Design, Synthesis, and Spectroscopic Study of 7-Azaindolyl ...
Research Article Synthesis and Spectroscopic and ...
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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)
4 International Journal of Inorganic Chemistry
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)
Minimal inhibition concentration (MIC) (gmL)
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
International Journal of Inorganic Chemistry 5
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)
6 International Journal of Inorganic Chemistry
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
International Journal of Inorganic Chemistry 7
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
8 International Journal of Inorganic Chemistry
[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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CatalystsJournal of
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)
4 International Journal of Inorganic Chemistry
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)
Minimal inhibition concentration (MIC) (gmL)
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
International Journal of Inorganic Chemistry 5
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)
6 International Journal of Inorganic Chemistry
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
International Journal of Inorganic Chemistry 7
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
8 International Journal of Inorganic Chemistry
[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
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
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)
4 International Journal of Inorganic Chemistry
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)
Minimal inhibition concentration (MIC) (gmL)
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
International Journal of Inorganic Chemistry 5
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)
6 International Journal of Inorganic Chemistry
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
International Journal of Inorganic Chemistry 7
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
8 International Journal of Inorganic Chemistry
[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
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
4 International Journal of Inorganic Chemistry
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)
Minimal inhibition concentration (MIC) (gmL)
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
International Journal of Inorganic Chemistry 5
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)
6 International Journal of Inorganic Chemistry
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
International Journal of Inorganic Chemistry 7
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
8 International Journal of Inorganic Chemistry
[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
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Inorganic Chemistry 5
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)
6 International Journal of Inorganic Chemistry
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
International Journal of Inorganic Chemistry 7
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
8 International Journal of Inorganic Chemistry
[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
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
6 International Journal of Inorganic Chemistry
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
International Journal of Inorganic Chemistry 7
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
8 International Journal of Inorganic Chemistry
[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
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
International Journal of Inorganic Chemistry 7
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
8 International Journal of Inorganic Chemistry
[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
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of
8 International Journal of Inorganic Chemistry
[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
Submit your manuscripts athttpwwwhindawicom
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Inorganic ChemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
International Journal ofPhotoenergy
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Carbohydrate Chemistry
International Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Advances in
Physical Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom
Analytical Methods in Chemistry
Journal of
Volume 2014
Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Analytical ChemistryInternational Journal of
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
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Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014
SpectroscopyInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014
Medicinal ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Chromatography Research International
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Applied ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Theoretical ChemistryJournal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Spectroscopy
Analytical ChemistryInternational Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Journal of
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Quantum Chemistry
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
Organic Chemistry International
ElectrochemistryInternational Journal of
Hindawi Publishing Corporation httpwwwhindawicom Volume 2014
Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014
CatalystsJournal of