A Highly Stable Nanotubular MOF Rotator for Selective Adsorption of Benzene and Separation of Xylene Isomers

Transcription

1 Electronic Supplementary Information (ESI) A Highly Stable Nanotubular MOF Rotator for Selective Adsorption of Benzene and Separation of Xylene Isomers Wei Huang, Jun Jiang, Dayu Wu, * Jun Xu, Bing Xue and Alexander M. Kirillov Jiangsu Key Laboratory of Advanced Catalytic Materials and Technology, Advanced Catalysis & Green Manufacturing Collaborative Innovation Center, School of Petrochemical Engineering, Changzhou University, Changzhou, , China; Centro de Quimica Estrutural, Complexo I, Instituto Superior Tecnico, Universidade de Lisboa, Av. Rovisco Pais, , Lisbon, Portugal wudy@cczu.edu.cn

2 Materials and Measurements. Reagents and solvents employed were commercially available and used without purification. H 2 L ligand was prepared by palladium-catalyzed cross-coupling reactions. IR absorption spectra of Zn-MOF were recorded in the range of cm -1 on a Nicolet (Impact 410) spectrometer with KBr pellets. C, H and N analyses were carried out with a Perkin Elmer 2400Ⅱ elemental analyzer. Powder X-ray diffraction (PXRD) measurements were performed on a D/max 2500 PC X-ray diffractometer. The as-synthesized samples were characterized by thermogravimetric analysis (TGA) on a NETZSCH TG209F3 thermogravimetric analyzer. 1 H NMR experiments were performed on a Bruker DMX500 spectrometer using tetramethylsilane (TMS) as an internal standard. Vapor-phase static adsorption experiments were performed on Intelligent Gravimetric Analyser (Hiden Isochema Ltd, IGA-100B). Experimental Section. The ligand, biphenyl-3,5-dicarboxylic acid, was synthesized according to the revised literature method as following [1] : 5-bromo-m-xylene(38.85 mmol,7.19 g) and phenylboronic acid (46.65 mmol, 5.69 g) were placed in a 250 ml round-bottom flask. K 2 CO 3 (90.13 mmol, g) was dissolved in C 2 H 5 OH(45 ml)/toluene(90 ml)/h 2 O(45 ml) and then added to the reaction mixture, which was deaerated under N 2 for 30 min. Pd(PPh 3 ) 4 (1.125 g, 0.97 mmol) was added to the reaction mixture with stirring, and the mixture was refluxed for 24 hours under N 2. The resultant mixture was evaporated to dryness under vaccum, extracted with CH 2 Cl 2 and then dried over MgSO 4. The crude product was obtained by evaporating the solvent under reduced pressure. The residue was chromatographed on silica gel using hexanes as eluent to afford a colorless liquid 1 (Scheme S1) (yield: 6.03 g, 85.3% based on 5-bromo-m-xylene). KMnO 4 (36.05 g, mmol) was added in 4 portions to a suspension of the colorless liquid 1 (6.03 g, mmol) in H 2 O (180 ml) and pyridine (90 ml), and the mixture was refluxed for 3 days. After cooling to room temperature, the solid mixture was filtered and washed with water repeatedly. The insoluble solid was filtered off and the filtrate was acidified with HCl to ph ~2. The white solid was obtained and dried under vaccum to give H 2 L (yield: 6.45 g, 80.4% based on 1). 1 H NMR (400 MHz, DMSO-d 6,298 K) δ 8.46 (s, 1H), 8.34 (s, 2H), 7.72 (d, 2H), 7.52 (t, 2H), 7.43 (t, 1H). Br Pd[P(Ph) 3 ] 4 KMnO 4 K 2 CO 3 B(OH) 2 HOOC COOH 1 H 2 L Scheme S1. Synthesis of the H 2 L (biphenyl-3,5-dicarboxylic acid)

3 Synthesis of [Zn(µ 4 -L)] n (Zn-MOF): A mixture of H 2 O/CH 3 OH (v:v 2:1, 8 ml) containing Zn(NO 3 ) 2 6H 2 O (0.15 mmol), H 2 L (0.1 mmol) and NaOH (0.2 mmol) was placed into a Teflon lined stainless steel autoclave and heated to 140 o C for 3 days, followed by cooling to room temperature at a rate of 10 o C h -1. The mother liquor was decanted from the solid, which was then sonicated and washed with water. The colorless needle-shaped crystals of Zn-MOF were recovered by filtration and dried in air. Yield: 56% (based on H 2 L). IR data (selected bands, cm -1 ): 1650 (s), 1530 (s), 1456 (m), 1425 (s), 722 (m), 680 (m). Elemental analysis (%) calcd for ZnC 14 H 8 O 4 : C 54.03, H Found: C 55.02, H X-ray Crystallography. Crystallographic data of Zn-MOF were collected on a Bruker Apex DUO CCD diffractometer with graphite-monochromated Mo Kα radiation (λ = Å) using the ω-scan technique. The intensity data were integrated by using the SAINT program. [2] An empirical absorption correction was applied using the SADABS program. [3] The structures were solved by direct method and the nonhydrogen atoms were located from the trial structures and then refined anisotropically with SHELXTL using full-matrix least-squares procedures based on F 2 values. [4] The positions of the non-hydrogen atoms were refined with anisotropic displacement factors. The hydrogen atoms were positioned geometrically by using a riding model. The data were collected at different temperature in cooling mode, i.e. 296 K, 250K, 180K and 120K to analyze the dynamics of disordered benzene ring. Gas adsorption measurements Low-pressure gas adsorption measurements were carried out on an ASAP (accelerated surface area and porosimetry) 2020 system. Before gas adsorption measurement, the sample was dried using the outgas function of the surface area analyzer for 12 h at 400 K. Adsorption experiments (liquid and gas phase) Liquid phase. Zn-MOF was immersed in benzene, toluene, ethylbenzene, o-, m-, or p-xylene liquid, respectively, for a week at room temperature. These guest molecules were extracted by CDCl 3 and the extract was then subjected to GC and 1 H NMR analysis. Vapor phase. Zn-MOF was exposed to benzene, toluene, ethylbenzene, o-, m-, or p-xylene vapors, respectively, for a week at room temperature. These guest molecules was extracted by CDCl 3 and the extract was then subjected to GC and 1 H NMR analysis. GC analysis. The CDCl 3 extracts from Zn-MOF subjected to prior adsorption from the equimolar mixture of three xylene isomers were analyzed by gas chromatography (GC-2010, SHIMADZU) fitted with an FFAP capillary column (60 m) and a flame ionization detector.

4 References: [1] Park, T.-H.; Cychosz, K. A.; Wong-Foy, A. G.; Dailly, A.; Matzger. A. J. Chem. Commun., 2011, 47, [2] SMART & SAINT Software Reference Manuals, version 6.45; Bruker Analytical X-ray Systems, Inc.: Madison, WI, [3] Sheldrick, G. M. SADABS: Software for Empirical Absorption Correction, version 2.05; University of Göttingen: Göttingen, Germany, [4] Sheldrick, G. M. SHELXL97: Program for Crystal Structure Refinement; University of Göttingen: Göttingen, Germany, 1997.

5 Fig. S1. IR spectrum of Zn-MOF at room temperature.

6 Fig. S2 Topological representation of an underlying binodal 4,4-connected 3D net with the ptr topology. Further details: views along c axes; 4-connected Zn nodes (cyan balls), centroids of 4-connected µ 4 -L nodes (gray).

7 50 (a) 30 (b) Uptake(cm 3 /g, STP) Uptake(cm 3 /g, STP) P / P P / P 0 (c) (d) pore width (nm) Fig. S3 (a) Gas adsorption isotherms of Zn-MOF for Ar (87 K, blue), N 2 (77 K, black). (b) Gas adsorption isotherms of Zn-MOF for CO 2 at 196 K. Filled shapes: adsorption, open shapes: desorption. (c) The BET plot for Zn-MOF based on N 2 adsorption in the chosen range (P/P 0 = ). (d) The pore size distribution calculated from the adsorption of N 2 at 77 K data.

8 after immersion in water before immersion in water theta Fig. S4. PXRD plots of Zn-MOF before and after immersion in water for 7 days.

9 after immersion before immersion theta Fig. S5. PXRD plots of Zn-MOF before and after immersion in CHCl 3 for 7 days.

10 Fig. S6. 1 H NMR spectrum recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of benzene. Note: The inner standard compound, 1,3,5-tri-tert-butylbenzene, was introduced in the solution. Fig. S7. 1 H NMR spectrum recorded for the CDCl 3 extract from Zn-MOF obtained by exposure to gas phase consisting of benzene.

11 Fig. S8. 1 H NMR spectrum recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of p-xylene. Note: The inner standard compound, 1,3,5-tri-tert-butylbenzene, was introduced in the solution.

12 Fig. S9. 1 H NMR spectrum recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of m-xylene. Note: The inner standard compound, 1,3,5-tri-tert-butylbenzene, was introduced in the solution.

13 Fig.S10. 1 H NMR spectrum recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of toluene.

14 Fig.S11. 1 H NMR spectrum recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of ethylbenzene.

15 Fig. S12. 1 H NMR spectrum (CDCl 3 ) recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of benzene/m-xylene(v:v,1:1). Note: The inner standard compound, 1,3,5-tri-tert-butylbenzene, was introduced in the solution.

16 Fig. S13. 1 H NMR spectrum (CDCl 3 ) recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of benzene/o-xylene(v:v,1:1). Note: The inner standard compound, 1,3,5-tri-tert-butylbenzene, was introduced in the solution.

17 Fig. S14. 1 H NMR spectrum (CDCl 3 ) recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of benzene/p-xylene(v:v,1:1). Note: The inner standard compound, 1,3,5-tri-tert-butylbenzene, was introduced in the solution.

18 Fig. S15. 1 H NMR spectrum (CDCl 3 ) recorded for the CDCl 3 extract from Zn-MOF obtained from liquid phase consisting of benzene/tolune (v:v,1:1). Note: The inner standard compound, 1,3,5-tri-tert-butylbenzene, was introduced in the solution.

19 Time (min) Summary of the main peaks Retention Peak Peak height(μv) time(min) area(μv*s) Component p-xylene m-xylene o-xylene Fig. S16. Gas chromatography of the CDCl 3 extracts from Zn-MOF subjected to prior adsorption from the equimolar mixture of three xylene isomers.

20 Fig.S17. 1 H NMR spectrum recorded for the CDCl 3 extract from Zn-MOF which is subject to prior adsorption of p-xylene and the subsequent extraction in CHCl 3.

21 Intensity(a.u) after (degree) before Fig. S18. PXRD plots of Zn-MOF before and after adsorption in liquid phase containing o-, p-, and m-xylene (1:1:1).

22 o-xylene m-xylene p-xylene 2.0 Q (mg/g) Pressure (mbar) Fig. S19. Static adsorption curves of xylene isomers by Zn-MOF at room temperature.