Supporting Information

Selective separation of cadmium (II) from Zinc (II) by a novel hydrophobic ionic

liquid including N,N,N׳,N׳-tetrakis(2-methylpyridyl)-1,2-phenylenediamine-4-amido

structure: A hard-soft donor combined method

Hao Wu, *1 Xiaoxia Zhang, 2 Xiangbiao Yin, 1 Inaba Yusuke, 1 Miki Harigai, 1 Kenji

Takeshita 1

1 Laboratory for Advanced Nuclear Energy, Tokyo Institute of Technology, 2-12-1

Ookayama, Meguro-ku, Tokyo 152-8550

2 Nuclear Technology Support Center, China Atomic Energy Authority, Haidian,

Beijing, PR China, 100080

* Corresponding authors. Tel./fax: +81 03-5734-3845.

E-mail addresses: wu.h.ac@m.titech.ac.jp

Electronic Supplementary Material (ESI) for Dalton Transactions.This journal is © The Royal Society of Chemistry 2018

Synthesis procedures: Thin layer chromatography analyses (TLC) were performed using analytical

TLC plates coated with aluminum oxide 60 F245 basic and silica gel 60 F245 (Merck Darmstadt, Germany). Activated alumina (about 75μm) and silica gel 60 (0.063-0.200 mm) purchased from Wako chemical was utilized for column chromatography purification. Nuclear magnetic resonance spectroscopy (NMR: 400MHz for 1H, 100MHz for 13C and 376 MHz for 19F) was utilized for characterization of each product by using deutrated solvent (Chloroform-d, DMSO-d6). Fourier transform infrared spectroscopy (FTIR) was recorded in JIR-SPX200. All reagents were obtained from commercial suppliers in the highest grade which could be commercially obtained and used without any further purification. All aqueous solutions were made with deionized water.

NCl

HCl+

H2N NH2 K2CO3, KI, MeCN

50 oC, 2~5 d N N

N N

N N1a 1b 1c

To a dehydrated acetonitrile solution (30 mL) of 1b (0.54 g, 5.0 mM), 2-(chloromethyl) pyridine hydrochloride (3.61 g, 22.0 mM), potassium iodide (3.65 g, 22.0 mM), and potassium carbonate (10.0 g, 75.0 mM) were added. The mixture was refluxed for 2-5 days at 50 oC under the protection of N2. The reaction mixture was cooled to room temperature and the solvent of MeCN was removed under rotary evaporator. Then the paste was diluted in deionized water. The solution was thoroughly extracted with chloroform (3 ⅹ 20 mL) and the combined organic phase was washed with water, saturated NaHCO3 solution, and dried by adding anhydrous Na2SO4. The dried chloroform was concentrated to a gummy residue which was purified by alumina column chromatography (Rf= 0.25, dichoromethane: ethyl acetate= 4:1) to give 1c (0.89 g, 1.9 mM, yield= 38%) as an orange oil. 1H NMR (CDCl3-d, 400 MHz, 25°C), δ/ppm: 4.74 (s, 8H), 6.77-6.90 (m, 4H, CH), 7.09 (m, 8H, C3, C5-pyr-H), 7.44 (td, 4H, C4-pyr-H), 8.51 (dt, 4H, C6-pyr-H). 13C NMR (CDCl3-d, 400 MHz, 25°C), δ/ppm: 57.3, 121.7, 122.1, 122.3, 123.0, 135.9, 142.1, 148.9, 158.7.

N N

N N

N N

O2N

N N

N N

N N

HAc, HNO3

60 oC, 3~8 h

1c 1d

To a dehydrated chloroform solution (10 mL) of 1c (0.89 g, 1.9 mM), acetic acid (10 mL) was added slowly while stirring. Nitration agent was prepared by mixing 5 mL HNO3 (65%) with 15 mL acetic acid, and then added dropwise over 30 min. After

stirring for 1 h at room temperature, the solution was heated to 60 oC and refluxed for another 3-8 h. After cooling to room temperature, pH value of the mixture was adjusted to around 8-9 by slowly adding saturated Na2CO3 solution. Aqueous phase was extracted with chloroform for three times (3×20 mL). The combined chloroform phase was dried over dehydrated Na2SO4. After filtration, the solvent was removed by evaporation under reduced pressured at 50 oC. The residue was purified by alumina column chromatography (dichloromethane: ethyl acetate= 8:1, Rf= 0.2) to give 1d as light-yellow oil (0.65 g, 1.25 mM, yield= 66%). 1H NMR (CDCl3-d, 400 MHz, 25°C), δ/ppm: 4.75 (s, 4H), 4.99 (s, 4H), 6.89 (d, 1H,CH), 7.12 (m, 8H, C3, C5-pyr-H), 7.52 (tt, 4H, C4-pyr-H), 7.65 (d, 1H, CH), 7.73 (d, 1H, CH), 8.51 (tt, 4H, C6-pyr-H). 13C NMR (CDCl3-d, 400 MHz, 25°C), δ/ppm: 56.4, 117.7, 118.2, 120.5, 122.0, 122.8, 123.3, 136.2, 140.8, 141.4, 148.4, 149.2, 157.4, 157.8.

N N

N N

N N

O2N

N N

N N

N N

H2N

N2H4 H2O, EtOH, Pt/C

60 oC, Overnight

1d 1f

Dehydrated ethanol solution (15 mL) of 1d (0.65 g, 1.25 mM) was degassed with nitrogen flow, followed by the addition of 0.2 g Pd/C catalyst and 15 mL hydrazine hydrate. The reduction reaction was carried out under reflux at 60 oC with the protection of N2 for the whole nihgt. After reaction, catalyst was separated by filtration and the obtained filtrate was cooled in the refrigerator for crystallization to give 1f as yellow crystal (0.55 g, 1.13 mM, yield> 90%). 1H NMR (DMSO-d6, 400 MHz, 25°C), δ/ppm: 4.39 (s, 4H, CH2), 4.46 (s, 2H, C-NH2), 4.57 (s, 4H, CH2), 5.89 (dd, 1H, CH), 6.13 (d, 1H, CH), 6.53 (d, 1H, CH), 7.11 (m, 8H, C3, C5-pyr-H), 7.52 (m, 4H, C4-pyr-H), 8.37 (m, 4H, C6-pyr-H). 13C NMR (DMSO-d6, 400 MHz, 25°C), δ/ppm: 57.7, 108.7, 109.5, 111.9, 121.6, 123.3, 129.5, 133.7, 135.5, 135.9, 141.9, 143.6, 148.9, 159.1.

NN + BrOH

O

Solvent Free

70 oC, overnight2a 2b

N+N OH

O

Br-

2c

2c was prepared by a simple solvent free method as described in previously published papers. 2b (2.64 g, 12.6 mM) was added dropwise into 2a (1.03 g, 12.6 mM). The mixture was stirred vigorously for 12 h at 70 oC under the protection of N2. The resulting viscous liquid was allowed to cool to RT, then treated with ethyl acetate (3ⅹ20 mL) and stirred vigorously for 30 min. The solvent was decanted and the process repeated several times. The product 2c (2.09 g, 60%) was dried under vacuum at 70 oC. 1H NMR (DMSO-d6, 400 MHz, 25°C), δ/ppm: δ 1.23(quint, 2H, CH2), 1.49(quint, 2H, CH2), 1.79(quint, 2H, CH2), 2.19(t, 2H, CH2), 3.88(s, 3H, N-CH3), 4.19(t, 2H, CH2-Nring), 7.79(t, 1H, CH), 7.87(t, 1H, CH), 9.38(s, 1H, CH). 13C NMR

(DMSO-d6, 400 MHz, 25°C), δ/ppm: 24.7, 25.5, 29.6, 36.1, 49.1, 118.4, 122.7, 136.9, 148.6, 158.2.

N+N OH

O

Br-

N+N Cl

O

Br-SOCl2, DMF

50 oC, 1~3 h

2c 2d

Excess thionyl chloride (1.64 g, 13.8 mmol) was used as reagent and solvent, stoichiometry amount of 2c (0.18 g, 0.67 mM) was weighed and added. The mixture was stirred vigorously to dissolve, and later 3 drops of dry DMF was added as catalyst. The mixture was heated at 50 oC for 2 h. After reaction, the excess thionyl chloride was distilled off under reduced pressure and the residue was dissolved in 5mL dehydrated MeCN and used in the next procedure as soon as possible.

N

N

N

N

N

N

N(SO2CF3)2-

3a

2. LiNTf2 aq.

1. MeCN, K2CO3Ice bath

1f, 2d

HN

ON+N

To a dehydrated MeCN solution (10 mL) of 1f (0.55 g, 1.13 mM) was added Na2CO3 followed by dropwise adding 2d dissolved in dehydrated MeCN solution (2 mL). The mixture was stirred for 12 h under the protection of N2. The color of the solution was changed gradually from yellow to brown while adding 2d. The resulting solution was filtered, and the solvent was evaporated under reduced pressure to give precursor as dark brown oil. The residue was dissolved in deionized water (20 mL), excess LiNTf2 (1.0 g, 3.5 mM) dissolved in deionized water (10 mL) was added and stirred at room temperature for 24 h. 3a was formed in the bottom of the aqueous layer. 3a was separated by centrifugation, and washed several times with aliquots of water until bromide residue were no longer detected by the AgNO3 test. The pure product 3a (0.58 g, 0.63 mM, Total yeild= 9.87%) was obtained as an orange viscous liquid. 1H NMR (DMSO-d6, 400 MHz, 25°C), δ/ppm: 1.25(m, 2H, CH2), 1.57(m, 2H, CH2), 1.82(m, 2H, CH2), 2.22(m, 2H, CH2), 3.85(s, 3H, CH3), 4.17(dt, 2H, CH2), 4.58(s, 4H, CH2), 4.63(s, 4H, CH2), 6.93(dd, 1H, CH), 7.12(dd, 1H, CH), 7.20(d, 1H, CH), 7.31(m, 8H, C3, C5-pyr-H), 7.76(m, 4H, C4-pyr-H), 8.52(m, 4H, C6-pyr-H), 9.07(s, 1H, CH), 9.10(s, 1H, CH), 9.57(s, 1H, CH). 13C NMR (DMSO-d6, 400 MHz, 25°C), δ/ppm: 24.2, 24.7, 25.6, 29.6, 36.2, 49.1, 56.8, 64.1, 113.1, 113.7, 115.2, 118.4, 121.6, 122.7, 124.2, 135.3, 136.9, 138.3, 143.3, 148.1, 157.7. 19F NMR (DMSO-d6, 400 MHz, 25°C), δ/ppm: -78.7.

N N

N N

N N

a

b c

d

e

fg

d ba,c

f,g

e

Figure S1. 1H NMR of 1c in CDCl3

5060708090100110120130140150160170ppm

57.3

4

121.

7112

2.09

122.

3212

3.03

135.

95

142.

14

148.

99

158.

74

Figure S2. 13C NMR of 1c in CDCl3

N N

N N

N N

O2N

ab c

d

ef

g

h

db

a,c

i

hi,g

e f

Figure S3. 1H NMR of 1d in CDCl3

0102030405060708090100110120130140150160170ppm

56.25

56.43

117.6

811

8.20

120.4

912

2.03

122.8

512

3.27

136.0

913

6.20

140.8

014

1.37

148.4

014

9.19

149.2

615

7.44

157.8

4

Figure S4. 13C NMR of 1d in CDCl3

0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.0ppm

3.91

2.01

3.97

0.96

1.06

1.00

8.18

4.14

4.04

4.56

4.60

4.74

6.13

6.13

6.15

6.15

6.29

6.30

6.68

6.71

7.04

7.05

7.06

7.07

7.08

7.10

7.12

7.14

7.16

7.39

7.40

7.41

7.41

7.43

7.43

7.45

7.45

7.46

7.47

8.46

8.48

8.49

8.50

N N

N N

N N

H2N

a

b c

d

ef

g

hi

j

d ba,c

hi g

e f

j

Figure S5. 1H NMR of 1f in CDCl3

0102030405060708090100110120130140150160170180190ppm

57.67

58.19

58.38

108.7

510

9.50

111.9

212

1.63

122.8

412

3.12

123.2

912

3.51

129.4

613

3.72

135.5

113

5.83

135.9

213

6.02

141.9

914

3.61

148.8

314

8.88

148.9

115

8.79

159.0

4

Figure S6. 13C NMR of 1f in CDCl3

0.00.51.01.52.02.53.03.54.04.55.05.56.06.57.07.58.08.59.09.5ppm

2.07

2.02

2.02

1.99

2.02

0.98

0.99

1.00

1.19

1.21

1.23

1.25

1.27

1.46

1.47

1.49

1.51

1.53

1.75

1.77

1.79

1.81

1.82

2.18

2.19

2.21

4.18

4.20

4.21

7.79

7.80

7.80

7.86

7.87

7.87

9.38

N+N OH

O

Br-a b

c d

e

f

g

h

i

a

b dc ei

f g h

Figure S7. 1H NMR of 2c in DMSO-d6

0102030405060708090100110120130140150160170180ppm

24.20

25.39

29.55

33.85

36.28

48.99

122.6

712

3.96

137.0

0

174.6

9

Figure S8. 13C NMR of 2c in DMSO-d6

N+N

O

N

N

N

N

N

N

HN

N-S SF3C CF3

O

O O

O

a b

c d

e

f

g

h

i

j k

lm n o

pq

a

b

c, d q

on, p

jl, k

m

e

i f g h

DMSO-d6

Figure S9. 1H NMR of 3a in DMSO-d6

0102030405060708090100110120130140150160ppm

24.17

24.74

25.59

29.46

29.64

36.19

36.40

49.09

56.75

57.06

57.27

121.5

812

2.70

123.0

912

4.06

124.2

112

4.35

136.9

813

7.66

138.1

213

8.22

138.3

114

8.09

148.1

414

8.25

157.7

0

Figure S10. 13C NMR of 3a in DMSO-d6

-210-200-190-180-170-160-150-140-130-120-110-100-90-80-70-60-50-40ppm

-78.7

4

N+N

O

N

N

N

N

N

N

HN

N-S SF3C CF3

O

O O

O

Figure S11. 19F NMR of 3a in DMSO-d6

Table S1 Summary numerical data in Fig. 2Time (h) ECd (%) EZn (%)

0.2 12.88 ± 0.3 3.01 ± 0.30.5 30.41 ± 0.1 12.08 ± 0.11 42.95 ± 0.3 27.17 ± 0.22 75.01 ± 0.2 39.75 ± 0.23 83.63 ± 0.2 43.22 ± 0.14 90.53 ± 0.2 42.98 ± 0.25 90.29 ± 0.1 43.41 ± 0.2

Table S2 Summary numerical data in Fig. 3pHeq ECd (%) EZn (%)5.2 90.19 ± 0.1 50.01 ± 0.14.3 90.16 ± 0.08 48.98 ± 0.063.1 90.85 ± 0.08 43.73 ± 0.051.8 89.83 ± 0.06 43.81 ± 0.070.9 26.58 ± 0.07 12.52 ± 0.10.5 12.6 ± 0.1 5.61 ± 0.08

Table S3 Summary numerical data in Fig. 4 [HNO3]= 1.0 M (upper), 2.0 M (lower)pHeq BECd (%) BEZn (%)

5.2 66.85 ± 0.1 60.95 ± 0.14.3 69.23 ± 0.1 61.14 ± 0.063.1 69.016 ± 0.08 50.34 ± 0.11.8 71.94 ± 0.05 46.26 ± 0.080.9 59.27 ± 0.1 35.67 ± 0.080.5 66.85 ± 0.2 60.95 ± 0.1

pHeq BECd (%) BEZn (%)5.2 96.85 ± 0.06 94.95 ± 0.074.3 99.23 ± 0.08 90.13 ± 0.083.1 99.02 ± 0.06 92.34 ± 0.081.8 95.94 ± 0.06 92.26 ± 0.050.9 99.27 ± 0.1 88.67 ± 0.10.5 96.85 ± 0.1 94.95 ± 0.06

Table S4 Summary numerical data in Fig. 5 [(C6mim)+] (M) ECd (%) EZn (%)

0.0 90.08 ± 0.04 43.19 ± 0.070.1 89.01 ± 0.06 42.39 ± 0.060.2 88.18 ± 0.06 40.18 ± 0.040.3 84.71 ± 0.05 37.09 ± 0.070.4 82.96 ± 0.05 33.11 ± 0.080.5 80.58 ± 0.08 25.19 ± 0.060.6 79.61 ± 0.1 20.21 ± 0.060.8 76.54 ± 0.06 18.29 ± 0.061.0 68.13 ± 0.05 16.2 ± 0.03

Table S5 Summary numerical data in Fig. 6[NO3

-] (M) ECd (%) EZn (%)0.00 89.52 ± 0.05 42.1 ± 0.040.02 93.23 ± 0.05 42.015 ± 0.050.04 85.61 ± 0.06 44.74 ± 0.040.06 88.72 ± 0.05 41.93 ± 0.050.08 89.08 ± 0.07 43.53 ± 0.05

Table S6 Summary numerical data in Fig. 7log [(IL-1,2-tpbd)+] log DCd log DZn

-1 -2.698 ± 0.06 -3 ± 0.07-0.301 -1.301 ± 0.06 -1.698 ± 0.08

0 0.191 ± 0.05 -0.715 ± 0.060.301 0.379 ± 0.04 -0.566 ± 0.040.477 0.98 ± 0.06 -0.109 ± 0.06

Table S7 Summary numerical data in Fig. 10Metal ions E (%)

Cd 100 ± 0.07Pb 76.348 ± 0.09Zn 45.179 ± 0.05Ni 13.769 ± 0.06Co 6.2098 ± 0.06Fe 0.892 ± 0.08Mg 0 ± 0.1Ca 0 ± 0.06

Table S8 A brief comparison of various IL extraction systems for Cd2+

Extractant DiluentTarget

metal ionsAqueous phase

Equilibration

time (min)Ref.

[N1888][C4SAc] etc. - Cd, Cu HNO3 aq. 30 1

Cyphos IL 104 toluene Cd, Zn1.0×10-3 ⁓ 2.0 M

HCl/HNO3/H2SO4< 6 2

[Nano-Si-OH-

Bmim+Tf2N-] sorbent- Cd

pHeq> 1.0

HCl aq.≥ 15 3

thio- and urea-based

IL[C4mim][PF6] Cd, Hg

pHeq= 1.0 and 7.0

HCl aq.4 4

Dithizone [C4mim][PF6] Cd, Pb, Zn pHeq> 1.9 2 5[A336][TS]-modified

Fe3O4- Cd

pHeq> 2.0

HNO3 aq.30 6

Cyphos IL 101 kerosene CdpHeq> 2.46

H2SO4 aq.5 7

[P66614][PTB] etc. - Cd, Zn, CupHeq = 7

HNO3 aq.> 24 h 8

(IL-1,2-tpbd)+NTf2- (C6mim)+NTf2

- CdpHeq= 0.5 ⁓ 5.2

HNO3 aq. ≈ 5 h

Present study

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