Mesoscopic architectures of porous coordination polymers ... · nm. After replication of this...

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Supplementary Information

Mesoscopic architectures of porous coordination polymers fabricated by pseudomorphic replication

Julien Reboul, Shuhei Furukawa*, Nao Horike, Manuel Tsotsalas, Kenji Hirai, Hiromitsu

Uehara, Mio Kondo, Nicolas Louvain, Osami Sakata, and Susumu Kitagawa*

* To whom correspondence should be addressed:

[email protected] (S.F.), [email protected] (S.K.)

Mesoscopic architectures of porous coordination polymers fabricated by pseudomorphic replication

SUPPLEMENTARY INFORMATIONDOI: 10.1038/NMAT3359

NATURE MATERIALS | www.nature.com/naturematerials 1

© 2012 Macmillan Publishers Limited. All rights reserved.

http://www.nature.com/doifinder/10.1038/nmat3XXX

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The supplementary material provides information about:

Part A: Supplementary characterizations of two-dimensional patterns after their

transformation into PCP-based materials (high magnification FESEM and

AFM).

Part B: Comparative time dependent experiments performed under conventional

hydrothermal treatment.

Part C: Application of the coordination replication method with different organic

ligands.

Part D: Water/separation ability of the aluminum naphthalene dicarboxylate

framework.

Part E: Characterization of the parent alumina aerogels and mesoscale PCP

architectures used for water/ethanol separation.

Part F: Comparison of the mesoscopic PCP architectures.

Part G: Water/ethanol separation with the macroporous alumina aerogel.

Part H: Experimental apparatus of the vapor-phase breakthrough experiments.

Part I: Characterization: method and instrumentation.

2 NATURE MATERIALS | www.nature.com/naturematerials

SUPPLEMENTARY INFORMATION DOI: 10.1038/NMAT3359



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Part A. Supplementary characterizations of two-dimensional patterns after their

transformation into PCP-based materials.

Figure S1. High magnification FESEM images of (a) the alumina two-dimensional pattern

and (b) the same pattern after the alumina transformation into PCPs.




http://www.nature.com/doifinder/10.1038/nmat3359

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Figure S2. Atomic force microscopy (AFM) image (left) and height profile (right)

corresponding to the alumina hexagonal pattern. Height of the walls (410 nm) and the thin

PCP layer within the macro-hole (140 nm) are indicated by the double arrows.





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Part B. Comparative time dependent experiments performed under conventional

hydrothermal treatment.

Figure S3. Top-view SEM images of the (a) alumina pattern and of the same sample after a

conventional hydrothermal treatment at 180°C for (b) 1 min, (c) 1 h, (d) 5 h, (e) 10 h and (f)

20 h. Scale bare = 1 µm.

The beneficial effect of microwave synthesis was also demonstrated by comparing

microwave results with those obtained under a conventional hydrothermal procedure.

Alumina patterns were placed in Teflon containers filled with H2ndc aqueous solutions of the

same molar composition than previous experiments performed under microwave synthesis.

These containers were then sealed and placed in a conventional oven at 180°C during

different reaction times (figure S3).

The power of the oven used during these experiments allows reaching the temperature

of 180°C in two hours. In order to examine the effect of such treatment over the alumina

pattern (Figure S7a), morphology of the sample surface was monitored by FESEM at different





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reaction times. Figure S3b clearly shows the disappearance of the alumina pattern 1 minute

after the end of the temperature increase. Instead, rectangular–shaped crystals with length of

about 100 nm were apparent over the overall sample surface. After crystallization for 1 h, the

surface was entirely covered by a two-dimensional network composed of fused crystals

(Figure S3c). We suggest that this film acted as seed from which grow small crystal

“bouquets” with size of about 200 nm. After 5 h of reaction, crystal “bouquets” got bigger and

the surface was more porous (Figure S3d). Figure S3e and f evidences the formation of

spherical crystal aggregates. These spherical crystal aggregates were deposited on a surface

composed of interconnected macropores with ill-defined shaped. Hence the slow increase of

temperature performed during a classical hydrothermal treatment disables the alumina pattern

replication to occur. In contrast, microwave radiation passes through the walls of the vessel

heating the contents directly by taking advantage of the ability of some liquids and solids to

transform electromagnetic radiation into heat.S1 Desired temperature is hence almost

immediately reached in the overall sample in a simultaneous way. This fast and homogeneous

temperature increase is necessary to obtained the appropriated alumina

dissolution/crystallization harmonization and create perfect PCP replicates.





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Part C. Application of the coordination replication method with different organic

ligands.

Figure S4. Top-view FESEM images of the three-dimensional alumina inverse opal crystal

after transformation with the benzene tricarboxylic acid. A three-dimensional alumina inverse

opal crystal architecture composed of inter-grown octahedral {[Al3O(OH)(H2O)2](btc)2}n

crystals was formed.





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Figure S5. X-ray diffraction pattern of the as-synthesized PCP-based replica and simulated

pattern of the as-synthesized {[Al3O(OH)(H2O)2](btc)2}n.

5 10 15 20

2θ (degree)

Experimental

Simulated





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Figure S6. Top-view FESEM images of the three-dimensional alumina inverse opal crystal

after transformation with the benzene dicarboxylic acid. A PCP replica based on an assembly

of [Al(OH)(bdc)]n crystals (known as MIL-53) with plate-like morphology.





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Figure S7. X-ray diffraction pattern of the as-synthesized PCP-based replica washed with

DMF and ethanol and the simulated pattern of [Al(OH)(bdc)]n obtained after thermal

treatment at high temperature.

5 10 15 20 2θ (degree)

Experimental

Simulated





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Part D. Water/separation ability of the aluminum naphthalene dicarboxylate framework.

D-1. Single component adsorption isotherm:

Figure S8. Single component adsorption isotherm of [Al(OH)(ndc)]n for ethanol at 298 K.





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D-2. binary vapor-phase breakthrough experiment for an equimolar mixture of water/ethanol:

Figure S9. Binary vapor-phase breakthrough experiment for an equimolar mixture of

water/ethanol. The water breakthrough curve appears in green and the ethanol breakthrough

curve appears in blue. Both ethanol and water relative pressures were set at P/P0 = 0.18.

Figure S9 shows that water appears earlier at the outlet of the column (Time = 15 min).

Then breakthrough of ethanol starts at Time = 40 min. From 23 min to 44 min, the

concentration of water measured at the outlet exceeds the concentration input at the inlet. This

phenomenon, known as “roll up effect”, is due to the replacement of the water molecules by

the ethanol molecules within the PCP, evidencing the difference of water and ethanol

affinities for the inner porosity of the hydrophobic [Al(OH)(ndc)]n framework. After 45 min,

the adsorption equilibrium is established, i.e., the concentration of both water and ethanol at

the outlet of the bed equal those at the inlet. The integration of the water and ethanol

experimental breakthrough curves between 0 and 45 min allows for determining the

equilibrium adsorbed amount of water and ethanol (qw and qe respectively).38 The average

selectivity of the PCP adsorbent then calculated from qw and qe was 2.26.





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Part E. Characterization of the mesoscale PCP architectures used for water/ethanol

separation.

E-1. Nitrogen sorption experiments:

Figure S10. Nitrogen adsorption isotherm measured at 77K of the alumina aerogel (blue

trace) and the PCP architecture Meso-PCP (red trace).

Both alumina aerogel and PCP architecture Meso-PCP gives a Type IV isotherm

(according IUPAC classification). The inset shows the pore size distribution as determined by

nitrogen adsorption (blue trace for the aerogel and red trace for Meso-PCP). The data were

analyzed by the BJH (Barret-Joyner-Halenda) method. BET surface area of 397 m2g-1 and

pore volume of 5.34 cm3g-1 was obtained for the alumina aerogel with a mean pore size of 94

nm. After replication of this material into PCP architecture, the BET surface area and pore

volume decreased to 221 m2g-1 and 0.72 cm3g-1 respectively and the resulting mean pore size

was 68 nm. Hence, PCP crystal formation conduces to the formation of a PCP architecture

comprising large mesopores (Meso-PCP).

0

500

1000

1500

2000

2500

3000

3500

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Volu

me

ads

STP

(cm

3 g-1

)

P/P0

1" 10" 100"

D (nm)





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Figure S11. Nitrogen adsorption isotherms measured at 77K of the macroporous alumina

aerogel (blue trace) and mesoporous/macroporous PCP architecture (Macro-PCP) (red

trace).

Both alumina aerogel and PCP architecture Macro-PCP gives a Type IV isotherm

(according IUPAC classification). The inset shows the pore size distribution as determined by

nitrogen adsorption (blue trace for the macroporous aerogel and red trace for Macro-PCP).

The data were analyzed by the BJH (Barret-Joyner-Halenda) method. BET surface area of

407 m2g-1 and pore volume of 3.44 cm3g-1 was obtained for the alumina aerogel with a mean

pore size of 38 nm. After replication of this material into PCP architecture, the BET surface

area and pore volume decreased to 221 m2g-1 and 0.72 cm3g-1 respectively and the resulting

mean pore size was 29 nm. The transformation of the alumina structure composing the

alumina aerogel skeleton of the macroporous alumina aerogel into PCP crystals conduces to

the formation of a PCP architecture comprising large mesopores in addition to the

macroporosity (Macro-PCP).

0

500

1000

1500

2000

2500

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Volu

me

ads

STP

(cm

3 g-1

)

P/P0

1 10 100

D (nm)





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Figure S12. Nitrogen adsorption isotherms of the PCP powder (black trace), meso-PCP (red

trace) and macro-PCP (green trace) measured at 77K.

A BET surface area of 110 m2g-1 was obtained for the PCP powder. The sharp increase

of adsorbed volume of nitrogen observed below P/P0 = 0.1 in case of the PCP powder is due

to the PCP crystal microporosity. The higher amount of adsorbed nitrogen below P/P0 = 0.1

in the case of Meso-PCP and Macro-PCP is possibly due to an additional intercrystalline

microporosity. In contrast with the nitrogen adsorption isotherm of the PCP powder, the

significant nitrogen uptake observed on the nitrogen adsorption isotherm of both Meso-PCP

and Macro-PCP at P/P0 above 0.8, evidences the mesoscopic architecture of these two

materials.

Mesopores of the alumina aerogel are larger that the mesopores of the

macroporous alumina aerogel. The macroporous structure of the aerogel at the origin of

0

100

200

300

400

500

600

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

Volu

me

ads

STP

(cm

3 g-1

)

P/P0





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Macro-PCP is the result of a phase separation induced by the introduction of poly(ethylene

oxide) (PEO) during the aerogel synthesis. Tokudome and collaborators showed that the

presence of PEO in the synthesis medium contributes to producing smaller mesopores within

the walls of the final macroporous alumina obtained (ref. 37). The alumina walls of the

macroporous aerogel (precursor of Macro-PCP) contain hence smaller mesopores than the

“non-macrostructured” aerogel (precursor of Meso-PCP). Therefore, after coordination

replication, size of the Macro-PCP mesopores is lower than the size of the Meso-PCP

mesopores.

Impact of the difference of textural properties of Meso-PCP and Macro-PCP on

the water/ethanol separation efficiency. The higher surface area of Meso-PCP measured by

nitrogen sorption compared to Macro-PCP indicates that the total external surface of the PCP

crystals exposed within Meso-PCP is higher. Hence we assume that adsorption sites within

the PCP crystals composing Meso-PCP are more accessible than the adsorption sites located

within Macro-PCP. Therefore, better ethanol retention and separation selectivity are obtained

with Meso-PCP.





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E-2. Field emission scanning electron microscopy (FESEM) characterization of the parent

alumina aerogels:

Figure S13. FESEM images of the aerogel (a) low magnification (b) high magnification. A

disordered large mesoporosity with pore size of 50-100nm (size in line with the pore size

distribution obtained from the nitrogen sorption measurement Fig. S10) was observed.





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Figure S14. FESEM images of the macroporous aerogel (a) low magnification (b) high

magnification. A macroporosity (pore size = 1 µm) was observed. The mesoporosity revealed

by means of nitrogen sorption analysis (Fig. S11) was also observed on the high

magnification image (Fig. S14b).





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E-3. Schematic view of the parent alumina aerogels amd mesoscopic PCP architectures.

Figure S15. Schematic representation of the parent alumina aerogels and of the mesoscopic

PCP architectures Meso-PCP and Macro-PCP. Porosity of each alumina aerogels and PCP-

based architectures are summarized as followed:

The alumina aerogel contains larges mesopores (revealed by nitrogen sorption

measurements, Fig. S10 and FESEM Fig. S13)

The macroporous alumina aerogel contains large mesopores and macropores

(revealed by nitrogen sorption measurements, Fig. S11 and FESEM Fig. S14)

Meso-PCP contains:

- micropores from the [Al(OH)(ndc)]n PCP crystals (revealed by carbon dioxide sorption

measurements, Fig. S19)





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- micropores from the intercrystalline porosity (revealed by nitrogen sorption measurements,

Fig. S12)

- mesopores inherited from the parent aerogel (revealed by nitrogen sorption measurements,

Fig. S10 and FESEM image, Fig S16a)

Macro-PCP contains:

- micropores from the [Al(OH)(ndc)]n PCP crystals (revealed by carbon dioxide sorption

measurements, Fig. S19)

- micropores from the intercrystalline porosity (revealed by nitrogen sorption measurements,

Fig. S12)

- mesopores inherited from the parent aerogel (revealed by nitrogen sorption measurements,

Fig. S11)

- macropores inherited from the parent aerogel (revealed by FESEM measurements, Fig.

S14)





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E-4. Field-emission scanning electron microscopy (FESEM) characterisation of the

mesoscopic PCP architectures:

Figure S16. a. High magnification FESEM image. b. low magnification FESEM image of

Meso-PCP. Mesopores between rod-shaped PCP crystals were observed on the high

magnificatiom FESEM image.





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Figure S17. a. High magnification FESEM image. b. low magnification FESEM image of

Macro-PCP. Macropores of about 1 µm were observed.





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E-5. Powder X-ray diffraction:

Figure S18. X-ray diffraction patterns of (a) the mesoporous PCP architecture (Meso-PCP)

and (b) the mesoporous/macroporous PCP architecture (Macro-PCP). Diffraction peak

intensities observed on the two diffraction patterns are identical.





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E-6. CO2 sorption measurements:

Figure S19. CO2 adsorption-desorption isotherms of the mesoporous PCP architecture

(Meso-PCP) (red trace) and mesoporous/macroporous PCP architecture (Macro-PCP) (blue

trace).

As reported by Comotti et al.,30 [Al(OH)(ndc)]n PCP framework accommodates CO2.

Here we use this gaseous molecule to probe the microporosity of the [Al(OH)(ndc)]n based

architectures. The CO2 adsorption isotherm profiles are similar (Type I according the IUPAC

classification). Volumes of CO2 adsorbed in both PCP-based architectures at P/P0=0.95 are

very similar; 155cm3 (STP) g-1 for Meso-PCP, and 145 cm3 (STP) g-1 for Macro-PCP.





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Figure S20. Carbon dioxide adsorption-desorption isotherms of (a) the macroporous alumina

parent aerogel and (b) the mesoporous/macroporous PCP architecture (Macro-PCP).

Figure S20 shows a significant increase of carbon dioxide adsorption at low relative

pressure after the replication of the alumina parent structure ranging from 0 to 0.1 indicating

the formation of the PCP microporosity. Importantly, the shape (type I according to the

IUPAC classification) and the saturation capacity (up to 143 cm3 (STP) g-1) of the mesoscale

PCP architecture is comparable with the shape and carbon dioxide saturation capacity of the

PCP powder synthesised from the aluminum salt,30 (the adsorption isotherm is of Type I

according to the IUPAC classification and the carbon dioxide saturation capacity is 138 cm3

(STP) g-1). This result suggests that the whole microporosity within the PCP crystals

composing the PCP architecture is accessible and can be used for the ethanol adsorption.





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Part F. Comparison of the mesoscopic PCP architectures.

F-1. Field-Emission Scanning Electron Microscopy (FESEM):

Figure S21. FESEM images of (a) the mesoporous PCP architecture (Meso-PCP) and (b) the

macroporous PCP architecture (Macro-PCP). PCP crystals composing the two materials are

nanorods of similar size (the length of the nanorods is about 100nm).





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F-2. Low magnification Field-Emission Scanning Electron Microscopy (FESEM):

Figure S22. Low magnification FESEM images of (a) the mesoporous PCP architecture

(Meso-PCP) and (b) the macroporous PCP architecture (Macro-PCP). Size distribution and

shapes of the pieces of both Meso-PCP and Macro-PCP materials packed within the

separation columns are identical.





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Part G. Water/ethanol separation with the macroporous alumina aerogel.

Figure S23. Binary breakthrough profile for an equimolar water/ethanol mixture performed

with the macroporous alumina aerogel packed in the column. The water breakthrough is in

green and the ethanol breakthrough profile is in blue.

The macroporous alumina aerogel was packed into the column before the replication

into the analogous PCP architecture. Because of the hydrophilic nature of the alumina wall

surfaces within the aerogel, water is more retained within the column than ethanol during a

first step ranging from 0 to 55 min. Then, further adsorption of ethanol leads to the

displacement of the remaining water after 59 min, resulting in a significant roll up effect. The

replication of the macroporous alumina aerogel into Macro-PCP turns the separation bed to

be hydrophobic, resulting in unambiguous adsorption selectivity towards ethanol (Figure 6).





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Part H. Experimental apparatus of the vapor-phase breakthrough experiments.

Figure S24. Schematic diagram of the vapor-phase breakthrough experimental apparatus.

(He) Helium gas tank, (MFC) Mass Flow Controller, (W) water saturator, (E) Ethanol

saturator, (Col.) Separation column filled with the PCP crystals, (SL) Sample Loop, (GC) gas

chromatography, (TCD) Thermal Conductivity Detector, (Comp.) Computer.

The separation ability of the columns filled with the [Al(OH)(ndc)]n powder, Meso-

PCP or Macro-PCP, was evaluated by means of breakthrough experiments for equimolar

water/ethanol mixtures. The experimental apparatus used for this study is composed of three

main sections:

- the “vapor-mixture generator section” which consists in a mass flow controller, generats the

equimolar water/ethanol vapor mixture by passing the carrier gas (Helium) through two

parallel saturators, one filled with water, the other filled with ethanol. The relative pressures





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of water and ethanol are both equal to 0.18. The vapor-mixture prepared is introduced into the

system at a constant flow rate of 20 ml/min.

- the “separation section” contains the experimental separation column made of a glass tube

(L =5 cm; di = 3 mm) packed with 0.09 g of a PCP crystals (or packed bed). This column is

set in an oven at 80°C. Before packing the PCP powders and PCP architectures are heated at

120°C under vacuum overnight. After packing and before each measurement, the separation

column is activated by heating to 140°C for 12 h under a flow of dried helium.

- the “analytical section” is composed of a proper gas chromatographic column, a thermal

conductivity detector and a computer for collecting the data. Samples coming from the outlet

of the PCP packed column are collected in a sample loop located at the entrance of the

analytical section and are injected in the gas chromatographic column every 2.5 minutes.





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Part I: Characterization: method and instrumentation.

Field-emission scanning electron microscopy (FESEM) observations were performed with a

JEOL Model JSM-7001F4 SEM system operating at 15.0 kV. The samples were deposited on

carbon tape and coated with osmium prior to measurement. Synchrotron X-ray diffraction

measurements for film-structural analysis were performed with a four-circle diffractometer

having f, c, q, and 2q circles at SPring-8 with beamline BL13XU for surface and interface

structures. The q -2q scan was carried out with a 0.15º step (l = 1.55011 Å). Carbon dioxide,

nitrogen and ethanol sorption measurements were performed using BELSORPmax volumetric

sorption equipment from BEL JAPAN, inc. Before adsorption measurements, the samples

were degassed under vacuum at 283 K for 12h. The ethanol solution was degassed four times

before utilisation.

References:

S1. http://www.biotage.com





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