Research Article Synthesis and Spectroscopic and...

Research ArticleSynthesis and Spectroscopic and AntimicrobialStudies of Schiff Base Metal Complexes Derived from2-Hydroxy-3-methoxy-5-nitrobenzaldehyde

K R Joshi1 A J Rojivadiya1 and J H Pandya2

1 Department of Chemistry MD Science College Porbandar Gujarat 360575 India2Department of Chemistry Shree DKV Arts amp Science College Jamnagar Gujarat 361008 India

Correspondence should be addressed to A J Rojivadiya lekhrajrgmailcom and J H Pandya jhpandyagmailcom

Received 22 July 2014 Revised 13 October 2014 Accepted 14 October 2014 Published 17 November 2014

Academic Editor Daniel L Reger

Copyright copy 2014 K R Joshi et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Two new series of copper(II) and nickel(II) complexes with two new Schiff base ligands 2-((24-dimethylphenylimino)methyl)-6-methoxy-4-nitrophenol and 2-((34-difluorophenylimino)methyl)-6-methoxy-4-nitrophenol have been prepared The Schiff baseligands were synthesized by the condensation of 2-hydroxy-3-methoxy-5-nitrobenzaldehyde with 24-dimethylaniline or 34-difluoroaniline The ligands and their metal complexes have been characterized by IR 1H NMR mass and electronic spectra andTG analysisThe Schiff base ligands and their metal complexes were tested for antimicrobial activity against Gram positive bacteriaStaphylococcus aureus and Streptococcus pyogenes and Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa andfungus Candida albicans Aspergillus niger and Aspergillus clavatus using Broth Dilution Method

1 Introduction

Vanillin and o-vanillin are such natural compounds whichhave both phenolic OH and aldehyde group They arepositional isomers in which O-vanillin shows contradictoryeffects There are several reports indicating that o-vanillininduces mutations and it has also been found to enhancechromosomal aberrations in in vitro systems [1ndash4] Schiffbases derived from 2-hydroxy-3-methoxybenzaldehyde(o-vanillin) have not been investigated so thoroughlyThe mono- and bis-Schiff bases of o-vanillin and 23-diaminopyridine have been used as ionophores in a Cu(II)selective electrochemical sensor [5] These compounds aswell as their metal complexes have been found to possessbiological activity [6] Antibacterial activity has also beenreported for the ruthenium(II) complex of the Schiff base ofo-vanillin and 2-aminopyridine [7] Furthermore the Schiffbases are very important tools for the inorganic chemists asthey are widely used to design molecular ferromagnets aswell as in biological modeling applications They are alsoused as liquid crystals and heterogeneous catalysts [8ndash10]Schiff base ligands containing various donor atoms (like N

O S etc) show broad biological activity and are of specialinterest because of the variety of ways in which they arebonded to the transition metal ions [11 12]

2 Materials and Methods

2-Hydroxy-3-methoxy-5-nitrobenzaldehydewas synthesizedaccording to the method reported in the literature [13]Copper(II) and nickel(II) were used as nitrate salts and wereobtained from Rankem All amines were used from Merckorganic solvents EtOH MeOH DMF and DMSO were ofreagent grade

21 Physical Measurements IR spectra (4000ndash400 cmminus1)of the ligands and metal complexes were obtained usingKBr discs on 8400 FT-IR SHIMADZU spectrometer Massspectra were recorded on QP 2010 SHIMADZU GCMSspectrometer1H NMR spectra of ligands were recorded onBruker Avance-II 400MHz FT-NMR spectrometer usingTMS as an internal standard andCDCl

3as a solvent ESImass

spectra of complexes were recorded byVG-70S Spectrometer

Hindawi Publishing CorporationInternational Journal of Inorganic ChemistryVolume 2014 Article ID 817412 8 pageshttpdxdoiorg1011552014817412

2 International Journal of Inorganic Chemistry

Electronic spectra of the metal complexes in DMF wererecorded on a Perkin Elmer Lambda 19 spectrophotometerand molar conductance of the metal complexes was deter-mined on Systronics direct reading conductivity meter typeCM-82T A simultaneous TGDTA was recorded on PerkinElmer Pyris-1 model DSC was carried out on Perkin ElmerPyris-7 instrument Elemental analysis (C H and N) wascarried out on elemental analyzer PERKIN ELMER 2400while analysis ofmetal was also carried out by EDTA titrationmethod in which the metal complex first evaporates in concnitric acid and prepares a stock solution This solution withammonia then titrates against EDTA by using appropriateindicator The MP of ligands was carried out by standardlaboratory thermometer Magnetic susceptibility measure-ments of the complexes were carried out by Gouy balanceusing Hg[Co(CN)

4] as calibrant IR and mass spectra and

elemental analysis of compoundswere done inDepartment ofChemistry Saurashtra University Rajkot TG-DTA-DSC wascarried out in Department of Physics Saurashtra UniversityRajkot 1H NMR and ESI mass spectra of compounds werecarried out in SAIF Chandigarh Electronic spectra andconductance measurement of compounds were done in theDepartment of Chemistry DKV College Jamnagar

22 Preparation of Schiff Base Ligands

221 Synthesis of 2-((24-Dimethylphenylimino)methyl)-6-methoxy-4-nitrophenol (MPM) The Schiff base ligandMPM was synthesized by adding 2-hydroxy-3-methoxy-5-nitrobenzaldehyde (49 g 25mmol) dissolved in hot absoluteEtOH (20 cm3) to 24-dimethylaniline (30 g 250mmol) inabsolute EtOH (20 cm3) The reaction mixture was heatedto reflux for 4 h The products obtained were filtered offand washed several times with EtOH and then ether andair dried The products were kept in desiccators until usedRecrystallization was carried out in EtOH The progress ofreaction was monitored by TLC

222 Synthesis of 2-((34-Difluorophenylimino)methyl)-6-methoxy-4-nitrophenol (FPM) The Schiff base ligandFPM was synthesized by adding 2-hydroxy-3-methoxy-5-nitrobenzaldehyde (49 g 25mmol) dissolved in hot absoluteEtOH (20 cm3) to 34-difluoroaniline (32 g 250mmol) inabsolute EtOH (20 cm3) The reaction mixture was heatedto reflux for 4 h The products obtained were filtered offand washed several times with EtOH and then ether andair dried The products were kept in desiccators until usedRecrystallization was carried out in EtOH The progress ofreaction was monitored by TLC

23 Preparation ofMetal Complexes All themetal complexesof Schiff base ligands were prepared by the followingmethodThe metal salt was dissolved in water and the solution wasadded to a hot ethanolic solution of the corresponding Schiffbases After the complete addition little amount of sodiumacetate was added and the mixture was refluxed for 4 hA crystalline solid was obtained which was isolated by

C

O

H

N C

O

HN

M

R R

OCH3

O2N

H3CO

NO2

R = 24 dimethyl-for MPM and34 difluoro-for FPM ligandM = Ni(II) Cu(II)

Scheme 1 General structure of metal complex

filtration washed with hot water and dried in airThe generalstructure of the metal complexes is given in Scheme 1

24 Antimicrobial Screening All newly synthesized com-pounds were tested for their antibacterial activities againstGram positive bacteria Staphylococcus aureus and Strepto-coccus pyogenes and Gram negative bacteria Escherichia coliand Pseudomonas aeruginosa and antifungal activity againstCandida albicans Aspergillus niger and Aspergillus clavatusThe method used to evaluate the antimicrobial activity wasldquoBroth Dilution Methodrdquo It is one of the nonautomatedin vitro susceptibility tests The MIC (minimal inhibitoryconcentration) of the control organism is read to check theaccuracy of the drug concentrations The lowest concentra-tion inhibiting growth of the organism is recorded as theMIC The MIC values of the newly synthesized compoundshave been compared with the standard drugs ampicillinchloramphenicol nystatin and griseofulvin [14]

3 Results and Discussion

The Schiff base ligands MPM and FPM were prepared by thecondensation of 2-hydroxy-3-methoxy-5-nitrobenzaldehydewith 24-dimethylaniline and 34-difluoroaniline in molarratio 1 1 The formation of Schiff bases and their metalcomplexes were confirmed by various analytical techniquessuch as IR 1H NMR mass and electronic spectra con-ductance and TG-DT analysis Table 1 lists the physical andanalytical data of the Schiff bases and their metal complexesThe antimicrobial activities of Schiff base ligands and metalcomplexes are listed in Tables 2(a) and 2(b)

31 Characterization of the Ligands The IR spectra of Schiffbase ligands are depicted in Figures 1(a) and 1(b) The IRspectra of the ligands show a broad band at 3420ndash3460 cmminus1due to the stretching vibrations of phenolic hydroxyl groupThe broadness is due to intermolecular hydrogen bondingbetween the phenolic group and the azomethine group Thestrong band observed at 1614 cmminus1 is assigned to the stretch-ing vibrations of the azomethine group Two moderately

International Journal of Inorganic Chemistry 3

Table1Th

ephysic

alandanalyticaldataof

Schiffbase

ligands

andtheirm

etalcomplexes

Ligand

orcomplex

Form

ula

MW

Color

Yield(

)MP

(∘ C)120583efffoun

d(calcd)BM

Elem

entalanalysis

foun

d(calcd)

CH

NM

(1)M

PMC 1

6H16N

2O4

300

Yello

w87

210

mdash64

04(6399)

532

(537

)94

0(933

)mdash

(2)F

PMC 1

4H10F 2N

2O4

308

Redd

ishyello

w91

188

mdash5461(5455)

325

(327)

904(909)

mdash(3)[Cu

(MPM

) 2]

C 32H

30Cu

N4O

8662

Deepblue

88gt300

194(173)

5800(5804)

460

(457)

852

(846)

967(960)

(4)[Ni(M

PM) 2]

C 32H

30N

4NiO

8657

Redd

ishgreen

85gt300

280

(282)

5845(5847)

456

(460)

857

(852

)90

0(893)

(5)[Cu

(FPM

) 2]

C 28H

18Cu

F 4N

4O8

676

Deepblue

90gt300

180(173)

4953

(496

0)271

(268)

830

(826)

943(937

)(6)[Ni(F

PM) 2]

C 28H

18F 4N

4NiO

8673

Redd

ishgreen

87gt300

290

(282)

4990(499

6)268

(270)

839

(832

)880

(872)


Table 2 (a) Antibacterial activity of Schiff bases and their metal complexes (b) Antifungal activity of Schiff base ligands and their metalcomplexes

(a)

Minimal inhibition concentration (MIC) (gmL)

Sr number Ligandcomplex E coli P aeruginosa S aureus S pyogenesMTCC-443 MTCC-441 MTCC-96 MTCC-442

1 MPM 250 250 250 2502 FPM 250 100 250 2503 [Cu(MPM)2] 50 100 150 1004 [Ni(MPM)2] 500 500 100 2505 [Cu(FPM)2] 125 250 250 1006 [Ni(FPM)2] 250 100 50 125

Standard drugs1 Ampicillin 100 100 250 1002 Chloramphenicol 50 50 50 50

(b)


Sr number Ligandcomplex C albicans A niger A clavatusMTCC-227 MTCC-282 MTCC-1323

1 MPM 1000 100 5002 FPM 250 250 2503 [Cu(MPM)2] 500 100 5004 [Ni(MPM)2] 100 100 2505 [Cu(FPM)2] 250 250 1006 [Ni(FPM)2] 100 100 250

Standard drugs1 Nystatin 100 100 1002 Griseofulvin 500 100 100

466

4750

681

90

885

897

75

1101

01208

512

796

1330

214

827

1549

116

142

3003

3

3449

2

42 44 46 48 50 52 54 56 58 60 62 64

Tran

smitt

ance

()

500 1000 1500 2000 2500 3000 3500 4000

lowastVN-2 4 ME

Wavenumbers (cmminus1)

(a)

488

761

70

747

281

86

869

597

03

1098

511

468

1203

913

29214

89816

149

2985

230

494

3441

6

16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Tran

smitt

ance

()

500 1000 1500 2000 2500 3000 3500 4000Wavenumbers (cmminus1)

lowastVN-3 4 F

(b)

Figure 1 (a) The IR spectrum of Schiff base ligand MPM (b) The IR spectrum of Schiff base ligand FPM

intense bands observed at 3049ndash3060 and 2985ndash3005 cmminus1are due to aromatic and aliphatic 120592(CndashH) respectively [1516]

The 1HNMR spectra of ligands were recorded in CDCl3

The proton NMR spectrum of one of the ligands is shownin Figure 2 The signal due to methyl protons (ligand MPM)

appeared as singlet at 120575 237 and 244 ppm whereas signaldue to methoxy protons appeared as singlet in the range120575 401ndash403 ppm In the aromatic region a few doubletsand in few cases some overlapping doubletsmultiplets areobserved in the range 120575 712ndash808 ppm These signals aredue to aryl protons of benzene rings The signals due to


01234567891011121314151617

90 88 86 84 82 80 78 76 74 72 70 68 66 64

111

102

100

110

203

(ppm)

(ppm)

097

111

102

100

110

203

307

301

332

Figure 2 1H NMR spectrum of Schiff base ligand MPM

100

90

80

70

60

50

40

30

20

10

40 60 70 90 110 130 150 170 180 200 220 240 260 280 300

mz

308

307290279261

244

232

219203

190

180

166140

129

113

1019579

63

44

Figure 3 Mass spectrum of Schiff base ligand FPM

azomethine proton (ndashCH=Nndash) appeared as singlet at 120575865 ppm Another singlet corresponding to one proton isobserved in the range 120575 1443ndash1598 ppm is due to phe-nolic ndashOH group and may disappear during complexation[16 17]

The mass spectra of ligands MPM and FPM revealed themolecular ion peak at me 300 for the former ligand andme 308 for the latter ligand which are coincident with theformulaweights and support the identity of the structures [18](Figure 3)


1000950900850800750700650600550500450400350300250200150100

700680660640620600580560540520

100

0

100

0

()

()

mz

mz

67621526621

846491151

6471262

63311186181

93

6112148

6091277

5962153

5942318

58901805741

156

5731308

5721 2265591105

5460184

5511

5450503

92

5430940

5361529

5231185

5221563

52011240

67789

6762152

5430940

49012077

47632810

475310154

43201573

386026093601

230027911931

278110144

256131244

24112191

22691949

17303025

13005939

104011420

Figure 4 ESI mass spectrum of metal complex [Cu(FPM)2]

32 Characterization of the Metal Complexes The IR spectraof metal complexes show sharp band in the range 1607ndash1603 cmminus1 which is shifted to lower frequency as compared toligand suggesting coordination of the azomethine nitrogento the metal ion The disappearance of 120592(OndashH) shows thedeprotonation of the ndashOH group and its subsequent coordi-nation to the central metal atom Two new bands observedat 578ndash564 and 481ndash470 cmminus1 are characteristic of MndashO andMndashN absorptions respectively [19 20]

ESI mass spectra in the positive mode were measuredafter adding CsCl to the binuclear Cu(II) and Ni(II) neutralcomplexes in solution (water methanol = 1 1) [21 22]For the ESI-MS of the binuclear complexes the peaks ofall complexes are consistent with the calculated isotopicdistributions for all the binuclear complexes as in Figure 4

The observed molar conductance values of the metal(II) complexes in 10minus3 molar DMF solution are in therange 14ndash29Ωminus1 cm2 molminus1 The molar conductance valuesare consistent with the nonelectrolytic nature for all metalcomplexes [23]

Electronic spectra of all the complexes (Figure 5) wererecorded in dimethylformamide (DMF) For square planerCu(II) the expected transitions are 2B

1g rarr2A1g and

2B1g rarr

2Eg with respective absorptions at 505ndash520 and 665ndash650 nmDue to Jahn-Teller (J-T) distortions square planar Cu(II)complexes give a broad absorption between 600 and 700 nmand the peak at 505ndash520 nm merges with the broad bandand thus only one broad band is observed [24] The Ni(II)complexes showed one strong band at 550 nm which isassigned to the square planar 1A

1g rarr1A2g transition This

0

05

1

15

2

25

3

401

421

441

461

481

501

521

541

561

581

601

621

641

661

681

701

721

741

761

781

Abso

rban

ce

Wave length (nm)

CuNi

Figure 5 Electronic spectra of metal complex

value lies within the range 600ndash450 nm region which isresponsible for the reddish color [25]

Thermal analyses of all the complexes were carried outby the TG DTA and DSC techniques The experimentalresults revealed that the degradation occurred in multiplestages following a complex mechanism (Figure 6) For eachstage the kinetic parameters and the thermogravimetriccharacteristics have been estimated Thermal behavior of allcomplexes explains as follows The TG curve follows thedecrease in sample mass with increase in temperature In thepresent investigation heating rates were suitably controlled


750700650600550500450400350300250200150100500

750700650600550500450400350300250200150100500

0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

minus45

minus50

minus55

minus60

minus65

minus70

minus75

minus80

minus85

400

380

360

340

320

300

280

260

240

220

200

180

160

140

120

100

80

60

40

20

0

minus20

180

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

minus10

dM-rel[VN4-16-06-1115]DTA-signal (smoothed) [VN4-16-06-Heat flow (smoothed) [VN4-16-06

DTA

-sig

nal (

smoo

thed

) (120583

V) E

xo

dM-r

el (

)

Temperature (smoothed) (∘C)

Temperature (∘C)

Hea

t flow

(sm

ooth

ed) (

sm) (

mJs

)

Figure 6 TG-DT-DSC analysis of metal complex [Cu(FPM)2]

at 5∘Cminminus1 and mass loss followed up to 25ndash800∘C Thecomplexes slowly started decomposition between 200 and300∘C The first mass loss up to 300∘C is attributed to theremoval of two NO

2molecules This process is accompanied

by exothermic process at around 200ndash320∘C in DTA curvesof all complexes The mass loss occurring at temperature of330ndash500∘C corresponds to the decomposition of the ligandmolecules The final product of the thermal decompositionat 500ndash800∘C metal oxide was determined by elementalanalysis [18 26]

33 Antimicrobial Activities Theminimal inhibitory concen-tration (MIC) against bacteria and fungi of Schiff base ligandsand theirmetal complexeswas comparedwith theMICvaluesof standard drugs [14 27 28] The results of the biologicalscreening of the ligands and their metal complexes revealthat the antimicrobial activities of the chelated ligands areenhanced as compared to the free ligands (Tables 2(a) and2(b))

4 Conclusion

On the basis of the above studies the general structure ofthe metal complexes is proposed as shown in Scheme 1 TheSchiff base ligands are behaving as O N donor bidentate forCu(II) and Ni(II) metal ions The antimicrobial activity of

ligands and metal complexes show good results as comparedto standard drugs

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors are thankful to the MD Science College Por-bandar for laboratory facilities Department of Physics andDepartment of Chemistry Saurashtra University Rajkot andSAIF Chandigarh for providing the analytical services andthe Microcare Laboratory Surat for providing antimicrobialactivity of compounds Authors are also thankful to Dr PH Parsania Head Department of Chemistry SaurashtraUniversity Rajkot

References

[1] A Barik K I Priyadarsini and H Mohan ldquoRedox reactionsof 2-hydroxy-3-methoxybenzaldehyde (o-vanillin) in aqueoussolutionrdquo Radiation Physics and Chemistry vol 70 no 6 pp687ndash696 2004


[2] H Matsumura K Watanabe and T Ohta ldquoo-Vanillin enhanceschromosome aberrations induced by alkylating agents in cul-tured Chinese hamster cellsrdquo Mutation ResearchGenetic Toxi-cology vol 298 no 3 pp 163ndash168 1993

[3] K Takahashi M Sekiguchi and Y Kawazoe ldquoA specificinhibition of induction of adaptive response by 119900-vanillina potent comutagenrdquo Biochemical and Biophysical ResearchCommunications vol 162 p 1376 1989

[4] K Watanabe and T Ohta ldquoMutation enhancing effect of o-vanillin in the lacZ gene of Escherichia coli characterization ofmutational spectrumrdquoMutation Research Letters vol 302 no 1pp 13ndash18 1993

[5] L P Singh and J M Bhatnagar ldquoCopper(II) selective electro-chemical sensor based on Schiff Base complexesrdquo Talanta vol64 no 2 pp 313ndash319 2004

[6] L K W Henri J Tagenine and B M Gupta ldquoSynthetic andantibacterial studies of Schiff base complexes derived from 23-diaminopyridine and o-vanillinrdquo Indian Journal of Chemistry Avol 40 no 9 pp 999ndash1003 2001

[7] KN Kumar andR Ramesh ldquoSynthesis characterization redoxproperty and biological activity of Ru(II) carbonyl complexescontaining ON-donor ligands and heterocyclic basesrdquo Spec-trochimica Acta Part A vol 60 no 12 pp 2913ndash2918 2004

[8] M Imran J Iqbal S Iqbal and N Ijaz ldquoIn vitro antibacte-rial studies of ciprofloxacin-imines and their complexes withCu(II)Ni(II)Co(II) andZn(II)rdquoTurkish Journal of Biology vol31 no 2 pp 67ndash72 2007

[9] G-J Kim and J-H Shin ldquoApplication of new unsymmetricalchiral Mn(III) Co(IIIII) and Ti(IV) salen complexes in enan-tioselective catalytic reactionsrdquo Catalysis Letters vol 63 no 1-2pp 83ndash90 1999

[10] B TThaker P Patel A D Vansadia andH G Patel ldquoSynthesischaracterization and mesomorphic properties of new liquid-crystalline compounds involving ester-azomethine central link-ages lateral substitution and a thiazole ringrdquoMolecular Crystalsand Liquid Crystals vol 466 no 1 pp 13ndash22 2007

[11] N Nishat Asma and S Dhyani ldquoSynthesis spectral andantimicrobial studies of transition metal complexes with novelmacrocyclic ligand containing C=N and COndashNH grouprdquo Jour-nal of Coordination Chemistry vol 62 no 18 pp 3003ndash30112009

[12] P Krishnamoorthy P Sathyadevi K Deepa and N DharmarajldquoStudies on the synthesis spectra catalytic and antibacterialactivities of binuclear ruthenium(II) complexesrdquo Spectrochim-ica Acta AMolecular and Biomolecular Spectroscopy vol 77 no1 pp 258ndash263 2010

[13] V K Ahluwalia B Pooja A Renu and C Ramesh Intermedi-ates for Organic Synthesis IK International Publishing HouseNew Delhi India 1994

[14] K R Joshi J H Pandya and A J Rojivadiya ldquoSpectroscopicstudies and biological evaluation of transition metal complexesof Schiff bases derived from 5-nitro-o-vanillinerdquo ICAIJ vol 4no 3 pp 110ndash114 2009

[15] J H Pandya and K J Ganatra ldquoSynthesis characterizationand biological evaluation of bis-bidentate Schiff base metalcomplexesrdquo Inorganic Chemistry An Indian Journal vol 3 no3 pp 182ndash187 2008

[16] J C Lindon G E Tranter and J L Holmes Encyclopedia ofSpectroscopy and Spectrometry vol 1 Elsevier New York NYUSA 2000

[17] I S Ahmed andM A Kassem ldquoSynthesis solvatochromaticityand bioactivities of some transition metal complexes with

2-(R-benzylideneamino)-pyridin-3-ol Schiff base derivativesrdquoSpectrochimica Acta Part A Molecular and Biomolecular Spec-troscopy vol 77 no 2 pp 359ndash366 2010

[18] K M Vyas R N Jadeja V K Gupta and K R Surati ldquoSyn-thesis characterization and crystal structure of some bidentateheterocyclic Schiff base ligands of 4-toluoyl pyrazolones and itsmononuclear Cu(II) complexesrdquo Journal ofMolecular Structurevol 990 no 1ndash3 pp 110ndash120 2011

[19] A A A Emara ldquoStructural spectral and biological studiesof binuclear tetradentate metal complexes of N

3O Schiff base

ligand synthesized from 46-diacetylresorcinol and diethylene-triaminerdquo Spectrochimica Acta A Molecular and BiomolecularSpectroscopy vol 77 no 1 pp 117ndash125 2010

[20] R N Jadeja and N J Parmar ldquoOxovanadium(IV) Cr(III)Fe(III) Fe(II) Ni(II) Cu(II) Zn(II) and UO

2(VI) chelates

from onno donor Schiff base ligandrdquo Synthesis and Reactivityin Inorganic and Metal-Organic Chemistry vol 35 pp 111ndash1172005

[21] S Kaizaki Y Kato-Igawa T Tsukuda and M Nakano ldquoSyn-thesis and characterization of a series of bis(L-tartrate)-bridgeddinuclear transition metal complexes with 221015840-bipyridinerdquoJournal of Coordination Chemistry vol 63 no 6 pp 967ndash9762010

[22] J H Pandya R N Jadeja andK J Ganatra ldquoSpectral character-ization and biological evaluation of Schiff bases and their mixedligand metal complexes derived from 46-diacetylresorcinolrdquoJournal of Saudi Chemical Society vol 18 no 3 pp 190ndash1992014

[23] B TThaker K R Surati S Oswal R N Jadeja andV K GuptaldquoSynthesis spectral thermal and crystallographic investigationson oxovanadium(IV) and manganese(III) complexes derivedfrom heterocyclic 120573-diketone and 2-amino ethanolrdquo StructuralChemistry vol 18 no 3 pp 295ndash310 2007

[24] M R P Kurup S V Chandra and K Muraleedharan ldquoSynthe-sis spectral and thermal studies of o-vanillin oxime complexesof zinc(II) cadmium(II) and mercury(II)rdquo Journal of ThermalAnalysis and Calorimetry vol 61 no 3 pp 909ndash914 2000

[25] N P Moorjani K M Vyas and R N Jadeja ldquoSynthesis amp char-acterization of cu(ii) complexes derived from acyl pyrazolone amp2-amino phenolrdquo Journal of Pure and Applied Sciences vol 18pp 68ndash72 2010

[26] M H Habibi E Askari M Amirnasr A Amiri Y Yamaneand T Suzuki ldquoSyntheses spectral electrochemical and ther-mal studies of mononuclear manganese(III) complexes withligands derived from 12-propanediamine and 2-hydroxy-3 or5-methoxybenzaldehyde self-assembled monolayer formationon nanostructure zinc oxide thin filmrdquo Spectrochimica Acta AMolecular and Biomolecular Spectroscopy vol 79 no 3 pp 666ndash671 2011

[27] A Cukurovali I Yilmaz S Gur and C Kazaz ldquoSynthesisantibacterial and antifungal activity of some new thiazolylhy-drazone derivatives containing 3-substituted cyclobutane ringrdquoEuropean Journal of Medicinal Chemistry vol 41 no 2 pp 201ndash207 2006

[28] H Unver M Yıldız B Dulger O Ozgend E Kendi and TNuri Durlu ldquoSpectroscopic studies antimicrobial activities andcrystal structures of N-(2-hydroxy-3-methoxybenzalidene)1-aminonaphthalenerdquo Journal of Molecular Structure vol 737 no2-3 pp 159ndash164 2005

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Inorganic ChemistryInternational Journal of

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Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

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Electronic spectra of the metal complexes in DMF wererecorded on a Perkin Elmer Lambda 19 spectrophotometerand molar conductance of the metal complexes was deter-mined on Systronics direct reading conductivity meter typeCM-82T A simultaneous TGDTA was recorded on PerkinElmer Pyris-1 model DSC was carried out on Perkin ElmerPyris-7 instrument Elemental analysis (C H and N) wascarried out on elemental analyzer PERKIN ELMER 2400while analysis ofmetal was also carried out by EDTA titrationmethod in which the metal complex first evaporates in concnitric acid and prepares a stock solution This solution withammonia then titrates against EDTA by using appropriateindicator The MP of ligands was carried out by standardlaboratory thermometer Magnetic susceptibility measure-ments of the complexes were carried out by Gouy balanceusing Hg[Co(CN)

4] as calibrant IR and mass spectra and

elemental analysis of compoundswere done inDepartment ofChemistry Saurashtra University Rajkot TG-DTA-DSC wascarried out in Department of Physics Saurashtra UniversityRajkot 1H NMR and ESI mass spectra of compounds werecarried out in SAIF Chandigarh Electronic spectra andconductance measurement of compounds were done in theDepartment of Chemistry DKV College Jamnagar

22 Preparation of Schiff Base Ligands

221 Synthesis of 2-((24-Dimethylphenylimino)methyl)-6-methoxy-4-nitrophenol (MPM) The Schiff base ligandMPM was synthesized by adding 2-hydroxy-3-methoxy-5-nitrobenzaldehyde (49 g 25mmol) dissolved in hot absoluteEtOH (20 cm3) to 24-dimethylaniline (30 g 250mmol) inabsolute EtOH (20 cm3) The reaction mixture was heatedto reflux for 4 h The products obtained were filtered offand washed several times with EtOH and then ether andair dried The products were kept in desiccators until usedRecrystallization was carried out in EtOH The progress ofreaction was monitored by TLC

222 Synthesis of 2-((34-Difluorophenylimino)methyl)-6-methoxy-4-nitrophenol (FPM) The Schiff base ligandFPM was synthesized by adding 2-hydroxy-3-methoxy-5-nitrobenzaldehyde (49 g 25mmol) dissolved in hot absoluteEtOH (20 cm3) to 34-difluoroaniline (32 g 250mmol) inabsolute EtOH (20 cm3) The reaction mixture was heatedto reflux for 4 h The products obtained were filtered offand washed several times with EtOH and then ether andair dried The products were kept in desiccators until usedRecrystallization was carried out in EtOH The progress ofreaction was monitored by TLC

23 Preparation ofMetal Complexes All themetal complexesof Schiff base ligands were prepared by the followingmethodThe metal salt was dissolved in water and the solution wasadded to a hot ethanolic solution of the corresponding Schiffbases After the complete addition little amount of sodiumacetate was added and the mixture was refluxed for 4 hA crystalline solid was obtained which was isolated by

C

O

H

N C

O

HN

M

R R

OCH3

O2N

H3CO

NO2

R = 24 dimethyl-for MPM and34 difluoro-for FPM ligandM = Ni(II) Cu(II)

Scheme 1 General structure of metal complex

filtration washed with hot water and dried in airThe generalstructure of the metal complexes is given in Scheme 1

24 Antimicrobial Screening All newly synthesized com-pounds were tested for their antibacterial activities againstGram positive bacteria Staphylococcus aureus and Strepto-coccus pyogenes and Gram negative bacteria Escherichia coliand Pseudomonas aeruginosa and antifungal activity againstCandida albicans Aspergillus niger and Aspergillus clavatusThe method used to evaluate the antimicrobial activity wasldquoBroth Dilution Methodrdquo It is one of the nonautomatedin vitro susceptibility tests The MIC (minimal inhibitoryconcentration) of the control organism is read to check theaccuracy of the drug concentrations The lowest concentra-tion inhibiting growth of the organism is recorded as theMIC The MIC values of the newly synthesized compoundshave been compared with the standard drugs ampicillinchloramphenicol nystatin and griseofulvin [14]

3 Results and Discussion

The Schiff base ligands MPM and FPM were prepared by thecondensation of 2-hydroxy-3-methoxy-5-nitrobenzaldehydewith 24-dimethylaniline and 34-difluoroaniline in molarratio 1 1 The formation of Schiff bases and their metalcomplexes were confirmed by various analytical techniquessuch as IR 1H NMR mass and electronic spectra con-ductance and TG-DT analysis Table 1 lists the physical andanalytical data of the Schiff bases and their metal complexesThe antimicrobial activities of Schiff base ligands and metalcomplexes are listed in Tables 2(a) and 2(b)

31 Characterization of the Ligands The IR spectra of Schiffbase ligands are depicted in Figures 1(a) and 1(b) The IRspectra of the ligands show a broad band at 3420ndash3460 cmminus1due to the stretching vibrations of phenolic hydroxyl groupThe broadness is due to intermolecular hydrogen bondingbetween the phenolic group and the azomethine group Thestrong band observed at 1614 cmminus1 is assigned to the stretch-ing vibrations of the azomethine group Two moderately


Table1Th

ephysic


Schiffbase

ligands

andtheirm

etalcomplexes

Ligand

orcomplex

Form

ula

MW

Color

Yield(

)MP


d(calcd)BM

Elem

entalanalysis

foun

d(calcd)

CH

NM

(1)M

PMC 1

6H16N

2O4

300

Yello

w87

210

mdash64

04(6399)

532

(537

)94

0(933

)mdash

(2)F

PMC 1

4H10F 2N

2O4

308

Redd

ishyello

w91

188

mdash5461(5455)

325

(327)

904(909)

mdash(3)[Cu

(MPM

) 2]

C 32H

30Cu

N4O

8662

Deepblue

88gt300

194(173)

5800(5804)

460

(457)

852

(846)

967(960)

(4)[Ni(M

PM) 2]

C 32H

30N

4NiO

8657

Redd

ishgreen

85gt300

280

(282)

5845(5847)

456

(460)

857

(852

)90

0(893)

(5)[Cu

(FPM

) 2]

C 28H

18Cu

F 4N

4O8

676

Deepblue

90gt300

180(173)

4953

(496

0)271

(268)

830

(826)

943(937

)(6)[Ni(F

PM) 2]

C 28H

18F 4N

4NiO

8673

Redd

ishgreen

87gt300

290

(282)

4990(499

6)268

(270)

839

(832

)880

(872)



(a)





(b)





466

4750

681

90

885

897

75

1101

01208

512

796

1330

214

827

1549

116

142

3003

3

3449

2

42 44 46 48 50 52 54 56 58 60 62 64

Tran

smitt

ance

()

500 1000 1500 2000 2500 3000 3500 4000

lowastVN-2 4 ME


(a)

488

761

70

747

281

86

869

597

03

1098

511

468

1203

913

29214

89816

149

2985

230

494

3441

6

16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Tran

smitt

ance

()


lowastVN-3 4 F

(b)







01234567891011121314151617

90 88 86 84 82 80 78 76 74 72 70 68 66 64

111

102

100

110

203

(ppm)

(ppm)

097

111

102

100

110

203

307

301

332


100

90

80

70

60

50

40

30

20

10

40 60 70 90 110 130 150 170 180 200 220 240 260 280 300

mz

308

307290279261

244

232

219203

190

180

166140

129

113

1019579

63

44





1000950900850800750700650600550500450400350300250200150100

700680660640620600580560540520

100

0

100

0

()

()

mz

mz

67621526621

846491151

6471262

63311186181

93

6112148

6091277

5962153

5942318

58901805741

156

5731308

5721 2265591105

5460184

5511

5450503

92

5430940

5361529

5231185

5221563

52011240

67789

6762152

5430940

49012077

47632810

475310154

43201573

386026093601

230027911931

278110144

256131244

24112191

22691949

17303025

13005939

104011420






1g rarr2A1g and

2B1g rarr



0

05

1

15

2

25

3

401

421

441

461

481

501

521

541

561

581

601

621

641

661

681

701

721

741

761

781

Abso

rban

ce

Wave length (nm)

CuNi





750700650600550500450400350300250200150100500

750700650600550500450400350300250200150100500

0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

minus45

minus50

minus55

minus60

minus65

minus70

minus75

minus80

minus85

400

380

360

340

320

300

280

260

240

220

200

180

160

140

120

100

80

60

40

20

0

minus20

180

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

minus10


DTA

-sig

nal (

smoo

thed

) (120583

V) E

xo

dM-r

el (

)


Temperature (∘C)

Hea

t flow

(sm

ooth

ed) (

sm) (

mJs

)






4 Conclusion





Acknowledgments


References






















3O Schiff base



2(VI) chelates



















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


Table1Th

ephysic


Schiffbase

ligands

andtheirm

etalcomplexes

Ligand

orcomplex

Form

ula

MW

Color

Yield(

)MP


d(calcd)BM

Elem

entalanalysis

foun

d(calcd)

CH

NM

(1)M

PMC 1

6H16N

2O4

300

Yello

w87

210

mdash64

04(6399)

532

(537

)94

0(933

)mdash

(2)F

PMC 1

4H10F 2N

2O4

308

Redd

ishyello

w91

188

mdash5461(5455)

325

(327)

904(909)

mdash(3)[Cu

(MPM

) 2]

C 32H

30Cu

N4O

8662

Deepblue

88gt300

194(173)

5800(5804)

460

(457)

852

(846)

967(960)

(4)[Ni(M

PM) 2]

C 32H

30N

4NiO

8657

Redd

ishgreen

85gt300

280

(282)

5845(5847)

456

(460)

857

(852

)90

0(893)

(5)[Cu

(FPM

) 2]

C 28H

18Cu

F 4N

4O8

676

Deepblue

90gt300

180(173)

4953

(496

0)271

(268)

830

(826)

943(937

)(6)[Ni(F

PM) 2]

C 28H

18F 4N

4NiO

8673

Redd

ishgreen

87gt300

290

(282)

4990(499

6)268

(270)

839

(832

)880

(872)



(a)





(b)





466

4750

681

90

885

897

75

1101

01208

512

796

1330

214

827

1549

116

142

3003

3

3449

2

42 44 46 48 50 52 54 56 58 60 62 64

Tran

smitt

ance

()

500 1000 1500 2000 2500 3000 3500 4000

lowastVN-2 4 ME


(a)

488

761

70

747

281

86

869

597

03

1098

511

468

1203

913

29214

89816

149

2985

230

494

3441

6

16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Tran

smitt

ance

()


lowastVN-3 4 F

(b)







01234567891011121314151617

90 88 86 84 82 80 78 76 74 72 70 68 66 64

111

102

100

110

203

(ppm)

(ppm)

097

111

102

100

110

203

307

301

332


100

90

80

70

60

50

40

30

20

10

40 60 70 90 110 130 150 170 180 200 220 240 260 280 300

mz

308

307290279261

244

232

219203

190

180

166140

129

113

1019579

63

44





1000950900850800750700650600550500450400350300250200150100

700680660640620600580560540520

100

0

100

0

()

()

mz

mz

67621526621

846491151

6471262

63311186181

93

6112148

6091277

5962153

5942318

58901805741

156

5731308

5721 2265591105

5460184

5511

5450503

92

5430940

5361529

5231185

5221563

52011240

67789

6762152

5430940

49012077

47632810

475310154

43201573

386026093601

230027911931

278110144

256131244

24112191

22691949

17303025

13005939

104011420






1g rarr2A1g and

2B1g rarr



0

05

1

15

2

25

3

401

421

441

461

481

501

521

541

561

581

601

621

641

661

681

701

721

741

761

781

Abso

rban

ce

Wave length (nm)

CuNi





750700650600550500450400350300250200150100500

750700650600550500450400350300250200150100500

0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

minus45

minus50

minus55

minus60

minus65

minus70

minus75

minus80

minus85

400

380

360

340

320

300

280

260

240

220

200

180

160

140

120

100

80

60

40

20

0

minus20

180

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

minus10


DTA

-sig

nal (

smoo

thed

) (120583

V) E

xo

dM-r

el (

)


Temperature (∘C)

Hea

t flow

(sm

ooth

ed) (

sm) (

mJs

)






4 Conclusion





Acknowledgments


References






















3O Schiff base



2(VI) chelates



















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



(a)





(b)





466

4750

681

90

885

897

75

1101

01208

512

796

1330

214

827

1549

116

142

3003

3

3449

2

42 44 46 48 50 52 54 56 58 60 62 64

Tran

smitt

ance

()

500 1000 1500 2000 2500 3000 3500 4000

lowastVN-2 4 ME


(a)

488

761

70

747

281

86

869

597

03

1098

511

468

1203

913

29214

89816

149

2985

230

494

3441

6

16 18 20 22 24 26 28 30 32 34 36 38 40 42 44 46 48

Tran

smitt

ance

()


lowastVN-3 4 F

(b)







01234567891011121314151617

90 88 86 84 82 80 78 76 74 72 70 68 66 64

111

102

100

110

203

(ppm)

(ppm)

097

111

102

100

110

203

307

301

332


100

90

80

70

60

50

40

30

20

10

40 60 70 90 110 130 150 170 180 200 220 240 260 280 300

mz

308

307290279261

244

232

219203

190

180

166140

129

113

1019579

63

44





1000950900850800750700650600550500450400350300250200150100

700680660640620600580560540520

100

0

100

0

()

()

mz

mz

67621526621

846491151

6471262

63311186181

93

6112148

6091277

5962153

5942318

58901805741

156

5731308

5721 2265591105

5460184

5511

5450503

92

5430940

5361529

5231185

5221563

52011240

67789

6762152

5430940

49012077

47632810

475310154

43201573

386026093601

230027911931

278110144

256131244

24112191

22691949

17303025

13005939

104011420






1g rarr2A1g and

2B1g rarr



0

05

1

15

2

25

3

401

421

441

461

481

501

521

541

561

581

601

621

641

661

681

701

721

741

761

781

Abso

rban

ce

Wave length (nm)

CuNi





750700650600550500450400350300250200150100500

750700650600550500450400350300250200150100500

0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

minus45

minus50

minus55

minus60

minus65

minus70

minus75

minus80

minus85

400

380

360

340

320

300

280

260

240

220

200

180

160

140

120

100

80

60

40

20

0

minus20

180

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

minus10


DTA

-sig

nal (

smoo

thed

) (120583

V) E

xo

dM-r

el (

)


Temperature (∘C)

Hea

t flow

(sm

ooth

ed) (

sm) (

mJs

)






4 Conclusion





Acknowledgments


References






















3O Schiff base



2(VI) chelates



















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


01234567891011121314151617

90 88 86 84 82 80 78 76 74 72 70 68 66 64

111

102

100

110

203

(ppm)

(ppm)

097

111

102

100

110

203

307

301

332


100

90

80

70

60

50

40

30

20

10

40 60 70 90 110 130 150 170 180 200 220 240 260 280 300

mz

308

307290279261

244

232

219203

190

180

166140

129

113

1019579

63

44





1000950900850800750700650600550500450400350300250200150100

700680660640620600580560540520

100

0

100

0

()

()

mz

mz

67621526621

846491151

6471262

63311186181

93

6112148

6091277

5962153

5942318

58901805741

156

5731308

5721 2265591105

5460184

5511

5450503

92

5430940

5361529

5231185

5221563

52011240

67789

6762152

5430940

49012077

47632810

475310154

43201573

386026093601

230027911931

278110144

256131244

24112191

22691949

17303025

13005939

104011420






1g rarr2A1g and

2B1g rarr



0

05

1

15

2

25

3

401

421

441

461

481

501

521

541

561

581

601

621

641

661

681

701

721

741

761

781

Abso

rban

ce

Wave length (nm)

CuNi





750700650600550500450400350300250200150100500

750700650600550500450400350300250200150100500

0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

minus45

minus50

minus55

minus60

minus65

minus70

minus75

minus80

minus85

400

380

360

340

320

300

280

260

240

220

200

180

160

140

120

100

80

60

40

20

0

minus20

180

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

minus10


DTA

-sig

nal (

smoo

thed

) (120583

V) E

xo

dM-r

el (

)


Temperature (∘C)

Hea

t flow

(sm

ooth

ed) (

sm) (

mJs

)






4 Conclusion





Acknowledgments


References






















3O Schiff base



2(VI) chelates



















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


1000950900850800750700650600550500450400350300250200150100

700680660640620600580560540520

100

0

100

0

()

()

mz

mz

67621526621

846491151

6471262

63311186181

93

6112148

6091277

5962153

5942318

58901805741

156

5731308

5721 2265591105

5460184

5511

5450503

92

5430940

5361529

5231185

5221563

52011240

67789

6762152

5430940

49012077

47632810

475310154

43201573

386026093601

230027911931

278110144

256131244

24112191

22691949

17303025

13005939

104011420






1g rarr2A1g and

2B1g rarr



0

05

1

15

2

25

3

401

421

441

461

481

501

521

541

561

581

601

621

641

661

681

701

721

741

761

781

Abso

rban

ce

Wave length (nm)

CuNi





750700650600550500450400350300250200150100500

750700650600550500450400350300250200150100500

0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

minus45

minus50

minus55

minus60

minus65

minus70

minus75

minus80

minus85

400

380

360

340

320

300

280

260

240

220

200

180

160

140

120

100

80

60

40

20

0

minus20

180

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

minus10


DTA

-sig

nal (

smoo

thed

) (120583

V) E

xo

dM-r

el (

)


Temperature (∘C)

Hea

t flow

(sm

ooth

ed) (

sm) (

mJs

)






4 Conclusion





Acknowledgments


References






















3O Schiff base



2(VI) chelates



















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


750700650600550500450400350300250200150100500

750700650600550500450400350300250200150100500

0

minus5

minus10

minus15

minus20

minus25

minus30

minus35

minus40

minus45

minus50

minus55

minus60

minus65

minus70

minus75

minus80

minus85

400

380

360

340

320

300

280

260

240

220

200

180

160

140

120

100

80

60

40

20

0

minus20

180

170

160

150

140

130

120

110

100

90

80

70

60

50

40

30

20

10

0

minus10


DTA

-sig

nal (

smoo

thed

) (120583

V) E

xo

dM-r

el (

)


Temperature (∘C)

Hea

t flow

(sm

ooth

ed) (

sm) (

mJs

)






4 Conclusion





Acknowledgments


References






















3O Schiff base



2(VI) chelates



















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





















3O Schiff base



2(VI) chelates



















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

Research Article Synthesis and Spectroscopic and...

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