Supporting Information
Pyrazolate-Based Porphyrinic MOF with Extraordinary
Base-Resistance
Kecheng Wang,†,‡,# Xiu‐Liang Lv,†,# Dawei Feng,‡ Jian Li,§ Shuangming Chen,$ Junliang
Sun,§ Li Song,$ Yabo Xie,† Jian‐Rong Li,*,† and Hong‐Cai Zhou*,‡
†
Beijing Key Laboratory for Green Catalysis and Separation and Department of
Chemistry and Chemical Engineering, College of Environmental and Energy Engineering,
Beijing University of Technology, Beijing 100124, P. R. China.
‡
Department of Chemistry, Texas A&M University, College Station, Texas 77842‐3012,
USA
§
College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R.
China.
$
National Synchrotron Radiation Laboratory, University of Science and Technology of
China, Hefei 230026, P. R. China.
# K.W. and X.L. contributed equally to this work.
*To whom correspondence should be addressed, E-mail: jrli@bjut.edu.cn and
zhou@chem.tamu.edu.
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Contents
Section 1. Chemicals and Instruments...........................................................................................S3
Section 2. Synthesis of H4TPP and PCN-601 ...............................................................................S5
Section 3. Scanning Electron Microscope Image of PCN-601 .....................................................S7
Section 4. Thermal Stability of PCN-601. ............................................................................................S8
Section 5. Topological and Geometrical Analysis of PCN-601....................................................S9
Section 6. Rietveld Refinement and Crystallographic Data of PCN-601 ...................................S11
Section 7. X-ray Absorption Spectroscopy (XAS) Analysis of PCN-601 ..................................S13
Section 8. Powder X-Ray Diffraction for PCN-601 Samples .....................................................S13
Section 9. N2 Adsorption/Desorption Isotherms for PCN-601 Sample ......................................S15
Section 10. Crystal Field Stabilization Energy Anaylsis. ...........................................................S17
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Section 1. Chemicals and Instruments
N,N-dimethylformamide (DMF), Acetone, Nickel(II) acetate tetrahydrate (Ni(AcO)2·4H2O),
and Triethylamine (Et3N) were bought from Alfa Aesar. Sodium bicarbonate (NaHCO3),
Magnesium sulphate (MgSO4), Dichloromethane (CH2Cl2), Aluminum oxide (Al2O3),
Propionic acid, Hydrochloric acid (HCl), Dioxane, 4-Iodo-1H-pyrazole, Ethilvinylether,
Ethylmagnesium bromide and Pyrrole were purchased from AcroSeal. All commercial
chemicals were used without further purification unless otherwise mentioned.
High resolution powder X-ray powder diffraction (PXRD) was performed on a PANalytical
X’Pert PRO diffractometer equipped with a Pixel detector and using Cu Kα1 radiation (λ =
1.5406 Å). The powder samples were placed in a 0.4 mm diameter glass capillary that was
spun during the experiment. Rietveld refinements of the crystal structures were performed by
the software TOPAS.1 Other PXRD was carried out with a BRUKER D8-Focus BraggBrentano X-ray Powder Diffractometer equipped with a Cu sealed tube (λ = 1.54178 Å) at 40
kV and 40 mA. Thermogravimetry analysis (TGA) was conducted on a TGA-50
(SHIMADZU) thermogravimetric analyzer. Nuclear magnetic resonance (NMR) data were
collected on a Mercury 300 spectrometer. FT-IR data were recorded on an SHIMADZU IR
Affinity-1 instrument. N2 adsorption-desorption isotherms were measured using a
Micrometritics ASAP 2420 system at 77 K. The UV-vis absorption spectra were recorded on
a Shimadzu UV-2450 spectrophotometer. The surface and cross-section morphologies of the
prepared membranes were observed by scanning electron microscope (SEM) (Model SU8020,
Hitachi, Japan). Elemental analysis (EA) was performed by vario EL cube (Elementar).
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Inductively Coupled Plasma-Optical Emission Spectrometer (ICP-OES) data was collected on
Thermo iCAP-6300. The Ni K-edge X-ray absorption spectroscopy (XAS) measurements
were made in the transmission mode at the beam-line 14W1 in Shanghai Synchrotron
Radiation Facility (SSRF).
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Section 2. Synthesis of 5,10,15,20-tetra(1H-pyrazol-4-yl)porphyrin (H4TPP)
and PCN-601
Synthesis of TPP:
Scheme S1. Synthesis procedure for H4TPP.
A. 1-(1-Ethoxyethyl)-4-iodo-1H-pyrazole (2)
1-(1-ethoxyethyl)-4-iodo-1H-pyrazole (2) was obtained by a modified literature method.1 4Iodo-1H-pyrazole (1, 19.4 g, 100 mmol ) was dissolved in toluene (150 mL). Ethilvinylether
(20.0 mL, 211 mmol) and 2 mL HCl were added, and the mixture was heated at 50 oC. The
progress of the reaction was detected by TLC. After the reaction completed, the mixture was
poured into a saturated solution of NaHCO3 (50 mL) and extracted by CH2Cl2 (50 mL × 3),
the organic phase was dried over MgSO4 and filtered. The product 2 was obtained by column
chromatographer on Al2O3 (CH2Cl2 as eluent), yield 22.0 g (82.5 %). 1H NMR (300 MHz,
CDCl3) δ (ppm): 7.62 (s, 1H), 7.49 (s, 1H), 5.48 (q, 1H), 3.30-3.45 (m, 2H), 1.61 (d, 3H),
1.13 (t, 3H).
B. 4-Formyl-1(H)-pyrazole (3)
4-Formyl-1(H)-pyrazole (3) was synthesized by following a reported method.2 1H NMR (300
MHz, DMSO) δ (ppm): 9.87 (s, 1H), 8.25 (s, 2H).
C. 5,10,15,20-Tetra(1H-pyrazol-4-yl)porphyrin (H4TPP) (5)
To a refluxed propionic acid (100 mL) in a three necked flask, 4-formyl-1(H)-pyrazole (3, 4.8
S5
g, 0.050 mol) was added and stirred for 15 min. Then pyrrole (4, 3.5 mL, 0.050 mol) was
added dropwise to the reaction mixture for 30 min, then the solution was refluxed for 10 h in
darkness. After the reaction mixture was cooled to room temperature and stand overnight, the
crystalline product of 5 was collected by filtration and washed by acetone (1.30 g, 2.26 mmol,
18.1% yield). 1H NMR (300 MHz, DMSO) δ (ppm) 13.62 (s, 4H), 9.14 (s, 8H), 8.55 (s, 8H), 2.68 (s, 2H).
Synthesis of PCN-601
Ni(AcO)2·4H2O (800 mg), H4TPP (400 mg), Et3N (2 mL), and water (8 mL) in 80 mL of
DMF were ultrasonically dissolved in a 150 mL high pressure vessel. The mixture was heated
in 75 °C for 4 days. After cooling down to room temperature, reddish powder in colorless
solution was obtained (yield: ~96%). ICP: Ni (19.23%); EA: N (12.69%), C (34.91%), H
(4.79%).
Figure S1. FT-IR of H4TPP and PCN-601.
S6
Section 3: Scanning Electron Microscope (SEM) Image of PCN-601
Figure S2. Scanning electron microscope (SEM) image of PCN-601 sample.
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Section 4. Thermal Stability of PCN-601
Figure S3. Thermogravimetric analysis trace of as-made PCN-601 sample. The
decomposition temperature is around 300 °C.
S8
Section 5. Topological and Geometrical Analysis of PCN-601
Figure S4. Topological and geometrical analysis of the combination of different porphyrinic
ligands and Zr clusters.
When we consider the geometry details of our desired ligand to construct the hypothetic
structure, PCN-221 and PCN-228 are chosen as references, because they are also porphyrinic
MOFs with a ftw-a topology. But, in fact, the ligands in these topologically equivalent MOFs
are geometrically different. In PCN-221, coordination parts (carboxylate groups) are vertical
to porphyrin center (type A ligand), while in PCN-228, they are parallel (type B ligand).
Further analysis indicates both type A and B ligands are assigned as 4-connected nodes with
D4h symmetry. At the same time, [Zr6] in PCN-228 and [Zr8] (short for [Zr8O6(CO2)12]8+) in
PCN-221 can all be considered as 12-connected nodes with Oh symmetry. Intuitively, any
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combination of these two porphyrinic ligands and two Zr-SBUs are compatible to form ftw-a
networks. However, some of these topologically allowed combinations are geometrically
forbidden. As illustrated in the right part of Figure 2, after the two nodes in the ftw-a network
are replaced with porphyrin center and different Zr-SBUs, two structures with unconnected
fragments are obtained. In the front face of the unit cell with [Zr6], carboxylate groups are
parallel to porphyrin center. While in the structure with [Zr8], they are vertical. Obviously,
only combinations of [Zr6] and Type B ligand or [Zr8] and Type A ligand are sterically
allowed to form ftw-a networks. Owing to the geometrical similarity between [Ni8] and [Zr8],
we finally choose 5,10,15,20-tetra(1H-pyrazol-4-yl)porphyrin (H4TPP) as ligand in which the
four Pz groups are vertical to the porphyrin center.
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Section 6. Rietveld Refinement and Crystallographic Data of PCN-601
The Rietveld refinement of PCN-601 against PXRD data was performed using Topas V4.2.
Background was fitted with a 21st order Chebychev polynomial. The refinement was
conducted using a Thompson-Cox-Hastings pseudo-Voight peak profile function, followed by
refinement of unit cells and zero-shift. The rigid bodies were applied on the porphyrin ligand.
The unit cell parameters were determined directly from the high solution PXRD pattern by
TREOR.3 30 diffraction peaks (Table S1) were used to index and no peaks was not indexed.
The figure of merit (FOM) was 52.00. The diffraction intensities were extracted by Le Bail
fitting using JANA2006.4 We applied charge-flipping iterations on the extracted intensities
using the software Superflip.5 From the best electron density maps (Figure S5) with the
lowest R values, the space group (Pm-3m) and the position of Ni and O were determined.
Other framework atoms were located from the difference Fourier maps, the occupancy were
confirmed by ICP and EA. According to the data of ICP, Ni2+, which was located in the center
of TPP, is not full occupied, and its occupancy was 0.5911 after refinement. A few disordered
small organic molecules (DMF and/or Et3N) still remain in the pores even activated.
Molecular formula is defined as skeleton formula not including disordered H2O and a few
small organic molecules in pores.
Figure S5. Electron density maps of PCN-601.
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Table S1. The peaks for data indexing of PCN-601.
No.
Pos. [2θ.]
FWHM Left [2θ.]
Backgr.[counts]
d-spacing [Å]
Height [counts]
1
5.7388
0.1791
788.7
15.40036
16224.02
2
8.1041
0.1791
788.7
10.91005
8120.65
3
9.9378
0.2047
788.7
8.90075
11178.44
4
11.4455
0.1663
788.7
7.73139
2575.67
5
14.087
0.1535
788.7
6.28707
946.78
6
17.247
0.2047
713.41
5.14161
299.4
7
18.1667
0.1279
669.88
4.88334
1616.33
8
19.946
0.1535
585.68
4.45154
301.89
9
20.7877
0.2047
545.85
4.27317
154.58
10
23.0445
0.1535
446.97
3.85954
346.53
11
23.8098
0.2047
415.4
3.73719
1040.65
12
24.5267
0.2047
385.83
3.62955
439.35
13
26.5180
0.2558
303.69
3.36136
554.74
14
27.0799
0.2558
280.51
3.29287
134.29
15
28.3609
0.2047
251.08
3.14698
93.63
16
29.5122
0.2047
253.8
3.02678
440.73
17
31.7824
0.1535
259.14
2.81557
294.45
18
32.8989
0.2558
261.78
2.72253
296.12
19
33.3463
0.1791
262.83
2.68702
428.04
20
35.9165
0.2047
268.88
2.50041
311.98
21
37.8066
0.2558
273.34
2.37964
346.2
22
39.2020
0.3070
276.62
2.2981
177.8
23
41.3922
0.2047
281.78
2.18142
350.4
24
41.8385
0.2047
282.84
2.15917
354.6
25
44.2837
0.2558
288.60
2.04546
255.09
26
45.9338
0.2047
292.48
1.97575
434.47
27
46.372
0.2558
293.52
1.9581
382.69
28
47.9119
0.2558
297.14
1.8987
186.66
29
50.2099
0.3070
305.78
1.81706
104.71
30
55.2069
0.8187
213.05
1.66383
32.09
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Section 7. X-ray Absorption Spectroscopy (XAS) Analysis of PCN-601
XAS Measurement. The Ni K-edge XAS measurements were made in the transmission mode
at the beam-line 14W1 in Shanghai Synchrotron Radiation Facility (SSRF). The X-ray was
monochromatized by a double-crystal Si(111) monochromator, and the energy were
calibrated using a nickel metal foil for Ni K-edge.
Figure S6. Normalized Ni K-edge XANES spectroscopy of PCN-601.
This figure shows the normalized Ni K-edge X-ray absorption near edge spectroscopy
(XANES) of PCN-601. It can be seen that the intensity of pre-edge peak is quite weak in
contrast to the white line peak at around 8350 ev. This is suggesting that Ni atom should lie in
a symmetrical position such as octahedral or square-planar center.6 Considering N and O
atoms are almost indistinguishable in this case, the experimental result is consistent very well
with our crystallographically structural determination.
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Section 8. Powder X-Ray Diffraction for PCN-601 Sample
Figure S7. PXRD profiles of PCN-601.
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Section 9. N2 Adsorption/Desorption Isotherms for PCN-601 Sample
After the solvothermal reaction in the synthesis of PCN-601, the colorless mother
solution suggests the almost complete consumption of H4TPP. Therefore, the resulting
powder was just washed with DI water for several times to remove excess inorganic salt.
Then the sample was washed with acetone for 3 times. After being soaked in acetone for 12 h,
the sample was activated at 100 OC under vacuum for 12 h. Then, its N2 uptake was measured
at 77 K.
Figure S8. N2 adsorption/desorption isotherms of PCN-601 at 77 K.
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Figure S9. Plot of the linear region on the N2 isotherm of PCN-601 for the BET equation.
The calculated BET surface area is 1309 m2/g.
Figure S10. DFT pore size distribution for PCN-601 deducing from N2 adsorption isotherm
at 77 K.
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Section 10. Crystal Field Stabilization Energy Analysis
Figure S11. The d orbital splitting of Ni2+ in octahedral coordination sphere. Δ0,O is the crystal
field splitting parameter in OH- (or H2O) coordination sphere; Δ0,N is the crystal field splitting
parameter in pyrazolate coordination sphere
The crystal field stabilization energy of Ni2+ in OH- (or H2O) coordination sphere (CFSEO) and
the crystal field stabilization energy of Ni2+ in pyrazolate coordination sphere (CFSEN) can be
expressed as:
Therefore:
Since:
Therefore:
It suggests the pyrazolate coordinated Ni2+ is more thermodynamically stable.
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References
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