research article optical waveguiding organic nanorods...

Hindawi Publishing CorporationIndian Journal of Materials ScienceVolume 2013 Article ID 136178 7 pageshttpdxdoiorg1011552013136178

Research ArticleOptical Waveguiding Organic Nanorods Coated with ReversiblySwitchable Fe(II) Spin Transition Nanoparticles

Supratim Basak Ajay Kumar Botcha M Thameem Ansari and Rajadurai Chandrasekar

Functional Molecular NanoMicro Scale Laboratory School of Chemistry University of Hyderabad Hyderabad 500 046 India

Correspondence should be addressed to Rajadurai Chandrasekar chandrasekar100yahoocom

Received 12 July 2013 Accepted 11 September 2013

Academic Editors K Kalantar-Zadeh M Lavorgna and M Romero Perez

Copyright copy 2013 Supratim Basak 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 dual functional nanohybrid object combining photonic and magnetic properties was successfully prepared through a ldquobottom-uprdquo self-assembly approach In this method spin transition Fe(II) coordination nanoparticles and optical wave guiding organicnanorods were generated in situ and successfully integrated together in a single pot through self-assemblyThe Fe(II) nanoparticlescoated on organic nanorods (nanohybrids) display temperature dependent reversible spin transition (Paramagnetic 119878 = 2 harrdiamagnetic 119878 = 0) behavior The nano-hybrids show efficient optical wave guiding behavior which demonstrates the futurepossibility to perform light induced excited spin state trapping (LIESST) experiments on a single spin transition nanoparticlelevel These photonic and magnetic ldquonanohybridsrdquo offer promising option to externally manipulate spin state of the spin transitionnanoparticles using temperature as well as remote laser light

1 Introduction

Bottom-up nanofabrication of self-assembled multifunc-tional nanoobjects and study of their uncharted physicalproperties at the nanoscale level are an active and sophis-ticated research area of nanoscience and technology [1ndash13] Particularly programming the in situ growth of self-assembled organic and inorganic nanostructures from dif-ferent molecular components and also their integration toform hybrid nanoscale objects in the same pot is a lessexplored area A successful groundwork in this disciplinemight lead to new advanced functional hybrid nanomaterialscapable of performing a sensing electronic photonic andmechanical function [1ndash13] For example integration of mag-netically bistable inorganic nanoparticles (NPs) and opticalwave guiding organic nanostructures could facilitate remotemanipulation of the light sensitive spin states of individualNPs through guided laser light Recently we have reportedfor the first time on the passive wave guiding behavior oforganic tubes and also demonstrated the remote electronicexcitation of a mesotetratolylporphyrin nanosheet using a20120583m long optical wave guiding organic tube [14ndash16] Hencewe intended to study the propensity of the 1D organic solidscoated with spin transition NPs [17ndash37] (ST-NPs) to guide

source laser light under laser confocal microscope setup Itwas anticipated that the dielectric difference between the 1Dnano-hybrid solid and the surroundingmediumwould guidethe optical wave along the growth axis of the waveguide

Among NPs Fe(II) ST-NPs are of interest due to theirswitchable bistable magnetic spin states between paramag-netic high-spin state (119878 = 2 119905

2119892

41198905

2) and diamagnetic low-spin state (119878 = 0 119905

2119892

6119890119892

0) [17ndash37] ST-NPs undergo reversiblemagnetic switching between low-spin (LS) and high-spin(HS) states due to the modulation of ligand field strengthsdepending on the temperature light and pressure Till nowthere is no direct in situ method available on the integrationof ST-NPs on other self-assembled organic nanoobjectsRecently our group reported an efficient solvent-assistedtechnique for the preparation of organic submicrotubes froma back-to-back coupled ditopic ligand 441015840-bis(26-di(1H-pyrazol-1-yl)pyridin-4-yl)biphenyl L in dichloromethane[12] We found that L also forms crystalline organic nanorods(ONRs) in hexane Additionally L is also a good candidate forthe syntheses of 1D ST metallosupramolecular coordinationpolymers [38 39] due to its readily available two tridentatemetal chelating sites on either side of the molecule Theexposure and reactivity of the chelating molecules L available

2 Indian Journal of Materials Science

Hexane

Self-assembly of NPs coated

Hexane

ST-NPs coatedONR

Mixing

Ligands in ethanol

nL

Mixing

= surfactant

+

2

1

n

1D ST polymer

FeII (BF4)2

Fe(II) salt in water

organic nano-rods (ONRs)

NN

N

NN

NN

N

NN

= FeII salt

Scheme 1 Representation of the components used in the reverse micelle technique for the fabrication of spin transition nanoparticles (ST-NPs) coated organic nanorods (ONRs)

on the surface of the preorganized ONRs to reactants such asFeII ion and surfactant may also facilitate the surface selectivegrowth of ST coordination NPs there by finally formingintegrated functional ST nanohybrids

To realize our idea by following reversemicelle technique[40] we developed a singlestep method to fabricate ONRsfrom L which are coated with ST-NPs (Scheme 1) Hereinwe report our nanohybrid preparation procedure (i) self-assembly of L to form ONRs and (ii) self-assembly of ST-NPs from molecules L available on the surface of the ONRsin presence of FeII salt and surfactants We also report theelectron (SEM FESEM and TEM) atomic force microscopy(AFM) and Raman spectroscopy images of the nanoobjectsand also the variable temperaturemagnetic properties of bulk1D ST coordination polymer 1 and ST-NPs coated onONRs 2Finally we also present our preliminary results on the opticalwave guiding tendency of the nano-hybrids

2 Materials and Methods

21 Materials The materials citrazinicacid [Pd(PPh3)4] tri-

fluoroacetic acid sodium dioctyl sulphosuccinate (SDS)docosanic acid Fe(BF

4)2sdot6H2O and pyrazole were purchased

from Aldrich Sodium azide KI K2CO3 NaNO

2 sodium

thiosulfate and diethyl ether were purchased from Merckchemicals Oxalyl chloride POCl

3 iodine and NaHCO

3

were purchased from Avra Synthesis Hyderabad The sol-vents were distilled and dried before reactions and forextracting purposes IR spectra were recorded on JASCOFTIR-5300 Elemental analysis was recorded on a ThermoFinnigan Flash EA 1112 analyzer Size and morphology ofthe nanostructures were examined by using a Philips XL30ESEM Scanning electron microscope (SEM) using a beamvoltage of 20 kV and a Tecnai G2 FEI F12 transmissionelectron microscope (TEM) at an accelerating voltage of120 kV FESEM measurements were performed on a Hitachi

Indian Journal of Materials Science 3

(a)

Close-endedfeature

(b)

ONR

ST-NPs

(c)

EDAXon a

ST-NPs

(d)

EDAX

CSi

O Na

FeMg Au

Mo CaCa

4002000

121

242

363

484

(e)

ONR

ST-NPs

(f)

00

05

05

05

10

10

15

15

20

20

25 30 35

35

40

40

45

45

50

(120583m

)

(120583m)

2530 ST-NPs

(g)

ST-NPs

0 1 2 3 4 5

Plane (120583m)

0

05

10

15

(120583m

)

(h)

Figure 1 SEM (a) FESEM ((b)ndash(e)) TEM (f) and AFM ((g)-(h)) micrographs and data of ONRs coated with coordination ST-NPs 2 (a) Abunch of ONRs coated with ST-NPs (b) close-ended feature of a ONR ((c) (d)) a nanorod clearly shows the presence of spherical ST-NPaggregates on it (e) energy dispersive X-ray analysis (EDAX) data collected on ST-NPs coated onONR (f) the dark (ST-NPs) and grey colour(ONR) contrast clearly distinguish the NPs from the ONRs (g) AFM image of a single ONR coated with ST-NPs (h) Cross-section profilealong the red line in (g) Scale bars are (a) 10 120583m (b) (c) 2120583m (d) 1 120583m and (f) 200 nm

S-4500 SEN instrument operating at 20 kV AFM imagingwas carried out onNT-MDTModel Solver ProMmicroscopeusing semicontact mode Variable temperature magneticsusceptibility measurements of the solid samples (1 and 2)were recorded in the temperature range of 5 harr 375K usinga Quantum Design VSM-SQUID magnetometer with anapplied DC magnetic field of 1000 G Powder sample waspacked in a nonmagnetic sample holder and mounted on anonmagnetic straw

22 Confocal Micro-Raman SpectroscopyWaveguiding Stud-ies Raman spectra of the samples were recorded on a Wi-Tec alpha 300 confocal Raman spectrometer (back scatteringgeometry) equipped with a Peltier-cooled CCD detector A400 nm Ar+ laser was used for the experiments Using a600 groovesmm grating BLZ = 500 nm the integration time

was typically 05000 s Ten accumulations were performedfor acquiring a single spectrum All measurements werecollected in air and room temperature Optical waveguidingstudies were also performed on this setup

23 Experimental Methods Preparation of coordinationpolymer is as following (1) 40mg (0069mmol) of lig-and 441015840-bis(26-di(1H-pyrazol-1-yl)pyridin-4-yl)biphenyl Lwas dissolved in a deaerated dichloromethane (30mL) Tothis a deaerated methanolic solution containing 355mg(0139mmol) of Fe(BF

4)2sdot6H2O was added and stirred for

2 days under N2atmosphere The solvents were evaporated

from the turbid solution and the obtained yellow precip-itate was collected and washed with dichloromethane andmethanol and finally air-dried Yield 53mg FTIR (KBr]cmminus1) 3524 3435 3128 2924 2854 1631 1572 1523 1460


800 1000 1200 1400 1600 1800 200016

07

1444

1364128312

23

112599

6 L

1607

144413

781289

1021 1

Ram

an in

tens

ity (a

u)

1378

1256

1256

1021

1607

1444

1364

128912

23

1125996

2

(a) (b)

Raman shift (cmminus1)

Figure 2 Comparative confocal Raman micro spectroscopic data collected from L 1 and the FeII coordination nanoparticles coated organicnano-rods 2 (a) Raman image of the 1021 cmminus1 region (b) Raman image of the region between 1580 and 1631 cmminus1

(a) (b)

(c)

400 500 600 700

10

20

Inte

nsity

(au

)

Wavelength (nm)

(d)

Figure 3 Confocal fluorescence microscopy data of nanorodscoated with ST-NPs 2 (a) Before excitation ((b) (c)) after excitationby Ar-ion UV laser (d) Emission spectrum of rods shown in (b) and(c)

1406 1253 1219 1053 966 819 761 Elemental analysis ()calculated for C

34H24B2F8FeN10 C 5091 H 302 N 1746

found C 5141 H 295 N 1725Preparation of ST nanoparticles coated nanorod is as

follows (2) Fe(BF4)2sdot6H2O (146mg 0664mmol) was dis-

solved in water (2mL) and added to a mixture of sodiumdioctyl sulphosuccinate (0256 g) in 10mL of hexane Aftera few minutes of stirring behenic acid (394mg 1328)was added to this suspension 441015840-Bis(26-di(1H-pyrazol-1-yl)pyridin-4-yl)biphenyl (100mg 0174mmol) was sus-pended to ethanol (10mL) added to the above mixture

and vigorously stirred for 36 h Afterwards the mixture wasevaporated to get a sticky solid which is contaminated bysurfactants which was removed by centrifuging with ethanolfor several times The powder obtained was finally driedunder vacuum to afford a yellow powder of 2 (50mg) FTIR(KBr ]cmminus1) 3148 2918 2849 1707 1612 1572 1539 15101462 1394 1261 1207 1035 952 935 914 871 823 787 767628 605 486

3 Result and Discussion

In the bulk state treatment of L with FeII (BF4)2(1 1 stoi-

chiometry) in acetonitrile immediately formed an insolubleyellow precipitate which indicated the formation of a 1Dlinear coordination polymer [FeII(L

2)(BF4)2]1198991 We have

employed an in situ reverse micelle technique to grow self-assembled nano-hybrids that is ONRs coated with ST-NPsFirstly dispersion of an ethanol solution of L in hexanefollowed by treatment with sodium dioctyl sulfosuccinatesurfactant formed micelle containing L stabilized by thesurfactant Secondly dispersal of an aqueous solution ofFeII salt in hexane followed by the treatment of surfactantproduced a FeII carrying micelle stabilized by the surfactantsMixing followed by stirring of the two solutions containingmicelle carrying L and FeII salt formed a yellow precipitate ofST-NPs coated ONRs 2 Filtration of the resultant precipitatefollowed by drying gave a light yellow powder of 2

The electron microscopy (SEM FESEM and TEM)images of 2 clearly exhibited the formation of ST-NPs onONRs The SEM images of 2 showed the ONRs of differentlengths varying from 5ndash30 120583m lengths and widths in therange of ca 1ndash4120583m (Figure 1(a)) FESEM measurementsclearly showed the growth of spherical NPs on the surfaceof the ONRs (Figures 1(b)ndash1(d)) Furthermore the energydispersive X-ray analysis (EDAX) measurement performedonNPs coated onONRs clearly indicated the presence of ironions in the spherical NPs (Figure 1(e))


0 50 100 150 200 250 300 350 400

05

10

15

20

25

30

35

40

0 75 150 225 300 3750

20406080

100120

Temperature (K)

Temperature (K)

1

120594T

(em

umiddotK

mol

)

1120594

(em

uminus1

Kminus1

mol

)

(a)

Temperature (K)

Temperature (K)0 50 100 150 200 250 300 350 400

005

010

015

020

025

030

035

040

045

050

055

0 75 150 225 300 3750

200400600800

1000

1120594(e

mu

g)

2

120594T

(em

umiddotK

g)

(b)

Figure 4 120594119879 = 119891(119879) plots for bulk sample of 1 and the FeII coordination nanoparticles coated organic nanorods 2 Inset figures show the 1120594versus 119879 plots

With 488 LPEF filter

5120583m

(a)

(b)

(c)

(d)

(e)

(f)

(g)

Figure 5 Confocal micrographs of a wave guiding ONR under 488 nm Ar+ laser illumination ((a)ndash(d)) without 488 nm LPEF ((e)ndash(g))with 488 nm LPEF filter Red circles show laser illumination point and bluegreen arrows show the propagation direction

Additionally AFM measurements confirmed thecoassembly of ST-NPs on ONRs (Figures 1(g) and 1(h))A typical width times height range profile of selected ONRs isca 1ndash4 times 04ndash15120583m Direct visualization of ST-NPs (blackcontrast) on the surface of the ONRs (grey contrast) wasachieved by TEM measurements (Figure 1(f)) The NPs arespherical in shape and the sizes were in the range of ca70ndash200 nm The spherical particles were aggregated togetheron the surface of the ONRs Furthermore confocal Ramanmicro spectroscopic data (with 488 nm Ar+ laser backscattering mode) confirmed the presence of ST-NPs on thesurface of the ONR by exhibiting characteristic Raman shiftscorresponding to L and 1 (Figure 2) Raman imaging of aselected ONR using the NPs marker modes 992 cmminus1 to1031 cmminus1 showed that the particles are mostly concentratedat the centre and at the rod ends The confocal fluorescencemicroscopy studies of the nanorods coated with ST-NPs

2 displayed a blue emission at 443 nm demonstrating thefluorescence property of the nano-rods and also possibilityto utilize these rods as active waveguides (Figure 3)

The temperature dependentmagneticmeasurements dataof 1 and 2 in the range of 375 harr 5K at 1000 Oe DCmagnetic field are shown in Figure 4 For 1 the product ofmagnetic susceptibility and temperature (120594119879) versus 119879 curveindicated the presence of a reversible ST behavior The valueof 120594119879 at 375K is ca 35 emusdotKmol which indicated theHS state of 1 Upon cooling down to 293K the 120594119879 valuefurther decreased to 285 emusdotKmol This demonstrated thepresence ofHS and LS fractions at room temperature Furthercooling showed a steep decrease of the 120594119879 value whichreached a minimum value of ca 05 emusdotKmol at 5 K Thisspecified the completion of the ST event The 120594119879 curveshowed a similar trend even in the heating mode performedup to 375K The ST temperature of 1 is ca 201 K Since


the process of ST is very sensitive to environmental changesto explore the ST tendency of the NPs coated on ONRs thevariable temperature magnetic properties of sample 2 werealso investigated Interestingly the reversible ST property wasretained for 2 but with a change in the ST temperature (ca160K) and its propensity compared to 1 The shifting of theST to lower temperature side is perhaps due to the decreaseof the long-range cooperatives in the NP state Additionallythe origin of smooth ST compared to 1 is probably due to thepresence of ST-NPs of various particle size ranges [25]

For the passive optical wave guiding studies a visible lightlaser (488 nm Ar+) was employed to circumvent the elec-tronic absorption of a laser light by the molecular buildingblocks of the rods (Figure 5(a)) The laser beam was coupledto the ONR kept on a thin glass substrate through a 50xobjective (NA = 090) Orthogonal illumination of a laserbeam at any one of the ends of a rod (optical coupling point)showed propagation of guided laser light to the opposite endof the rod (Bright field images Figures 5(b) and 5(c)) whileirradiation of laser at the center of the rod showed guidedlight propagation to both ends of the rod (Figure 5(d)) Thecorresponding dark field images taken with a 488 long passedge filter (LPEF) are shown in Figures 5(e)ndash5(g) Fe(II) ST-NPs are known to display light induced electron spin statetrapping (LIESST) effect [41] that is metastable high-spinstate (119878 = 2) upon illumination with laser light at cryogenictemperature In all of the reported literature works theseLIESST experiments were performed on a bulk ST samples[41ndash44] Our preliminary experimental results demonstratethat the LIESST studies can be done on single ST-NP levelusing a waveguiding organic nanorods coated with ST-NPs

4 Conclusions

The presented results clearly demonstrate a successful in situpreparation of organic and inorganic nanostructures such asST-NPs andONRs in a single pot to create ldquonanohybridsrdquoTheoptical wave guiding nature of the ONRs can be exploitedto control the spin state of the ST-NPs using guided laserlight This is an attempt towards the ldquobottom-uprdquo fabricationof externally switchable ldquonanohybridsrdquo

References

[1] S Mann ldquoSelf-assembly and transformationof hybrid nano-objects and nanostructures under equilibrium and non-equilibrium conditionsrdquo Nature Materials vol 8 pp 781ndash7922009

[2] C AMirkin and CM NiemeyerNanobiotechnology II Wiley-VCH Weinheim Germany 2007

[3] C A Mirkin R L Letsinger R C Mucic and J J StorhoffldquoA DNA-based method for rationally assembling nanoparticlesintomacroscopic materialsrdquoNature vol 382 no 6592 pp 607ndash609 1996

[4] E Katz and I Willner ldquoIntegrated nanoparticle-biomoleculehybrid systems synthesis properties and applicationsrdquo Ange-wandte Chemie International Edition vol 43 pp 6042ndash61082004

[5] T Nakanishi ldquoSupramolecular soft and hard materials basedon self-assembly algorithms of alkyl-conjugated fullerenesrdquoChemical Communications vol 46 no 20 pp 3425ndash3436 2010

[6] K J C van Bommel A Friggeri and S Shinkai ldquoOrganic tem-plates for the generation of inorganic materialsrdquo AngewandteChemie International Edition vol 42 no 9 pp 980ndash999 2003

[7] M Li C Viravaidya and S Mann ldquoPolymer-mediated synthe-sis of ferritin-encapsulated inorganic nanoparticlesrdquo Small vol3 no 9 pp 1477ndash1481 2007

[8] M Okuda Y Kobayashi K Suzuki et al ldquoSelf-organizedinorganic nanoparticle arrays on protein latticesrdquo Nano Lettersvol 5 no 5 pp 991ndash993 2005

[9] P J Meadows E Dujardin S R Hall and S Mann ldquoTemplate-directed synthesis of silica-coated j-aggregate nanotapesrdquoChemical Communications no 29 pp 3688ndash3690 2005

[10] A J Patil M Li E Dujardin and S Mann ldquoNovel bioinorganicnanostructures based on mesolamellar intercalation or single-molecule wrapping of DNA using organoclay building blocksrdquoNano Letters vol 7 no 9 pp 2660ndash2665 2007

[11] M Sofos J Goldberger D A Stone et al ldquoA synergistic assem-bly of nanoscale lamellar photoconductor hybridsrdquo NatureMaterials vol 8 no 1 pp 68ndash75 2009

[12] N Chandrasekhar and R Chandrasekar ldquoEngineering self-assembled fluorescent organic nanotapes and submicrotubesfrom n-conjugated moleculesrdquo Chemical Communications vol46 no 17 pp 2915ndash2917 2010

[13] S Basak and R Chandrasekar ldquoMultiluminescent hybridorganicinorganic nanotubular structures one-pot fabrica-tion of tricolor (Blue Red-Purple) luminescent parallepipedicorganic superstructure grafted with europium complexesrdquoAdvanced Functional Materials vol 21 no 4 pp 667ndash673 2011

[14] N Chandrasekhar M A Mohiddon and R ChandrasekarldquoOrganic submicro tubular optical waveguides self-assemblydiverse geometries efficiency and remote sensing propertiesrdquoAdvanced Optical Materials vol 1 no 4 pp 305ndash311 2013

[15] P Hui and R Chandrasekar ldquoLight propagation in high-spin organic microtubes self-assembled from shape persistentmacrocycles carrying oxo-verdazyl biradicalsrdquo Advanced Mate-rials vol 25 no 21 pp 2963ndash2967 2013

[16] N Chandrasekhar and R Chandrasekar ldquoReversibly shape-shifting organic optical waveguides formation of organicnanorings nanotubes and nanosheetsrdquo Angewandte ChemieInternational Editio vol 51 no 15 pp 3556ndash3561 2012

[17] P Gutlich andHAGoodwin Eds Spin Crossover in TransitionMetal Compounds I vol 233 of Topics in Current ChemistrySpringer Berlin Germany 2004

[18] H Spiering Spin Crossover in Transition Metal CompoundsIII vol 235 of Topics in Current Chemistry Springer BerlinGermany 2004

[19] E Konig ldquoStructural changes accompanying continuous anddiscontinuous spin-state transitionsrdquo in Progress in InorganicChemistry vol 35 p 527 1987

[20] A B Gaspar V Ksenofontov M Seredyuk and P GutlichldquoMultifunctionality in spin crossover materialsrdquo CoordinationChemistry Reviews vol 249 no 23 pp 2661ndash2676 2005

[21] P Gutlich Y Garcia and T Woike ldquoPhotoswitchable coordi-nation compoundsrdquo Coordination Chemistry Reviews vol 219ndash221 pp 839ndash879 2001

[22] M A Halcrow ldquoIron(II) complexes of 26-di(pyrazol-1-yl)pyridinesmdasha versatile system for spin-crossover researchrdquoCoordination Chemistry Reviews vol 253 no 21-22 pp 2493ndash2514 2009


[23] T Forestier S Mornet N Daro et al ldquoNanoparticles of iron(II)spin-crossoverrdquo Chemical Communications no 36 pp 4327ndash4329 2008

[24] E Coronado J R Galan-Mascaros M Monrabal-Capilla JGarca-Martnez and P Pardo-Ibanez ldquoBistable spin-crossovernanoparticles showing magnetic thermal hysteresis near roomtemperaturerdquo Advanced Materials vol 19 pp 1359ndash1361 2007

[25] F Volatron L Catala E Riviere A Gloter O Stephan and TMallah ldquoSpin-crossover coordination nanoparticlesrdquo InorganicChemistry vol 47 no 15 pp 6584ndash6586 2008

[26] I Boldog A B Gaspar V Martinez et al ldquoSpin-crossovernanocrystals with magnetic optical and structural bistabilitynear room temperaturerdquo Angewandte Chemie InternationalEdition vol 47 no 34 pp 6433ndash6437 2008

[27] J Larionova L Salmon Y Guari et al ldquoTowards the ultimatesize limit of the memory effect in spin-crossover solidsrdquoAngewandte Chemie International Edition vol 47 no 43 pp8236ndash8240 2008

[28] J-F Letard ldquoPhotomagnetism of iron(II) spin crossovercomplexes-the T(LIESST) approachrdquo Journal of MaterialsChemistry vol 16 pp 2550ndash2559 2006

[29] R Chandrasekar F Schramm O Fuhr and M RubenldquoAn iron(II) spin-transition compound with thiol anchoringgroupsrdquo European Journal of Inorganic Chemistry no 17 pp2649ndash2653 2008

[30] M Cavallini I Bergenti S Milita et al ldquoMicro and nanopat-terning of spin-transition compounds into logical structuresrdquoAngewandte Chemie International Edition vol 47 no 45 pp8596ndash8600 2008

[31] C Rajadurai F Schramm S Brink et al ldquoSpin transitionin a chainlike supramolecular iron(II) complexrdquo InorganicChemistry vol 45 no 25 pp 10019ndash10021 2006

[32] C Rajadurai O Fuhr R Kruk M Ghafari H Hahnand M Ruben ldquoAbove room temperature spin transitionin a metallo-supramolecular coordination oligomerpolymerrdquoChemical Communications no 25 pp 2636ndash2638 2007

[33] C Rajadurai Z Qu O Fuhr et al ldquoLattice-solvent controlledspin transitions in iron(ii) complexesrdquo Dalton Transactions no32 pp 3531ndash3537 2007

[34] N Chandrasekhar and R Chandrasekar ldquolsquoSuper hybrid triden-tate ligandsrsquo 4-substituted-2-(1-butyl-1H-123-triazol-4-yl)-6-(1H-pyrazol-1-yl)pyridine ligands coordinated to Fe(ii) ionsdisplay above room temperature spin transitionsrdquoDaltonTrans-actions vol 39 no 41 pp 9872ndash9878 2010

[35] S Basak P Hui and R Chandrasekar ldquoFlexible and opti-cally transparent polymer embedded nanomicro scale spincrossover Fe(II) complex patternsarraysrdquo Chemistry of Mate-rials vol 25 no 17 pp 3408ndash3413 2013

[36] I Salitros J Pavlik R Boca O Fuhr C Rajadurai and MRuben ldquoSupramolecular lattice-solvent control of iron(ii) spintransition parametersrdquo Crystal Engineering Communicationsvol 12 no 8 pp 2361ndash2368 2010

[37] R Gonzalez-Prieto B Fleury F Schramm et al ldquoTun-ing the spin-transition properties of pyrene-decorated 26-bispyrazolylpyridine based Fe(ii) complexesrdquo Dalton Transac-tions vol 40 no 29 pp 7564ndash7570 2011

[38] N Chandrasekhar and R Chandrasekar ldquolsquoClick-fluorsrsquo synthe-sis of a family of120587-conjugated fluorescent back-to-back coupled26-bis(triazol-1-yl)pyridines and their self-assembly studiesrdquoJournal of Organic Chemistry vol 75 pp 4852ndash4855 2010

[39] S Basak P Hui S Boodida and R Chandrasekar ldquoMicropat-terning of metallopolymers syntheses of back-to-back coupledoctylated 26-Bis(pyrazolyl)pyridine ligands and their solution-processable coordination polymersrdquo Journal of Organic Chem-istry vol 77 no 7 pp 3620ndash3626 2012

[40] S Vaucher M Li and S Mann ldquoSynthesis of prussian bluenanoparticles and nanocrystal superlattices in reverse micro-emulsionrdquo Angewandte Chemie International Edition vol 39no 10 pp 1793ndash1796 2000

[41] P Chakraborty M L Boillot A Tissot and A HauserldquoPhotoinduced relaxation dynamics in iron(ii) spin-crossovernanoparticles the significance of crystallinityrdquo AngewandteChemie International Edition vol 52 no 1 p 1 2013

[42] S Decurtins P Gutlich C P Kohler and H Spiering ldquoNewexamples of light-induced excited spin state trapping (liesst) iniron(ii) spin-crossover systemsrdquo Journal of the Chemical SocietyChemical Communications no 7 pp 430ndash432 1985

[43] J-F Letard P Guionneau L Rabardel et al ldquoStructuralmagnetic and photomagnetic studies of amononuclear iron(II)derivative exhibiting an exceptionally abrupt spin transi-tion light-induced thermal hysteresis phenomenonrdquo InorganicChemistry vol 37 no 17 pp 4432ndash4441 1998

[44] N O Moussa E Trzop S Mouri et al ldquoWavelength selectivelight-induced magnetic effects in the binuclear spin crossovercompound [Fe(bt)(NCS)

2]2(bpym)rdquo Physical Review B vol 75

no 5 Article ID 054101 2007

Submit your manuscripts athttpwwwhindawicom

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Journal ofNanomaterials


Hexane

Self-assembly of NPs coated

Hexane

ST-NPs coatedONR

Mixing

Ligands in ethanol

nL

Mixing

= surfactant

+

2

1

n

1D ST polymer

FeII (BF4)2

Fe(II) salt in water

organic nano-rods (ONRs)

NN

N

NN

NN

N

NN

= FeII salt

Scheme 1 Representation of the components used in the reverse micelle technique for the fabrication of spin transition nanoparticles (ST-NPs) coated organic nanorods (ONRs)

on the surface of the preorganized ONRs to reactants such asFeII ion and surfactant may also facilitate the surface selectivegrowth of ST coordination NPs there by finally formingintegrated functional ST nanohybrids

To realize our idea by following reversemicelle technique[40] we developed a singlestep method to fabricate ONRsfrom L which are coated with ST-NPs (Scheme 1) Hereinwe report our nanohybrid preparation procedure (i) self-assembly of L to form ONRs and (ii) self-assembly of ST-NPs from molecules L available on the surface of the ONRsin presence of FeII salt and surfactants We also report theelectron (SEM FESEM and TEM) atomic force microscopy(AFM) and Raman spectroscopy images of the nanoobjectsand also the variable temperaturemagnetic properties of bulk1D ST coordination polymer 1 and ST-NPs coated onONRs 2Finally we also present our preliminary results on the opticalwave guiding tendency of the nano-hybrids

2 Materials and Methods

21 Materials The materials citrazinicacid [Pd(PPh3)4] tri-

fluoroacetic acid sodium dioctyl sulphosuccinate (SDS)docosanic acid Fe(BF

4)2sdot6H2O and pyrazole were purchased

from Aldrich Sodium azide KI K2CO3 NaNO

2 sodium

thiosulfate and diethyl ether were purchased from Merckchemicals Oxalyl chloride POCl

3 iodine and NaHCO

3

were purchased from Avra Synthesis Hyderabad The sol-vents were distilled and dried before reactions and forextracting purposes IR spectra were recorded on JASCOFTIR-5300 Elemental analysis was recorded on a ThermoFinnigan Flash EA 1112 analyzer Size and morphology ofthe nanostructures were examined by using a Philips XL30ESEM Scanning electron microscope (SEM) using a beamvoltage of 20 kV and a Tecnai G2 FEI F12 transmissionelectron microscope (TEM) at an accelerating voltage of120 kV FESEM measurements were performed on a Hitachi


(a)

Close-endedfeature

(b)

ONR

ST-NPs

(c)

EDAXon a

ST-NPs

(d)

EDAX

CSi

O Na

FeMg Au

Mo CaCa

4002000

121

242

363

484

(e)

ONR

ST-NPs

(f)

00

05

05

05

10

10

15

15

20

20

25 30 35

35

40

40

45

45

50

(120583m

)

(120583m)

2530 ST-NPs

(g)

ST-NPs

0 1 2 3 4 5

Plane (120583m)

0

05

10

15

(120583m

)

(h)










800 1000 1200 1400 1600 1800 200016

07

1444

1364128312

23

112599

6 L

1607

144413

781289

1021 1

Ram

an in

tens

ity (a

u)

1378

1256

1256

1021

1607

1444

1364

128912

23

1125996

2

(a) (b)



(a) (b)

(c)

400 500 600 700

10

20

Inte

nsity

(au

)

Wavelength (nm)

(d)



34H24B2F8FeN10 C 5091 H 302 N 1746








2)(BF4)2]1198991 We have




0 50 100 150 200 250 300 350 400

05

10

15

20

25

30

35

40

0 75 150 225 300 3750

20406080

100120

Temperature (K)

Temperature (K)

1

120594T

(em

umiddotK

mol

)

1120594

(em

uminus1

Kminus1

mol

)

(a)

Temperature (K)

Temperature (K)0 50 100 150 200 250 300 350 400

005

010

015

020

025

030

035

040

045

050

055

0 75 150 225 300 3750

200400600800

1000

1120594(e

mu

g)

2

120594T

(em

umiddotK

g)

(b)



5120583m

(a)

(b)

(c)

(d)

(e)

(f)

(g)








4 Conclusions


References























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




(a)

Close-endedfeature

(b)

ONR

ST-NPs

(c)

EDAXon a

ST-NPs

(d)

EDAX

CSi

O Na

FeMg Au

Mo CaCa

4002000

121

242

363

484

(e)

ONR

ST-NPs

(f)

00

05

05

05

10

10

15

15

20

20

25 30 35

35

40

40

45

45

50

(120583m

)

(120583m)

2530 ST-NPs

(g)

ST-NPs

0 1 2 3 4 5

Plane (120583m)

0

05

10

15

(120583m

)

(h)










800 1000 1200 1400 1600 1800 200016

07

1444

1364128312

23

112599

6 L

1607

144413

781289

1021 1

Ram

an in

tens

ity (a

u)

1378

1256

1256

1021

1607

1444

1364

128912

23

1125996

2

(a) (b)



(a) (b)

(c)

400 500 600 700

10

20

Inte

nsity

(au

)

Wavelength (nm)

(d)



34H24B2F8FeN10 C 5091 H 302 N 1746








2)(BF4)2]1198991 We have




0 50 100 150 200 250 300 350 400

05

10

15

20

25

30

35

40

0 75 150 225 300 3750

20406080

100120

Temperature (K)

Temperature (K)

1

120594T

(em

umiddotK

mol

)

1120594

(em

uminus1

Kminus1

mol

)

(a)

Temperature (K)

Temperature (K)0 50 100 150 200 250 300 350 400

005

010

015

020

025

030

035

040

045

050

055

0 75 150 225 300 3750

200400600800

1000

1120594(e

mu

g)

2

120594T

(em

umiddotK

g)

(b)



5120583m

(a)

(b)

(c)

(d)

(e)

(f)

(g)








4 Conclusions


References























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




800 1000 1200 1400 1600 1800 200016

07

1444

1364128312

23

112599

6 L

1607

144413

781289

1021 1

Ram

an in

tens

ity (a

u)

1378

1256

1256

1021

1607

1444

1364

128912

23

1125996

2

(a) (b)



(a) (b)

(c)

400 500 600 700

10

20

Inte

nsity

(au

)

Wavelength (nm)

(d)



34H24B2F8FeN10 C 5091 H 302 N 1746








2)(BF4)2]1198991 We have




0 50 100 150 200 250 300 350 400

05

10

15

20

25

30

35

40

0 75 150 225 300 3750

20406080

100120

Temperature (K)

Temperature (K)

1

120594T

(em

umiddotK

mol

)

1120594

(em

uminus1

Kminus1

mol

)

(a)

Temperature (K)

Temperature (K)0 50 100 150 200 250 300 350 400

005

010

015

020

025

030

035

040

045

050

055

0 75 150 225 300 3750

200400600800

1000

1120594(e

mu

g)

2

120594T

(em

umiddotK

g)

(b)



5120583m

(a)

(b)

(c)

(d)

(e)

(f)

(g)








4 Conclusions


References























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




0 50 100 150 200 250 300 350 400

05

10

15

20

25

30

35

40

0 75 150 225 300 3750

20406080

100120

Temperature (K)

Temperature (K)

1

120594T

(em

umiddotK

mol

)

1120594

(em

uminus1

Kminus1

mol

)

(a)

Temperature (K)

Temperature (K)0 50 100 150 200 250 300 350 400

005

010

015

020

025

030

035

040

045

050

055

0 75 150 225 300 3750

200400600800

1000

1120594(e

mu

g)

2

120594T

(em

umiddotK

g)

(b)



5120583m

(a)

(b)

(c)

(d)

(e)

(f)

(g)








4 Conclusions


References























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






4 Conclusions


References























































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



research article optical waveguiding organic nanorods...

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