Supporting material

A Facile Synthesis of UiO-66 Systems and their Hydrothermal Stability

Hirofumi Motegi, Kazuhisa Yano*, Norihiko Setoyama, Yoriko Matsuoka, Tetsushi

Ohmura, Arimitsu Usuki

1. Materials

2. Characterizations

3. Detailed synthesis and a large scale synthesis

4. SEM images of MOF particles

5. PXRD analysis of as-synthesized UiO-66 and MOF801 for hydrothermal tests.

6. Large-scale synthesis

7. Elemental analysis for MOF801 and UiO-66

8. Thermal Desorption-Gas Chromatograph/Mass Spectroscopy (TD-GC/MS) analysis

9. Pore activation by different solvent system for MOF801

1. Materials.N,N-dimethylformamide (99.5%), acetone (99.0%), methanol (99.8%), formic acid

(98.0%), Zirconyl chloride octahydrate (99.0%), terephthalic acid (98.0%) and fumaric acid

(99.0%) were purchased from Wako pure chemical industries, ltd. All of the chemicals were

used without purification.

2. Characterizations2.1. Powder X-ray diffraction (PXRD)

Each synthesized crystalline sample was measured by using Cu-Kα radiation

(Rigaku ULTIMA-IV, 40 kV, 40 mA).

2.2. Temperature-resolved PXRDEach synthesized crystalline sample was measured by using Cu-Kα radiation

(Bruker AXS, D8 ADVANCE, 35 kV, 40 mA). Each sample was heated by 10 oC per minute

in order to reach the desired temperatures, which are 100 oC, 200 oC, 250 oC, 300 oC, 350 oC, 400 oC and 450 oC. When temperature was reached at each point, the temperature was

kept for 30 minutes prior to PXRD analysis.

2.3. Scanning electron microscopyScanning electron microscopy (SEM) images were recorded by using Hitachi S-

5500 microscope operated at an acceleration voltage of 1.0 kV. The crystalline samples

were coated with Pt or Os prior to the analysis.

2.4. Surface area analysisNitrogen adsorption and desorption isotherms were measured using a

Quantachrome autosorb MP-1.

2.5. Elemental AnalysisA bulk crystalline sample was analyzed with Perkin-Elmer PE2400 II for C, H and

N for as-synthesized UiO-66 and MOF801. In addition, the percentage of chloride anion for

the methanol exchanged UiO-66 was analyzed with Exeter Analytical CE-440 Elemental

Analyzer with ion chromatography.

2.6. Thermogravimetric(TG) analysisEach crystalline sample was measured with a Rigaku thermoplus TG8210. About

3 to 10.0 mg sample was placed in a platinum sample pan. The TG profile of the sample

was obtained by heating from ambient temperature to 800 oC with heating rate 10 oC/min

under flow of air.

2.7. Hydrothermal stabilityHydrothermal stability tests were performed in a scintillation vial. About 150 mg of

crystalline solids were immersed in 10 mL of water and it was heated in an oven at 80 oC.

3. Detailed synthesis and a large scale synthesisAll of the reaction was performed in a round-bottom flask equipped with a reflux

condenser under nitrogen atmosphere. The system was heated with an aluminum block

reactor under a vigorous stirring condition. In our method, the nucleation starts within three

to five minutes after heating and the total reaction time is usually about two hours. The

filtration was performed while it was hot and washed with DMF followed by acetone.

3.1. Synthesis of UiO-66

ZrOCl2·8H2O (1.6 g, 5.0 mmol) and terephthalic acid (0.80 g, 4.8 mmol) were

dissolved in 30 mL of DMF at room temperature under stirring condition. Formic acid (15.0

mL, 397.5 mmol) was added and heated at 140 oC for 2 hours under vigorous stirring

condition. The white crystalline powder was filtered after cooling to room temperature and

washed with 20 mL of DMF once and 50 mL of acetone. Then, the collected solids were

dried under vacuum for overnight. (Yield: 1.61 g; containing possible lattice solvents and

unreacted ligands)

Figure S1. (i) PXRD patterns of UiO-66 (a) simulated and (b) as-synthesized, (ii) TG profile

of UiO-66 for as-synthesized and methanol-treated crystalline sample.

3.2. Synthesis of MOF801ZrOCl2·8H2O (1.6 g, 5.0 mmol) and fumaric acid (0.60 g, 5.2 mmol) were dissolved

in 20 mL of DMF at room temperature under stirring condition. Formic acid (7.0 mL, 185.5

mmol) was added and heated at 140 oC for 2 hours under vigorous stirring condition. The

white crystalline powder was filtered after cooling to room temperature and washed with 20

mL of DMF once and 50 mL of acetone. Then, the collected solids were dried under

vacuum for overnight. (Yield: 1.46 g; containing possible lattice solvents and unreacted

ligands)

3.2.1. Synthesis of MOF801 with defects; a possible inclusion of formate anion.When we added 10 mL (265.0 mmol) of formic acid rather than 7.0 mL (185.5

mmol) for the reaction system, the PXRD pattern was slightly different than the reported

PXRD patterns and the synthetic condition we performed in 3.2 (Figure S2). We did not

investigate further synthetic conditions in terms of concentration of formic acid and DMF at

this time.

Figure S2. (i) PXRD patterns of MOF801 (a) simulated, (b) DMF:HCOOH=20:7 and (c)

DMF:HCOOH=20:10, (ii) TG profiles of MOF801 for as-synthesized and water-treated

crystalline sample.

As-synthesized UiO-66 particles were refluxed in MeOH for 6 hours, whereas

MOF-801 particles were refluxed in water for 2 hours. We evaluated our results of TG

profiles before and after the post-treatment in order to investigate residual solvents. It is

difficult to tell whether DMF molecules were fully exchanged with methanol for UiO-66

system (Figure S1 (ii)) and MOF801 (Figure S2 (ii)). Thus, we have performed TD-GC/MS

to inspect residual DMF or other possible unreacted starting molecules (Figure S15 and

S16).

3.3 Temperature-resolved PXRD

Figure S3. Temperature-resolved Powder X-ray diffraction: PXRD patterns for UiO-66 (a)

as-synthesized and (b) methanol treated and for MOF801 (c) as-synthesized and (d) water

treated.

Temperature-resolved Powder X-ray diffraction (TR-PXRD) was used to confirm

the crystallinity and thermal stability of UiO-66 and MOF801 (Figure S3). In a case of as-

synthesized UiO-66, PXRD patterns were maintained up to 300 oC. Then, between 300 and

350 oC, the peak intensity was dramatically decreased and thus this is an indication of

structural decomposition. In a case of as-synthesized MOF801, PXRD patterns were

maintained up to 250 oC. Then, between 250 and 300 oC, the peak intensity was

dramatically decreased and thus this is an indication of structural decomposition.

4. SEM images of MOF particles

Figure S4. SEM images of as-synthesized (a) UiO-66 and (b) MOF801, after hydrothermal

test for 14 days(c) UiO-66 and (d) MOF801.

Each crystalline particle was observed as relatively uniform-shape and size by this

synthetic method. In a case of MOF801, the particle size was about one third smaller than

that of UiO-66. These 100-300nm size particles of MOF801 were highly crystalline and

showed excellent hydrothermal stability as shown in Figure 4 and S4.

5. Large-scale synthesis5.1. A 1.0L(100 gram)-scale synthesis of UiO-66ZrOCl2·8H2O (85.0 g, 264mmol) and terephthalic acid (41.5 g, 250 mmol) were dissolved in

1.0 L of DMF at room temperature under stirring condition. Formic acid (0.50 L, 13.25 mol)

was added and heated at 150 oC for 4 hours under vigorous stirring condition. The white

crystalline powder was filtered while it was hot and washed with 100 mL of DMF once and

100 mL of acetone. Then, the collected solids were dried at 45 oC for overnight under air.

Figure S7. PXRD patterns of UiO-66-1.0L(100 gram)-scale synthesis.

Figure S8. A TG profile of UiO-66-1.0L(100 gram)-scale synthesis.

Figure S9. A SEM image of UiO-66-1.0L(100 gram)-scale synthesis.

Figure S10. N2 isotherm for the 1.0L(100 gram)-scale synthesis of UiO-66.

For the 100 gram scale synthesis of UiO-66, the quality of crystallinity was lower

than that of two-gram scale synthesis. In the SEM investigation, the bulk crystalline solids

were observed as a range of 500 nm size or smaller and we could not identify octahedral

crystalline solids in the same magnification as two-gram synthesis. Secondary particles

were constructed and N2 sorption resulted to show macroporous behavior.

5.2. A 1.0L(100 gram)-scale synthesis of MOF801ZrOCl2·8H2O (80 g, 248mmol) and fumaric acid (30 g, 259 mmol) were dissolved

in 1.0 L of DMF at room temperature under stirring condition. Formic acid (0.35 L, 9.275

mol) was added and heated at 140 oC for 4 hours under vigorous stirring condition. The

white crystalline powder was filtered while it was hot and washed with 50 mL of DMF once

and 100 mL of acetone. Then, the collected solids were dried at 45 oC for overnight under

air.

Figure S11. PXRD patterns of 1.0L(100 gram)-scale synthesis of MOF801

PXRD patterns were recorded at each time interval during hydrothermal tests for a

bulk sample of 1.0L-scale synthesis of MOF801. The crystallinity of as-synthesized 1.0L-

scale MOF801 was maintained after 14 days. Thus, the large scale synthesis of MOF801

was successfully shown its hydrothermal stability. The intensity of PXRD was slightly lower

than that of the as-synthesized sample. This could be due to the insufficient amount of

sample for PXRD analysis.

Figure S12. TG profiles of MOF801-1.0L(100 gram)-scale synthesis

Figure S13. A SEM image of 1.0L(100 gram)-scale synthesis for MOF801.

The morphology of bulk material was revealed by SEM. The bulk material was

revealed to be particle aggregation with some degree of fine reflection and shapes of

octahedron. The morphology of 1.0L scale synthesis was different than the smaller scale

synthesis, especially the size of particle was about forty times larger than that of gram-

scale synthesis (Figure S3). This could be due to insufficient stirring during the synthesis.

We may need to perform mechanical stirring method for larger scale synthesis to maintain

homogeneous mixing and heat transfer in the reaction system

.

Figure S14. N2 isotherm for the 1.0L(100 gram)-scale synthesis of MOF801.

The BET surface areas were observed as 838 m2/g for 0h, 789 m2/g for 4 days

and 784 m2/g for 14 days after hydrothermal test. This result of hydrothermal test was

slightly different than that of the smaller scale synthesis(Figure 4). We hypothesized that

hot filtration may have caused higher surface area to start for as-synthesized 1.0L-scale

batch. The unreacted ligand and solvent molecules could have removed by this filtration

method. Also, there is a hysteresis between 0.4-0.6 on P/P0 axis after hydrothermal tests.

This could be a potential cracks on bulk particles. The overall surface area after

hydrothermal test showed a similar trend as the small scale.

6. Elemental analysis for UiO-66 and MOF801Table S2 a crystalline sample of UiO-66 after methanol treatment

C(%) H(%) N(%) Cl(%)

Observed (before) 29.94 1.79 0.72 0.143

Observed (after) 27.99 1.72 0.39 0.166

Calculated* 29.78 1.74 0.73 0.138

Table S3 crystalline sample of MOF801 after water treatment

C(%) H(%) N(%)

Observed 17.05 1.47 -0.11

Calculated** 19.13 0.80 0.00

Each crystalline sample was thermally treated equipped with vacuum line at 150 oC for 3 hours prior to the analysis. This treatment could remove lattice DMF, H2O or

methanol molecules in order to get a precise CHN values. However, those activated UiO-66

and MOF801 may contain residual solvent or unreacted reagent molecules because TG

profiles cannot tell if the crystalline sample can be fully activated by a simple thermal

treatment under vacuum. Thus, it is very difficult to determine molecular formula based on

elemental analysis. Thus, in section 8, we have analyzed TD-GC/MS for a better

understanding of chemical composition of each crystalline particle.