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Research ArticleFive-Coordinate Zinc(II) Complex Synthesis CharacterizationMolecular Structure and Antibacterial Activities of Bis-[(E)-2-hydroxy-N 1015840-1-(4-methoxyphenyl)ethylidenebenzohydrazido]dimethylsulfoxidezinc(II) Complex

Zhi-Qiang Liu1 Yoke Mooi Ng2 Pei Jen Tiong2 Ruwaida Asyikin Abu Talip2

Nornadia Jasin2 Vivien Yi Mian Jong3 andMeng Guan Tay2

1State Key Lab of Crystal Materials Shandong University Jinan 250100 China2Department of Chemistry Faculty of Resource Science and Technology Universiti Malaysia Sarawak94300 Kota Samarahan Sarawak Malaysia3Center of Applied Sciences Universiti Teknologi MARA Kampus Kota Samarahan 2 94300 Kota Samarahan Sarawak Malaysia

Correspondence should be addressed to Meng Guan Tay mgtayunimasmy

Received 14 March 2017 Accepted 26 April 2017 Published 15 June 2017

Academic Editor Hakan Arslan

Copyright copy 2017 Zhi-Qiang Liu 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

The titled Zn(II) complex was synthesized by reacting the compound (E)-2-hydroxy-N1015840-1-(4-methoxyphenyl)ethylide-nebenzohydrazide with zinc(II) acetate dihydrate in alkaline DMSO and ethanol solution under reflux condition for 28 hoursThe resulting solid was filtered and recrystallized from the mixture of ethanol and DMSO The hydrazone Schiff base and itsZn(II) complex were characterized using 1H 13C NMR FTIR UV-Vis spectroscopy and single crystal X-ray diffraction analysisMeanwhile their antibacterial activities were examined using disc diffusionmethodThe spectral studies showed that the hydrazoneSchiff base underwent keto-enol tautomerization forming a bidentate ligand (NO) towards Zn(II) ion Surprisingly on top of thetwo hydrazone Schiff base molecules which coordinated to the Zn metal center an additional DMSOmolecule was found attachedto the Znmetal center in the crystal data resulting in a 5-coordinate distorted trigonal bipyramidal Zn(II) complex Both hydrazoneSchiff base and its Zn(II) complexes were found to exhibit low antibacterial activity even when the concentrations were increasedto 800 ppm

1 Introduction

Hydrazone Schiff base plays an important role in inorganicchemistry as it can easily form stable complexes with mosttransition metal ions due to its ability to form keto-enoltautomerism (Figure 1) [1ndash4] In coordination chemistrythe hydrazone Schiff base ligand normally presents in enolconformation in order to bind with the metal center throughthe nitrogen atom from imine moiety [5ndash7] and oxygen fromhydroxyl group [8 9]

Complexation with Zn(II) metal center usually resultsin complexes with 4-coordination number and a tetrahedralgeometry This is due to the fact that Zn is a late transitionmetal with full d valence electrons which means that a stable

18-electron complex can be formed through 4-coordinationnumber with its ligands Due to this reason 5-coordinate Zncomplex is considered unusual and expected to be unstableNevertheless 5-coordinate Zn complexes were previouslyreported [10ndash14] Similar to 4-coordinate Zn complexes thecommon oxidation state for Zn ion in 5-coordinate Zncomplexes is +2 however the one reported by Song etal is in 0 oxidation state [13] In this paper the synthesis(Scheme 1) and spectroscopic and crystallographic data ofa 5-coordinate trigonal bipyramid bis-[(E)-2-hydroxy-N1015840-1-(4-methoxyphenyl)ethylidenebenzohydrazido] dimeth-ylsulfoxidezinc(II) complex are reported In addition theantibacterial activities of both hydrazone Schiff base L1 andZn(II) complex have also been examined

HindawiInternational Journal of Inorganic ChemistryVolume 2017 Article ID 7520640 8 pageshttpsdoiorg10115520177520640

2 International Journal of Inorganic Chemistry

NNH

O

Keto form

NN

OH

Enol form

C（3C（3

Figure 1 Keto-enol tautomerization of a hydrazone Schiff base compound

2KOH

reflux 15 hoursMeO

C

Me

NN

OHOHMeO

C

Me

NN

OKOK

refluxed 28 hours

Me

NN

O

OH

Me

NN

O

OHZn

O

MeMeO

Salicylhydrazide

Abs ethanolreflux 24 hours

L1

OH

O

NH

O

SMeMe

MeO

OMe

5-coordinate Zn(II) complex

N（2

+

4-Methoxyacetophenone

Zn(（3)2middot2（2O

（ + ＄MSOAbs EtO

（ + ＄MSOAbs EtO

Scheme 1 Synthetic pathway of L1 and its 5-coordinate Zn(II) complex

2 Experimental

21 Equipment or Instrumentation The IR spectra of L1 andthe Zn(II) complex were recorded in KBr disks by usingThermo ScientificNicolet iS10 8001PC FTIR Spectrometerwith the wavelength range from 400 to 4000 cmminus1 JascoV-630 UV-visible spectrophotometer was used to record theelectronic absorption spectra with DCM solvent JEOL ECA-500 NMR spectrometer with 500MHz was used to recordall the 1H and 13C NMR spectra 1H-NMR chemical shiftwas reported relative to TMS and referenced via residualproton NMR resonance of the appropriate deuterated solvent(DMSO-d

6 250 ppm CD

2Cl2 532 ppm) Stuart SMP3Melt-

ing Point was used to measure the melting point of L1 andthe Zn(II) complexes The elemental analysis was conductedby using CHN Analyzer Thermo-Flash EA 1112 series at thetemperature up to 900∘C and vanadium pentoxide was usedas oxidizer to prevent inhibition caused by sulphur

X-ray measurements for the Zn complex were performedon a Bruker SMART diffractometer equipped with a graphitemonochromated Mo Ka (120582 = 071073) radiation sourceand a CCD detector The frame integration was performedusing the program SAINT [15] The structure was solved by

direct method provided by the program package SHELXTL-97 and refined a full matrix least square against F2 for alldata [16] All nonhydrogen atoms were refined anisotrop-ically All hydrogen atoms were introduced at idealizedpositions and were allowed to refine isotopically Crystal-lographic data for Zn(II) complexes has been depositedin the Cambridge Crystallographic Data Centre CCDCnumber 1508885 The data are available free of charge viahttpswwwccdccamacukdata_requestcif (or from theCCDC 12 Union Road Cambridge CB2 1EZ UK +44 1223336033 e-mail depositccdccamacuk)

22 Antibacterial Study of the Compounds The antibacterialstudy was carried out on hydrazone Schiff base L1 andits Zn(II) complex using disc diffusion method [17] Onecolony of Bacillus cereus ATCC 33019 from a streak platewas inoculated in 20mL of LB broth After 16 hours of incu-bation the optical density of the inoculums was measuredand further diluted to achieve McFarland standard of 05Using sterile cotton swab agar plate was uniformly swabbedwith diluted inoculums of the bacteria After that sterilefilter papers (6mm) which were impregnated with differentconcentrations (ie 200 400 and 800 ppm using DCM as

International Journal of Inorganic Chemistry 3

4478354888

57470

61446

66927

99105

118299

153254

160597

291971

342873

minus6

minus4

minus2

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

T

500100015002000250030003500

Wavenumbers (cＧminus1)

Figure 2 IR spectrum of the Zn(II) complex

minus010

Abs 1

2

Wavelength (nm)

320 nm

600500400300250

(a)

minus01

0

Abs 05

1

345nm

Wavelength (nm)600500400300250

(b)

Figure 3 UV-Vis spectra of (a) L1 and (b) its Zn(II) complex

the solvent) of L1 and its Zn(II) complex were placed on theagarThe inhibitory zones inmillimeters were measured after24 hours of incubation Similar procedures were conductedin another set for Escherichia coli ATCC 35150 All theantibacterial assays were performed in triplicate

23 Synthesis

231 Preparation of (E)-2-Hydroxy-N1015840-(1-(4-methoxyphenyl)ethylidene)benzohydrazide (L1) [18] Salicylhydrazide (1522 g10mmol) was dissolved in 25mL of ethanol and added toa round bottom flask with constant stirring An ethanolic

solution of 41015840-methoxyacetophenone (1501 g 10mmol) wasthen added dropwise The mixture was refluxed for 24 hoursfollowed by cooling to room temperature The precipitatewhich appeared as white crystals was filtered washed withethanol and dried in vacuo over silica gel Yield 214 g 754MP 2102ndash2157∘CAnal Calcd forC

16H16N2O3 C 6709H

545 N878 Found C 6759 H 567 N 985 IR (KBr diskcmminus1) 3435 (s) 3270 (s) 1605 (s) 982 (m) 1HNMR (DMSO-d6 120575) 1181 (s 1H N-H) 1128 (s 1H Ar-OH) 799 (d 1H J =

8Hz Ar-H) 782 (d 2H J = 8Hz Ar-H) 742 (t 1H J = 8HzAr-H) 697 (m 4H Ar-H) 381 (s 3H OCH

3) 230 (s 3H

H3C-C=N) 13C NMR (DMSO-d

6 120575) 16208 16040 15666


092

097

192

192201

3

398

288

0

01

02

03

04

Abun

danc

e

05

06

07

08

09

20304050607080

81223

81188

81062

73894

72451

72267

69633

69496

69473

69359

67217

54975

53246

53223

53200

36434

25532

22165

15374

15077

X parts per million 1H

Figure 4 1H NMR spectrum of the Zn(II) complex

15235 11376 11689 11784 11964 12798 13030 1304613329 15235 5524 1378 UV-Vis [DCM 120582max] 320 nm

232 Preparation and Crystallization of Bis-[(E)-2-hydroxy-N1015840

-1-(4-methoxyphenyl)ethylidenebenzohydrazido]dimeth-ylsulfoxidezinc(II) Complex The compound (E)-2-hydroxy-N1015840-(1-(4-methoxyphenyl)ethylidene)benzohydrazide (0142 g05mmol) was dissolved in 5mL of DMSO in a roundbottom flask with constant stirring Potassium hydroxideKOH (0056 g 1mmol) was dissolved in 10mL of absoluteethanol and added to the flask dropwise The resultingmixture was refluxed for 15 hours followed by dropwiseaddition of zinc(II) acetate dihydrate (011 g 05mmol)solution in 5mL DMSO The mixture turned from yellow

to golden yellow color After being refluxed for 28 hoursthe solution was cooled to room temperature followed byfiltration and recrystallization from the mixture of DMSOand absolute ethanol A yellow crystal was obtained afterone week which was then filtered and washed with DMSOYield 017 g 929 MP 2659ndash2722∘C Anal Calcd for Zn(C34H36N4O7S) C 5751 H 511 N789 Found C 5778 H

539 N 839 IR (KBr disk cmminus1) 3443 (s) 1606 (s) 1098(m) 992 (w) 669 (m) 1H NMR (CD

2Cl2 120575) 812 (d 1H J

= 6Hz Ar-H) 740 (t 1H J = 6Hz Ar-H) 724 (d 2H J =9Hz Ar-H) 695 (d amp t 2H J = 7Hz Ar-H) 671 (d 2HJ = 9Hz Ar-H) 362 (s OCH

3 3H) 253 (s 3H SCH

3)

219 (s 3H H3C-C=N) 13C NMR (CD

2Cl2 120575) 17233

16478 16219 16056 13310 13039 12982 12840 11885


C17

O3

O2 O1

C12

C11O4

C4

C2

C5C6

C7

N1

N2C10

C9

S1

(a)

O1

O3

O2

C2

C3

C1

C4

C8

C9 C10

C11

C13

C12

C17

C14

C16

C5

C7

N1

N2

Zn1

(b)

S1

O1

O3

O2

C2C3

C1

C4

C8C9

C10C11

C14

C13C12

C17C16

C5

C7

N2

N1

Zn1

(c)

S1O1

O3

O2

C2

C3 C1

C4

C8

C9

C10

C11

C6

C13

C12

C17

C16

C5 C7

N2

N1

Zn1

(d)

Figure 5 Molecular structure of bis-[(E)-2-hydroxy-N1015840-1-(4-methoxyphenyl)ethylidenebenzohydrazido]dimethylsulfoxidezinc(II) com-plex in different angles

11733 11707 11436 5402 4141 1862 UV-Vis [DCM 120582max]345 nm

3 Result and Discussion

31 Synthesis and Characterization Hydrazone Schiff baseL1 was successfully synthesized through condensation reac-tion between salicylhydrazide and 41015840-methoxyacetophenoneunder reflux for 24 hours at 75∘C The color remainedunchanged even after the addition of hot ethanolic salicylhy-drazide into ethanolic solution of 41015840-methoxyacetophenonewith stirring and heating A white color precipitate started toform after 12 hours with the yield of 75 However L1 wasnot able to be analyzed using GC-MS due to low solubilityin DCM Despite low solubility in DCM the molecularstructure of L1 has been reported by Qiu and coworkersin 2006 [18] The ligand L1 was then reacted with zinc(II)acetate under open air reflux condition for 28 hours Uponcompletion of the reaction the dark yellow solution wasfiltered and the Zn(II) complex appeared as tiny pale yellowcrystal after a week

Based on the IR spectra of L1 (see Fig S1 in Supplemen-tary Material available online at httpsdoiorg10115520177520640) and Zn(II) complex (Figure 2) the absence ofthe v(N-H) and v(C=O) peak in the IR spectrum of Zn(II)

complex indicates enolization of keto group in L1 whichcoordinated to the Zn metal center through enolate oxygenThis is supported by the appearance of new band attributedto v(C-O) at 1098 cmminus1 after the complexation reaction [19]However the changes of v(C=N) chemical shift from 1605 to1606 cmminus1 in the IR spectra were rather insignificant after thecomplexation This result is indeed parallel to the findingfrom Tay et al [5] where the IR frequency of C=N was alsoshifted by only 2 cmminus1 from 1621 cmminus1 to 1619 cmminus1 after theirbis-21015840-hydroxy Schiff base compound bound to Zn(II) metalcenter

In fact the IR data is supported by the UV-Vis result(Figure 3) where the 119899 rarr 120587lowast transition in C=N bond shiftedfrom 320 nm to 345 nm after binding to the Zn metal centerThe bathochromic shift is due to the backbonding from Znto the C=N bond in L1 and subsequently weakened the bondenergy of C=N

The 1H NMR spectrum of Zn(II) complex (Figure 4)also shows some differences compared to L1 (see Fig S2) Abroad signal at 1181 ppm and a singlet present at 1128 ppmin the 1H NMR spectrum of L1 are assigned to the N-H of azomethine and phenolic proton in L1 respectivelyThese two NMR resonances indicate that L1 is of keto formThis is also supported by the IR spectrum of L1 with the


Table 1 Summary of crystallographic and refinement data forZn(II) complex

Compound Zn(II) complexCrystal system Monoclinica (A) 245646 (10)b (A) 87981 (3)c (A) 157993 (6)120572 (A) 9000120573 (A) 966410 (3)120574 (A) 9000Volume (A3) 33917 (2)119885 8Density (Mgm3) 1726Absorption coefficient (mmminus1) 1482Θ range for data collection 246ndash2420Reflections collected 3924Independent reflections 2565Datarestraintsparameter 39240231

Final 119877 indices 1198771 = 00913

1199081198772 = 025

119877 indices (all data) 1198771 = 01263

1199081198772 = 02739

presence of v(N-H) and v(C=O) at 3270 and 1604 cmminus1respectively The two NMR resonances at 1181 and 1128 ppmdisappeared after complexation reaction indicating that thestructure of L1 changed from keto to enol conformation andthe O atom from phenolic group has bound to the Zn metalcenter On top of these a new peak at 255 ppm was foundin the 1H NMR spectrum of Zn(II) complex Based on theintegration this singlet is the combination of the protonsfrom dimethyl sulfoxide (DMSO) and enolic proton afterforming the complex The presence of DMSO is due to thesolvent used during the recrystallization process and thecrystal data also confirms that a DMSO molecule is boundto Zn metal center

The crystallographic molecular structure of bis-[(E)-2-hydroxy-N1015840-1-(4-methoxyphenyl)ethylidenebenzohydraz-ido]dimethylsulfoxidezinc(II) complex is shown in Figure 5The molecular structure is shown in different angles [Figures5(a)ndash5(d)] for better clarity to show each coordination toZn metal center The crystal data is presented in Table 1and selected bond lengths as well as bond angles are shownin Table 2 The complex crystallizes in monoclinic systemand the molecule is believed to exhibit a distorted trigonalbipyramidal geometry The molecular formula of the Zn(II)complex conforms to the C H and N which were foundfrom the elemental analysis

The bond distance for Zn1-N1 is 2209 A whereas thebond length for Zn1-O1 is 1974 A The longer bond lengthin Zn-N compared to Zn-O indicates that the Zn-N bond isweaker than Zn-O This is due to the stronger trans-effect ofC=N bond compared to that of the C-O bond The reasonfor that is because C=N contains 120587-bond which plays an

Table 2 Selected bond lengths (A) and bond angles (∘) for Zn(II)complex

Bond lengths A Bond angles (∘)Zn1-N1 2209 O1-Zn1-N1 10235Zn1-O1 1974 O1-Zn-O1 1110Zn1-O1AA 2049 N1-Zn-N1 1798C9-N1 1291N1-N2 1405N2-C1AA 1317C1AA-O1 1276

important role in trans-effect Besides the two L1 chelatingligands a disordered DMSOmolecule [Figures 5(a) and 5(c)]was found to coordinate to the Zn metal center via oxygenatom The bond distance Zn-O4 is 2049 A Meanwhile theinteratomic distance for C8-N2 N1-N2 N1-C1 and C1-O1 inthe azomethine group (-C=N-N=C-O) moiety is 1294 14031317 and 1278 A respectivelyThe longer bond lengths of C8-N2 and N1-C1 than the normal C=N bond (1279 A) and theshorter bond length for N1-N2 than the previously reporteddata (1420 A) [20] suggested the presence of a conjugationsystem along C=N-N=C moiety This indicates that the N1-N2 bond became stronger in parallel with the data obtainedin the IR in which the v(N-N) underwent positive shift in theIR spectrum of the complex Moreover the bond length forC1-O1 is shorter than the normal C-O bond length (15 A) dueto keto-enol tautomerization [2 3]

The dihedral angle between O1-Zn1-N1 planes of two L1chelating ligands is 10235∘ The bond angles for O1-Zn-O1and N1-Zn-N1 are 1110∘ and 1798∘ respectively The bondangle for the O1-Zn-O1 deviates from the ideal bond angle forsquare planar (180∘) This can be explained by the presenceof the disordered DMSO The bond angles and the X-raystructure observed suggested that the chelating ligands whichcoordinate to the zinc metal ion are perpendicular to eachother parallel to the description of square planar

32 Antibacterial Screening The antibacterial activity ofhydrazone Schiff base L1 and its Zn(II) complex was exam-ined using disc diffusion method and the results weretabulated in Table 3 and Figure 6 The results show that bothL1 and its Zn(II) complex are considered nontoxic to gram-positive (Bacillus cereus) and gram-negative (Escherichiacoli) bacteria as there is no significant difference in theinhibition areas with increasing concentration of both L1 andits Zn(II) complex even the concentration was increasedup to 800 ppm The possible reason to this could be theabsence of lipophilic group such as long carbon chains inboth structures Birnie and coworkers [21] reported the use oflong carbon chains substituents such as C

8H17

and C10H21

in enhancing the antibacterial activity

4 Conclusion

The synthesis and molecular structure of 5-coordinated bis-[(E)-2-hydroxy-N

1015840

-1-(4-methoxyphenyl)ethylidenebenzo-hydrazido]dimethylsulfoxidezinc(II) complex were reported


Table 3 Results of antibacterial activity for hydrazone Schiff base L1 and its Zn(II) complex

Conc (ppm) in DCMBacillus cereus ATCC 33019 Escherichia coli ATCC 35150

Diameter of inhibition zone mm (average of triplicates)L1 Zn(II) complex L1 Zn(II) complex

0 100 100 100 100200 95 95 110 95400 100 90 120 115800 100 100 120 100

(a) (b)

(c) (d)

Figure 6 Antibacterial activity of L1 (a and b) and its Zn(II) complex (c and d) Bacillus cereus (a and c) and Escherichia coli (b and d)

The molecular structure and formula of the Zn(II) complexare in agreement with the results from CHN elementalanalysis and 1H NMR spectroscopy In addition thebathochromic shift of C=N wavelength in absorption spectra

indicates the binding of nitrogen atom from C=N to Zn(II)metal center From the result of antibacterial study bothL1 and its Zn(II) complex are considered nontoxic to bothgram-positive and gram-negative bacteria


Conflicts of Interest

The authors declare that there are no conflicts of interestregarding the publication of this paper

Acknowledgments

The authors are grateful to the research funding fromMalaysian Ministry of Higher Education under ResearchAcculturation Grant Scheme (RAGS) with no RAGSST01(1)10382013(05)

References

[1] G Dutkiewicz B Narayana S Samshuddin H S Yathi-rajan and M Kubicki ldquoSynthesis and crystal structures oftwo new Schiff base hydrazones derived from biphenyl-4-carbohydraziderdquo Journal of Chemical Crystallography vol 41no 10 pp 1442ndash1446 2011

[2] P Fita E Luzina T Dziembowska et al ldquoKeto-enol tau-tomerism of two structurally related Schiff bases Direct andindirect way of creation of the excited keto tautomerrdquo ChemicalPhysics Letters vol 416 no 4-6 pp 305ndash310 2005

[3] S R Kelode and P R Mandlik ldquoSynthesis characteriza-tion thermal and antibacterial studies of cobalt(II) nickel(II)copper(II) and zinc(II) complexes of hydrazone Schiff baserdquoInternational Journal of Chemical and Pharmaceutical Sciencesvol 3 no 3 pp 30ndash33 2012

[4] H H Monfared O Pouralimardan and C Janiak ldquoSynthe-sis and spectral characterization of hydrazone schiff basesderived from 24-dinitrophenylhydrazine Crystal structureof salicylaldehyde-24-dinitrophenylhydrazonerdquo Zeitschrift furNaturforschungmdashSection B Journal of Chemical Sciences vol 62pp 717ndash720 2007

[5] M G Tay Z Ngaini M A Mohd Arif et al ldquoComplexation ofbis-2-(benzylideneamino)phenol to cobalt(II) and zinc(II) andtheir spectroscopic studiesrdquo Borneo Journal of Resource Scienceand Technology vol 3 no 1 pp 26ndash34 2013

[6] Z A Siddiqi M Shahid M Khalid and S Kumar ldquoAntimicro-bial and SOD activities of novel transition metal ternary com-plexes of iminodiacetic acid containing 120572-diimine as auxiliaryligandrdquo European Journal of Medicinal Chemistry vol 44 no 6pp 2517ndash2522 2009

[7] L S Kumar K S Prasad and H D RevanasiddappaldquoSynthesis characterization antioxidant antimicrobial DNAbinding and cleavage studies of mononuclear Cu(II) andCo(II) complexes of 3-hydroxy-N1015840-(2-hydroxybenzylidene)-2-naphthohydraziderdquo European Journal of Chemistry vol 2 no 3pp 394ndash403 2011

[8] S R Yaul A R Yal G B Pethe and A S Aswar ldquoSynthesisand characterization of transition metal complexes with NO-chelating hydrazone Schiff base ligandrdquo American-EurasianJournal of Scientific Research vol 4 no 4 pp 229ndash234 2009

[9] M Neelamma P V Rao and G H Anuradha ldquoSynthesisand structural studies on transition metal complexes derivedfrom 4-hydroxy-4-methyl-2-pentanone-1H-benzimidazol-2-yl-hydrazonerdquo E-Journal of Chemistry vol 8 no 1 pp 29ndash362011

[10] M Franks A Gadzhieva L Ghandhi et al ldquoFive coordinateM(II)-diphenolate [M = Zn(II) Ni(II) and Cu(II)] Schiff basecomplexes exhibitingmetal-and ligand-based redox chemistryrdquoInorganic Chemistry vol 52 no 2 pp 660ndash670 2013

[11] E Szłyk A Wojtczak A Surdykowski and M Gozdzikiew-icz ldquoFive-coordinate zinc(II) complexes with optically activeSchiff bases derived from (1R2R)-(-)cyclohexanediamineX-ray structure and CP MAS NMR characterization of [cyclo-hexylenebis(5-chlorosalicylideneiminato)zinc(II) pyridine] and[cyclohexylenebis(5-bromosalicylideneiminato)zinc(II)pyri-dine]rdquo Inorganica Chimica Acta vol 358 no 3 pp 467ndash4752005

[12] J M Newman C A Bear T W Hambley and H C Free-man ldquoStructure of bis(glycinato)zinc(II) monohydrate a five-coordinate zinc(II) complexrdquo Acta Crystallographica Section CCrystal Structure Communications vol C46 pp 44ndash48 1990

[13] X-W Song X-J Gao H-X Liu H Chen and C-N ChenldquoSynthesis and characterization of a supramolecular assemblybased on a pyridyl-functionalized [FeFe]-hydrogenase mimicand zinc tetraphenylporphyrinrdquo Inorganic Chemistry Commu-nications vol 70 pp 1ndash3 2016

[14] W Che T Yu D Jin et al ldquoA simple oxazoline as fluorescentsensor for Zn2+ in aqueous mediardquo Inorganic Chemistry Com-munications vol 69 pp 89ndash93 2016

[15] Siemens SMART ampamp SAINT Siemens analytical X-rayinstruments inc Madison Wisconsin USA 1996

[16] GM Sheldrick ldquoSHELXL-97 and SHELXS-97rdquo 1997Universityof Gottingen Germany

[17] A A Osowole ldquoSynthesis spectroscopic characterization in-vitro antibacterial and antiproliferative activities of some metal(II) complexes of 34-dihydronaphthalen-1(2H)-one Schiffbaserdquo Experimental and Clinical Sciences vol 11 pp 338ndash3452012

[18] X-Y Qiu Q-Y Luo S-L Yang andW-S Liu ldquo(E)-2-Hydroxy-N1015840-[1-(4-methoxyphenyl)-ethylidene]benzohydraziderdquo ActaCrystallographica Section E Structure Reports Online vol E62no 10 pp o4291ndasho4292 2006

[19] M D Sagolsem and M S Akojiam ldquoSynthesis and studiesof nickel(II) and cobalt(II) complexes of furfural isonicotinoylhydrazone (FINH)rdquo in Proceedings of the vol 2 pp 290ndash2962012

[20] F H Allen O Kennard D G Watson L Brammer A GOrpen and R Taylor ldquoTables of bond lengths determinedby X-ray and neutron diffraction Part 1 Bond lengths inorganic compoundsrdquo Journal of the Chemical Society PerkinTransactions 2 no 12 pp S1ndashS19 1987

[21] C R Birnie D Malamud and R L Schnaare ldquoAntimi-crobial evaluation of N-alkyl betaines and N-alkyl-N N-dimethylamine oxides with variations in chain lengthrdquo Antimi-crobial Agents and Chemotherapy vol 44 no 9 pp 2514ndash25172000

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NNH

O

Keto form

NN

OH

Enol form

C（3C（3

Figure 1 Keto-enol tautomerization of a hydrazone Schiff base compound

2KOH

reflux 15 hoursMeO

C

Me

NN

OHOHMeO

C

Me

NN

OKOK

refluxed 28 hours

Me

NN

O

OH

Me

NN

O

OHZn

O

MeMeO

Salicylhydrazide

Abs ethanolreflux 24 hours

L1

OH

O

NH

O

SMeMe

MeO

OMe

5-coordinate Zn(II) complex

N（2

+

4-Methoxyacetophenone

Zn(（3)2middot2（2O

（ + ＄MSOAbs EtO

（ + ＄MSOAbs EtO

Scheme 1 Synthetic pathway of L1 and its 5-coordinate Zn(II) complex

2 Experimental

21 Equipment or Instrumentation The IR spectra of L1 andthe Zn(II) complex were recorded in KBr disks by usingThermo ScientificNicolet iS10 8001PC FTIR Spectrometerwith the wavelength range from 400 to 4000 cmminus1 JascoV-630 UV-visible spectrophotometer was used to record theelectronic absorption spectra with DCM solvent JEOL ECA-500 NMR spectrometer with 500MHz was used to recordall the 1H and 13C NMR spectra 1H-NMR chemical shiftwas reported relative to TMS and referenced via residualproton NMR resonance of the appropriate deuterated solvent(DMSO-d

6 250 ppm CD

2Cl2 532 ppm) Stuart SMP3Melt-

ing Point was used to measure the melting point of L1 andthe Zn(II) complexes The elemental analysis was conductedby using CHN Analyzer Thermo-Flash EA 1112 series at thetemperature up to 900∘C and vanadium pentoxide was usedas oxidizer to prevent inhibition caused by sulphur

X-ray measurements for the Zn complex were performedon a Bruker SMART diffractometer equipped with a graphitemonochromated Mo Ka (120582 = 071073) radiation sourceand a CCD detector The frame integration was performedusing the program SAINT [15] The structure was solved by

direct method provided by the program package SHELXTL-97 and refined a full matrix least square against F2 for alldata [16] All nonhydrogen atoms were refined anisotrop-ically All hydrogen atoms were introduced at idealizedpositions and were allowed to refine isotopically Crystal-lographic data for Zn(II) complexes has been depositedin the Cambridge Crystallographic Data Centre CCDCnumber 1508885 The data are available free of charge viahttpswwwccdccamacukdata_requestcif (or from theCCDC 12 Union Road Cambridge CB2 1EZ UK +44 1223336033 e-mail depositccdccamacuk)

22 Antibacterial Study of the Compounds The antibacterialstudy was carried out on hydrazone Schiff base L1 andits Zn(II) complex using disc diffusion method [17] Onecolony of Bacillus cereus ATCC 33019 from a streak platewas inoculated in 20mL of LB broth After 16 hours of incu-bation the optical density of the inoculums was measuredand further diluted to achieve McFarland standard of 05Using sterile cotton swab agar plate was uniformly swabbedwith diluted inoculums of the bacteria After that sterilefilter papers (6mm) which were impregnated with differentconcentrations (ie 200 400 and 800 ppm using DCM as


4478354888

57470

61446

66927

99105

118299

153254

160597

291971

342873

minus6

minus4

minus2

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

T

500100015002000250030003500



minus010

Abs 1

2

Wavelength (nm)

320 nm

600500400300250

(a)

minus01

0

Abs 05

1

345nm


(b)



23 Synthesis



16H16N2O3 C 6709H



3) 230 (s 3H


6 120575) 16208 16040 15666


092

097

192

192201

3

398

288

0

01

02

03

04

Abun

danc

e

05

06

07

08

09

20304050607080

81223

81188

81062

73894

72451

72267

69633

69496

69473

69359

67217

54975

53246

53223

53200

36434

25532

22165

15374

15077



15235 11376 11689 11784 11964 12798 13030 1304613329 15235 5524 1378 UV-Vis [DCM 120582max] 320 nm





2Cl2 120575) 812 (d 1H J


3 3H) 253 (s 3H SCH

3)


2Cl2 120575) 17233

16478 16219 16056 13310 13039 12982 12840 11885


C17

O3

O2 O1

C12

C11O4

C4

C2

C5C6

C7

N1

N2C10

C9

S1

(a)

O1

O3

O2

C2

C3

C1

C4

C8

C9 C10

C11

C13

C12

C17

C14

C16

C5

C7

N1

N2

Zn1

(b)

S1

O1

O3

O2

C2C3

C1

C4

C8C9

C10C11

C14

C13C12

C17C16

C5

C7

N2

N1

Zn1

(c)

S1O1

O3

O2

C2

C3 C1

C4

C8

C9

C10

C11

C6

C13

C12

C17

C16

C5 C7

N2

N1

Zn1

(d)


11733 11707 11436 5402 4141 1862 UV-Vis [DCM 120582max]345 nm










Final 119877 indices 1198771 = 00913

1199081198772 = 025

119877 indices (all data) 1198771 = 01263

1199081198772 = 02739









8H17

and C10H21


4 Conclusion


1015840






0 100 100 100 100200 95 95 110 95400 100 90 120 115800 100 100 120 100

(a) (b)

(c) (d)







Acknowledgments


References































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


4478354888

57470

61446

66927

99105

118299

153254

160597

291971

342873

minus6

minus4

minus2

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

T

500100015002000250030003500



minus010

Abs 1

2

Wavelength (nm)

320 nm

600500400300250

(a)

minus01

0

Abs 05

1

345nm


(b)



23 Synthesis



16H16N2O3 C 6709H



3) 230 (s 3H


6 120575) 16208 16040 15666


092

097

192

192201

3

398

288

0

01

02

03

04

Abun

danc

e

05

06

07

08

09

20304050607080

81223

81188

81062

73894

72451

72267

69633

69496

69473

69359

67217

54975

53246

53223

53200

36434

25532

22165

15374

15077



15235 11376 11689 11784 11964 12798 13030 1304613329 15235 5524 1378 UV-Vis [DCM 120582max] 320 nm





2Cl2 120575) 812 (d 1H J


3 3H) 253 (s 3H SCH

3)


2Cl2 120575) 17233

16478 16219 16056 13310 13039 12982 12840 11885


C17

O3

O2 O1

C12

C11O4

C4

C2

C5C6

C7

N1

N2C10

C9

S1

(a)

O1

O3

O2

C2

C3

C1

C4

C8

C9 C10

C11

C13

C12

C17

C14

C16

C5

C7

N1

N2

Zn1

(b)

S1

O1

O3

O2

C2C3

C1

C4

C8C9

C10C11

C14

C13C12

C17C16

C5

C7

N2

N1

Zn1

(c)

S1O1

O3

O2

C2

C3 C1

C4

C8

C9

C10

C11

C6

C13

C12

C17

C16

C5 C7

N2

N1

Zn1

(d)


11733 11707 11436 5402 4141 1862 UV-Vis [DCM 120582max]345 nm










Final 119877 indices 1198771 = 00913

1199081198772 = 025

119877 indices (all data) 1198771 = 01263

1199081198772 = 02739









8H17

and C10H21


4 Conclusion


1015840






0 100 100 100 100200 95 95 110 95400 100 90 120 115800 100 100 120 100

(a) (b)

(c) (d)







Acknowledgments


References































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


092

097

192

192201

3

398

288

0

01

02

03

04

Abun

danc

e

05

06

07

08

09

20304050607080

81223

81188

81062

73894

72451

72267

69633

69496

69473

69359

67217

54975

53246

53223

53200

36434

25532

22165

15374

15077



15235 11376 11689 11784 11964 12798 13030 1304613329 15235 5524 1378 UV-Vis [DCM 120582max] 320 nm





2Cl2 120575) 812 (d 1H J


3 3H) 253 (s 3H SCH

3)


2Cl2 120575) 17233

16478 16219 16056 13310 13039 12982 12840 11885


C17

O3

O2 O1

C12

C11O4

C4

C2

C5C6

C7

N1

N2C10

C9

S1

(a)

O1

O3

O2

C2

C3

C1

C4

C8

C9 C10

C11

C13

C12

C17

C14

C16

C5

C7

N1

N2

Zn1

(b)

S1

O1

O3

O2

C2C3

C1

C4

C8C9

C10C11

C14

C13C12

C17C16

C5

C7

N2

N1

Zn1

(c)

S1O1

O3

O2

C2

C3 C1

C4

C8

C9

C10

C11

C6

C13

C12

C17

C16

C5 C7

N2

N1

Zn1

(d)


11733 11707 11436 5402 4141 1862 UV-Vis [DCM 120582max]345 nm










Final 119877 indices 1198771 = 00913

1199081198772 = 025

119877 indices (all data) 1198771 = 01263

1199081198772 = 02739









8H17

and C10H21


4 Conclusion


1015840






0 100 100 100 100200 95 95 110 95400 100 90 120 115800 100 100 120 100

(a) (b)

(c) (d)







Acknowledgments


References































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


C17

O3

O2 O1

C12

C11O4

C4

C2

C5C6

C7

N1

N2C10

C9

S1

(a)

O1

O3

O2

C2

C3

C1

C4

C8

C9 C10

C11

C13

C12

C17

C14

C16

C5

C7

N1

N2

Zn1

(b)

S1

O1

O3

O2

C2C3

C1

C4

C8C9

C10C11

C14

C13C12

C17C16

C5

C7

N2

N1

Zn1

(c)

S1O1

O3

O2

C2

C3 C1

C4

C8

C9

C10

C11

C6

C13

C12

C17

C16

C5 C7

N2

N1

Zn1

(d)


11733 11707 11436 5402 4141 1862 UV-Vis [DCM 120582max]345 nm










Final 119877 indices 1198771 = 00913

1199081198772 = 025

119877 indices (all data) 1198771 = 01263

1199081198772 = 02739









8H17

and C10H21


4 Conclusion


1015840






0 100 100 100 100200 95 95 110 95400 100 90 120 115800 100 100 120 100

(a) (b)

(c) (d)







Acknowledgments


References































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Final 119877 indices 1198771 = 00913

1199081198772 = 025

119877 indices (all data) 1198771 = 01263

1199081198772 = 02739









8H17

and C10H21


4 Conclusion


1015840






0 100 100 100 100200 95 95 110 95400 100 90 120 115800 100 100 120 100

(a) (b)

(c) (d)







Acknowledgments


References































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of





0 100 100 100 100200 95 95 110 95400 100 90 120 115800 100 100 120 100

(a) (b)

(c) (d)







Acknowledgments


References































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Acknowledgments


References































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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