research article synthesis, spectral characterization, and...

Research ArticleSynthesis Spectral Characterization and BiologicalEvaluation of Transition Metal Complexes of Bidentate N ODonor Schiff Bases

Sajjad Hussain Sumrra1 Muhammad Ibrahim2 Sabahat Ambreen3

Muhammad Imran4 Muhammad Danish1 and Fouzia Sultana Rehmani3

1 Department of Chemistry Institute of Chemical and Biological Sciences University of Gujrat Gujrat 50700 Pakistan2Department of Applied Chemistry Government College University Faisalabad 38000 Pakistan3Department of Chemistry University of Karachi Karachi 75270 Pakistan4Department of Chemistry Government Emerson College Multan 60700 Pakistan

Correspondence should be addressed to Fouzia Sultana Rehmani fsrehmaniuokedupk

Received 28 May 2014 Revised 7 July 2014 Accepted 9 July 2014 Published 23 July 2014

Academic Editor Konstantinos Tsipis

Copyright copy 2014 Sajjad Hussain Sumrra et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

New series of three bidentate N O donor type Schiff bases (L1)ndash(L3) were prepared by using ethylene-12-diamine with 5-methylfurfural 2-anisaldehyde and 2-hydroxybenzaldehyde in an equimolar ratio These ligands were further complexed with Co(II)Cu(II) Ni(II) and Zn(II) metals to produce their new metal complexes having an octahedral geometry These compounds werecharacterized on the basis of their physical spectral and analytical data Elemental analysis and spectral data of the uncomplexedligands and their metal(II) complexes were found to be in good agreement with their structures indicating high purity of all thecompounds All ligands and their metal complexes were screened for antimicrobial activity The results of antimicrobial activityindicated that metal complexes have significantly higher activity than corresponding ligands This higher activity might be due tochelation process which reduces the polarity of metal ion by coordinating with ligands

1 Introduction

Schiff bases played an important role as ligands even a centuryafter their discovery in coordination chemistry [1] Schiffbases are derived from the condensation reaction of aro-maticaliphatic aldehydes and aminesThey are an importantclass of organic ligands being extensively studied Schiff basecomplexes of transition metals are still relevant to be of greatinterest in inorganic chemistry although this topic has beenextensively studied [2ndash4]The chelating ability and biologicalapplications of metal complexes have attracted remarkableattention [5] Metal complexes having N O donor atoms arevery important because of their significant biological prop-erties such as antibacterial [6 7] antifungal [8] anticancer[9] and herbicidal [10] activity In view of the significantstructural and biological applications of ethylenediaminecompounds we wish to report the synthesis of a new class of

Schiff bases (L1)ndash(L3) derived from the reaction of ethylene-12-diamine with 5-methyl furfural 2-anisaldehyde and 2-hydroxybenzaldehyde respectively and their Co(II) Cu(II)Ni(II) and Zn(II) metal complexes (1)ndash(12) (Scheme 2) Thecompounds were characterized on the basis of physical prop-erties elemental analysis infrared and UV-visible spectraand antimicrobial activities The Schiff bases and their metalchelates were screened for antibacterial activity against sixbacterial strains Escherichia coli Streptococcus faecalis Pseu-domonas aeruginosa Klebsiella pneumoniae Staphylococcusaureus and Bacillus subtilis and also screened for antifungalactivity against following six fungal strains Trichophytonmentogrophytes Epidermophyton floccosumAspergillus nigerMicrosporum canis Fusarium culmorum and Trichophytonschoenleinii The Schiff bases showed increased antibacte-rial activity against certain strains and their activities wereenhanced on chelation (see Figures 1 and 2)

Hindawi Publishing CorporationBioinorganic Chemistry and ApplicationsVolume 2014 Article ID 812924 10 pageshttpdxdoiorg1011552014812924

2 Bioinorganic Chemistry and Applications

O OHCH3 OCH3

(L1) = R =(L2) = R = (L3) = R =

NR

+

NH2

NH2

H2NRndashCHO

Scheme 1

2 Experimental

21 Materials and Methods Chemicals used were of analyt-ical grade and purchased from commercial sources SigmaAldrich and were used without further purification Allligand synthesis reactions were carried out in solvents thatwere purified and dried before use using standard literaturemethods The redistilled and deionized water was used in allexperiments Gallenkamp apparatus was used to determinemelting points of synthesized ligands and decompositiontemperature of themetal complexes Infrared spectra of solids(in a KBrmatrix) were recorded in the 3700ndash370 cmminus1 regionon a Nicolet FT-IR Impact 400D infrared spectrometer1H and 13CNMR spectra were run on a Bruker Advance300MHz instrument Mass spectrometry work was carriedout by Ms B Woods NUI Maynooth using an AgilentTechnologies 6210 Time-of-Flight LCMS UV spectra wereobtained on a Hitachi UV-3200 spectrophotometer Micro-analysis (C H and N) of the synthesized compoundswas carried out using a CHN Analyzer on Perkin Elmer2400 series II Molar conductances of the transition metalcomplexesweremeasured in 001M inDMF solutionusing anInolab Cond 720 Conductivity Bridge at room temperatureA Stanton SM12S Gouy balance was used to measure themagnetic susceptibility of the metal complexes at roomtemperature by using mercury acetate as a standard

22 Chemistry of Synthesis of Ligands Different aldehydessuch as 5-methyl furfural 2-anisaldehyde and 2-hydroxy-benzaldehyde in methanol (20mL) were added to a refluxedsolution of ethylene-12-diamine in same solvent in anequimolar ratio for 10 minutes followed by 2-3 drops ofacetic acid Then the reaction mixture was refluxed for 6 h bymonitoring through TLCWhen the reaction was completedit was cooled to room temperature filtered and volumereduced to about one-third using rotary evaporatorThe solidproduct thus obtained was filtered washed with methanoland dried It was recrystallized in hot methanolether (2 1)The ligands (L1)ndash(L3) were prepared by following the abovementioned method

221 N-[(E)-(5-Methylfuran-2-yl)methylidene]ethane-12-diam-ine (L1) Yield (112 g 73) mp 175∘C color reddish brown1HNMR (ppm d

6

-DMSO) 235 (s CH3

) 305 (s 2H) 368 (s2H) 485 (s NH

2

) 634 (d 2H) 668 (d 2H) 718 (s HC=N)13CNMR (ppmd

6

-DMSO) 135 430 558 1072 1166 14641533 1626 IR (KBr cmminus1) 3250 (NH

2

) 1632 (HC=N) 1575

0

5

10

15

20

25

30

35

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

SD

Zone

of i

nhib

ition

(m

m)

CompoundsE coliS faecalisP aeruginosa

K pneumoniaeS aureusB subtilis

(L1)

(L2)

(L3)

Figure 1 Comparison of antibacterial activity of Schiff bases versusmetal(II) complexes

0

20

40

60

80

100

120

Inhi

bitio

n (

)

T mentogrophytesE floccosumA niger

M canisF culmorumT schoenleinii(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

SD

Compounds(L

1)

(L2)

(L3)

Figure 2 Comparison of antifungal activity of Schiff bases versusmetal(II) complexes

1545 (C=C) 1090 (CndashO) Mass Spectrum (ESI) [M]+ = 15219Anal calcd for C

8

H12

N2

O (15219) C 6313 H 795 N 1841Found C 6308 H 793 N 1837

222 N-[(E)-(2-Methoxyphenyl)methylidene]ethane-12-diam-ine (L2) Yield (121 g 67) mp 142∘C color dark brown 1HNMR (ppm d

6

-DMSO) 295 (s OCH3

) 315 (s 2H) 385 (s2H) 487 (s NH

2

) 687 (t 1H) 695 (d 1H) 732 (t 1H) 759(d 1H) 878 (s HC=N) 13C NMR (ppm d

6

-DMSO) 442536 563 1147 1229 1237 1296 1345 1605 1623 IR (KBrcmminus1) 3255 (NH

2

) 2920 (OCH3

) 1635 (HC=N) 1577 1543(C=C) Mass Spectrum (ESI) [M]+ = 17823 Anal calcd forC10

H14

N2

O (17823) C 6739 H 792 N 1572 Found C6733 H 788 N 1569

223 2-(E)-[(2-Aminoethyl)imino]methylphenol (L3) Yield(120 g 73) mp 155∘C color (yellow) 1H NMR (ppm d

6

-DMSO) 340 (s 2H) 398 (s 2H) 489 (s NH

2

) 693 (t 1H)711 (d 1H) 743 (t 1H) 772 (d 1H) 885 (s HC=N) 997(s OH) 13C NMR (ppm d

6

-DMSO) 448 529 1184 11951222 1315 1331 1592 1623 IR (KBr cmminus1) 3385 (OH) 3253(NH2

) 1638 (HC=N) Mass Spectrum (ESI) [M]+ = 16420Anal calcd for C

9

H12

N2

O (16420) C 6583 H 737 N 1706Found C 6577 H 732 N 1702

Bioinorganic Chemistry and Applications 3

N O

NO

M

N

N

M

N

O

N

O M

NH2

NH2

NH2

H2O

H2O

O2H

O2H

H2O

OH2

CH3

OCH3 OCH3

H3C

H2N

H2N

H2N

Cl2 Cl2

M = Co Ni Cu ZnMetal complexes (1)ndash(4) of (L1)



Scheme 2

23 Chemistry of Synthesis of the Transition Metal(II) Com-plexes All complexes were prepared according to the follow-ing procedure to a hot magnetically refluxed methanol solu-tion (30mL) of the respective Schiff base ligand (10mmol)a methanol solution (20mL) of respective metal(II) saltchloridesdotnH

2

O (5mmol) was added (119899 = 0 2 or 6) Themixture was refluxed for 3 h during which a precipitatedproduct was formed It was then cooled to room temperaturefiltered and washed with methanol and finally with diethylether The precipitated product thus obtained was dried andrecrystallized in a mixture of hot aqueous methanol (1 2) toobtain TLC pure product

231 Co(II)Metal Complex of (L1) (1) Yield (145 g 62)mp232ndash234∘C IR (KBr) 3465 (H

2

O) 1617 (HC=N) 1074 (CndashO)525 (MndashN) 457 (MndashO) UV (DMSO) 120582max (cm

minus1) 8515 17511and 29982 conductance (Ωminus1 cm2molminus1) 985 BM (120583eff)468 Anal calcd for C

16

H28

N4

O4

CoCl2

(47035) C 4078H 595 N 1191 Co 1253 Found C 4071 H 591 N 1188Co 1248

232 Ni(II) Metal Complex of (L1) (2) Yield (150 g 64)mp 225ndash227∘C IR (KBr) 3474 (H

2

O) 1619 (HC=N) 1077 (CndashO) 527 (MndashN) 454 (MndashO) UV (DMSO) 120582max (cm

minus1) 862317620 25890 and 29895 conductance (Ωminus1 cm2molminus1) 974BM (120583eff) 342 Anal calcd for C16H28N4O4NiCl2 (47011)C 4084 H 595 N 1191 Ni 1248 Found C 4077 H 593N 1186 Ni 1245

233 Cu(II) Metal Complex of (L1) (3) Yield (137 g 58)mp 238ndash240∘C IR (KBr) 3469 (H

2

O) 1616 (HC=N) 1072(CndashO) 523 (MndashN) 454 (MndashO) UV (DMSO) 120582max (cm

minus1)

8515 17511 and 29982 conductance (Ωminus1 cm2molminus1) 989BM (120583eff) 197 Anal calcd for C16H28N4O4CuCl2 (47496)C 4042 H 589 N 1179 Cu 1338 Found C 4034 H 583N 1172 Cu 1331

234 Zn(II) Metal Complex of (L1) (4) Yield (151 g 63)mp 216ndash218∘C 1H NMR (ppm d

6

-DMSO) 246 (s CH3

)315 (s 2H) 383 (s 2H) 498 (s NH

2

) 648 (d 2H) 680(d 2H) 748 (s HC=N) 105 (s 4H H

2

O) 13C NMR (ppmd6

-DMSO) 139 434 564 1079 1177 1476 1546 1638 IR(KBr) 3480 (H

2

O) 1612 (HC=N) 1077 (CndashO) 529 (MndashN)459 (MndashO) UV (DMSO) 120582max (cm

minus1) 28382 conductance(Ωminus1 cm2molminus1) 975 BM (120583eff) diamagnetic Anal calcdfor C16

H28

N4

O4

ZnCl2

(47682) C 4026 H 587 N 1174Zn 1371 Found C 4018 H 583 N 1169 Zn 1366

235 Co(II) Metal Complex of (L2) (5) Yield (155 g 59)mp 248ndash251∘C IR (KBr) 3465 (H

2


minus1) 869017823 and 29622 conductance (Ωminus1 cm2molminus1) 977 BM(120583eff) 455 Anal calcd for C20H32N4O4CoCl2 (52242) C4594 H 612 N 1071 Co 1128 Found C 4588 H 608N 1169 Co 1128


2




Table 1 Antibacterial bioassay of ligands and their metal(II) complexes (zone of inhibition in mm)

Compounds (a) (b) (c) (d) (e) (f) SA(L1) 14 18 16 17 13 17 194(L2) 13 15 18 10 17 15 288(L3) 16 19 14 15 09 14 327(1) 20 14 19 23 16 19 315(2) 15 18 21 14 18 16 253(3) 18 24 18 19 12 16 392(4) 24 21 22 23 21 18 207(5) 26 23 24 23 20 21 214(6) 21 14 17 18 22 16 303(7) 18 15 20 15 19 20 232(8) 17 21 18 19 17 22 210(9) 22 20 19 25 21 22 207(10) 26 22 24 26 23 22 183(11) 22 17 18 12 16 23 405(12) 16 17 15 21 19 17 207SD 30 27 28 29 29 28 105(a) E coli (b) S faecalis (c) P aeruginosa (d) K pneumoniae (e) S aureus (f) B subtilis SD standard drug weaker = 0ndash10mm moderate = 11ndash15mm above15mm = significant and SA = statistical analysis


2


minus1)8705 17215 and 29528 conductance (Ωminus1 cm2molminus1) 977BM (120583eff) 192 Anal calcd for C20H32N4O4CuCl2 (52704)C 4553 H 607 N 1062 Cu 1205 Found C 4548 H 601N 1069 Cu 1201


6

-DMSO) 303 (s OCH3

)322 (s 2H) 393 (s 2H) 496 (s NH

2

) 695 (t 1H)702 (d 1H) 742 (t 1H) 765 (d 1H) 893 (s HC=N)105 (s 4H H

2

O) 13C NMR (ppm d6

-DMSO) 446 539568 1153 1237 1246 1304 1349 1608 1635 IR (KBr)3480 (H

2

O) 1612 (HC=N) 1382 (CndashO) 527 (MndashN) 454(MndashO) UV (DMSO) 120582max (cmminus1) 28538 conductance(Ωminus1 cm2molminus1) 935 BM (120583eff) diamagnetic Anal calcdfor C20

H32

N4

O4

ZnCl2



2


minus1) 858717967 and 29745 conductance (Ωminus1 cm2molminus1) 156 BM(120583eff) 432 Anal calcd for C18H26N4O4Co (42136) C 5131H 622 N 1330 Co 1399 Found C 5122 H 616 N 1324Co 1392


2


minus1) 859917645 25661 and 29717 conductance (Ωminus1 cm2molminus1) 142BM (120583eff) 339 Anal calcd for C18H26N4O4Ni (42112) C

5134 H 622 N 1330 Ni 1394 Found C 5126 H 619 N1326 Ni 1388


2


minus1)8670 17371 and 29732 conductance (Ωminus1 cm2molminus1) 134BM (120583eff) 193 Anal calcd for C18H26N4O4Cu (42596) C5075 H 615 N 1315 Cu 1492 Found C 5068 H 611 N1310 Cu 1485

2312 Zn(II) Metal Complex of (L3) (12) Yield (151 g 71)mp 239ndash241∘C 1HNMR (ppm d

6

-DMSO) 354 (s 2H) 414(s 2H) 40 (s NH

2

) 709 (t 1H) 734 (d 1H) 755 (t 1H) 787(d 1H) 898 (s HC=N) 105 (s 4HH

2

O) 13CNMR (ppmd6

-DMSO) 452 535 1187 1197 1227 1319 1335 1597 1629 IR(KBr) 3480 (H

2



H26

N4

O4

Zn (42783) C 5053 H 613 N 1310 Zn1529 Found C 5045 H 609 N 1305 Zn 1522

24 Biological Activity

241 In Vitro Antibacterial Activity All newly synthesizedSchiff bases (L1)ndash(L3) and their transition metal(II) com-plexes (1)ndash(12) were screened for their in vitro antibacterialactivity against (Escherichia coli Streptococcus faecalis Pseu-domonas aeruginosa Klebsiella pneumoniae Staphylococcusaureus and Bacillus subtilis) bacterial strains by the agar-well diffusion method [11] and recorded in Table 1 Smallportion (10mL) of nutrient broth was inoculated with thetest organisms and incubated at 37∘C for 24 h Using a sterile


Table 2 Antifungal bioassay of ligands and their metal(II) complexes ( inhibition)

Compounds (a) (b) (c) (d) (e) (f) SA(L1) 43 57 00 45 48 49 2033(L2) 58 50 41 00 55 39 2121(L3) 49 46 55 42 38 60 816(1) 55 65 18 58 56 59 1694(2) 65 57 55 11 71 41 2164(3) 44 60 68 43 49 15 1822(4) 73 62 39 58 67 55 1171(5) 60 71 78 66 57 74 816(6) 61 00 63 55 67 42 2507(7) 63 72 59 28 56 68 1565(8) 58 70 35 56 42 63 1313(9) 69 38 56 60 55 00 2484(10) 63 72 78 75 61 70 668(11) 56 67 38 40 55 36 1248(12) 43 55 34 70 49 62 1301(a)Tmentogrophytes (b) E floccosum (c)A niger (d)M canis (e) Fculmorum (f)T schoenleinii weaker = 0ndash30moderate = 31ndash54 55ndash100= significantand SA = statistical analysis

pipette 06mL of the broth culture of the test organismwas added to 60mL of molten agar which had been cooledto 45∘C mixed well and poured into a sterile petri dishDuplicate plates of each organism were prepared The agarwas allowed to set and harden and the required numbersof holes were cut using a sterile cork borer ensuring properdistribution of holes on the border and one in the centerAgar plugs were removed Different cork borers were used fordifferent test organisms Using a 01mL pipette 100120583L of thetest sample dissolved in an appropriate solvent was pouredinto appropriately labelled cups The same concentrations ofthe standard antibacterial agent (streptomycin in 1mgmL)and the solvent (as control) were used The plates were left atroom temperature for 2 h to allow diffusion of the sample andincubated face upwards at 37∘C for 24 h The diameter of thezones of inhibition was measured to the nearest mm

242 In Vitro Antifungal Activity Antifungal activities of allcompounds were studied against six fungal strainsTrichophy-ton mentogrophytes Epidermophyton floccosum Aspergillusniger Microsporum canis Fusarium culmorum and Tri-chophyton schoenleinii according to recommended procedure[12] and recorded in Table 2 Test sample was dissolved insterile DMSO to serve as stock solution Sabouraud dextroseagar was prepared by mixing Sabouraud 4 glucose agar andagar in distilled water It was then stirred with a magneticstirrer to dissolve it and a known amount was dispensed intoscrew capped test tubes Test tubes containing media wereautoclaved at 121∘C for 15min Tubes were allowed to cool to50∘C and the test sample of desired concentrations pipettedfrom the stock solution into the nonsolidified Sabouraudagar media Tubes were then allowed to solidify in a slantingposition at room temperature Each tube was inoculated witha 4mm diameter piece of inoculum removed from a seven-day-old culture of fungi

243 Minimum Inhibitory Concentration (MIC) Com-pounds containing promising antibacterial activity wereselected for minimum inhibitory concentration (MIC) stud-ies [13] The minimum inhibitory concentration was deter-mined using the disc diffusion technique by preparing discscontaining 10 25 50 and 100 120583gmLminus1 concentrations of thecompounds along with standards at the same concentrations

3 Results and Discussion

The condensation of ethylene-12-diamine and 5-methylfurfural 2-anisaldehyde and 2-hydroxybenzaldehyde in 1 1molar ratio afforded three Schiff base ligands (L1)ndash(L3)(Scheme 1) These ligands were air and moisture stable com-pounds All of them were colored compounds These weremicrocrystalline solids which melted at 145ndash175∘C All weresoluble in DMSO and DMF at room temperature and solubleon heating in methanol and ethanol

These bidentate ligands reacted readily with Co(II)Cu(II) Ni(II) and Zn(II) metals as their chlorides[CoCl

2

sdot6H2

O NiCl2

sdot6H2

O CuCl2

sdot2H2

O and ZnCl2

]in methanol to form their metal(II) complexes (Scheme 2)All the synthesized metal(II) complexes were intenselycolored except Zn(II) complexes which were white and allcomplexes were microcrystalline in nature The metal(II)complexes decomposed without melting They were allinsoluble in common organic solvents such as ethanolmethanol dichloromethane and acetone but soluble inDMSO and DMF

The spectral data and elemental analysis of the preparedligands and their metal(II) complexes were in good agree-ment with their structure indicating the high purity of all thecompounds The analytical data of the complexes indicated a1 2 metal ligand stoichiometry


31 IR Spectra These ligands can coordinate through theazomethine-N furanyl-O methoxy-O and oxygen atomfrom the deprotonation of the phenolic group Some of thecharacteristic IR spectral data were reported in experimentalpartThe ligands (L1)ndash(L3) displayed band at 3250ndash3255 cmminus1resulting from NH

2

vibrations [14] The ligand (L3) showedband resulting from OH vibrations [15] at 3385 cmminus1 How-ever the IR spectra of the ligand (L2) demonstrated vibrationsat 2920 cmminus1 due to OCH

3

stretching [16] The Schiff bases(L1)ndash(L3) possessed the characteristic azomethine (HC=N)stretching [17] at 1632ndash1638 cmminus1 hence giving clue of con-densation product The ligand (L1) showed the bands at1090 cmminus1 due to (CndashO) vibrations [18] The comparisonof the IR spectra of the Schiff bases (L1)ndash(L3) with theirmetal(II) complexes (1)ndash(12) indicated that the Schiff baseswere principally coordinated to themetal(II) ions bidentatelyThe IR bands of azomethine group appearing in Schiff basescomplexes shifted to lower frequency (10ndash15 cmminus1) at 1612ndash1623 cmminus1 confirming the coordination of the azomethinenitrogen [19] with the metal(II) atoms IR bands at 3250ndash3255 cmminus1 resulting from NH

2

vibrations of ligands (L1)ndash(L3) remained unchanged in all the complexes showing theirno involvement in the coordinationThe following evidencesfurther support the mode of chelation

(i) Appearance of the new bands in their metal com-plexes at 520ndash539 and 441ndash465 cmminus1 which wereassigned to v(MndashN) [20] and v(MndashO) vibrationsrespectively and these bands were absent in theiruncomplexed ligands

(ii) The (CndashO) vibrations of ligand (L1) at 1090 cmminus1were shifted to lower frequency 1072ndash1077 cmminus1 in themetal(II) complexes (1)ndash(4) This in turn supportedthe evidence of the participation of heteroatom-O inthe coordination

(iii) Appearance of the new bands at 1377ndash1383 cmminus1 dueto v(CndashO) vibrations in the metal(II) complexes (5)ndash(8) indicated the coordination of OCH

3

group withthe metal atoms [21]

(iv) The disappearance of ](OH) band at 3385 cmminus1 in(8)ndash(12) complexes and appearance of new bands at1375ndash1381 cmminus1 due to the ](CndashO) stretching modein the complexes revealed the deprotonation of thehydroxyl OH group found in the ligand (L3) It inturn indicated that the proton of the OH groupwas replaced by the metal ions in the formation ofcomplexes

(v) All the metal(II) complexes displayed new broadpeaks at 3465ndash3480 cmminus1 which were assigned towater molecules

These new bands were only observed in the spectra of thecomplexes but absent in the spectra of the Schiff basesTherefore these clues supported the evidence of the par-ticipation of heteroatom-O deprotonation of benzilidene-Oand azomethine-N in the coordination All these evidencescompromise with the complexation of the metal(II) ions tothe prepared Schiff bases

32 1119867 NMR Spectra 1H NMR spectra of the Schiff basesand their diamagnetic Zn(II) complexes were recorded inDMSO-d

6

1H NMR spectral data of the Schiff bases (L1)ndash(L3) and their diamagnetic Zn(II) complexes are provided inthe experimental section The 1H NMR spectra of the Schiffbase ligands (L1)ndash(L3) demonstrated characteristic amino(NH2) and azomethine (CH=N) protons at 485ndash489 and718ndash885 ppm as a singlet respectively The (CH

3

) protons ofthe ligands (L1) were observed at 235 ppm as a singlet The(OCH3) proton present in the ligand (L2) was observed at295 ppm as a singlet The (CH2) protons present in all theligands (L1)ndash(L3)were observed at 305ndash398 ppm as a singletIn case of the ligand (L3) the OndashH proton was observed at997 ppm as a singlet The furan protons of ligand (L1) werefound at 634ndash668 ppm as a doublet The phenyl protonsfound in ligands (L2) and (L3) were found at 687ndash775 ppmas a doublet double doublet and triplet

The coordination of the azomethine (HC=N) nitrogenwas assigned by the downfield shifting of the azomethineproton signal from 718ndash885 in fee ligands to 878ndash888 ppmin their Zn(II) complexes respectively This downfield shift-ing of azomethine proton in Zn(II) complexes was attributedto the discharging of electronic cloud towards the Zn(II)ion The hydroxyl (OH) proton at 997 ppm in the ligand(L3) disappeared in the spectra of its Zn(II) complexesindicating deprotonation and coordination of the oxygenwith the metal ion All other protons underwent downfieldshift by 07ndash030 ppm owing to the increased conjugation oncomplexation with the zinc metal atom Thus the number ofprotons calculated from the integration curves [22 23] andobtained values of the expected CHN analysis agreed wellwith each other

33 13119862 NMR Spectra 13C NMR spectra of the Schiff basesand their diamagnetic Zn(II) complexes were recorded inDMSO-d

6

The 13C NMR spectral data are reported alongwith their possible assignments in the Experimental sectionand all the carbons were found in the expected regionsThe 13CNMR spectra of the Schiff base ligands (L1)ndash(L3)showed characteristic azomethine (CH=N) carbons at 1617ndash1639 ppm The (CH

3

) (CH2

) and (OCH3

) carbons of theligands were observed at 135 430ndash558 and 563 ppmrespectively All the furanyl and phenyl carbons were foundat 1072ndash1605 ppm

Downfield shifting of the azomethine carbons from 1205751617ndash1639 ppm in the free ligands to 1629ndash1638 ppm in itsZn(II) complexes was due to shifting of electronic densitytowards the Zn(II) ion Similarly all carbons of hetero-aromatic and phenyl rings being near to the coordinationsites also showed downfield shifting by 010ndash060 ppm dueto the increased conjugation and coordination with themetal atoms The downfield shifting also confirmed thecoordination of the azomethine to the zinc metal atomMoreover the presence of the number of carbons is well inagreement with the expected values [24 25] Furthermorethe conclusions drawn from these studies present furthersupport to the modes of bonding discussed in their IR and1H NMR spectra


34 Mass Spectra The mass fragmentation pattern of theligands (L1)ndash(L3) followed the cleavage of C=N (exocyclic)C=C and CndashO bonds The mass spectral data and the moststable fragmentation values of the ligands were depicted inExperimental section All the ligands showed pronouncedmolecular ion peaks The data of the Schiff bases shown bymass spectra strongly confirmed the formation of the ligandspossessing proposed structures and also their bonding pat-tern

35 Molar Conductances Molar conductance studies of thecomplexes were carried out in DMF The data of molar con-ductances (935ndash987 ohmminus1 cm2molminus1) of metal(II) com-plexes (1)ndash(8) showed that these complexes were electrolytic[26] in nature The metal(II) complexes (9)ndash(12) exhibitedconductances in the range 131ndash159 thus indicating theirnonelectrolytic [27 28] nature

36 Magnetic Measurements The magnetic moment (BM)values of all the metal(II) complexes (1)ndash(12) were obtainedat room temperature The observed magnetic momentvalues of Co(II) complexes were found in the range of432ndash468 BM indicating the Co(II) complexes as high-spin suggesting three unpaired electrons in an octahedralenvironment [29] The Ni(II) complexes showed magneticmoment values in the range of 339ndash355 BM indicativeof two unpaired electrons per Ni(II) ion suggesting thesecomplexes to have an octahedral [30] geometry The mea-sured magnetic moment values 193ndash197 BM for Cu(II)complexes are indicative of one unpaired electron per Cu(II)ion for d9-system suggesting octahedral [31] geometry Allthe Zn(II) complexes were found to be diamagnetic [32] asexpected

37 Electronic Spectra The electronic spectra of Co(II) com-plexes generally exhibited [33] three absorption bands inthe regions 8515ndash8690 17511ndash17967 and 29542ndash29982 cmminus1which may be assigned to 4T

1

grarr 4T2

g(F) 4T1

grarr 4A2

g(F)and 4T

1

grarr 4Tg(P) transitions respectively and are sug-gestive of octahedral geometry around the Co(II) ion Theelectronic spectral data of Ni(II) complexes showed [34] thebands in the regions 8599ndash8762 17620ndash17850 and 25661ndash25890 cmminus1 assigned respectively to the d-d transitions of3A2

g(F)rarr 3T2

g(F) and 3A2

g(F)rarr 3T1

g(F) Also a strongband due to metal to ligand charge transfer appeared at29675ndash29895 cmminus1 The electronic spectra of all the Cu(II)complexes exhibited [35] absorption bands in the regionat 8515ndash8737 and 17215ndash17672 cmminus1 which may be assignedto the transitions 2Egrarr 2T

2

g The high energy band at29528ndash29982 cmminus1 was due to forbidden ligand to metalcharge transfer On the basis of electronic spectra octahedralgeometry around the Cu(II) ion was suggested The Zn(II)complexes did not show any d-d transition thus showingdiamagnetic nature and their spectra were dominated onlyby a charge transfer band [36] at 28382ndash28653 cmminus1

38 Biological Evaluation

381 Antibacterial Bioassay (In Vitro) The newly synthe-sized Schiff bases (L1)ndash(L3) and their metal(II) complexes(1)ndash(12) have been subjected for the screening of their invitro antibacterial activity against Escherichia coli Strepto-coccus faecalis Pseudomonas aeruginosa Klebsiella pneumo-niae Staphylococcus aureus and Bacillus subtilis bacterialstrains according to standard procedure [11] and results werereported in Table 1 The obtained results were comparedwith those of the standard drug streptomycin The synthe-sized ligand (L1) exhibited a significant (16ndash18mm) activ-ity against Streptococcus faecalis Pseudomonas aeruginosaKlebsiella pneumoniae and Bacillus subtilis bacterial strainsandmoderate (13-14mm) activity against Escherichia coli andStaphylococcus aureus The ligand (L2) showed a significant(17-18mm) activity against Pseudomonas aeruginosa andStaphylococcus aureus moderate (13-14mm) activity againstEscherichia coli Streptococcus faecalis and Bacillus subtilisand weaker (10mm) against Klebsiella pneumoniae Theligand (L3) demonstrated a significant (16ndash19mm) activityagainst Escherichia coli and Streptococcus faecalis moderate(11ndash15mm) against Pseudomonas aeruginosa Klebsiella pneu-moniae and Bacillus subtilis and weaker (09mm) activity byStaphylococcus aureusThemetal complexes (4) (5) and (8)ndash(10) displayed overall significant (ge16mm) activity againstall the bacterial strains Compounds (1)ndash(3) exhibited overalla significant (16ndash20mm) activity against all bacterial strainsexcept Streptococcus faecalis and Staphylococcus aureus of(1) Escherichia coli and Klebsiella pneumoniae of (2) andStaphylococcus aureus of (3) which possessed moderate (12ndash15mm) activity Beside this the compounds (6) (7) and(9) exhibited overall a significant (16ndash24mm) activity againstall bacterial strains except Streptococcus faecalis of (6) andStreptococcus faecalis and Klebsiella pneumoniae of (7) whichpossessedmoderate (14-15mm) activity Also compound (11)showed significant (15ndash22mm) activity against Escherichiacoli Streptococcus faecalis Pseudomonas aeruginosa Kleb-siella pneumoniae and Staphylococcus aureus and moderate(13mm) activity was shown against Klebsiella pneumoniaeCompound (12) exhibited significant (15ndash21mm) activityagainst Escherichia coli Streptococcus faecalisKlebsiella pneu-moniae Staphylococcus aureus and Bacillus subtilis exceptPseudomonas aeruginosa which possessed moderate (11ndash14mm) activity

382 Antifungal Bioassay (In Vitro) The antifungal screen-ing of all compounds was carried out against Trichophytonmentogrophytes Epidermophyton floccosumAspergillus nigerMicrosporum canis Fusarium culmorum and Trichophytonschoenleinii fungal strains (Table 2) according to the litera-ture protocol [12] The results of inhibition were comparedwith the results of standard drugs miconazole and ampho-tericin B The ligand (L1) possessed significant (57) activityagainst Epidermophyton floccosum fungal strain moderate(37ndash49) againstTrichophytonmentogrophytesMicrosporumcanis Fusarium culmorum and Trichophyton schoenleiniibut no activity against Aspergillus niger The ligand (L2)


Table 3 Minimum inhibitory concentration (120583gmL) of the selected compounds (3)ndash(5) and (9)ndash(12) against selected bacteria

Number E coli S faecalis P aeruginosa K pneumoniae S aureus B subtilis(3) mdash 5264 mdash mdash mdash mdash(4) 4568 mdash mdash mdash mdash mdash(5) 5217 3316 3534 mdash mdash mdash(9) mdash mdash mdash 5122 mdash mdash(10) 3834 4721 4441 3367 mdash mdash(11) mdash mdash mdash mdash mdash 4926(12) 5341 3567 4394 3211 4033 4782

showed significant (55ndash58) activity against Trichophytonmentogrophytes and Fusarium culmorum and moderate (39ndash50) activity against Epidermophyton floccosum Aspergillusniger and Trichophyton schoenleinii and it was inactiveagainst Microsporum canis However (L3) exhibited signif-icant (55ndash60) activity against Fusarium culmorum andAspergillus niger but showed moderate (38ndash49) activityagainst Trichophyton mentogrophytes Epidermophyton floc-cosum Microsporum canis and Trichophyton schoenleiniiThe compound (1) showed significant (55ndash65) activityagainst all fungal strains except Aspergillus niger strain whichhad weaker (18) activity Similarly compound (2) alsopossessed significant (55ndash71) activity against Trichophy-ton mentogrophytes Epidermophyton floccosum Aspergillusniger and Fusarium culmorum and moderate (41) activityagainst Trichophyton schoenleinii but weaker (11) activ-ity against Microsporum canis As well the compound (3)displayed significant (60ndash68) activity against Epidermo-phyton floccosum and Aspergillus niger moderate (43ndash49)against Trichophyton mentogrophytes Microsporum canisand Fusarium culmorum and also weaker (15) activityagainstTrichophyton schoenleiniiThe compounds (4) and (5)similarly possessed significant (55ndash74) activity against allfungal strains exceptAspergillus niger strain of compound (4)which observed moderate (39) activity The compound (6)exhibited significant (55ndash72) activity against Trichophytonmentogrophytes Aspergillus niger Microsporum canis andFusarium culmorum fungal strains but strain Trichophy-ton schoenleinii showed moderate (42) activity and wasinactive against Epidermophyton floccosum Besides this thecompound (7) demonstrated significant (56ndash75) activityagainst all strains except Microsporum canis which hadweaker (28) activity The compound (8) showed significant(56ndash70) activity against Trichophyton mentogrophytes Epi-dermophyton floccosum Microsporum canis and Trichophy-ton schoenleinii and also moderate (35ndash42) activity wasobserved against Aspergillus niger and Fusarium culmorumrespectively The compound (9) showed significant (55ndash69) activity againstTrichophytonmentogrophytesMicrospo-rum canis Aspergillus niger and Fusarium culmorum andmoderate (38) activity against Epidermophyton floccosumand it was inactive against Trichophyton schoenleinii Onthe contrary the compound (10) exhibited significant (61ndash78) activity against all fungal strains The compound(11) presented significant (55ndash67) activity against Tri-chophyton mentogrophytes Epidermophyton floccosum and

Fusarium culmorum fungal strains and other left behindstrains Aspergillus niger Microsporum canis and Trichophy-ton schoenleinii showed moderate (36ndash40) activity Sim-ilarly the compound (12) showed significant activity (55ndash70) against Epidermophyton floccosumMicrosporum canisand Trichophyton schoenleinii although left behind strainsTrichophytonmentogrophytesAspergillus niger and Fusariumculmorumdisplayedmoderate (34ndash49) activity It is obviousfrom the data reported in Table 2 that (L3) showed overallgood fungal activity as compared to other two ligands TheNi(II) complex (10) of (L3) was found to be the most activecomplex The metal(II) complexes showed enhanced activityresults rather than their uncomplexed Schiff bases due tocomplexation

383 Minimum Inhibitory Concentration (MIC) The syn-thesized ligands and their transition metal(II) complexesshowing promising antibacterial activity (above 80) wereselected for MIC studies and obtained results are reportedin Table 3 The antibacterial results indicated that all themetal(II) complexes (3)ndash(5) and (9)ndash(12) were found todisplay activity more than 80 therefore these complexeswere selected for their MIC screening The MIC values ofthese compounds fall in the range 3211 to 5341 120583gmLAmongst these the compound (12) was found to be the mostactive possessing maximum inhibition 3211 120583gmL againstbacterial strain K pneumoniae

4 Conclusions

Three bidentate N O donor type Schiff bases were preparedby using ethylene-12-diamine with 5-methyl-2-furaldehyde2-anisaldehyde and 2-hydroxybenzaldehyde in an equimolarratio These ligands were further complexed with transitionmetals to produce their new metal complexes Elementalanalysis and spectral data of the uncomplexed ligands andtheir metal(II) complexes were found to be in good agree-ment with their structures indicating high purity of all thecompounds All ligands and their metal complexes werescreened for antimicrobial activity The results of antimi-crobial activity indicated that metal complexes have signifi-cantly higher activity than corresponding ligandsThis higheractivity might be due to chelation process which reduces thepolarity of metal ion by coordinating with ligands


Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper and are responsiblefor the contents and writing of the paper

Acknowledgments

The authors are thankful to HEJ Research Institute ofChemistry International Center for Chemical and BiologicalSciences University of Karachi Pakistan for providing theirhelp in taking NMR and mass spectra and for the help incarrying out antibacterial and antifungal bioassay

References

[1] V Ambike S Adsule F Ahmed et al ldquoCopper conjugates ofnimesulide Schiff bases targeting VEGF COX and Bcl-2 inpancreatic cancer cellsrdquo Journal of Inorganic Biochemistry vol101 no 10 pp 1517ndash1524 2007

[2] N H Patel H M Parekh and M N Patel ldquoSynthesischaracterization and biological evaluation of manganese(II)cobalt(II) nickel(II) copper(II) and cadmium(II) complexeswithmonobasic (NO) andneutral (NN) Schiff basesrdquoTransitionMetal Chemistry vol 30 no 1 pp 13ndash17 2005

[3] Y J Thakor S G Patel and K N Patel ldquoSynthesis characteri-zation and biocidal studies of some transition metal complexescontaining tetra dentate and neutral bi dentate schiff baserdquoJournal of Chemical and Pharmaceutical Research vol 2 no 5pp 518ndash525 2010

[4] R Ramesh P K Suganthy andK Natarajan ldquoSynthesis spectraand electrochemistry of Ru(III) complexes with tetradentateschiff basesrdquo Synthesis and Reactivity in Inorganic and Metal-Organic Chemistry vol 26 no 1 pp 47ndash60 1996

[5] M M Abd-Elzaher ldquoSpectroscopic characterization of sometetradentate schiff bases and their complexes with nickelcopper and zincrdquo Journal of the Chinese Chemical Society vol48 no 2 pp 153ndash158 2001

[6] A A Jarrahpour M Motamedifar K Pakshir N Hadi and MZarei ldquoSynthesis of novel azo Schiff bases and their antibacterialand antifungal activitiesrdquo Molecules vol 9 no 10 pp 815ndash8242004

[7] P Nagababu J N Latha P Pallavi S Harish and S Satyanara-vana ldquoStudies on antimicrobial activity of cobalt(III) ethylene-diamine complexesrdquo Canadian Journal of Microbiology vol 52no 12 pp 1247ndash1254 2006

[8] K Sasikala and S Arunachalam ldquoAntimicrobial activityspectral studies and micellar properties of some surfactant-cobalt(III) complexesrdquo Chemical Science Transactions vol 2supplement 1 pp S157ndashS166 2013

[9] J M Lazic L Vucicevic S Grguric-Sipka et al ldquoSynthesisand in vitro anticancer activity of octahedral platinum(IV)complexes with cyclohexyl-functionalized ethylenediamine-NN1015840-diacetate- type ligandsrdquo ChemMedChem vol 5 no 6 pp881ndash889 2010

[10] M H K Mostafa H I Eman G M Gehad M Z Ehab and BAhmed ldquoSynthesis and characterization of a novel schiff basemetal complexes and their application in determination of ironin different types of natural waterrdquo Open Journal of InorganicChemistry vol 2 no 2 pp 13ndash21 2012

[11] A U Rahman M I Choudhary and W J Thomsen BioassayTechniques for Drug Development HarwoodAcademic Publish-ers Amsterdam The Netherlands 2001

[12] A U Rahman M I Choudhary and W J Thomsen BioassayTechniques for Drug Development Harwood Academic Ams-terdam The Netherlands 2001

[13] J L McLaughlin C-J Chang and D L Smith ldquoldquoBench Toprdquobioassays for the discovery of bioactive natural products anupdate structure and chemistry (part-B)rdquo in Studies in NaturalProducts Chemistry Atta-ur-Rahman Ed vol 9 p 383 ElsevierScience Amsterdam The Netherlands 1991

[14] B S Holla M Mahalinga M S Karthikeyan B Poojary PM Akberali and N S Kumari ldquoSynthesis characterizationand antimicrobial activity of some substituted 123-triazolesrdquoEuropean Journal of Medicinal Chemistry vol 40 no 11 pp1173ndash1178 2005

[15] P Noblıa M Vieites B S Parajon-Costa et al ldquoVanadium(V)complexes with salicylaldehyde semicarbazone derivativesbearing in vitro anti-tumor activity toward kidney tumor cells(TK-10) crystal structure of [V119881O

2

(5-bromosalicylaldehydesemicarbazone)]rdquo Journal of Inorganic Biochemistry vol 99 no2 pp 443ndash451 2005

[16] G B Bagihalli P S Badami and S A Patil ldquoSynthesis spectralcharacterization and in vitro biological studies of Co(II) Ni(II)andCu(II) complexes with 124-triazole Schiff basesrdquo Journal ofEnzyme Inhibition and Medicinal Chemistry vol 24 no 2 pp381ndash394 2009

[17] Y Prashanthi and S Raj ldquoSynthesis and characterization oftransition metal complexes with NONN and SN-donorSchifff base ligandsrdquo Journal of Scientific Research vol 2 no 1pp 114ndash126 2010

[18] A D Shinde B Y Kale B B Shingate and M S ShingareldquoSynthesis and characterization of 1-benzofuran-2-yl thiadi-azoles triazoles and oxadiazoles by conventional and non-conventional methodsrdquo Journal of the Korean Chemical Societyvol 54 no 5 pp 582ndash588 2010

[19] S H Sumrra and Z H Chohan ldquoMetal based new triazolestheir synthesis characterization and antibacterialantifungalactivitiesrdquo Spectrochimica Acta A Molecular and BiomolecularSpectroscopy vol 98 pp 53ndash61 2012

[20] M Hanif and Z H Chohan ldquoDesign spectral characterizationand biological studies of transition metal(II) complexes withtriazole Schiff basesrdquo Spectrochimica Acta A Molecular andBiomolecular Spectroscopy vol 104 pp 468ndash476 2013

[21] Z H Chohan and S H Sumrra ldquoSynthesis characterizationand biological studies of oxovanadium (IV) complexes withtriazole-derived Schiff basesrdquo Applied Organometallic Chem-istry vol 24 no 2 pp 122ndash130 2010

[22] R A Nyquist Interpreting Infrared Raman and Nuclear Mag-netic Resonance Spectra vol 2 Academic Press New York NYUSA 2001

[23] H Gunther NMR Spectroscopy Basic Principles Concepts andApplications in Chemistry JohnWileyamp Sons 2nd edition 1995

[24] R A Freeman Handbook of Nuclear Magnetic ResonanceLongman Essex UK 2nd edition 1997

[25] M Levitt SpinDynamics Basics of NuclearMagnetic ResonanceJohn Wiley amp Sons 2001

[26] W J Geary ldquoThe use of conductivity measurements in organicsolvents for the characterisation of coordination compoundsrdquoCoordination Chemistry Reviews vol 7 no 1 pp 81ndash122 1971


[27] I S Raja M Christudhas and G A G Raj ldquoSynthesis charac-terizationmetal ion intake and antibacterial activity of cardanolbased polymeric Schiff base transition metal complexes usingEthylenediaminerdquo Journal of Chemical and PharmaceuticalResearch vol 3 no 6 pp 127ndash135 2011

[28] J Liu B Wu B Zhang and Y Liu ldquoSynthesis and characteriza-tion ofmetal complexes of Cu(II) Ni(II) Zn(II) Co(II) Mn(II)and Cd(II) with tetradentate schiff basesrdquo Turkish Journal ofChemistry vol 30 no 1 pp 41ndash48 2006

[29] S Sarkar and K Dey ldquoSynthesis and spectroscopic characteri-zation of some transitionmetal complexes of a new hexadentateN2

S2

O2

Schiff base ligandrdquo Spectrochimica Acta A Molecularand Biomolecular Spectroscopy vol 62 no 1-3 pp 383ndash3932005

[30] K Serbest H Kayi M Er K Sancak and I DegirmenciogluldquoNi(II) Cu(II) and Zn(II) complexes of tetradentate schiff basecontaining two thiadiazoles units Structural spectroscopicmagnetic properties and molecular modeling studiesrdquo Het-eroatom Chemistry vol 19 no 7 pp 700ndash712 2008

[31] R M El-Shazly G A A Al-Hazmi S E Ghazy M S El-Shahawi and A A El-Asmy ldquoSpectroscopic thermal andelectrochemical studies on some nickel(II) thiosemicarbazonecomplexesrdquo Spectrochimica Acta A Molecular and BiomolecularSpectroscopy vol 61 no 1-2 pp 243ndash252 2005

[32] S Chandra and L K Gupta ldquoEPR mass IR electronic andmagnetic studies on copper (II) complexes of semicarbazonesand thiosemicarbazonesrdquo Spectrochimica Acta A vol 61 no 1-2 pp 269ndash275 2005

[33] Z H Chohan and H A Shad ldquoMetal-based new sulfonamidesdesign synthesis antibacterial antifungal and cytotoxic prop-ertiesrdquo Journal of Enzyme Inhibition and Medicinal Chemistryvol 27 no 3 pp 403ndash412 2012

[34] H Temel U Cakir B Otludil and H I Ugras ldquoSynthesisspectral and biological studies of Mn(II) Ni(II) Cu(II) andZn(II) complexes with a tetradentate Schiff base ligand Com-plexation studies and the determination of stability constants(Ke)rdquo Synthesis and Reactivity in Inorganic and Metal-OrganicChemistry vol 31 no 8 pp 1323ndash1337 2001

[35] D L Pavia G M Lampman G S Kriz and J R VyvyanSpectroscopy BrooksCole Florence Ky USA 2007

[36] W E Estes D P Gavel W E Hatfield and D J HodgsonldquoMagnetic and structural characterization of dibromo- anddichlorobis(thiazole)copper(II)rdquo Inorganic Chemistry vol 17no 6 pp 1415ndash1421 1978

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy


Carbohydrate Chemistry

International Journal of


Journal of

Chemistry


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


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of


Chromatography Research International


Applied ChemistryJournal of



Theoretical ChemistryJournal of


Journal of

Spectroscopy

Analytical ChemistryInternational Journal of


Journal of


Quantum Chemistry


Organic Chemistry International

ElectrochemistryInternational Journal of



CatalystsJournal of


O OHCH3 OCH3

(L1) = R =(L2) = R = (L3) = R =

NR

+

NH2

NH2

H2NRndashCHO

Scheme 1

2 Experimental

21 Materials and Methods Chemicals used were of analyt-ical grade and purchased from commercial sources SigmaAldrich and were used without further purification Allligand synthesis reactions were carried out in solvents thatwere purified and dried before use using standard literaturemethods The redistilled and deionized water was used in allexperiments Gallenkamp apparatus was used to determinemelting points of synthesized ligands and decompositiontemperature of themetal complexes Infrared spectra of solids(in a KBrmatrix) were recorded in the 3700ndash370 cmminus1 regionon a Nicolet FT-IR Impact 400D infrared spectrometer1H and 13CNMR spectra were run on a Bruker Advance300MHz instrument Mass spectrometry work was carriedout by Ms B Woods NUI Maynooth using an AgilentTechnologies 6210 Time-of-Flight LCMS UV spectra wereobtained on a Hitachi UV-3200 spectrophotometer Micro-analysis (C H and N) of the synthesized compoundswas carried out using a CHN Analyzer on Perkin Elmer2400 series II Molar conductances of the transition metalcomplexesweremeasured in 001M inDMF solutionusing anInolab Cond 720 Conductivity Bridge at room temperatureA Stanton SM12S Gouy balance was used to measure themagnetic susceptibility of the metal complexes at roomtemperature by using mercury acetate as a standard

22 Chemistry of Synthesis of Ligands Different aldehydessuch as 5-methyl furfural 2-anisaldehyde and 2-hydroxy-benzaldehyde in methanol (20mL) were added to a refluxedsolution of ethylene-12-diamine in same solvent in anequimolar ratio for 10 minutes followed by 2-3 drops ofacetic acid Then the reaction mixture was refluxed for 6 h bymonitoring through TLCWhen the reaction was completedit was cooled to room temperature filtered and volumereduced to about one-third using rotary evaporatorThe solidproduct thus obtained was filtered washed with methanoland dried It was recrystallized in hot methanolether (2 1)The ligands (L1)ndash(L3) were prepared by following the abovementioned method

221 N-[(E)-(5-Methylfuran-2-yl)methylidene]ethane-12-diam-ine (L1) Yield (112 g 73) mp 175∘C color reddish brown1HNMR (ppm d

6

-DMSO) 235 (s CH3

) 305 (s 2H) 368 (s2H) 485 (s NH

2

) 634 (d 2H) 668 (d 2H) 718 (s HC=N)13CNMR (ppmd

6

-DMSO) 135 430 558 1072 1166 14641533 1626 IR (KBr cmminus1) 3250 (NH

2

) 1632 (HC=N) 1575

0

5

10

15

20

25

30

35

(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

SD

Zone

of i

nhib

ition

(m

m)

CompoundsE coliS faecalisP aeruginosa

K pneumoniaeS aureusB subtilis

(L1)

(L2)

(L3)

Figure 1 Comparison of antibacterial activity of Schiff bases versusmetal(II) complexes

0

20

40

60

80

100

120

Inhi

bitio

n (

)

T mentogrophytesE floccosumA niger

M canisF culmorumT schoenleinii(1)

(2)

(3)

(4)

(5)

(6)

(7)

(8)

(9)

(10)

(11)

(12)

SD

Compounds(L

1)

(L2)

(L3)

Figure 2 Comparison of antifungal activity of Schiff bases versusmetal(II) complexes

1545 (C=C) 1090 (CndashO) Mass Spectrum (ESI) [M]+ = 15219Anal calcd for C

8

H12

N2

O (15219) C 6313 H 795 N 1841Found C 6308 H 793 N 1837

222 N-[(E)-(2-Methoxyphenyl)methylidene]ethane-12-diam-ine (L2) Yield (121 g 67) mp 142∘C color dark brown 1HNMR (ppm d

6

-DMSO) 295 (s OCH3

) 315 (s 2H) 385 (s2H) 487 (s NH

2

) 687 (t 1H) 695 (d 1H) 732 (t 1H) 759(d 1H) 878 (s HC=N) 13C NMR (ppm d

6

-DMSO) 442536 563 1147 1229 1237 1296 1345 1605 1623 IR (KBrcmminus1) 3255 (NH

2

) 2920 (OCH3

) 1635 (HC=N) 1577 1543(C=C) Mass Spectrum (ESI) [M]+ = 17823 Anal calcd forC10

H14

N2

O (17823) C 6739 H 792 N 1572 Found C6733 H 788 N 1569

223 2-(E)-[(2-Aminoethyl)imino]methylphenol (L3) Yield(120 g 73) mp 155∘C color (yellow) 1H NMR (ppm d

6

-DMSO) 340 (s 2H) 398 (s 2H) 489 (s NH

2

) 693 (t 1H)711 (d 1H) 743 (t 1H) 772 (d 1H) 885 (s HC=N) 997(s OH) 13C NMR (ppm d

6

-DMSO) 448 529 1184 11951222 1315 1331 1592 1623 IR (KBr cmminus1) 3385 (OH) 3253(NH2

) 1638 (HC=N) Mass Spectrum (ESI) [M]+ = 16420Anal calcd for C

9

H12

N2

O (16420) C 6583 H 737 N 1706Found C 6577 H 732 N 1702


N O

NO

M

N

N

M

N

O

N

O M

NH2

NH2

NH2

H2O

H2O

O2H

O2H

H2O

OH2

CH3

OCH3 OCH3

H3C

H2N

H2N

H2N

Cl2 Cl2




Scheme 2


2



2



16

H28

N4

O4

CoCl2



2




2


minus1)



6

-DMSO) 246 (s CH3

)315 (s 2H) 383 (s 2H) 498 (s NH

2

) 648 (d 2H) 680(d 2H) 748 (s HC=N) 105 (s 4H H

2

O) 13C NMR (ppmd6

-DMSO) 139 434 564 1079 1177 1476 1546 1638 IR(KBr) 3480 (H

2



H28

N4

O4

ZnCl2



2




2







2




6

-DMSO) 303 (s OCH3

)322 (s 2H) 393 (s 2H) 496 (s NH

2


2

O) 13C NMR (ppm d6

-DMSO) 446 539568 1153 1237 1246 1304 1349 1608 1635 IR (KBr)3480 (H

2


H32

N4

O4

ZnCl2



2




2



5134 H 622 N 1330 Ni 1394 Found C 5126 H 619 N1326 Ni 1388


2




6

-DMSO) 354 (s 2H) 414(s 2H) 40 (s NH

2


2

O) 13CNMR (ppmd6

-DMSO) 452 535 1187 1197 1227 1319 1335 1597 1629 IR(KBr) 3480 (H

2



H26

N4

O4













2

sdot6H2

O NiCl2

sdot6H2

O CuCl2

sdot2H2

O and ZnCl2





2


3


2





3






6


3




6


3

) (CH2

) and (OCH3








1

grarr 4T2

g(F) 4T1

grarr 4A2

g(F)and 4T

1


g(F)rarr 3T2

g(F) and 3A2

g(F)rarr 3T1


2











4 Conclusions





Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


N O

NO

M

N

N

M

N

O

N

O M

NH2

NH2

NH2

H2O

H2O

O2H

O2H

H2O

OH2

CH3

OCH3 OCH3

H3C

H2N

H2N

H2N

Cl2 Cl2




Scheme 2


2



2



16

H28

N4

O4

CoCl2



2




2


minus1)



6

-DMSO) 246 (s CH3

)315 (s 2H) 383 (s 2H) 498 (s NH

2

) 648 (d 2H) 680(d 2H) 748 (s HC=N) 105 (s 4H H

2

O) 13C NMR (ppmd6

-DMSO) 139 434 564 1079 1177 1476 1546 1638 IR(KBr) 3480 (H

2



H28

N4

O4

ZnCl2



2




2







2




6

-DMSO) 303 (s OCH3

)322 (s 2H) 393 (s 2H) 496 (s NH

2


2

O) 13C NMR (ppm d6

-DMSO) 446 539568 1153 1237 1246 1304 1349 1608 1635 IR (KBr)3480 (H

2


H32

N4

O4

ZnCl2



2




2



5134 H 622 N 1330 Ni 1394 Found C 5126 H 619 N1326 Ni 1388


2




6

-DMSO) 354 (s 2H) 414(s 2H) 40 (s NH

2


2

O) 13CNMR (ppmd6

-DMSO) 452 535 1187 1197 1227 1319 1335 1597 1629 IR(KBr) 3480 (H

2



H26

N4

O4













2

sdot6H2

O NiCl2

sdot6H2

O CuCl2

sdot2H2

O and ZnCl2





2


3


2





3






6


3




6


3

) (CH2

) and (OCH3








1

grarr 4T2

g(F) 4T1

grarr 4A2

g(F)and 4T

1


g(F)rarr 3T2

g(F) and 3A2

g(F)rarr 3T1


2











4 Conclusions





Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





2




6

-DMSO) 303 (s OCH3

)322 (s 2H) 393 (s 2H) 496 (s NH

2


2

O) 13C NMR (ppm d6

-DMSO) 446 539568 1153 1237 1246 1304 1349 1608 1635 IR (KBr)3480 (H

2


H32

N4

O4

ZnCl2



2




2



5134 H 622 N 1330 Ni 1394 Found C 5126 H 619 N1326 Ni 1388


2




6

-DMSO) 354 (s 2H) 414(s 2H) 40 (s NH

2


2

O) 13CNMR (ppmd6

-DMSO) 452 535 1187 1197 1227 1319 1335 1597 1629 IR(KBr) 3480 (H

2



H26

N4

O4













2

sdot6H2

O NiCl2

sdot6H2

O CuCl2

sdot2H2

O and ZnCl2





2


3


2





3






6


3




6


3

) (CH2

) and (OCH3








1

grarr 4T2

g(F) 4T1

grarr 4A2

g(F)and 4T

1


g(F)rarr 3T2

g(F) and 3A2

g(F)rarr 3T1


2











4 Conclusions





Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










2

sdot6H2

O NiCl2

sdot6H2

O CuCl2

sdot2H2

O and ZnCl2





2


3


2





3






6


3




6


3

) (CH2

) and (OCH3








1

grarr 4T2

g(F) 4T1

grarr 4A2

g(F)and 4T

1


g(F)rarr 3T2

g(F) and 3A2

g(F)rarr 3T1


2











4 Conclusions





Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of



2


3


2





3






6


3




6


3

) (CH2

) and (OCH3








1

grarr 4T2

g(F) 4T1

grarr 4A2

g(F)and 4T

1


g(F)rarr 3T2

g(F) and 3A2

g(F)rarr 3T1


2











4 Conclusions





Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of






1

grarr 4T2

g(F) 4T1

grarr 4A2

g(F)and 4T

1


g(F)rarr 3T2

g(F) and 3A2

g(F)rarr 3T1


2











4 Conclusions





Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of







4 Conclusions





Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Acknowledgments


References
















2

















S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





S2

O2


















Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of










Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of

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