supplementary information - nature · 2011-02-22 · and purification such as removal/separation of...

1

Supplementary Information

Rationally Tuned Micropores within Enantiopure Metal-Organic Frameworks for

Highly Selective Separation of Acetylene and Ethylene

Shengchang Xiang, †

Zhangjing Zhang, †

Cong-Gui Zhao, †

Kunlun Hong, ‡

Xuebo Zhao, §

De-Rong Ding,†

Ming-Hua Xie, ¶

Chuan-De Wu, ¶

Madhab C. Das,† Rachel Gill,

§ K. Mark

Thomas*,§

and Banglin Chen*,†

Contribution from †Department of Chemistry, University of Texas at San Antonio, San Antonio, Texas

78249-0698, ‡

Chemical Sciences Divisions, Oak Ridge National Laboratory, Oak Ridge, Tennessee

37831, USA ¶ Department of Chemistry, Zhejiang University, Hangzhou 310027, China

§Northern

Carbon Research Laboratories, Sir Joseph Swan Institute and School of Chemical Engineering and

Advanced Material, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU, UK

* To whom correspondence should be addressed. Email addresses: [email protected]; [email protected]

2

Supplementary Methods:

Single Crystal Studies. Intensity data for M’MOF-1 ⊃⊃⊃⊃PEA, M’MOF-2 and M’MOF-3 ⊃⊃⊃⊃PEA were

collected using Bruker X8 APEX II diffractometer (Mo Kα radiation) in a cold nitrogen stream.

Structures were solved by direct methods and refined by full-matrix least squares, using SHELXL97.48

All H atoms were placed in idealized positions and refined using a riding model. The intensity data sets

of M’MOF-3 was collected on a Rigaku Saturn724 diffractometer equipped with graphite-

monochromated Mo Kα radiation (λ = 0.71073 Å) using an ω-scan technique at 98 K. The data set was

reduced by CrystalClear and CrystalStructure programs.49 For M’MOF-1 ⊃⊃⊃⊃PEA, M’MOF-2 and

M’MOF-3, the electron density contribution of the diffuse scattering of the disordered guest molecules

(DMF and H2O) was handled using the SQUEEZE procedure in the PLATON software suite,50 because

these guest molecules make the refinements difficult to converge. The detailed crystallographic data are

shown in Supplementary Table S1.

Powder X-ray Diffraction Studies. Powder XRD patterns were obtained with a Scintag X1 powder

diffractometer system using Cu Kα radiation with a variable divergent slit and a solid-state detector. The

routine power was 1400 W (40 kV, 35 mA). Low background quartz XRD slides (Gem Depot, Inc.,

Pittsburgh, PA) were used. For analyses, powder samples were dispersed on glass slides.

Adsorption Characterization.

Isotherm Models. In order to evaluate the adsorption equilibrium selectivity and predict adsorption of

gas mixture from pure component isotherms, the Henry’s law linear isotherm equation and the Langmuir

model were used to correlate the C2H2 and C2H4 adsorption on M’MOF-2a and M’MOF-3a. The

Henry’s isotherm equation is

q = KP

where q is the adsorbed amount per unit weight of adsorbent(cm3 g-1), P is the adsorbate gas pressure at

equilibrium (torr), and K is the Henry’s law constant (cm3 g-1 torr-1).

The Langmuir isotherm is formulated as

3

bP

bPqq m

+=

1

where qm (cm3 g-1) and b (torr-1) are the Langmuir isotherm equation parameters. The values of qm and b

were determined can be determined from the slope and intercept of a linear Langmuir plot of (1/q)

versus (1/P).

Adsorption Equilibrium Selectivity. In order to evaluate the efficacy of an adsorbent for gas separation

and purification such as removal/separation of C2H2 from ethylene by adsorption, it is necessary to know

the adsorbent selectivity. The adsorption equilibrium selectivity α12 between components 1 and 2 is

defined as

22

11

2

1

1

2

2

112

bq

bq

K

K

Y

Y

X

X

m

m==∗=α ,

where component 1 is the stronger adsorbate and 2 is the weaker adsorbate. X1 and X2 are the molar

fractions of components 1 and 2 on the adsorbent surface (or in the adsorbed phase), Y1 and Y2 are the

molar fractions of components 1 and 2 in the gas phase. qm1 and qm2 and b1 and b2 are the Langmuir

equation constants for components 1 and 2. K1 and K2 are the Henry’s constants for components 1 and 2.

The Henry’s constants and the equilibrium selectivity for different gases on the two M’MOFs are listed

in Table 1.

Virial Equation Analysis The virial equation can be written51 as follows:

⋅⋅⋅+++=

2210ln nAnAA

p

n (S1)

where n is the amount adsorbed (mol g-1) at pressure p (Pa). At low surface coverage, the A2 and higher

terms can be neglected and the equation becomes

nAAp

n10ln +=

(S2)

A linear graph of ln(n/p) versus n is obtained at low surface coverage and this is consistent with

neglecting higher terms in equation (S2). A0 quantifies the adsorbate-adsorbent interactions while A1 is

related to adsorbate-adsorbate interactions. This equation has been used extensively in probe molecule

4

studies of adsorption on carbon molecular sieves,52 and hydrogen adsorption on porous carbons53 and

MOFs.54

Enthalpies of Adsorption

Zero surface coverage The isosteric enthalpies of adsorption at zero surface coverage (Qst,n=0) are a

fundamental measure of adsorbate-adsorbent interactions and these values were obtained from the A0

values obtained by extrapolation of the virial graph to zero surface coverage.

Van’t hoff isochore The isosteric enthalpies of adsorption as a function of surface coverage were

calculated from the isotherms using the van’t Hoff isochore, which is given by the following equation.

R

S

RT

Hp

∆+

∆−=)ln( (S3)

A graph of lnP versus 1/T at constant amount adsorbed (n) allows the isosteric enthalpy and entropy of

adsorption to be determined. The pressure values for a specific amount adsorbed were calculated from

the adsorption isotherms by the following methods 1) assuming a linear relationship between adjacent

isotherm points starting from the first isotherm point, 2) using the virial equation at low surface

coverage.

Chiral GC analysis. The enantiomeric excess for the encapsulated PEA in the methanol solution was

performed on a 5890A GC equipped with β-cyclodextrin (Supelco Beta-Dex™120; 30 m × .25 mm i.d.,

film thickness 0.25µm) chiral capillary column. Hydrogen was used as the carrier gas. The oven

temperature programme comprised of an initial 80 ºC for 1 min, then programmed to rise at 1.5 ºC/min

to 180 ºC, and maintained at 180 ºC for 30 min.

Thermogravimetric (TGA) Studies. TGA data were obtained on a Shimadzu Thermogravimetric

Anlayzer TGA-50 instrument with a heating rate of 5 K min-1 under N2 atmosphere.

5

Supplementary Figure S1 | The 36 tessellated sheets for the three M’MOFs. Zn3(BDC)3 sheet for

M’MOFs-1 and –2 (upper), and Zn3(CDC)3 sheet (bottom) for M’MOF-3 (Zn, pink; O, red; C, grey; N, blue; H, white).

6

Supplementary Figure S2 | Crystal structure of 3D pillared framework M’MOF-2. (Zn, pink; Cu,

cyan; O, red; C, grey; N, blue; H, white).

7

a b

0.05 0.10 0.15 0.20 0.25 0.30 0.35

0.001

0.002

0.003

0.004

1/(

q(P

0/P

-1)

P/P0

Equation y = a + b*x

Adj. R-Square 0.99968

Value Standard Error

D Intercept 1.176E-4 1.71647E-5

D Slope 0.0134 8.47384E-5

BET =0.195*6.023/22414/(0.0134+0.0001176)*100000=387.6

40 60 80 100 120 140 160 180 200 2200.6

0.8

1.0

1.2

1.4

1.6

1.8

2.0

2.2

P/Q

(m

mH

g c

m-3 g

)

Pressure (mmHg)




F Intercept 0.32845 0.03687

F Slope 0.00876 2.62416E-4

Langmuir = 0.195*6.023/22414/0.00876*100000 = 598.2

Supplementary Figure S3 | The surface areas for M’MOF-2a obtained from the adsorption of CO2

at 195 K. The BET (a) and Langmuir (b) surface areas are of 387.6 and 598.2 cm2/g, respectively.

8

a b

0.05 0.10 0.15 0.20 0.25 0.30

0.006

0.008

0.010

0.012

0.014

0.016

1/(

q(P

0/P

-1)

P/P0




D Intercept 0.00272 3.59609E-4

D Slope 0.04487 0.00188

BET=0.195*6.023/22414/(0.04487+0.00272)*1E5 = 110.1

100 120 140 160 180 200 220

5.5

6.0

6.5

7.0

7.5

8.0

8.5

P/q

(m

mH

g c

m-3 g

)

Pressure (mmHg)




P/Q Intercept 3.6909 0.29978

P/Q Slope 0.02205 0.00193

Lagmuir = =0.195*6.023/22414/0.02205*100000 =237.64

Supplementary Figure S4 | The surface areas for M’MOF-3a obtained from the adsorption of CO2

at 195 K. The BET (a) and Langmuir (b) surface areas are of 110.1 and 237.6 cm2/g, respectively.

9

a b

300 400 500 600 700 800

2.5

3.0

3.5

4.0

4.5

5.0

P/Q

(m

mH

g c

m-3 g

)

Pressure (mmHG)




F Intercept 0.54816 0.01574

F Slope 0.00558 2.77415E-5

Langmuir =0.195*6.023/22414/0.00558*100000 = 939.1

300 400 500 600 700 8004

5

6

7

8

9

P/Q

(m

mH

g c

m-3 g

)Pressure (mmHg)




P/Q Intercept 1.06646 0.02477

P/Q Slope 0.01025 4.20451E-5

Lagmuir =0.195*6.023/22414/0.01025*100000 = 511.2

Supplementary Figure S5 | The overall Langmuir surface areas for the two acticated M’MOFs.

Assuming that the second step for CO2 adsorption isotherms at 195 K still fit into the monolayer

coverage model, the overall Langmuir surface areas of 939.1 and 551.2 m2/g can be respectively

obtained for M’MOF-2a (a) and -3a (b).

10

a b

0.0000 0.0003 0.0006 0.0009 0.0012

-17.5

-17.0

-16.5

-16.0

-15.5

-15.0

ln(n

/P)

(ln

(mol g

-1 P

a-1))

n (mol/g)




ln(n/P) Intercept -15.23377 0.00585

ln(n/P) Slope -1770.32806 6.8558

0.0000 0.0004 0.0008 0.0012-18.0

-17.6

-17.2

-16.8

-16.4

ln(n

/P)

(ln

(mol g

-1 P

a-1))

n (mol/g)




ln(n/P) Intercept -16.30201 0.00535

ln(n/P) Slope -1551.37755 7.7043

Supplementary Figure S6 | The virial graphs for adsorption of C2H4 on M’MOF-2a. At 273 K (a) and 295 K (b).

11

a b

0.0004 0.0008 0.0012 0.0016

-16.5

-16.0

-15.5

-15.0

-14.5

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)




ln(n/P) Intercept -14.07031 0.01161

ln(n/P) Slope -1621.28538 11.43818

0.0000 0.0004 0.0008 0.0012 0.0016

-17.2

-16.8

-16.4

-16.0

-15.6

-15.2

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)




ln(n/P) Intercept -15.30009 0.01059

ln(n/P) Slope -1353.20079 11.13305

Supplementary Figure S7 | The virial graphs for adsorption of C2H2 on M’MOF-2a. At 273 K (a) and 295 K(b).

12

a b

0.0000 0.0002 0.0004 0.0006 0.0008

-16.4

-16.2

-16.0

-15.8

-15.6

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)

Equation y = a + b*



ln(n/P) Intercept -15.59125 0.01323

ln(n/P) Slope -1070.62756 35.23149

0.0000 0.0002 0.0004 0.0006 0.0008-17.4

-17.2

-17.0

-16.8

-16.6

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)




ln(n/P) Intercept -16.65235 0.00668

ln(n/P) Slope -939.93743 15.61319

Supplementary Figure S8 | The virial graphs for adsorption of CO2 on M’MOF-2a. At 273 K (a) and 295 K (b).

13

a b

0.0001 0.0002 0.0003

-17.6

-17.4

-17.2

-17.0

-16.8




ln(n/P) Intercept -16.67929 0.02585

ln(n/P) Slope -3117.33498 137.77733

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)

0.00008 0.00016 0.00024

-18.5

-18.4

-18.3

-18.2

-18.1




ln(n/P) Intercept -17.99888 0.00675

ln(n/P) Slope -1902.5939 33.45488

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)

Supplementary Figure S9 | The virial graphs for adsorption of CO2 on M’MOF-3a. At 273 K (a) and 295 K (b).

14

a b

0.0004 0.0008 0.0012

-17.0

-16.5

-16.0

-15.5

-15.0

-14.5

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)




ln(n/P) Intercept -14.20258 0.02556

ln(n/P) Slope -2056.96543 25.8711

0.0003 0.0006 0.0009 0.0012 0.0015

-17.4

-17.1

-16.8

-16.5

-16.2

-15.9

-15.6

-15.3




ln(n/P) Intercept -15.08651 0.0421

ln(n/P) Slope -1693.17553 41.68586

ln(n

/P)

(ln

(mo

l g

-1 P

a-1))

n (mol/g)

Supplementary Figure S10 | The virial graphs for adsorption of C2H2 on M’MOF-3a. At 273 K (a) and 295 K(b).

15

0.00015 0.00030 0.00045 0.00060-18.6

-18.4

-18.2

-18.0

-17.8

-17.6

-17.4




ln(n/P) Intercept -17.02017 0.00321

ln(n/P) Slope -2143.05977 6.9401

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)

(a)

0.00010 0.00015 0.00020 0.00025

-18.50

-18.45

-18.40

-18.35

-18.30

-18.25

-18.20




ln(n/P) Intercept -17.90567 0.01802

ln(n/P) Slope -2199.72848 94.19905

ln(n

/P)

(ln(m

ol g

-1 P

a-1))

n (mol/g)

(b)

0.0000 0.0002 0.0004 0.0006 0.0008-19.2

-18.8

-18.4

-18.0

-17.6

-17.2 295 K

273 K

ln(n

/P)

(ln

(mo

l g

-1 P

a-1))

n (mol/g)

(c)

Supplementary Figure S11 | The virial graphs for adsorption of C2H4 on M’MOF-3a. At 273 K (a) and 295 K (b). The A1 parameters are very close at the two temperatures, so it was supposed that A1(273 K) is also –2199.72848 g mol-1, then A0 (273 K) is –17.01296 (ln(mol g-1 Pa-1)). It is apparent that the virial graphs with the same A1 have very good linearity in the low pressure at the two temperatures (c): green line for the virial equation at 273 K, red line for that at 295 K.

16

Supplementary Figure S12 | The x-ray crystal structures for M’MOF-1 and M’MOF-1 ⊃⊃⊃⊃ R/S-

PEA. After immersed into the solution of racemic D,L-1-phenylethyl alcohol (D,L-1-PEA), the 3D pillared framework of achiral Zn3(BDC)3[Cu(SalPyen)] (left, M’MOF-1) will encapsulate PEA in both the R- and S- forms (CPK model) to form M’MOF-1 ⊃ R/S-PEA (right), accompanying with the rotation of half of the Cu(SalPyen) pillars (Zn, pink; Cu, green; O, red; C, grey; N, blue; H, white). For clear comparison, the structures of the encapsulated PEA in R or S forms are shown on the top of the corresponding CPK styles.

17

100 200 300 400 500 600 700 8000

20

40

60

80

100

M'MOF-2

M'MOF-3

TG

A (

%)

Temperature (oC)

-27.99% -28.67%

Supplementary Figure S13 | TGA curves for the two mixed metal-organic frameworks. M’MOF-2 (blue) and M’MOF-3 (red) (Calculated solvent weight loss are 28.41% and 28.19%, respectively, for M’MOF-2 and M’MOF-3).

18

0 10 20 30 40 50

Inte

nsi

ty

2 Theta

Supplementary Figure S14 | Powder X-ray diffraction (PXRD) patterns of M’MOF-2. The simulated (black), the as-synthesized M’MOF-2 (red) and the de-solvated M’MOF-2a (blue).

19

0 10 20 30 40 50

Inte

nsi

ty

2 Theta

Supplementary Figure S15 | Powder X-ray diffraction patterns of M’MOF-3. The simulated (black), the as-synthesized M’MOF-3 (red) and the de-solvated M’MOF-3a (blue)

20

0 10 20 30 40 50

Inte

nsi

ty

2 Theta

Supplementary Figure S16 | Powder X-ray diffraction pattern comparison. The as-synthesized M’MOF-2 (black), M’MOF-3 (red), and the de-solvated M’MOF-2a (blue) and M’MOF-3a (green)

21

0 10 20 30 40 50

Inte

nsi

ty

2 Theta

Supplementary Figure S17 | Powder X-ray diffraction patterns of M’MOF-3⊃⊃⊃⊃PEA. The simulated (black) and the as-synthesized patterns (red).

22

3600 3000 2400 1800 1200 600

40

60

80

100

M'MOF-2

Wavelength (cm-1)

3600 3000 2400 1800 1200 600

20

40

60

80

100

M'MOF-3

tra

nsm

itta

nce

Supplementary Figure S18 | FT-IR of the as-synthesized M’MOFs. M’MOF-2 (blue) and M’MOF-3 (red).

23

2931.7

6

1575.

69

1503.

16

147

0.5

0

135

8.3

2

1244.4

4

113

7.3

4

101

6.3

59

84.8

2

901.2

1

824

.35

781.4

1742.5

8

661

.34

500100015002000250030003500

Wavenumber cm-1

50

100

150

200

Tra

nsm

itta

nce [

%]

Supplementary Figure S19 | FT-IR of M’MOF-2a.

24

2928.6

8

2856.5

3

1535.8

7

147

0.6

6

139

4.86

1272.3

11243.

47

121

1.8

9

113

8.26

1043.

16

984.8

1

901

.35

780.7

9

663.5

0

500100015002000250030003500

Wavenumber cm-1

50

100

150

200

Tra

nsm

itta

nce [

%]

Supplementary Figure S20 | FT-IR of M’MOF-3a.

25

Compounds M’MOF 2 M’MOF 3 M’MOF 3 ⊃⊃⊃⊃PEA M’MOF 1 ⊃⊃⊃⊃ PEA

Formula Zn3(C8H4O4)3

(CuC20H22N4O2) Zn3(C8H10O4)3

(CuC20H22N4O2)

Zn3(C8H10O4)3

(CuC20H22N4O2) (C8H10O)

(C3H7NO)5

Zn3(C8H4O4)3

(CuC16H20N4O2) (C8H10O)

Fw 1102.40 1120.55 1608.26 1170.47

color light blue light blue purple purple

shape platelet platelet platelet platelet

crystal system orthorhombic monoclinic orthorhombic monoclinic

space group P2(1)2(1)2(1) C2 P2(1)2(1)2(1) Cc

a/Å 9.640(5) 41.163(8) 9.7495(13) 41.064(2)

b/Å 18.350(7) 10.087(2) 18.576(3) 9.2924(4)

c/Å 41.530(18) 17.963(4) 41.636(6) 18.8508(9)

α/deg 90.00 90.00 90.00 90.00

β/deg 90.00 102.70(3) 90.00 94.681(2)

γ/deg 90.00 90.00 90.00 90.00

V/Å3 7346(6) 7276(3) 7540.4(18) 7169.2(6)

T/K 173(2) 173(2) 173(2) 173(2)

Z 4 4 4 4

Dcalc/g⋅cm3 0.997 1.023 1.417 1.084

F(000) 2228 2300 3363 2372

abs coeff /mm–1 1.297 1.310 1.295 1.334

Reflns collected /unique (Rint)

15056/10144 (0.0625)

24669/12662 (0.0425)

88808/15348 (0.0632)

29110/13208 (0.0493)

Parameter/Data(obs.)

595/6911 695/11365 745/13413 605/8777

GOF 1.013 1.044 1.048 1.047

R1, ωR2(I > 2.0σ(I))

0.0624, 0.1243 0.0594, 0.1498 0.0637, 0.1649 0.0547, 0.1188

R, ωR2(all data) 0.0838, 0.1314 0.0645, 0.1547 0.0737, 0.1715 0.0783, 0.1262

Flack Parameter 0.08(2) 0.089(19) 0.065(16) 0.471(17)

Supplementary Table S1 | Crystal data and structure refinement for the mother M’MOFs and the

PEA-encapsulated Frameworks.

26

Supplementary References

48. Sheldrick, G. M. A short history of SHELX. Acta Cryst. A 64, 112-122 (2008).

49. CrystalClear User’s Manual, Version 1.3, Molecular Structure Corporation, 2001.

50. Spek, A. L. PLATON, A Multipurpose Crystallographic Tool; Utrecht University: Utrecht, The Netherlands, 2001.

51. O'koye, I. P.; Benham, M. & Thomas, K. M. Adsorption of gases and vapors on carbon molecular sieves. Langmuir 13, 4054-4059 (1997).

52. (a) Reid, C. R. & Thomas, K. M. Adsorption of gases on a carbon molecular sieve used for air separation: Linear adsorptives as probes for kinetic selectivity. Langmuir 15, 3206-3218 (1999). (b) Reid, C. R. & Thomas, K. M. Adsorption kinetics and size exclusion properties of probe molecules for the selective porosity in a carbon molecular sieve used for air separation. J. Phys.

Chem. B 105, 10619-10629 (2001).

53. Zhao, X.; Villar-Rodil, S.; Fletcher, A. J. & Thomas, K. M. Kinetic isotope effect for H2 and D2 quantum molecular sieving in adsorption/desorption on porous carbon materials. J. Phys. Chem.

B 110, 9947-9955 (2006).

54. Chen, B.; Zhao, X.; Putkham, A.; Hong, K.; Lobkovsky, E. B.; Hurtado, E. J.; Fletcher, A. J. & Thomas, K. M. Surface and quantum interactions for H2 confined in metal-organic framework pores. J. Am. Chem. Soc. 130, 6411-6423 (2008).

supplementary information - nature · 2011-02-22 · and purification such as removal/separation of...

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