Ionic Liquids as Recycling Solvents for The Synthesis of Magnetic

Electronic Supplementary Information

Ionic Liquids as Recycling Solvents for The Synthesis of Magnetic Nanoparticles

Flavia C. C. Oliveira,a Fernando B. Effenberger,b Marcelo H. Sousa,c Renato F. Jardim,d Pedro K. Kiyohara,d Jairton Dupont,e Joel C. Rubim*a and Liane M. Rossi*b

1. Experimental details

Synthesis of ionic liquids

The synthesis of BMI.NTf2 and BMI.PF6 were done by modification of the process developed by Cassol et al.( C. C. Cassol,

G. Ebeling, B. Ferrera, J. Dupont, Adv. Synth. Catal. 348 (2006) 243) and involves the following steps:

Synthesis of Butyl Methanesulfonate: Methanesulfonyl chloride (1.60 mol) was added under vigorous stirring to a solution of

n-butanol (1.60 mol) and triethylamine (1.60 mol) in dichloromethane. The reaction temperature was kept between 10-20oC.

Then, the organic layer was washed with water. The combined organic extracts were dried over MgSO4 and the solvent was

removed under reduced pressure to give a colorless liquid.

Synthesis of 1-Butyl-3-methylimidazolium Methanesulfonate: equimolar amounts of butyl methanesulfonate and 1-

methylimidazole (1.59 mol) were mixed and the reaction mixture was kept at room temperature. One crystal of 1-butyl-3-

methyl imidazolium methanesulfonate was added and the resulting crystalline reaction mass was kept at room temperature for

24 h. Recrystallization was performed using acetone as solvent.

Synthesis of 1-n-butyl-3-methylimidazolium trifluoromethanosulfonimide (BMI.NTf2): A mixture of 1-butyl-3-

methylimidazolium methanesulfonate (165 mmol), LiNTf2 (174 mmol) and distilled water (65 mL) were vigorously stirred for

30 min and dichloromethane (200mL) was added. The organic phase was separated, washed with water and dried with MgSO4

and filtered through a basic alumina column. Solvent evaporation system was used to dichloromethane evaporation.The final

product was a viscous and colorless liquid, the BMI.Tf2N ionic liquid. The purity (> 97%) of the ionic liquid was determined

by 1HNMR using the intensity of the 13C satellites of the imidazolium N-methyl group as internal standard. The 1HNMR

spectrum was recorded on a Varian Mercury Plus spectrometer (300 MHz) at room temperature.

Synthesis of 1-n-butyl-3-methylimidazolium hexafluorophophate (BMI.PF6): A mixture of 1-butyl-3-methylimidazolium

methanesulfonate (470 mmol), KPF6 (493 mmol) and distilled water (250 mL) were vigorously stirred for 30 min. The upper

aqueous phase was separated and discarded. Then, KPF6 (23 mmol) and distilled water (40 mL) were added to the remaining

layer. The mixture was stirred for 15 min followed by the addition of 200 mL of dichloromethane. The organic phase was

separated, dried with MgSO4 and filtered through a basic alumina column. Solvent evaporation system was used to

dichloromethane evaporation. The purity (> 94%) of the product was verified as described above for the BMI.NTf2.

Electronic Supplementary Material (ESI) for Physical Chemistry Chemical PhysicsThis journal is © The Owner Societies 2011

2

2. Characterization techniques

NIR spectra of Fe3O4 NPs obtained at 150 oC (a) and 250 oC

Figure S-1. NIR spectra of Fe3O4 NPs obtained at 150 oC (a)

and 250 oC (b). The spectra were recorded from a thin film of

the sample dispersed in hexane in a NaCl window.

FTIR spectra of Fe3O4 NPs obtained at 250 oC

Figure S-2. Infrared spectra of: (a) BMI.NTf2 ionic liquid

before the reaction; (b) a thin film of the magnetite NPs covered

by oleylamine as obtained in the synthesis;

(c) BMI.NTf2 ionic liquid after the 20th reaction is completed at

250 oC in 1.5 h of reaction.

.

Figure S-3. Photographs of a magnetic fluid (Fe3O4 NPs dispersed in cyclohexane) exposed to a permanent magnet (Nd): far

from the sample (a), closer (b) and touching the glass wall (c)

0

.1

.2

.3

.4

.5

.6

3500 3000 2500 2000 1500 1000 500 wavenumber/cm-1

Abs

orba

nce

(a)

(b)

(c)

ν(N

H)

ν(CH)

ν(Fe

-O)

δ(N

H)

0

.1

.2

.3

.4

.5

.6

3500 3000 2500 2000 1500 1000 500 wavenumber/cm-1

Abs

orba

nce

(a)

(b)

(c)

ν(N

H)

ν(CH)

ν(Fe

-O)

δ(N

H)

.14

.16

.18

.2

.22

.24

.26

800 1000 1200 1400 1600 1800 2000 2200 2400 Wavelength/nm

Abs

orba

nce

(b)

(a)

.14

.16

.18

.2

.22

.24

.26

800 1000 1200 1400 1600 1800 2000 2200 2400 Wavelength/nm

Abs

orba

nce

.14

.16

.18

.2

.22

.24

.26

800 1000 1200 1400 1600 1800 2000 2200 2400

.14

.16

.18

.2

.22

.24

.26

800 1000 1200 1400 1600 1800 2000 2200 2400 Wavelength/nm

Abs

orba

nce

(b)

(a)


3

CHN Analysis

Table S-1. Results of CHN analysis for samples prepared at 150 oC

TGA results

Figure S-4. TGA curves for the indicated samples

(magnetite/OA obtained at 150 oC in BMI.NTf2). Note

the weight loss of 13.5% begins near 250 oC and ends

near 400 oC (red curve). This is due to the release of OA

from the magnetite surface. This weight % corresponds

to nearly one monolayer of OA.

1H-NMR analysis

Figure S-5. 1H-NMR spectra of pure cyclohexene (upper curve) and of

the cyclohexene solution containing Pd(OAc)2 as catalyst after ten

minutes of purging with the gas liberated in the synthesis of Fe3O4

nanoparticles (lower curve). The Pd(OAc)2 catalyst promotes the

hydrogenation of cyclohexene leading to the formation of cyclohexane.

IL %C

(m/m)

%H

(m/m)

%N

(m/m)

%oleylamine

(m/m)

%oleylamine

(m/m) calc.1

BMI.NTf2 11.42 2.17 0.62 14.13 12.7 1 Mass percent of OA calculated for a monolayer of OA and considering that two molecules of OA

occupies 1 nm2.

ca

0246 PPM

cb

ab

d

d

a

b

c


4

Results for the BMI.PF6

Figure S-6. FTIR spectra of (a) BMI.PF6 and (b)

Fe3O4 NPs obtained in BMI.PF6 at 250 oC after 1.5 h

of reaction.

TEM and HRTEM (BMI.PF6)

Figure S-7 (left) TEM image and histrogram (inset, mean diameter 6.2 ±0.9 nm) of Fe3O4 NPs obtained in BMI.PF6 at 150 oC

and 1.5 h of reaction in the presence of OA. (right) a HRTEM image of a Fe3O4 nanocrystal.

Table S-2 CHN Analysis for the Fe3O4 obtained in BMI.PF6 at 150 oC in 1.5 h of reaction

IL %C (m/m)

%H (m/m)

%N (m/m)

%oleylamine (m/m)

%oleylamine (m/m) calc.1

BMI.PF6 12.28 2.29 0.55 15.12 16.7 1 Mass percent of OA calculated for a monolayer of OA and considering that two molecules of OA

occupies 1 nm2


5

Magnetization measurements

Figure S-8. Hysteresis loop at 300 K for the Fe3O4 NPs

obtained at 150 oC in BMI.PF6.

TEM Results for NiFe2O4 and MnFe2O4 obtained in BMI.NTf2

Figure S-9. TEM micrographs and histograms of NiFe2O4 (e,f) and MnFe2O4 (g,h) NPs. (e,g) were obtained after 1.5 h and

(f,h) after 3.0 h of reaction at 200 oC.

Figure S-10. HRTEM images of Fe3O4 NPs obtained after 1.5 h (a) and 3.0 h of reaction at 200 oC.

100 nm 100 nm

(h)

100 nm

(g)

Fre

que

ncy

/ %

5 6 7 8 9 10 11 12 13 140

10

20

30

40

50

Particle size / nm

5 6 7 8 9 10 11 12 13 140

5

10

15

20

25

30F

req

ue

ncy

/ %

Particle size / nm100 nm 100 nm100 nm

(h)

100 nm

(g)

Fre

que

ncy

/ %

5 6 7 8 9 10 11 12 13 140

10

20

30

40

50

Particle size / nm

5 6 7 8 9 10 11 12 13 140

5

10

15

20

25

30F

req

ue

ncy

/ %

Particle size / nm5 6 7 8 9 10 11 12 13 14

0

5

10

15

20

25

30F

req

ue

ncy

/ %

Particle size / nm

100 nm

(e)

100 nm

(f)

Fre

que

ncy

/ %

3 4 5 6 7 8 9 10 11 120

5

10

15

20

25

30

35

Particle size / nm

3 4 5 6 7 8 9 10 11 1205

10152025303540

Fre

que

ncy

/ %

Particle size / nm

100 nm

(e)

100 nm

(f)

Fre

que

ncy

/ %

3 4 5 6 7 8 9 10 11 120

5

10

15

20

25

30

35

Particle size / nm3 4 5 6 7 8 9 10 11 12

0

5

10

15

20

25

30

35

Particle size / nm

3 4 5 6 7 8 9 10 11 1205

10152025303540

Fre

que

ncy

/ %

Particle size / nm

3 4 5 6 7 8 9 10 11 1205

10152025303540

Fre

que

ncy

/ %

Particle size / nm

-80000 -40000 0 40000 80000-30

-20

-10

0

10

20

30

M (

em

u/g)

H (Oe)


6

Magnetic measurements

Figure S-11. Hysteresis loops at 300 K for (c) Fe3O4 and (d) MnFe2O4 obtained at 200 oC for (○) 1.5 h and (●) 3 h reaction

times. The insets show the hysteresis loops at lower magnetic fields.

FTNIR and FTIR spectra

Figure S-12. NIR spectra of Fe3O4 (a) and CoFe2O4 (b) NPs

obtained at 200 oC in 1.5 h reaction. The spectra were recorded

from a thin film of the sample dispersed in hexane in a NaCl

window. The NIR spectrum of CoFe2O4 NPs shows two main

absorptions near 1640 and 1350 nm, as observed before for

CoFe2O4 NPs obtained by the co-precipitation method.

Figure S-13. FTIR spectra of Fe3O4 (a), CoFe2O4 (b), NiFe2O4

(c), and MnFe2O4 (d) NPs obtained in BMI.NTf2 after 1.5 h of

reaction at 200 oC.

Abs

orba

nce

Wavenumber/cm-1

0

.2

.4

.6

.8

1

3000 2500 2000 1500 1000 500

ν(CH)

572

581

589

571

(a)

(b)

(c)

(d)

δ(N

H)

Abs

orba

nce

Wavenumber/cm-1

0

.2

.4

.6

.8

1

3000 2500 2000 1500 1000 500

ν(CH)

572

581

589

571

(a)

(b)

(c)

(d)

δ(N

H)

Abs

orba

nce

0

.1

.2

.3

.4

800 1200 1600 2000 2400 Wavelength/nm

(a)

(b)Abs

orba

nce

0

.1

.2

.3

.4

800 1200 1600 2000 2400 Wavelength/nm

(a)

(b)

0

.1

.2

.3

.4

800 1200 1600 2000 2400 0

.1

.2

.3

.4

800 1200 1600 2000 2400 Wavelength/nm

(a)

(b)

-4.0 -2.0 0 2.0 4.0

-40

0

40

M/e

mu.

g-1

H/kOe

-400 -200 0 200 400

0

H/Oe

20

-20

-60

60

(c)

-4.0 -2.0 0 2.0 4.0

-40

0

40

M/e

mu.

g-1

H/kOe

-400 -200 0 200 400

0

H/Oe

20

-20

-60

60

(c)

-40

0

40

M/e

mu.

g-1

20

-20

-4.0 -2.0 0 2.0 4.0H/kOe

-400 -200 0 200 400H/Oe

0

(d)

-40

0

40

M/e

mu.

g-1

20

-20

-4.0 -2.0 0 2.0 4.0H/kOe

-400 -200 0 200 400H/Oe

0

(d)


7

Table S-3 CHN Analysis for the ferrite NPs obtained in BMI.NTf2 at 150 oC after 1.5 h of reaction

Sample %C

(m/m) %H (m/m)

%N (m/m)

%oleylamine (m/m) exp.

%oleylamine (m/m) calc.1

Wheightloss%2

Fe3O

4 14.13 2.71 0.77 13.30 14.6 12.3

CoFe2O

4 13.53 2.25 0.30 16.08 19.7 13.8

NiFe2O

4 11.83 1.98 0.72 14.51 14.6 12.2

MnFe2O

4 11.77 1.53 0.42 13.72 13.8 12.8

1 Mass percent of OA calculated for a monolayer of OA and considering that two molecules of OA occupies 1 nm2 2 Mass percent of OA as obtained by TGA (see Fig.S-14)

TGA results

Figure S-14. TGA measurements for Fe3O4 (a), CoFe2O4 (b), NiFe2O4 (c), and MnFe2O4 (d) samples obtained after 1.5 h of

reaction in BMI.NTf2 at 200 oC. (See Table S-3 for the weightlosses corresponding to the OA decomposition).

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

80.0

90.0

100.0

110.0

Wei

ghtlo

ss%

Fe3O4

(a)

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

80.0

90.0

100.0

110.0

Wei

ghtlo

ss%

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

80.0

90.0

100.0

110.0

Wei

ghtlo

ss%

Fe3O4

(a)

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

80.0

90.0

100.0

Wei

ghtlo

ss%

CoFe2O4

(b)

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

80.0

90.0

100.0

Wei

ghtlo

ss%

CoFe2O4

(b)

80.0

90.0

100.0

110.0

Wei

ghtlo

ss%

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

(c)

NiFe2O4

80.0

90.0

100.0

110.0

Wei

ghtlo

ss%

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

(c)

NiFe2O4

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

80.0

90.0

100.0

110.0

Wei

ghtlo

ss%

MnFe2O4

(d)

100.0 200.0 300.0 400.0 500.0 600.0

Temperature/oC

80.0

90.0

100.0

110.0

Wei

ghtlo

ss%

MnFe2O4

(d)


8

Results for the synthesis in DPE

TEM Results for Fe3O4 obtained in DPE and OA

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 190

5

10

15

20

Fre

quen

cy (

%)

Particle size / nm

Figure S-15. TEM micrograph and size distribution histogram (lognormal function) of Fe3O4 NPs prepared by decomposition

of Fe(Acac)3 in DFE and oleylamine.

CHN Analysis

Table S-4. Results of CHN analysis for samples prepared in DPE

TGA results

Figure S-16. TGA measurements for Fe3O4 obtained in DPE.

(See Table S-4 for the weightloss corresponding to the OA

decomposition).

%C

(m/m)

%H

(m/m)

%N

(m/m)

%

oleylamine

(m/m)

%

oleylamine

(m/m) calc.1

Wheightloss%2

16.07 1.60 0.68 19.9 18.5 9.1

1 Mass percent of OA calculated for a monolayer of OA and considering that two molecules of OA

occupies 1 nm2 2 Mass percent of OA as obtained by TGA (see Fig.S-16)

0 100 200 300 400 500 600 700 800

90

92

94

96

98

100

Wei

gh

tloss

/ %

Temperature /oC


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Ionic Liquids as Recycling Solvents for The Synthesis of Magnetic