789.
      25. S.F. Tan, Ang, K.P., Jatchandran, H.L., Transition Met. Chem. 1984 (9),390.
      26. Vaibhav N. Patange, B.R. Arbad, J. Serb. Chem. Soc. 2011, 76 (9), 1237-1246.