research article sonochemical synthesis of silver...

Research ArticleSonochemical Synthesis of Silver Nanoparticles Using StarchA Comparison

Brajesh Kumar1 Kumari Smita1 Luis Cumbal1

Alexis Debut1 and Ravinandan Nath Pathak2

1 Centro de Nanociencia y Nanotecnologia Universidad de las Fuerzas Armadas (ESPE) Sangolqui Ecuador2Department of Chemistry Kolhan University Chaibasa Jharkhand 833202 India

Correspondence should be addressed to Brajesh Kumar krmbrajgmailcom and Luis Cumbal lhcumbalespeeduec

Received 21 October 2013 Revised 25 November 2013 Accepted 26 November 2013 Published 22 January 2014

Academic Editor Konstantinos Tsipis

Copyright copy 2014 Brajesh Kumar et alThis 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

A novel approach was applied to synthesize silver nanoparticles using starch under sonication Colloidal silver nanoparticlessolution exhibited an increase of absorption from 420 to 440 nm with increase starch quantity Transmission electron microscopyfollowed by selected area electron diffraction pattern analysis indicated the formation of spherical polydispersed amorphous silvernanoparticles of diameter ranging from 23 to 97 nm with mean particle size of 456 nm Selected area electron diffraction (SAED)confirmed partial crystalline and amorphous nature of silver nanoparticles Silver nanoparticles synthesized in this manner canbe used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications The optimized reactionconditions include 10ml of 1mM AgNO

3 25mg starch 11 pH range and sonication for 20min at room temperature

1 Introduction

Nanoscale materials have received considerable attentionbecause their unusual optical chemical photoelectrochem-ical and electronic properties differ significantly from thoseof atoms and molecules as well as those of bulk materials [1ndash3] The synthesis of nanomaterials with the desired qualityis one of the most exciting aspects in modern nanoscienceand nanotechnology [4] Colloidal nanoparticles are smallin diameter but large in surface area and huge in currentmany exclusive medical and industrial applications such asbiological engineering catalysts and electronic devices [5]Colloidal silver nanoparticle (Ag-NP) with natural macro-molecule can be fabricated by physical [6 7] and chemicalreduction [8ndash10]methodsNowadays biomass starch as a rawmaterial for the synthesis of Ag-Nps has reflected significantsuperiority in some process However no literature is avail-able on its preparation in starch at different pH and polysac-charide by ultrasonic field The sonochemical methods areas follows formation development and the implosion of themicrocavities [11] When solutions are exposed to ultrasonicirradiation bubbles in the solution could be imploded by

acoustic fields Cavitationrsquos bubble collapse can also induce ashock wave in the solution and drive the rapid impact of theliquid to the surface of the particles [12] Use of the sonoelec-trochemical method for the preparation of spheres rods anddendrites shaped Ag-Nps with nitriloacetate (NTA) [13] Itwas found that the electrolyte composition that comes alongreaction time can greatly affect the shape and growth of theNPs Branched silver structure with 120582max 440 nm and averagediameter of 115 nm was formed using an aqueous extract ofMesua ferrea Linn leaf [14] Nagata and coworkers formedstable colloidal dispersions of silver prepared by ultrasonicirradiation of aqueous AgNO

3or AgClO

4solutions in the

presence of surfactants [15] Amorphous Ag-NPs of 20 nmsize were prepared from an aqueous solution of AgNO

3using

argon-hydrogen atmosphere [16] and AgBr in the presence ofgelatin [17] Sonochemical route using a hazardous reducingagent (NaBH

4) produced spherical silver nanoparticles of

sizes 10 nm [18]Many methods aiming at the formation of Ag-Nps

including the green ones make use of an organic moleculeThe latter interacts with the particles and provides themwith stability against oxidation and agglomeration or it can

Hindawi Publishing CorporationBioinorganic Chemistry and ApplicationsVolume 2014 Article ID 784268 8 pageshttpdxdoiorg1011552014784268

2 Bioinorganic Chemistry and Applications

even act as a matrix only In this sense polymer moleculeshave been widely employed because their long chain offersmany binding sites in which nanoparticles can be stabilized[19] Moreover natural polymers are extremely importantbecause many of them are biocompatible and nontoxicAmong such biomolecules are sucrose [20] maltose [20]chitosan [21] Arabic gum [22] and plant extracts such as theones obtained from Jatropha curcas [23] Murraya koenigii[24] andMangifera indica [25] More specifically the naturalrubber latex (NRL) extracted fromHevea brasiliensis a nativetree from the Amazon forest arises as a possible biomaterialfor use in the synthesis of nanoparticles [26]

The use of green capping and stabilizing attribute ofstarch in aqueous solution has recently become importantin synthesis methods of nanomaterials due to the fact thatthis biopolymer acts as an effective surfactant agent and isenvironmentally friendly It is possible to obtain Ag-NPs ofspherical shape by using sago starch as coating agent [27]Shervani et al [28] synthesized silver NPs of 15 and 43 nmusing 1 wt aqueous solution of starch Others studies [2930] found that stable Ag-NPs have could been synthesized byusing soluble starch both as reducing and stabilizing agentswith sizes in the range of 10ndash34 nm

In this paper we report a green approach toward thesonochemical synthesis and stabilization of Ag-Nps by usingstarch and its application as a catalyst for synthesis 2-(2-chlorophenyl)-1H-benzimidazole (Figure 1)

2 Material and Methods

21 Chemicals All chemicals used were of analytical gradeand used without any purification Silver nitrate (990) waspurchased from Spectrum (USA) Acetonitrile ethyl acetatehexane substituted benzaldehyde and o-phenylenediaminewere purchased from Thomas Baker (INDIA) MilliporeMilli-Q water was used in all experiments

22 Synthesis and Characterization of Starched Ag-NpsPreparation of starched Ag-Nps is quite straight forwardIn a typical preparation 25 and 30mg of starch was addedto 10mL of 1mM of AgNO

3 The mixture was stirred for

complete dissolution and agitated under sonication Ultra-sound irradiation was carried out with ultrasonic processors(DAIGGER GE 505 500W 20 kHz) immersed directly intothe reaction solution The operating condition was at 30 secpulse on and 30 sec pulse off time with amplitude of 72 at25∘C for 20 minutesThemixture was prepared and observedat different pH (55minus11) under sonication pH measurementsof silver nitrate solution were done by using pHmeter (SevenEasy pH METTLER TOLEDO AG 8603 Switzerland) Thereduction of silver ions was monitored at intervals of hoursand days followed by measurement of the UV-Vis spectrausing spectrophotometer (Thermo Spectronic GENESYS 8England Quartz Cell path length 10mm and Graph Plottedon Origin 61 program) To find the highest peak or 120582maxa spectral analysis was carried out by measuring the opticaldensity of the content from wavelength 200 to 800 nm Theparticle size distributions of nanoparticles were determined

N

NH

ClCHO

Cl

Exclusively

Ag-NPsNH2

NH2

+

1 eq 1 eq

Figure 1 Schematic scheme for synthesis of 2-(2-chlorophenyl)-1H-benzimidazole

using the HORIBA Dynamic Light Scattering Version LB-550 program Size and diffraction pattern of nanoparticlesare studied on transmission electron microscopy TEM (FEITECNAI G2 spirit twin Holland) A thin film of the samplewas prepared on a carbon-coated copper grid by droppinga very small amount of the sample on the grid Fouriertransform infrared (FTIR-ATR) spectra were recorded on aPerkinElmer (Spectrum two) spectrophotometer to hypoth-esized functional groups involved in the synthesis of starchesAg-Nps X-ray diffraction (XRD) studies on thin films ofthe nanoparticle were carried out using a BRUKER D8ADVANCE brand 120579-2120579 configuration (generator-detector)X-ray tube copper 120582 = 154 A and LYNXEYE PSD detectorThe diffracted intensities were recorded from 20∘ to 70∘ 2120579angles

23 Synthesis and Characterization of 2-(2-Chlorophenyl)-1H-benzimidazole A mixture of 12-phenylenediamine(10mmol) and o-chlorobenzaldehyde (10mmol) inacetonitrile (30mL) was taken and 100 120583L of Ag-Nps wasadded at room temperature The reaction solution wasstirred at room temperature for 10 minutes The reaction wasmonitored until its completion by thin layer chromatography(TLC) The filtrate was evaporated under vacuum andsubsequently dried to afford the crude product which waspurified by column chromatography using hexaneethylacetate as eluent to afford pure benzimidazole (approx 95)The structure was characterized by NMR ESI-MS andmelting point 1HNMR spectra of CDCl

3solutions were

obtained with an Advance 500 (Model Bruker 114 Tesla500MHz) spectrometer using tetramethylsilane (TMS) as theinternal standard ESI-MS were obtained on a Varian 91 500-LC ion trapmass spectrometerMelting points determined ona digital Stuart SMP 10 melting point apparatus (ST15 OSAUK) are uncorrected The thin layer chromatography (TLC)was performed using the aluminum sheets coated with silicagel 60 (MERCK) containing fluorescent indicators F254

3 Results and Discussion

31 Comparative Study of Carboxymethyl Cellulose Starchand Sucrose under Sonication at pH 85 The bonding natureof carbohydrate plays an important role in reduction of silverion into Ag-Nps So it is very important deciding factorfor choosing bioreductant We started our experiments ashit and trial method with carboxymethyl cellulose (CMC)starch and sucrose at pH 85 under sonication Addition of25mg of CMC (90000MW) starch and sucrose to the 1mMAgNO3 solution the reaction completed by 20min with

Bioinorganic Chemistry and Applications 3

00

02

04

06

08

10

12

14

Different carbohydratesCMC Starch Sucrose

Part

icle

size

(120583m

)

Figure 2 Size of Ag-Nps synthesized by using different carbohy-drates at pH 85

6 7 8 9 10 11000204060810121416182022

pH

12hrs4days7days

9days16days22days

Part

icle

size

(120583m

)

Figure 3 Effect of pH on particle size at different time duration

change of light yellow color Particle size analyzer (DLS) usedto examine the size of controlled nanoparticles in aqueoussuspensions Figure 2 shows the comparative graph of sizeof Ag-Nps which was recorded after the completion of thereaction We observed that starch (02437120583m) has givenbetter result in comparison to CMC (03595 120583m) and sucrose(1369 120583m)The cause behind this observation was that starchis polysaccharide that has 120572-glycosidic bond (which is acovalent bond between two monosaccharides that involvesthe carbon C1 anomeric of the first unit of glucose andcarbonC4 of the second unit of glucose) which cleaved underbasic medium and sonication to give free aldehyde groupSo it acts as reducing sugar and reduces Ag+ to Ag-Npsand gluconic acid [10] whereas CMC has also o-glycosidicbut less tendency to reduce due to its high cross-linkingstructure [31] Sucrose is a disaccharide consisting of oneunit of 120572-glucose and one unit of 120573-fructose linked by 120573-glycosidic bonds which is a covalent bond between twomonosaccharides that involves carbon C1 (anomeric) of the

200 300 400 500 600 700 8000204060810121416182022242628303234

Abso

rban

ce (a

u)

Wavelength (nm)

pH 55pH 70pH 80pH 85

pH 90pH 100pH 110

Figure 4 UV-Vis spectra at different pH after 4 days

200 300 400 500 600 700 800

00

05

10

15

20

25

30

35

Abso

rban

ce (a

u)

Wavelength (nm)

440nm

420nm

Using 25mg starch20mins24hrs48hrs


Figure 5 UV-Vis spectra of Ag-Nps at different time at pH 11

glucose and carbon C2 of the fructose So it has less tendencydue to its nonreducing 120573-glycosidic bond [20] On lookingthis reducing and stabilizing nature of starch we started ourfurther experiment only with starch

32 Effect of pH on Particle Size The pH of 10mL 1mMsilver nitrate was adjusted to 55 7 8 85 9 10 and 11 usingdilute sodiumhydroxide (01 N) 25mg starchwas addedwithcontinuous stirring After complete addition the reactionwasallowed to proceed under sonication for 20mins wherebysilver colloid was formed (Table 1) It is important to notethat we performed the reaction up to pH 11 because the


Table 1 Average size of sonochemical starched Ag-NPs at different pH

AgNO3starch (1mM) pH Sonication time UV-visible absorption (nm) Average particle size (120583m)10mL25mg 55 20min 560 0181110mL25mg 70 20min 500 0142410mL25mg 80 20min 440 0275710mL25mg 85 20min 480 0255810mL25mg 90 20min 460 0219210mL25mg 100 20min 440 0187610mL25mg 110 20min 420 0085710mL30mg 110 20min 440 00978

Mean = 00456120583m

SD = 00231120583m

0010 0100

5900

Freq

uenc

y (

)

00

Particle diameter (120583m)

(a)

Mean = 00743120583m

SD = 00347120583m

0010 0100

5900

Freq

uenc

y (

)

00


(b)Figure 6 DLS image of Ag-NPs synthesized under ultrasonic irradiation for 20min after 4 days (a) 25mg and (b) 30mg starch

very high alkaline condition of the medium may lead toweakening of the association (H-bonding) even for the starchmatrix and thereby diminishing its templating potential tosupport small sized nanoparticles [32] A further increase inthe basicity of the medium may be resulting in a red shiftof the peak position Figure 3 shows the respective graph ofparticle size (DLS) of the silver colloid obtained using starchas reducing and stabilizing agent at different pHs The resultsreveal a number of observations which may be summarizedas follows (a) increasing the pH of the solution from 55 to80 is accompanied by increase of particle size and pH of thesolution from 80 to 110 abrupt decrease of particle size (b)the smallest particle size was observed at pH 11 and the size ofAg-Nps decreases with time from 4 hrs to 22 days (00857 to00411 120583m) (c) particle size continuously increases with timefrompH55 to 85 in the reactionmixture (d) the particle sizedecreases from 12 hrs to 9 days and then increases from9 daysto 22 days at pH 9 and 10 (e) when the pH 11 is targeted thesize becomes smaller and could be assigned to the Ag-Nps

33 Effect of pH on UV-Visible Absorbance Figure 4 showsthe UV-Vis spectra of the silver colloid obtained using starchas reducing and stabilizing agent at different pHs In acidicpH the association between the functional groups of starchthrough H-bonding is expected to be more pronouncedwhich stabilizes the structures and as a result of whichthese compounds are not effectively utilized in the reductionprocess This feature is reversed with the increase in basicityWith the increase of pH up to 11 the intensity of the peakat 420 nm kept on increasing which indicates the progressive

generation of the nanoparticles The results reveal a numberof observations which may be summarized as follows (a)increasing the pH of the solution is accompanied by appre-ciable changes in the electronic absorption spectra (b) aband at higher energy that is 240 nm appears at pH 10 andthe intensity of this band decreases by decreasing the pHup to 55 (c) further decreases in the pH of the reactionmedium up to pH 11 lead to lowering intensity of this band(d) simultaneously another band at 420 nm starts to appearand the absorption peak that appeared is attributed to thesurface plasmon excitation of silver particles and reaches itsmaximum intensity at pH 11 (e) when the range of pH 11 istargeted the band becomes stronger and could be assigned tothe plasmon resonance of Ag-Nps

34 Effect of Starch on Particle Size

341 UV-Visible and DLS Analysis of Ag-Nps Figure 5 showsthe UV-Vis absorption spectra of silver nanoparticles col-loidal solutions prepared at different amounts of starch (25and 30mg) at pH 11 The data reveal several importantfindings which can be presented as follows (i) using 25 and30mg of starch with 1mMAgNO

3reaction under 20min

sonication leads to outstanding enhancement in the plasmonintensity indicating that large amounts of silver ions arereduced and used for cluster formation (ii) keeping bothreactions (25 and 30mg starch) from 20min to 48 hrs isaccompanied bymarginal increment in the absorption inten-sity which could be attributed to stability of Ag-Nps (iii) theabsorption intensity observed at 420 nm and 440 nm reveals


50nm

(a)

50nm

(b)

Figure 7 TEM and SAED pictures of Ag-Nps (a) 25mg starch and (b) 30mg starch

3338

2118

1637

T(

)

3304

2928 163913371149

1077

996

928860

761

4000 3500 3000 2500 2000 1500 1000 650(cmminus1)

(a)

(b)

Figure 8 FT-IR spectrum (a) synthesized Ag-Nps (b) Starch

2120579

20 30 40 50 60 70

Inte

nsity

(au

) (111)(200)

(111)(200)

Figure 9 X-ray diffraction pattern of starch impregnated with Ag-NPs

some aggregation of Ag-Nps at 30mg starch (iv) increasingthe reaction duration up to 48 hrs the band becomes strongerand could be assigned to the plasmon resonance of Ag-Npsat 420 and 440 nm Figure 6 shows the size distribution of 25and 30mg starchedAg-Npsmean and standard deviation for25mg starchedAg-Npswas 00456 and 00231120583mwhereas for

30mg starched Ag-Nps was 00743 and 00231 120583m DLS studyreveals that the size of 25mg starched Ag-Nps is smaller than30mg its value also agrees with the interpretation UV-Visdata (220 and 240 nm) due to aggregation of starchedAg-Npsat higher concentration

342 TEM and SAED Analyses of Ag-Nps Figure 7 showsthe TEM images of Ag-Nps formed after 4 days TEM imageshows small spherical shape and polydispersed particles Thecorresponding average size distribution for 25mg starchedAg-Nps is 10 to 25 nm whereas 30mg starched Ag-Nps are23 to 97 nmThe Ag-Nps are spherical in shape selected areaelectron diffraction pattern explains their partial crystallinenature and are not aggregated in solution with 25mg starchfor 20min sonication (Figure 7(a))This is due to the bindingforce between the Ag-NPs and the capping molecules thatmay get decreased whereas 30mg starched Ag-Nps wereaggregated The diffuse band in the electron diffractionpattern is due to the presence of starch and explains amor-phous nature Ag-Nps (Figure 7(b)) The smallest size of thesynthesized Ag-Nps is 10 nm and 23 nm by using 25 and30mg starch respectively

343 FTIR Analysis of Ag-Nps FT-IR measurements werecarried out to identify the possible functional group responsi-ble for the reduction of the Ag+ ions and capping of the biore-duced Ag-Nps synthesized by starch Figure 8(b) representsthe FTIR spectrum of starch and shows bands at 3304 cmminus1for ndashOH stretching (aliphatic hydroxyl group) 2928 cmminus1 forCndashH stretching (aliphatic CndashH) and 1639 cmminus1 for carbonylstretching (C=O carbonyl group) In Figure 8(a) there isdeviation of both hydroxyl and carbonyl group it appearsat 3338 and 1637 cmminus1 indicating that both were involved insynthesis of Ag-Nps

344 XRD Analysis of Ag-Nps In the XRD spectrum(Figure 9) the broad reflexion at 20∘ to 30∘ is due to the low


9 8 7 6 5 4 3 2 1

000

020

0732

008

93

348

57

725

937

2925

730

057

3068

731

267

3189

732

707

3665

737

057

3812

738

547

3962

740

077

4121

741

547

4269

743

007

4807

748

427

4960

749

917

6856

839

098

3948

840

588

4101

139

1

210

02

115

104

51

945

100

0

(ppm)

ClN

NH

(a)

ClN

NH

1A

100

75

50

25

0

()

100 200 300 400 500 600 700 800 900 1000

23119002e + 6

22911537e + 7

Spectrum 1A

Acquired range mz

9248min scan 313 100 1000 ion 1681120583sRIC 3924e + 7 BC

ClNNN

NNH

231119002e222 + 6

229115377e + 7

(b)

Figure 10 (a) 1H NMR and (b) ESI-MS spectra of 2-(2-chlorophenyl)-1H-benzimidazole

crystallinity of the starch and other peaks are assigned todiffractions from the (111) and (200) planes of face-centredcubic (fcc) silver (Ref no-01-087-0717) SAED pattern ofAgNPs (Figure 7) also showed a diffuse band correspondingto the polymorph of starch Because the diffraction patternof silver nanoparticles could not be observed it indirectlyexplains the amorphous nature of AgNPs We hypothesizedthat an extensive number of hydroxyl groups can facilitate thecomplexation of metal ions to the molecular starch matrixAg+ reduced to Ag and Ag may be completely wrapped or beinside the starch molecule XRD and SAED pattern indicatesthe partial amorphous nature of starched AgNPs

345 NMR-ESI MS Analysis of 2-(2-Chlorophenyl)-1H-benzimidazole [33] We used starched Ag-Nps as catalyst forsynthesis of 2-aryl benzimidazole derivatives In our initialexperiments we choose 12-phenylenediamine (10mmol)and o-chlorobenzaldehyde(10mmol) as a model reactionfor optimization of catalyst and reaction conditions Figures10(a) and 10(b) show 1HNMR and ESI-MS spectra of 2-(2-chlorophenyl)-1H-benzimidazole These results confirmedthat Ag-Nps significantly increased the selectivity for synthe-sis 2-aryl benzimidazole

Chemical formula C13H9ClN2 white solid (sim95) mp

230ndash232∘C 1HNMR (500MHz CDCl3) 120575 840 (dd 1H) 768

(br 2H) 748 (m 1H) 740 (m 2H) and 731 (m 2H) ESI-MS119898119911 = 2291 (M + 1)

346 Mechanism for Ag-NP Catalyzed Synthesis of 2-ArylBenzimidazole We inspired from oxidative properties ofAg-NPs well documented by Cong et al for the Diels-Alder cycloadditions of 21015840-hydroxychalcones [34] Basedon our experimental results we propose the brief workingmechanism generated by the AgNPrsquos for the synthesis of 2-aryl benzimidazole derivatives as shown in Figure 11 The

R

R

R

R

N

N

N

N

N

H

H

HH

H

H

NH2NH2

NH2

ACN

ACNAg-NP

Ag-NP

Ag-NP

Ag-NPAg-NP

+

O 120575minus

120575+∙∙

∙∙

∙∙

∙∙

∙∙

Figure 11 Generalizedmechanism for Ag-NP catalyzed synthesis of2-aryl benzimidazole

existence of electron transfer processes between the AgNPand an aldehyde substrate consistent with the electrontransfer processes in metal nanoparticle-catalyzed oxidationreactions [35ndash38]

4 Conclusions

In summary we have demonstrated a simple clean effectiveeconomical nontoxic and environment friendly techniquefor the synthesis of colloidal silver nanoparticle by usingstarch as reducing and stabilizing agent under sonicationSonochemical reduction route demonstrates a remarkablepotential for fabricating desired particle size colloidal silvernanoparticles Absorption spectra confirm the presence ofsurface plasmon resonance at 420 and 440 nm characteristicof Ag-Nps A diverse range of pHwas used to standardize the


reaction at room temperature In addition the use of sonica-tion for synthesis of Ag-Nps ismore environmentally friendlyand safer than other synthetic methodology Starched Ag-NPs showed efficient catalytic activity for the synthesis of 2-aryl benzimidazole

Conflict of Interests

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

Acknowledgments

This scientific work has been funded by the PrometeoProject of the National Secretariat of Science Technologyand Innovation (SENESCYT) Ecuador The authors thankDr Colon Velasquez (Director INIGEMM Ecuador) forproviding XRD instrumental assistance they also thankPROINSTRA Ecuador for providing FTIR facility

References

[1] L J Guo X Cheng and C F Chou ldquoFabrication of size-controllable nanofluidic channels by nanoimprinting and itsapplication for DNA stretchingrdquo Nano Letters vol 4 no 1 pp69ndash73 2004

[2] Q Xu B D Gates and G M Whitesides ldquoFabrication ofmetal structures with nanometer-scale lateral dimensions bysectioning using a microtomerdquo Journal of the American Chemi-cal Society vol 126 no 5 pp 1332ndash1333 2004

[3] F Rosei ldquoNanostructured surfaces challenges and frontiers innanotechnologyrdquo Journal of Physics Condensed Matter vol 16no 17 pp S1373ndashS1436 2004

[4] D Bhattacharya and R K Gupta ldquoNanotechnology and poten-tial of microorganismsrdquo Critical Reviews in Biotechnology vol25 no 4 pp 199ndash204 2005

[5] M C Daniel and D Astruc ldquoGold nanoparticles assemblysupramolecular chemistry quantum-size-related propertiesand applications toward biology catalysis and nanotechnol-ogyrdquo Chemical Reviews vol 104 no 1 pp 293ndash346 2004

[6] R Zamiri B Z Azmi M Darroudi et al ldquoPreparation ofstarch stabilized silver nanoparticles with spatial self-phasemodulation properties by laser ablation techniquerdquo AppliedPhysics A vol 102 no 1 pp 189ndash194 2011

[7] M Darroudi M B Ahmad R Zamiri et al ldquoPreparationand characterization of gelatin mediated silver nanoparticles bylaser ablationrdquo Journal of Alloys and Compounds vol 509 no 4pp 1301ndash1304 2011

[8] N M Huang H N Lim S Radiman et al ldquoSucroseester micellar-mediated synthesis of Ag nanoparticles and theantibacterial propertiesrdquo Colloids and Surfaces A vol 353 no 1pp 69ndash76 2010

[9] M Darroudi M B Ahmad A H Abdullah N A Ibrahimand K Shameli ldquoEffect of accelerator in green synthesis of silvernanoparticlesrdquo International Journal of Molecular Sciences vol11 no 10 pp 3898ndash3905 2010

[10] M Singh I Sinha and R K Mandal ldquoRole of pH in the greensynthesis of silver nanoparticlesrdquo Materials Letters vol 63 no3-4 pp 425ndash427 2009

[11] AGedanken ldquoSonochemistry and its application to nanochem-istryrdquo Current Science vol 85 no 12 pp 1720ndash1722 2003

[12] L P Jiang S Xu J M Zhu J R Zhang J J Zhu and H YChen ldquoUltrasonic-assisted synthesis of monodisperse single-crystalline silver nanoplates and gold nanoringsrdquo InorganicChemistry vol 43 no 19 pp 5877ndash5883 2004

[13] J Zhu S Liu O Palchik Y Koltypin and A GedankenldquoShape-controlled synthesis of silver nanoparticles by pulsesonoelectrochemical methodsrdquo Langmuir vol 16 no 16 pp6396ndash6399 2000

[14] R Konwarh N Karak C E Sawian S Baruah andMMandalldquoEffect of sonication and aging on the templating attribute ofstarch for ldquogreenrdquo silver nanoparticles and their interactions atbio-interfacerdquo Carbohydrate Polymers vol 83 no 3 pp 1245ndash1252 2011

[15] Y Nagata Y Watananabe S I Fujita T Dohmaru and STaniguchi ldquoFormation of colloidal silver in water by ultrasonicirradiationrdquo Journal of the Chemical Society Chemical Commu-nications no 21 pp 1620ndash1622 1992

[16] R A Salkar P Jeevanandam S T Aruna Y Koltypin and AGedanken ldquoThe sonochemical preparation of amorphous silvernanoparticlesrdquo Journal of Materials Chemistry vol 9 no 6 pp1333ndash1335 1999

[17] S LiuWHuang S Chen S Avivi andAGedanken ldquoSynthesisof X-ray amorphous silver nanoparticles by the pulse sonoelec-trochemicalmethodrdquo Journal of Non-Crystalline Solids vol 283no 1ndash3 pp 231ndash236 2001

[18] I A Wani A Ganguly J Ahmed and T Ahmad ldquoSilvernanoparticles ultrasonic wave assisted synthesis optical char-acterization and surface area studiesrdquoMaterials Letters vol 65no 3 pp 520ndash522 2011

[19] H S Shin H J Yang S B Kim and M S Lee ldquoMechanism ofgrowth of colloidal silver nanoparticles stabilized by polyvinylpyrrolidone in 120574-irradiated silver nitrate solutionrdquo Journal ofColloid and Interface Science vol 274 no 1 pp 89ndash94 2004

[20] E Filippo A Serra A Buccolieri and D Manno ldquoGreensynthesis of silver nanoparticles with sucrose and maltosemorphological and structural characterizationrdquo Journal of Non-Crystalline Solids vol 356 no 6ndash8 pp 344ndash350 2010

[21] Y K Twu Y W Chen and C M Shih ldquoPreparation of silvernanoparticles using chitosan suspensionsrdquo Powder Technologyvol 185 no 3 pp 251ndash257 2008

[22] I Medina-Ramirez S Bashir Z Luo and J L Liu ldquoGreensynthesis and characterization of polymer-stabilized silvernanoparticlesrdquo Colloids and Surfaces B vol 73 no 2 pp 185ndash191 2009

[23] H Bar D K Bhui G P Sahoo P Sarkar S P De and A MisraldquoGreen synthesis of silver nanoparticles using latex of Jatrophacurcasrdquo Colloids and Surfaces A vol 339 no 1ndash3 pp 134ndash1392009

[24] D Philip C Unni S A Aromal and V K Vidhu ldquoMurrayaKoenigii leaf-assisted rapid green synthesis of silver and goldnanoparticlesrdquo Spectrochimica Acta A vol 78 no 2 pp 899ndash904 2011

[25] D Philip ldquoMangifera Indica leaf-assisted biosynthesis of well-dispersed silver nanoparticlesrdquo Spectrochimica Acta A vol 78no 1 pp 327ndash331 2011

[26] E J Guidelli A P Ramos M E D Zaniquelli and O BaffaldquoGreen synthesis of colloidal silver nanoparticles using naturalrubber latex extracted from Hevea brasiliensisrdquo SpectrochimicaActa A vol 82 no 1 pp 140ndash145 2011


[27] D K Bozanic V Djokovic J Blanusa P S Nair M K Georgesand T Radhakrishnan ldquoPreparation and properties of nano-sized Ag and Ag2S particles in biopolymer matrixrdquo EuropeanPhysical Journal E vol 22 pp 51ndash59 2007

[28] Z Shervani Y Ikushima M Sato et al ldquoMorphology andsize-controlled synthesis of silver nanoparticles in aqueoussurfactant polymer solutionsrdquo Colloid and Polymer Science vol286 no 4 pp 403ndash410 2008

[29] N Vigneshwaran R P Nachane R H Balasubramanya and PV Varadarajan ldquoA novel one-pot rsquogreenrsquo synthesis of stable silvernanoparticles using soluble starchrdquo Carbohydrate Research vol341 no 12 pp 2012ndash2018 2006

[30] V K Sharma R A Yngard and Y Lin ldquoSilver nanoparticlesgreen synthesis and their antimicrobial activitiesrdquo Advances inColloid and Interface Science vol 145 no 1-2 pp 83ndash96 2009

[31] A A Hebeish M H El-Rafie F A Abdel-Mohdy E S Abdel-Halim and H E Emam ldquoCarboxymethyl cellulose for greensynthesis and stabilization of silver nanoparticlesrdquo Carbohy-drate Polymers vol 82 no 3 pp 933ndash941 2010


[33] M A Chari D Shobha E R Kenawy S S Al-Deyab B V SReddy and A Vinu ldquoNanoporous aluminosilicate catalyst with3D cage-type porous structure as an efficient catalyst for thesynthesis of benzimidazole derivativesrdquoTetrahedron Letters vol51 no 39 pp 5195ndash5199 2010

[34] H Cong C F Becker S J Elliott M W Grinstaff and J APorco Jr ldquoSilver nanoparticle-Catalyzed diels-alder cycloaddi-tions of 21015840-hydroxychalconesrdquo Journal of theAmericanChemicalSociety vol 132 no 21 pp 7514ndash7518 2010

[35] A Grirrane A Corma and H Garcıa ldquoGold-catalyzed synthe-sis of aromatic azo compounds from anilines and nitroaromat-icsrdquo Science vol 322 no 5908 pp 1661ndash1664 2008

[36] S G Sudrik N K Chaki V B Chavan et al ldquoSilver nanoclusterredox-couple-promoted nonclassical electron transfer an effi-cient electrochemical wolff rearrangement of 120572-diazoketonesrdquoChemistry vol 12 no 3 pp 859ndash864 2006

[37] R Xu DWang J Zhang and Y Li ldquoShape-dependent catalyticactivity of silver nanoparticles for the oxidation of styrenerdquoChemistry vol 1 no 6 pp 888ndash893 2006

[38] D P Debecker C Faure M E Meyre A Dene and E MGaigneaux ldquoA new bio-inspired route to metal-nanoparticle-based heterogeneous catalystsrdquo Small vol 4 no 10 pp 1806ndash1812 2008

Submit your manuscripts athttpwwwhindawicom

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Inorganic ChemistryInternational Journal of

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Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of


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even act as a matrix only In this sense polymer moleculeshave been widely employed because their long chain offersmany binding sites in which nanoparticles can be stabilized[19] Moreover natural polymers are extremely importantbecause many of them are biocompatible and nontoxicAmong such biomolecules are sucrose [20] maltose [20]chitosan [21] Arabic gum [22] and plant extracts such as theones obtained from Jatropha curcas [23] Murraya koenigii[24] andMangifera indica [25] More specifically the naturalrubber latex (NRL) extracted fromHevea brasiliensis a nativetree from the Amazon forest arises as a possible biomaterialfor use in the synthesis of nanoparticles [26]

The use of green capping and stabilizing attribute ofstarch in aqueous solution has recently become importantin synthesis methods of nanomaterials due to the fact thatthis biopolymer acts as an effective surfactant agent and isenvironmentally friendly It is possible to obtain Ag-NPs ofspherical shape by using sago starch as coating agent [27]Shervani et al [28] synthesized silver NPs of 15 and 43 nmusing 1 wt aqueous solution of starch Others studies [2930] found that stable Ag-NPs have could been synthesized byusing soluble starch both as reducing and stabilizing agentswith sizes in the range of 10ndash34 nm

In this paper we report a green approach toward thesonochemical synthesis and stabilization of Ag-Nps by usingstarch and its application as a catalyst for synthesis 2-(2-chlorophenyl)-1H-benzimidazole (Figure 1)

2 Material and Methods

21 Chemicals All chemicals used were of analytical gradeand used without any purification Silver nitrate (990) waspurchased from Spectrum (USA) Acetonitrile ethyl acetatehexane substituted benzaldehyde and o-phenylenediaminewere purchased from Thomas Baker (INDIA) MilliporeMilli-Q water was used in all experiments

22 Synthesis and Characterization of Starched Ag-NpsPreparation of starched Ag-Nps is quite straight forwardIn a typical preparation 25 and 30mg of starch was addedto 10mL of 1mM of AgNO

3 The mixture was stirred for

complete dissolution and agitated under sonication Ultra-sound irradiation was carried out with ultrasonic processors(DAIGGER GE 505 500W 20 kHz) immersed directly intothe reaction solution The operating condition was at 30 secpulse on and 30 sec pulse off time with amplitude of 72 at25∘C for 20 minutesThemixture was prepared and observedat different pH (55minus11) under sonication pH measurementsof silver nitrate solution were done by using pHmeter (SevenEasy pH METTLER TOLEDO AG 8603 Switzerland) Thereduction of silver ions was monitored at intervals of hoursand days followed by measurement of the UV-Vis spectrausing spectrophotometer (Thermo Spectronic GENESYS 8England Quartz Cell path length 10mm and Graph Plottedon Origin 61 program) To find the highest peak or 120582maxa spectral analysis was carried out by measuring the opticaldensity of the content from wavelength 200 to 800 nm Theparticle size distributions of nanoparticles were determined

N

NH

ClCHO

Cl

Exclusively

Ag-NPsNH2

NH2

+

1 eq 1 eq

Figure 1 Schematic scheme for synthesis of 2-(2-chlorophenyl)-1H-benzimidazole

using the HORIBA Dynamic Light Scattering Version LB-550 program Size and diffraction pattern of nanoparticlesare studied on transmission electron microscopy TEM (FEITECNAI G2 spirit twin Holland) A thin film of the samplewas prepared on a carbon-coated copper grid by droppinga very small amount of the sample on the grid Fouriertransform infrared (FTIR-ATR) spectra were recorded on aPerkinElmer (Spectrum two) spectrophotometer to hypoth-esized functional groups involved in the synthesis of starchesAg-Nps X-ray diffraction (XRD) studies on thin films ofthe nanoparticle were carried out using a BRUKER D8ADVANCE brand 120579-2120579 configuration (generator-detector)X-ray tube copper 120582 = 154 A and LYNXEYE PSD detectorThe diffracted intensities were recorded from 20∘ to 70∘ 2120579angles

23 Synthesis and Characterization of 2-(2-Chlorophenyl)-1H-benzimidazole A mixture of 12-phenylenediamine(10mmol) and o-chlorobenzaldehyde (10mmol) inacetonitrile (30mL) was taken and 100 120583L of Ag-Nps wasadded at room temperature The reaction solution wasstirred at room temperature for 10 minutes The reaction wasmonitored until its completion by thin layer chromatography(TLC) The filtrate was evaporated under vacuum andsubsequently dried to afford the crude product which waspurified by column chromatography using hexaneethylacetate as eluent to afford pure benzimidazole (approx 95)The structure was characterized by NMR ESI-MS andmelting point 1HNMR spectra of CDCl

3solutions were

obtained with an Advance 500 (Model Bruker 114 Tesla500MHz) spectrometer using tetramethylsilane (TMS) as theinternal standard ESI-MS were obtained on a Varian 91 500-LC ion trapmass spectrometerMelting points determined ona digital Stuart SMP 10 melting point apparatus (ST15 OSAUK) are uncorrected The thin layer chromatography (TLC)was performed using the aluminum sheets coated with silicagel 60 (MERCK) containing fluorescent indicators F254

3 Results and Discussion

31 Comparative Study of Carboxymethyl Cellulose Starchand Sucrose under Sonication at pH 85 The bonding natureof carbohydrate plays an important role in reduction of silverion into Ag-Nps So it is very important deciding factorfor choosing bioreductant We started our experiments ashit and trial method with carboxymethyl cellulose (CMC)starch and sucrose at pH 85 under sonication Addition of25mg of CMC (90000MW) starch and sucrose to the 1mMAgNO3 solution the reaction completed by 20min with


00

02

04

06

08

10

12

14


Part

icle

size

(120583m

)


6 7 8 9 10 11000204060810121416182022

pH

12hrs4days7days

9days16days22days

Part

icle

size

(120583m

)



200 300 400 500 600 700 8000204060810121416182022242628303234

Abso

rban

ce (a

u)

Wavelength (nm)


pH 90pH 100pH 110


200 300 400 500 600 700 800

00

05

10

15

20

25

30

35

Abso

rban

ce (a

u)

Wavelength (nm)

440nm

420nm









Mean = 00456120583m

SD = 00231120583m

0010 0100

5900

Freq

uenc

y (

)

00


(a)

Mean = 00743120583m

SD = 00347120583m

0010 0100

5900

Freq

uenc

y (

)

00











50nm

(a)

50nm

(b)


3338

2118

1637

T(

)

3304

2928 163913371149

1077

996

928860

761

4000 3500 3000 2500 2000 1500 1000 650(cmminus1)

(a)

(b)


2120579

20 30 40 50 60 70

Inte

nsity

(au

) (111)(200)

(111)(200)








9 8 7 6 5 4 3 2 1

000

020

0732

008

93

348

57

725

937

2925

730

057

3068

731

267

3189

732

707

3665

737

057

3812

738

547

3962

740

077

4121

741

547

4269

743

007

4807

748

427

4960

749

917

6856

839

098

3948

840

588

4101

139

1

210

02

115

104

51

945

100

0

(ppm)

ClN

NH

(a)

ClN

NH

1A

100

75

50

25

0

()

100 200 300 400 500 600 700 800 900 1000

23119002e + 6

22911537e + 7

Spectrum 1A

Acquired range mz


ClNNN

NNH

231119002e222 + 6

229115377e + 7

(b)








R

R

R

R

N

N

N

N

N

H

H

HH

H

H

NH2NH2

NH2

ACN

ACNAg-NP

Ag-NP

Ag-NP

Ag-NPAg-NP

+

O 120575minus

120575+∙∙

∙∙

∙∙

∙∙

∙∙



4 Conclusions






Acknowledgments


References

















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


00

02

04

06

08

10

12

14


Part

icle

size

(120583m

)


6 7 8 9 10 11000204060810121416182022

pH

12hrs4days7days

9days16days22days

Part

icle

size

(120583m

)



200 300 400 500 600 700 8000204060810121416182022242628303234

Abso

rban

ce (a

u)

Wavelength (nm)


pH 90pH 100pH 110


200 300 400 500 600 700 800

00

05

10

15

20

25

30

35

Abso

rban

ce (a

u)

Wavelength (nm)

440nm

420nm









Mean = 00456120583m

SD = 00231120583m

0010 0100

5900

Freq

uenc

y (

)

00


(a)

Mean = 00743120583m

SD = 00347120583m

0010 0100

5900

Freq

uenc

y (

)

00











50nm

(a)

50nm

(b)


3338

2118

1637

T(

)

3304

2928 163913371149

1077

996

928860

761

4000 3500 3000 2500 2000 1500 1000 650(cmminus1)

(a)

(b)


2120579

20 30 40 50 60 70

Inte

nsity

(au

) (111)(200)

(111)(200)








9 8 7 6 5 4 3 2 1

000

020

0732

008

93

348

57

725

937

2925

730

057

3068

731

267

3189

732

707

3665

737

057

3812

738

547

3962

740

077

4121

741

547

4269

743

007

4807

748

427

4960

749

917

6856

839

098

3948

840

588

4101

139

1

210

02

115

104

51

945

100

0

(ppm)

ClN

NH

(a)

ClN

NH

1A

100

75

50

25

0

()

100 200 300 400 500 600 700 800 900 1000

23119002e + 6

22911537e + 7

Spectrum 1A

Acquired range mz


ClNNN

NNH

231119002e222 + 6

229115377e + 7

(b)








R

R

R

R

N

N

N

N

N

H

H

HH

H

H

NH2NH2

NH2

ACN

ACNAg-NP

Ag-NP

Ag-NP

Ag-NPAg-NP

+

O 120575minus

120575+∙∙

∙∙

∙∙

∙∙

∙∙



4 Conclusions






Acknowledgments


References

















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of




Mean = 00456120583m

SD = 00231120583m

0010 0100

5900

Freq

uenc

y (

)

00


(a)

Mean = 00743120583m

SD = 00347120583m

0010 0100

5900

Freq

uenc

y (

)

00











50nm

(a)

50nm

(b)


3338

2118

1637

T(

)

3304

2928 163913371149

1077

996

928860

761

4000 3500 3000 2500 2000 1500 1000 650(cmminus1)

(a)

(b)


2120579

20 30 40 50 60 70

Inte

nsity

(au

) (111)(200)

(111)(200)








9 8 7 6 5 4 3 2 1

000

020

0732

008

93

348

57

725

937

2925

730

057

3068

731

267

3189

732

707

3665

737

057

3812

738

547

3962

740

077

4121

741

547

4269

743

007

4807

748

427

4960

749

917

6856

839

098

3948

840

588

4101

139

1

210

02

115

104

51

945

100

0

(ppm)

ClN

NH

(a)

ClN

NH

1A

100

75

50

25

0

()

100 200 300 400 500 600 700 800 900 1000

23119002e + 6

22911537e + 7

Spectrum 1A

Acquired range mz


ClNNN

NNH

231119002e222 + 6

229115377e + 7

(b)








R

R

R

R

N

N

N

N

N

H

H

HH

H

H

NH2NH2

NH2

ACN

ACNAg-NP

Ag-NP

Ag-NP

Ag-NPAg-NP

+

O 120575minus

120575+∙∙

∙∙

∙∙

∙∙

∙∙



4 Conclusions






Acknowledgments


References

















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


50nm

(a)

50nm

(b)


3338

2118

1637

T(

)

3304

2928 163913371149

1077

996

928860

761

4000 3500 3000 2500 2000 1500 1000 650(cmminus1)

(a)

(b)


2120579

20 30 40 50 60 70

Inte

nsity

(au

) (111)(200)

(111)(200)








9 8 7 6 5 4 3 2 1

000

020

0732

008

93

348

57

725

937

2925

730

057

3068

731

267

3189

732

707

3665

737

057

3812

738

547

3962

740

077

4121

741

547

4269

743

007

4807

748

427

4960

749

917

6856

839

098

3948

840

588

4101

139

1

210

02

115

104

51

945

100

0

(ppm)

ClN

NH

(a)

ClN

NH

1A

100

75

50

25

0

()

100 200 300 400 500 600 700 800 900 1000

23119002e + 6

22911537e + 7

Spectrum 1A

Acquired range mz


ClNNN

NNH

231119002e222 + 6

229115377e + 7

(b)








R

R

R

R

N

N

N

N

N

H

H

HH

H

H

NH2NH2

NH2

ACN

ACNAg-NP

Ag-NP

Ag-NP

Ag-NPAg-NP

+

O 120575minus

120575+∙∙

∙∙

∙∙

∙∙

∙∙



4 Conclusions






Acknowledgments


References

















































Journal of

Chemistry


Advances in

Physical Chemistry



Journal of

Volume 2014














Journal of

Spectroscopy



Journal of


Quantum Chemistry






CatalystsJournal of


9 8 7 6 5 4 3 2 1

000

020

0732

008

93

348

57

725

937

2925

730

057

3068

731

267

3189

732

707

3665

737

057

3812

738

547

3962

740

077

4121

741

547

4269

743

007

4807

748

427

4960

749

917

6856

839

098

3948

840

588

4101

139

1

210

02

115

104

51

945

100

0

(ppm)

ClN

NH

(a)

ClN

NH

1A

100

75

50

25

0

()

100 200 300 400 500 600 700 800 900 1000

23119002e + 6

22911537e + 7

Spectrum 1A

Acquired range mz


ClNNN

NNH

231119002e222 + 6

229115377e + 7

(b)








R

R

R

R

N

N

N

N

N

H

H

HH

H

H

NH2NH2

NH2

ACN

ACNAg-NP

Ag-NP

Ag-NP

Ag-NPAg-NP

+

O 120575minus

120575+∙∙

∙∙

∙∙

∙∙

∙∙



4 Conclusions






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

research article sonochemical synthesis of silver...

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