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1 A partially interpenetrated metal organic framework for selective hysteretic sorption of carbon dioxide Sihai Yang, 1 * Xiang Lin, 1 William Lewis, 1 Mikhail Suyetin, 1 Elena Bichoutskaia, 1 Mikhail Suyetin, 1 Julia E. Parker, 2 Chiu C. Tang, 2 David R. Allan, 2 Pierre J. Rizkallah, 3 Peter Hubberstey, 1 Neil R. Champness, 1 K. Mark Thomas, 4 * Alexander J. Blake, 1 * and Martin Schröder 1 * [ 1 ] School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (UK) Fax: M.Schroder@nottingham.ac.uk; Neil.Champness@nottingham.ac.uk [ 2 ] Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (UK) [ 3 ] STFC Daresbury Laboratory, Warrington, WA4 4AD (UK) [ 4 ] Northern Carbon Research Laboratories, Sir Joseph Swan Institute for Energy Research and School of Chemical Engineering and Advanced Materials, University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7RU (UK) Mark.Thomas@newcastle.ac.uk NATURE MATERIALS 1

2 1. Experimental section 1.1 Materials and Measurements All reagents and solvents were used as received from commercial suppliers without further purification. Analyses for C, H and N were carried out on a CE-440 elemental analyzer (EAI Company). Thermal gravimetric analyses (TGA) were performed under N 2 flow (100 ml/min) with a heating rate of 2 C/min using a TA SDT-600 thermogravimetric analyzer (TA Company). IR spectra were recorded using a Nicolet Avatar 360 FT-IR spectrophotometer. 1 H NMR spectra were recorded on a Bruker DPX300 NMR spectrometer with 5mm dual 1 H/ 13 C probe. Mass spectra were recorded on an LC-TOF spectrometer (Bruker Company) in ESI model. High resolution in situ synchrotron X-ray powder diffraction (PXRD) data were collected at Beamline I11 of Diamond Light Source by using multi-analysing crystal-detectors (MACs) and monochromated radiation [λ = (2) Å]. All the measurements were carried out in capillary mode and the temperature controlled by an Oxford Cryosystems open-flow nitrogen gas cryostat. Le Bail profile fitting was performed using Topas3 software. 1.2 X-ray single crystal diffraction X-ray diffraction data on five different sets of single crystals from five different batches of NOTT-202 were collected using five different radiation source: at 120(2) K on Station 9.8 of the Synchrotron Radiation Source at STFC Daresbury Laboratory; at 150(2) K on Bruker SMART1000 and Bruker SMART APEX CCD area detector diffractometers using graphite-monochromated Mo-Kα radiation from a sealed X-ray tube source; at 100(2) K on an Oxford Diffraction SuperNova CCD area detector diffractometer using graphite-monochromated Cu-Kα 1 radiation from a microfocus X-ray source; and at 200(2) K on Beamline I19 of the Diamond Light Source. All five datasets result in the same structural model for NOTT-202 as the one reported, and the refinement results are summarised in the Table S1. The structure was solved by direct methods and developed by difference Fourier techniques using the SHELXTL software package. 1 The hydrogen atoms on the ligands were placed geometrically and refined using a riding model. Geometric restraints were applied to the phenyl ring and the carboxylate group of the organic ligand. The unit cell volume includes a large region of disordered solvents and [(CH 3 ) 2 NH 2 ] + counter-cations, which could not be modelled as discrete atomic sites. We employed PLATON/SQUEEZE 2 to calculate the contribution to the 2 NATURE MATERIALS

3 SUPPLEMENTARY INFORMATION diffraction from the solvent region and thereby produced a set of solvent-free diffraction intensities. The final formula was calculated from the SQUEEZE 2 results combined with elemental analysis and TGA data: the contents of the solvent/cation region are therefore represented in the unit cell contents but were not included in the refinement model. Datasets 2, 3, 4, and 5 suffered from unexplained systematic errors, such as difference map minima of ~ e Å -3, and accordingly all numerical values and conclusions in this paper are based on dataset 1. It is worth noting that NOTT-202 crystallizes in the chiral space group F222, but the Flack parameter of each of five different crystals is refined to be ~0.50(5), indicating racemic twinning in the sample (Table S1). The occupancy ratio between net A and net B in NOTT-202 are consistent with results from five different batches of studies as shown in Fig. S1, confirming the partially-interpenetrated framework structure Occupancy % Network A Network B Dataset Figure S1. Comparison of the occupancies of networks A and B in five different datasets from different single crystals of NOTT-202. NATURE MATERIALS 3

4 Diffractometer Table S1. Summary of X-ray single crystal diffraction refinement results for five different batches of crystals of NOTT-202. Dataset 1 Dataset 2 Dataset 3 Dataset 4 Dataset 5 SMART APEXII CCD on Daresbury SRS Station 9.8 Bruker SMART APEX Bruker SMART1000 Oxford Diffraction SuperNova diffractometer Crystal Logic goniometer with Rigaku Saturn724+ CCD detector on Diamond Light Source Beamline I19 Wavelength (Å) / synchrotron /synchrotron Temperature (K) 120(2) 150(2) 150(2) 100(2) 200(2) Occupancy of network A Occupancy of 0.748(6) 0.788(6) 0.780(6) 0.744(6) 0.738(6) network B Flack parameter 0.56(6) 0.42(6) 0.47(5) 0.45(2) 0.49(5) R int R 1 [F > 4σ(F)] wr 2 [all F 2 ] GOF Difference map -1.39, , , , , extrema (e Å -3 ) 4 NATURE MATERIALS

5 SUPPLEMENTARY INFORMATION Single crystals of NOTT-202 were desolvated by degassing at ~1x10-4 bar for 30 min to give crystals of NOTT-202a, which were protected in Fomblin oil for transfer to the diffractometer. X-ray diffraction data on one single crystal of NOTT-202a were collected at 120(2), 150(2), 180(2), 200(2), 220(2), and 260(2) K on Beamline I19, Diamond Light Source. At temperatures above than 260 K, decomposition and loss of Bragg diffraction peaks were observed, so it was not possible to acquire single crystal data at ambient temperatures. The structures were solved by direct methods and developed by difference Fourier techniques using the SHELXTL software package. 1 The hydrogen atoms on the ligands were placed geometrically and refined using a riding model. Geometric restraints were applied to the dimethylamine cations [(CH 3 ) 2 NH 2 ] +. Although the single crystal of NOTT-202a was desolvated before data collection, the unit cell volume includes some disordered residual solvents, which could not be modelled as discrete atomic sites. We employed PLATON/SQUEEZE 2 to calculate the contribution to the diffraction from the solvent region and thereby produced a set of solvent-free diffraction intensities. The refinement results of datasets collected at six different temperatures are summarised in Table S2. The unit cell volume was found to expand with increasing temperature, this expansion being much larger than that due to expected thermal effects, thus confirming the framework flexibility. NATURE MATERIALS 5

6 Table S2. Summary of single crystal structural data for NOTT-202a. NOTT-202a_120K NOTT-202a_150K NOTT-202a_180K NOTT-202a_200K NOTT-202a_220K NOTT-202a_260K Formula C 73.5 H 52.5 In 1.75 N 1.75 O 14 C 73.5 H 52.5 In 1.75 N 1.75 O 14 C 73.5 H 52.5 In 1.75 N 1.75 O 14 C 73.5 H 52.5 In 1.75 N 1.75 O 14 C 73.5 H 52.5 In 1.75 N 1.75 O 14 C 73.5 H 52.5 In 1.75 N 1.75 O 14 Formula weight Wavelength (Å) /synchrotron /synchrotron /synchrotron /synchrotron /synchrotron /synchrotron Temperature (K) Space group C2/c C2/c C2/c C2/c C2/c C2/c a (Å) (7) (6) (3) (3) (4) (7) b (Å) (10) (8) (5) (5) (6) (10) c (Å) (10) (8) (5) (5) (6) (10) β ( o ) (6) (4) (2) (3) (4) (6) V (Å 3 ) 14580(9) 14680(7) 14789(4) 14838(4) 14995(6) 15140(9) Z D calc (g/cm 3 ) µ F(000) Diffraction number 12789/ / / / / /32807 Total/unique R int R 1 [F > 4σ(F)] 0.048/ / / / / /0.207 /wr 2 [all F 2 ] GOF Difference map extrema (e Å -3 ) CCDC number NATURE MATERIALS

7 SUPPLEMENTARY INFORMATION 1.3 Gas adsorption isotherms. H 2 and D 2 isotherms were recorded at 77 K (by liquid nitrogen) or 87 K (by liquid argon) on an IGA-003 system (Hiden Isochema, Warrington, UK) at the University of Nottingham under ultra high vacuum in a clean system with a diaphragm and turbo pumping system. Ultra-pure plus grade ( %) H 2 and high-purity (99.95%) D 2 were purchased from BOC and purified further using calcium aluminosilicate and activated carbon adsorbents to remove trace amounts of water and other impurities before introduction into the IGA system. CO 2, CH 4, N 2, O 2, and Ar isotherms were also recorded at 195 K (acetone-dry ice cold bath), K (cryofurnace from Hiden Isochema with temperature stability within 0.2 K), 258 K (salt-ice cold bath), and K (by temperature-programmed water bath from Hiden Company) on an IGA-003 system at the University of Nottingham under ultra high vacuum with diaphragm and turbo pumping system. All gases used were ultra-pure research grade ( %) and were purchased from BOC. The density of desolvated sample used in buoyancy corrections was 1.75 g cm -3 for NOTT-202a. This was estimated from the crystallographic density of the desolvated sample and derived from the PLATON/SQUEEZE 2 results. The density of liquid H 2 at its boiling point ( g cm -3 ) was used for the adsorbate buoyancy correction. N 2 and Ar adsorption data were recorded at 77 K (by liquid nitrogen) or 87 K (by liquid argon) on a Autosorb-1c instrument at the University of Nottingham under ultra high vacuum in a clean system with a diaphragm and turbo pumping system. Ultra-pure research grade ( %) N 2 and high-purity (99.999%) Ar were purchased from BOC. The BET surface areas and pore size distribution were calculated by using the software (version 1.60) integrated in the instrument. NATURE MATERIALS 7

8 2. Full investigation of interpenetration behaviour in this MOF family. To gain further insight into the control of interpenetration and the effect of partial interpenetration on structural porosity, a series of experiments has been carried out to determine systematically the degrees of interpenetration observed in NOTT-202a as a function of synthetic conditions. Nineteen attempts (four sets of experiments) to control the partial interpenetration of NOTT-202 were performed via systematic variation of metal/ligand ratio (set 1), concentration (set 2), solvent (set 3) or temperature (set 4). The detailed synthetic conditions of these nineteen experiments are listed in Table S3. Single crystals of NOTT-202 can only be successfully isolated from nine experiments as shown in Table S3, and two of these (numbers 2 and 15) represent optimised conditions with good yield and purity of NOTT-202 as reported in the manuscript. Additional X-ray diffraction data on seven different sets of single crystals from seven different batches (numbers 1, 4, 14, 16, 17, 18 and 19) of NOTT-202 were collected at 90(2) K on an Oxford Diffraction SuperNova CCD area detector diffractometer using graphite-monochromated Cu-Kα 1 radiation from a microfocus X-ray source. All seven datasets result in the same structural model for NOTT-202 as the one reported herein (i.e., 1.75 partial interpenetration), and the refinement results are summarised in Table S4. In general, the occupancy of ~0.75 for the secondary network is both robust and constant for all samples of NOTT-202 prepared under different conditions as suggested by all twelve independent crystallographic determinations (Table S1 and S4). Interestingly, the synthesis at higher temperatures ( o C) afforded a secondary phase (denoted as NOTT-214) in very low yield (below ~5%,Table S3). The crystal structure of NOTT-214, synthesised and isolated from batch 17, was successfully determined by single crystal diffraction on Beamline I19 at Diamond Light Source. Additional X-ray diffraction data on three different sets of single crystals from three different batches (number 16, 18 and 19) of NOTT-214 were also collected at 90(2) K on beamline I19 at Diamond light Source or on an Oxford Diffraction SuperNova CCD area detector diffractometer using graphite-monochromated Cu-Kα 1 radiation from a microfocus X-ray source. All four datasets result in the same structural model for NOTT-214 as the one reported herein, and the refinement results are summarised in the Table S5. All numerical values and conclusions in this paper are based on dataset of batch 17. NOTT-214 has an impressive 4-fold interpenetrated structure with four identical and independent networks. Each In(III) ion links to four different ligands, forming metal- and ligand-based tetrahedral nodes. 8 NATURE MATERIALS

9 SUPPLEMENTARY INFORMATION In NOTT-214 each network [InL] - is chemically-equivalent with the same 4,4-connected diamond topology as in NOTT-202. However, NOTT-214 has a more open pore geometry (Fig. S9) leading to interpenetration of three further networks. This observation may indicate that the formation of high-level interpenetration needs to overcome a high energy barrier, reflecting the high temperature required for formation of NOTT-214. The 4-fold interpenetration in NOTT-214 significantly reduces its structural porosity, and the available pore voids were estimated by using PLATON/SOLV to be less than 4%. Thus, NOTT-214 can be viewed as non-porous material, and therefore is not promising for high capacity gas storage or selective gas adsorption. Comparison of these two crystal structures (NOTT-202 and NOTT-214) indicates that the complex partial interpenetration in NOTT-202 helps to generate a large proportion of structural voids and vacancies, which play important roles in the observed high porosity and the resultant high gas uptake capacities. NATURE MATERIALS 9

10 1 st set 2 nd set 3 rd set 4 th set Table S3. Summary of the various experimental conditions for the synthesis of MOFs in this study. Batch M: L ratio Solvents Concentration Temp. ( o C) Results Yield Interpenetration 1 1.5:1.0 DMF/CH 3 CN x1.0 (1.5ml) 90 Pure NOTT-202 (single crystals are not as good as batch 2) 50% 0.708(8) 2* 1.0:1.0 DMF/CH 3 CN x1.0 (1.5ml) 90 Pure NOTT-202 (best conditions) 70% ~0.75 as reported 3 1.0:1.5 DMF/CH 3 CN x1.0 (1.5ml) 90 NOTT-202 and unknown phase (poorly crystalline) ~20% n.a :1.0 DMF/CH 3 CN x0.5 (0.75ml) 90 Pure NOTT-202(single crystals are not as good as batch 2) 60% 0.762(8) 5 1.0:1.0 DMF/CH 3 CN x2.0 (3.0ml) 90 Amorphous phase n.a. n.a :1.0 DMF/CH 3 CN x4.0 (6.0ml) 90 No precipitation n.a. n.a :1.0 CH 3 CN x1.0 (1.5ml) 90 Amorphous phase (ligand can t be dissolved without DMF) n.a. n.a :1.0 DMF/CH 3 OH x1.0 (1.5ml) 90 No precipitation n.a. n.a :1.0 DMF/CH 3 CH 2 OH x1.0 (1.5ml) 90 Amorphous phase n.a. n.a :1.0 DMF/1,4-dioxane x1.0 (1.5ml) 90 Amorphous phase n.a. n.a :1.0 DMF/THF x1.0 (1.5ml) 90 Amorphous phase n.a. n.a :1.0 DMF/CH 3 CN x1.0 (1.5ml) 60 No precipitation n.a. n.a :1.0 DMF/CH 3 CN x1.0 (1.5ml) 70 No precipitation n.a. n.a :1.0 DMF/CH 3 CN x1.0 (1.5ml) 80 Pure NOTT % 0.734(6) 15* 1.0:1.0 DMF/CH 3 CN x1.0 (1.5ml) 90 Pure NOTT-202 (best conditions, same as batch 2) 70% ~0.75 as reported :1.0 DMF/CH 3 CN x1.0 (1.5ml) 100 NOTT-202 (not pure, mixed with new phase NOTT-214) ~55% 0.696(8) NOTT-214 (not pure, mixed with NOTT-202) ~2% 4-fold :1.0 DMF/CH 3 CN x1.0 (1.5ml) 110 NOTT-202 (not pure, mixed with new phase NOTT-214) ~50% 0.728(6) NOTT-214 (not pure, mixed with NOTT-202) ~5% 4-fold :1.0 DMF/CH 3 CN x1.0 (1.5ml) 120 NOTT-202 (not pure, mixed with new phase NOTT-214) ~50% 0.702(8) NOTT-214 (not pure, mixed with NOTT-202) ~2% 4-fold 19# 1.0:1.0 DMF/CH 3 CN x1.0 (1.5ml) 130 NOTT-202 (not pure, mixed with new phase NOTT-214) ~20% 0.706(10) NOTT-214 (not pure, mixed with NOTT-202) < 1% 4-fold *Optimised conditions as reported in the manuscript. # DMF starts to decompose at this temperature, so no higher temperature was tried. Crystal structures of NOTT-214 from batches have been all fully analysed and the best resulting structure has been deposited with CCDC (CCDC number ). 10 NATURE MATERIALS

11 SUPPLEMENTARY INFORMATION Table S4. Summary of X-ray single crystal diffraction refinement results for additional seven different batches of crystals of NOTT-202 synthesised by using various condition listed in Table S3. Batch number in Table S Diffractometer Oxford Diffraction SuperNova diffractometer Wavelength (Å) Temperature (K) 90(2) 90(2) 90(2) 90(2) 90(2) 90(2) 90(2) Occupancy of network A Occupancy of network B 0.708(8) 0.762(8) 0.734(6) 0.696(8) 0.728(6) 0.702(8) 0.706(10) Flack parameter 0.44(2) 0.55(2) 0.59(2) 0.50(2) 0.57(2) 0.50(2) 0.57(2) R int R 1 [F > 4σ(F)] wr 2 [all F 2 ] GOF Difference map extrema (e Å -3 ) -2.62, , , , , , , NATURE MATERIALS 11

12 Table S5. Summary of X-ray single crystal diffraction refinement results for four different batches of crystals of NOTT-214 synthesised by using various condition listed in Table S3. Batch number in Table S Diffractometer Crystal Logic goniometer with Rigaku Saturn724+ CCD detector on Diamond Light Source Beamline I19 Oxford Diffraction SuperNova diffractometer Wavelength (Å) Temperature (K) 90(2) 90(2) 90(2) 90(2) Interpenetration 4-fold 4-fold 4-fold 4-fold R int R 1 [F > 4σ(F)] wr 2 [all F 2 ] GOF Difference map extrema (e Å -3 ) -0.51, , , , NATURE MATERIALS

13 SUPPLEMENTARY INFORMATION 3. Additional views of the X-ray crystal structures for NOTT-202, NOTT-202a and NOTT-214. Figure S2. Views of the structure of NOTT-202: (a) the co-ordination environment of the [In(O 2 CR) 4 ] node and ligands L 4- ; (b) a view of the (4,4)-connected diamondoid network. Figure S3. Views of the framework structure and topology of NOTT-202 (indium, green; oxygen, red; carbon, grey; hydrogen, white; cavity of In 4 L 6 : purple; cavity of In 6 L 4 : golden). (a) In 4 L 6 adamantoid cage (b) In 6 L 4 adamantoid cage; (c) diamondoid topology network. Indeed, network A is composed of two simplified adamantoid cages of composition [In 4 (L) 6 ] and [In 6 (L) 4 ] with the cations and free solvent molecules within the network pores being highly disordered. Both cages have T d symmetry and similar spherical cavities of approximate size Å, and are alternately linked over three dimensions. The topological connection of network A results in a large accessible void and a micropore diameter of up to 1.5 nm. NATURE MATERIALS 13

14 Figure S4. Space-filling views of NOTT-202: (a) along [101] and (b) along [010]. Network A is shown in blue and network B in grey. a b Figure S5. (a) View of interwoven network B in NOTT-202 along the crystallographic a-axis; (b) view of interwoven disordered networks B1 (pink) and B2 (blue) in network B of NOTT-202. Discussion and rationale for the observation of partial interpenetration in NOTT-202. The dominant net A is fully occupied. The secondary net B is only partially-occupied with an overall occupancy of This partially-occupied net B consists of two disordered, symmetry-related sub-nets B1 and B2 with occupancy for each. Net B1 and net B2 are present in different orientations and will clash with each other, so either a B1 net or a B2 net will be present in any region of the crystal, i.e. the only 14 NATURE MATERIALS

15 SUPPLEMENTARY INFORMATION allowed connections are of type B1-B1 or type B2-B2, while the B1-B2 linkage is forbidden because it leads to ligand components overlapping and steric clashes. There are two possible modes of net connections which could lead to the formation of a fully-occupied second net B: (1) Net B consists exclusively of either B1-B1 or B2-B2. Given the symmetry adopted by net A net, a unique net B would have to occupy a single position rather than two symmetry-related ones and the resultant flattening, even if geometrically feasible, would mean that it would not fit inside net A, so the molecular geometry and matching the repeat of net A essentially requires the presence of both nets B1 and B2. Our experimental data are clear that the crystal contains both B1 and B2 building blocks. (2) Net B consists of a 1:1 ratio of B1-B1 and B2-B2. There cannot be a 0.5 occupancy for each of B1 and B2 units since that would require the spaces between B1 and B2 nets to be filled with metal-ligand connections. This is not possible since bring B 1 close to B 2 causes steric clashes between these two components: thus the spaces B1 between B2 nets must be void and vacant in the desolvated material (Fig. S5b). The occupancy of 0.75 for net B can thus be traced to the presence of alternative blocks of B1 or B2 nets, because every time a B1-B1 or a B2-B2 linkage is broken, a number of molecules will be missing, generating vacancies, voids, defects and/or slits between blocks of B1 and B2 nets. Assuming that net B consists of discrete fragments of both B1 and B2, this model is entirely reasonable. We suggest that nets B1 and B2 are initiated at random within net A leading to these having the same occupancy of 0.375, with a total occupancy of 0.75 for the combined net B. a b Figure S6. Views of the structure of NOTT-202a: (a) the co-ordination environment of the [In(O 2 CR) 4 ] node and ligands L 4- and dimethylamine cation [C 4 H 12 N 2 ] 2+ (the O H N hydrogen bonds are highlighted in cyan: Indium: green; oxygen: red; carbon: grey; hydrogen: white); (b) view of the (4,4)-connected diamondoid network. NATURE MATERIALS 15

16 a b Figure S7. Space-filling views of NOTT-202a: (a) along [100] and (b) along [001]. One of the interpenetrating networks is shown in blue and the other in grey. a b 16 NATURE MATERIALS

17 SUPPLEMENTARY INFORMATION c d Figure S8. Views of X-ray crystal structure of NOTT-214: (a) along [100], (b) along [010], and (c) along [001]; (d) view of the crystal structure of NOTT-214 along [001] with the organic cations in the pore channels shown. The four interpenetrated networks are shown in blue, red, yellow and green. a b c Figure S9. Comparison of the crystal structure for the single network in NOTT-202(a), NOTT-202a (b) and NOTT-214 (c) (Indium: green; oxygen: red; carbon: black; hydrogen: dark grey). Comparison of (a) and (c) suggests that the pores in single network of NOTT-214 are wider than those in NOTT-202, thereby allowing the formation of three additional networks. This Figure illustrates the structural differences between NOTT-202 and NOTT-214 with the latter having a wider pore geometry. NATURE MATERIALS 17

18 4. TGA plots for NOTT-202. The unco-ordinated solvent molecules (DMF and H 2 O) in NOTT-202 can be readily exchanged for acetone and/or removed by heating at 180 C under a flow of N 2 or under vacuum as confirmed by TGA (Fig. S8). TGA shows that the as-synthesised sample NOTT-202 loses solvent slowly between 30 and 200 C, with a plateau observed from C indicating no further weight loss to give NOTT-202a. Above 380 C NOTT-202a decomposes rapidly. The weight loss of 45.7% from NOTT-202 between 20 and 180 C corresponds to a loss of 12 DMF and 10 water molecules per 1.75 indium (calc wt%) Weight wt% Temperature o C Figure S10. TGA plot for NOTT NATURE MATERIALS

19 SUPPLEMENTARY INFORMATION 5. Powder synchrotron X-Ray diffraction The powder sample of NOTT-202 was dried and ground for 5 min before loading into a capillary tube. Grinding provides a uniform and small (~20 micron) particle size essential for obtaining high-resolution X-ray patterns. During the grinding process, some of the solvent content was lost from the pores, and the framework starts to convert to its desolvated form NOTT-202a. Thus, all the PXRD patterns presented in this study correspond to the desolvated form, NOTT-202a. The poor crystallinity after desolvation and the complexity of the framework material, meant that despite patterns being collected using synchrotron radiation at Diamond Light Source, the data quality is not sufficient to allow the use of Rietveld refinement to locate the CO 2 molecules in the pore. Thus, the unit cell parameters at different CO 2 loadings have been refined by Le Bail method, which offers valuable information on changes to the framework structure. We also sought to probe the effect of changes in temperature on the PXRD of NOTT-202a in the absence of CO 2 to gauge the degree of flexibility in this material. Thermal expansion normally shifts peak positions in the PXRD pattern without significantly changing their intensities. PXRD data for NOTT-202a were collected from 100 K to 300 K (Fig. S15) and the lattice parameters were observed to change with significant shifts in peak positions and intensity changes. The expansion of the lattice parameters are anisotropic with Δa/a = -3.90%, Δb/b =3.49% Δc/c = 5.81% and Δβ/β = -4.76%, calculated from the 100 K and 300 K data, and giving a total cell volume increase of 6.35% (Table S5). Thus, the framework has the flexibility to tilt (Δβ), bend inward (Δa) and outward (Δb and Δc). In addition, when the data (Tables S6) are compared with the lattice parameters of NOTT-300 Al-MOF (Fig. S16, Table S7), the thermal expansion in this rigid structure shows a change in volume of < 1% volume with Δa/a = 0.37%, Δc/c =0.14%. Thus, the cell volume expansion of NOTT-202a is considerably larger (6.35%) than due to simple thermal effects consistent with flexible framework structure. Interestingly, NOTT-202a exhibits similar pressure-induced flexibility with Δa/a = -1.41%, Δb/b =1.25%, Δc/c = 1.95% and Δβ/β = -1.81% as calculated from the 0 and 1000 mbar CO 2 adsorption data at 195 K (Table S8) producing a total volume change of +1.97%. This expansion is thus related to the flexibility of the framework to adsorb CO 2 molecules into the lattice. NATURE MATERIALS 19

20 Simulation Experiment Intensity θ Figure S11. Comparison of simulated and experimental PXRD patterns for NOTT-202a at 195 K. This comparison confirms the purity of bulk sample of NOTT-202a. Small but noticeable peak shifts are attributed to the unit cell difference between the single crystal sample and bulk material, which is confirmed by Le Bail fitting (Fig. S10). 10,000 hkl_phase 0.00 % 9,500 9,000 8,500 8,000 7,500 7,000 6,500 6,000 5,500 5,000 4,500 Counts 4,000 3,500 3,000 2,500 2,000 1,500 1, ,000-1,500-2,000-2,500-3, Th Degrees Figure S12. Le Bail fitting results for experimental PXRD pattern of NOTT-202a: a = (22), b = (30), c = (95) Å, β = (9) o, V = (3)Å 3. Fitting agreement factor R wp = 6.30%. 20 NATURE MATERIALS

21 SUPPLEMENTARY INFORMATION Sample synthesised in DMF Acetone-exchanged sample Intensity θ Figure S13. Comparison of PXRD patterns for DMF as-synthesised sample NOTT-202 and acetone-exchanged sample NOTT-202 at 195 K. Le Bail fitting agreement factors for sample synthesised in DMF: a = (22), b = (30), c = (95) Å, β = (9) o, V = (3)Å 3, Rwp = 6.30%; for acetone-exchanged sample: a = (43) Å, b = (60) Å, c = (62) Å, β = (19) o, V = (6) Å 3, R wp = 6.00%. This comparison confirms that there is no structural phase change during the acetone exchange process. bare material in contact with moisture Intensity θ Figure S14. PXRD pattern of sample of NOTT-202a in contact with moisture. The activated sample of NOTT-202a is stable in dry air or under vacuum and the framework remains intact; NATURE MATERIALS 21

22 however, once in contact with moisture, the activated framework collapses rapidly. This is somewhat expected and reasonable, because the partial interpenetration will inevitably generate vacant indium sites which can potentially react with the water vapour. However, the temperature range in which the behaviour (selective hysteretic sorption of CO 2 ) is seen is below the triple point (216.7 K) of CO 2, and the water vapour pressure is equal to zero at these conditions. Thus, the competitive adsorption of water will not affect the observed carbon capture property of NOTT-202a. 100 K 220 K 260 K 300 K 100 K 220 K 260 K 300 K Intensity Intensity θ θ Figure S15. Variable temperature PXRD data for NOTT-202a collected at 100, 220, 260 and 300 K. The detailed pattern between 5-10 degrees is shown on the right hand side. Table S6. Summary of Le Bail refinement results and unit cell parameters for NOTT-202a. a (Å) b (Å) c (Å) β ( ) V (Å 3 ) R wp (%) Unit cell change (%) 100 K (16) (23) (21) (72) (21) K (94) (13) (13) (41) (12) K (69) (94) (10) (32) (95) K (69) (91) (98) (30) (93) NATURE MATERIALS

23 SUPPLEMENTARY INFORMATION 100 K 220 K 260 K 300 K 100 K 220 K 260 K 300 K Intensity Intensity θ Figure S16. Variable temperature PXRD data for MOF material NOTT-300 collected at 100, 220, 260 and 300 K. The details at degree are enlarged on the right hand side. 2θ Table S7. Summary of Le Bail refinement results and unit cell parameters for NOTT-300. a, b (Å) c (Å) V (Å 3 ) R wp (%) Unit cell change (%) 100 K (30) (35) (13) K (30) (34) (13) K (30) (35) (13) K (30) (36) (13) mbar ads 824 mbar ads 67 mbar ads 928 mbar ads 208 mbar ads 1000 mbar ads/des 434 mbar ads 440 mbar des 534 mbar ads 202 mbar des 707 mbar ads 60 mbar des Intensity θ Figure S17. Wide-angle in situ PXRD patterns for NOTT-202a at different CO 2 adsorption/desorption loadings at 195 K. Shifts in peak positions are observed upon different CO 2 loadings, indicating changes of unit cell parameters, but no structural phase change has been observed and the crystallographic symmetry is retained. NATURE MATERIALS 23

24 Table S8. Summary of Le Bail fitting results for unit cell parameters for NOTT-202a at 195 K obtained by in situ powder X-ray diffraction CO 2 Pressure a (Å) b (Å) c (Å) β ( o ) v (Å 3 ) R wp (%) (mbar) 0 (ads) (32) (44) (41) (14) (4) (ads) (25) (32) (33) (11) (3) (ads) (28) (37) (39) (12) (4) (ads) (20) (27) (26) (8) (3) (ads) (19) (24) (25) (8) (2) (ads) (17) (23) (25) (8) (2) (ads) (20) (25) (25) (7) (3) (ads) (18) (24) (29) (8) (3) (ads) (23) (30) (34) (10) (3) (des) (23) (30) (34) (10) (3) (des) (44) (54) (15) (18) (6) (des) (45) (62) (72) (21) (6) (des) (31) (44) (51) (14) (4) NATURE MATERIALS

25 SUPPLEMENTARY INFORMATION a axis (Angstrom) K ads 195 K des b axis (Angstrom) K ads 195 K des CO 2 pressure (mbar) a CO 2 pressure (mbar) b c axis (Angstrom) K ads 195 K des β angle (degree) K ads 195 K des CO 2 pressure (mbar) c CO 2 pressure (mbar) d Figure S18. Modulation of unit cell parameters with different CO 2 adsorption/desorption loadings for NOTT-202a at 195 K. The hysteresis of unit cell parameter changes is consistent with the hysteretic CO 2 uptakes observed in the gas isotherms. NATURE MATERIALS 25

26 0 mbar ads 508 mbar ads 1000 mbar ads/des 300 mbar des 0 mbar des Intensity θ Figure S19. Wide-angle in situ PXRD patterns for NOTT-202a at different CO 2 adsorption/desorption loadings at 273 K. No peak shifts or intensity changes were observed, indicating that the unit cell parameters remain constant at different CO 2 loadings at 273 K. Table S9. Summary of Le Bail fitting results for unit cell parameters for NOTT-202a at 273 K obtained by in situ X-ray diffraction. CO 2 Pressure a (Å) b (Å) c (Å) β ( o ) v (Å 3 ) R wp (%) (mbar) 0 (ads) (8) (11) (11) (4) (1) (ads) (8) (11) (11) (3) (1) (ads) (8) (11) (11) (3) (1) (des) (8) (11) (11) (3) (1) (des) (8) (11) (11) (4) (1) (des) (8) (12) (12) (4) (1) NATURE MATERIALS

27 SUPPLEMENTARY INFORMATION K ads 273 K des K ads 273 K des a axis (Angstrom) b axis (Angstrom) CO 2 pressure (mbar) CO 2 pressure (mbar) a b c axis (Angstrom) K ads 273 K des β angle (degree) K ads 273 K des CO 2 pressure (mbar) CO 2 pressure (mbar) c d Figure S20. Modulation of unit cell parameters of NOTT-202a at different CO 2 adsorption/desorption loadings at 273 K. This confirms that the unit cell parameters remain constant at different CO 2 loadings at 273 K. NATURE MATERIALS 27

28 bare material 67 mbar CO 2 loading Intensity θ Figure S21. Comparison of intensities of PXRD patterns for bare NOTT-202a and CO 2 -loaded material at 195 K. Given that the powder sample and beam intensity remain the same before and after the CO 2 loading, the increase in diffraction intensities on CO 2 loading confirms microscopic CO 2 -host ordering, consistent with the CO 2 sorption thermodynamic study. 28 NATURE MATERIALS

29 SUPPLEMENTARY INFORMATION 6. N 2 /Ar sorption isotherms and pore size distribution for NOTT-202a N 2 /Ar uptake (mmol/g) N 2 77K ads N 2 77K des Ar 87K ads Ar 87K des P/P 0 Figure S22. N 2 (77 K) and Ar (87 K) sorption isotherms for NOTT-202a. Pore size distribution (PSD) data and cumulative pore volume for NOTT-202a were determined by analysis of the Ar isotherm at 87 K using a non-local density functional theory (NLDFT) implementing a hybrid kernel based on a zeolite/silica model containing cylindrical and spherical pores 3 as implemented in the Autosorb1 software package. Analysis of the Ar adsorption data revealed a distribution of pores with a predominant diameter of 15.4 Å (Fig. S23). 1.0 Pore volume, dv/d(d) (cm 3 0.1nm -1 g -1 ) dv/d(d) Pore volume Cumulative pore volume (cm 3 g -1 ) Pore width (0.1nm) Figure S23: Pore size distribution and cumulative pore volume for NOTT-202a calculated from a NLDFT fit to the Ar adsorption data for NOTT-202a. NATURE MATERIALS 29

30 7. D 2 and H 2 uptake isotherms. Gravimetric H 2 and D 2 adsorption data were recorded over the range bar at 77 K. Importantly, D 2 isotherm experiments were used to validate and confirm that the observed H 2 adsorption was due to H 2 rather than other impurities. We obtained values of for the molar ratio of adsorbed D 2 /H 2 over the pressure range bar at 77 K, entirely consistent with the values ( ) observed experimentally for adsorption on MOF materials at 77 K. 4,5 The H 2 storage capacity of NOTT-202a is moderate, compared with some of the best MOF materials. 4,6 However, the H 2 storage capacity is higher than values previously reported for interpenetrated MOF materials, 6 the porosity of NOTT-202a being enhanced by the presence of partial interpenetration. 5 4 H 2 77K ads H 2 77K des H 2 uptake (wt%) H 2 uptake (mmol/g) Pressure (bar) Figure S24. H 2 sorption isotherm at 77 K for NOTT-202a. 30 NATURE MATERIALS

31 SUPPLEMENTARY INFORMATION H 2 /D 2 Uptake (wt%) H 2 ads H 2 des D 2 ads D 2 des Pressure (mbar) Figure S25. Total D 2 and H 2 uptake isotherms for NOTT-202a up to 1000 mbar at 77 K nd 2 /nh Pressure (mbar) Figure S26. Variation of nd 2 /nh 2 uptake on NOTT-202a (0-1 bar) at 77 K. 8. H 2 Adsorption Enthalpy simulation for NOTT-202a. The isosteric heat of adsorption Q st was determined by fitting a virial-type equation to the H 2 adsorption isotherms at 77 K and 87 K. The ln(p) values for a given amount adsorbed (n) were calculated from the linear regressions determined from the virial equation analysis using the following virial equation. 5,6 NATURE MATERIALS 31

32 2 ln( n p) = A + A n + A... (1) 0 1 2n where p is pressure, n is amount adsorbed and A 0, A 1 etc. are virial coefficients. The simulation data for H 2 adsorption at 77 K and 87 K for NOTT-202a between 100 and 900 mbar using equation (1) are shown in Figs. S27. Analysis of the virial A 1 parameters shows that the adsorption enthalpies are at a maximum of 4.72 kj.mol -1 at zero surface coverage for NOTT-202a, and decrease with increasing H 2 loading (Fig. S28). a b Figure S27. Virial plot for the adsorption of H 2 on NOTT-202a at 77 K (a) and 87K (b). Adsorption isosteric heat (kj/mol) H 2 adsorption heat H 2 loading (mmol/g) Figure S28. Isosteric enthalpies of adsorption of H 2 in NOTT-202a. 32 NATURE MATERIALS

33 SUPPLEMENTARY INFORMATION 9. Additional analysis and derivation of the thermodynamics of adsorption of CO 2. To estimate the isosteric enthalpies (Q st ) for CO 2 adsorption, all isotherms at K were fitted to the Van t Hoff equation (2): d ln( p) ΔH = d(1/ T ) R (2) where p is pressure, T is the temperature, R is the real gas constant. At low surface coverage (< 7 mmol.g -1 ), all isotherms at K can be fitted very well, indicating consistency of the isotherm data and CO 2 -host system over that temperature range. However, the fitting becomes non-linear above CO 2 uptakes of 7 mmol.g -1 (Fig. S30), indicating the presence of a different CO 2 -host system at 195 K at CO 2 uptakes above 7 mmol.g -1. Comparison of CO 2 isotherms at different temperatures shows that the final uptakes are very similar despite different adsorption isotherm profiles at lower partial pressures (Fig. 4a), indicating that CO 2 adsorption undergoes different processes at these temperatures, but reaching the same adsorbate/adsorbent system at P/P 0 =1.0 (Fig. S31). From the calculation of Q st from the isotherms measured between K, the CO 2 adsorption isotherm at a given temperature can be simulated by linear regression to the Van t Hoff isochore. Fig. S32 shows a comparison of the hysteretic adsorption isotherm observed at 195 K with the expected adsorption isotherm calculated from the adsorption isotherms at K. It is evident that the observed isotherm fits the calculated isotherm very well up to CO 2 uptakes of 7 mmol.g -1, indicating consistency in the isotherm data. Comparison of low pressure CO 2 isotherms for NOTT-202a at different temperatures are shown in Fig. S33. Within the non-hysteretic group of isotherms measured between 221 and 303 K, the low pressure CO 2 adsorption uptake increases progressively with decreasing temperature, and reaches a maximum at approximately the triple point temperature. However, in the hysteretic isotherms measured between 195 and 213 K, the low pressure CO 2 adsorption uptake decreases progressively with decreasing temperature below the triple point. This is a distinct and unique observation for physisorption within microporous materials, but is consistent with the thermodynamic analysis of the isotherms at K. NATURE MATERIALS 33

34 a b Figure S29. CO 2 adsorption isotherms at 213 K (a) and 205 K (b) for NOTT-202a. n = 1 mmol g-1 n = 2 mmol g-1 ln(p) y = x R 2 = /T ln(p) y = x R 2 = /T n = 3 mmol g-1 n = 4.2 mmol g-1 ln(p) y = x R 2 = /T ln(p) y = x R 2 = /T 34 NATURE MATERIALS

35 SUPPLEMENTARY INFORMATION n= 5 mmol g-1 n = 6 mmol g-1 ln(p) ln(p) y = x R 2 = y = x R 2 = /T 1/T n= 7 mmol g-1 n= 8 mmol g-1 ln(p) y = x R 2 = /T ln(p) /T n=9 mmol g-1 n =12 mmol g-1 ln(p) /T ln(p) /T Figure S30. Van t Hoff plots for the adsorption of CO 2 on NOTT-202a at K. The Qst and ΔS data at above 7 mmol.g -1 CO 2 loadings were calculated from isotherm data above the triple point temperature only. No mathematical fitting was performed at CO 2 loadings above 7 mmol.g -1. NATURE MATERIALS 35

36 20 Amount Adsorbed /mmol g K A 195K D 221K A 221K D 258K A 258K D 273K A 273K D 293K A 293K D 303K A 303K D P/P 0 Figure S31. CO 2 sorption isotherms for NOTT-202a at various temperatures. CO 2 uptake (mmol/g) Simulated adsorption at 195K Observed adsorption at 195K Observed desorption at 195K Pressure (bar) Figure S32. Simulated and observed CO 2 adsorption/desorption isotherms at 195 K for NOTT-202a. 36 NATURE MATERIALS

37 SUPPLEMENTARY INFORMATION CO 2 uptake (mmol/g) K ads 258K ads 273K ads 293K ads 303K ads P/P 0 a CO 2 uptake (mmol/g) K ads 205K ads 213K ads P/P 0 b Figure S33. Comparison of CO 2 adsorption isotherms for NOTT-202a at temperatures below (a) and above (b) the triple point of CO 2. NATURE MATERIALS 37

38 10. Calculation of Henry s Law selectivity. Calculation of selectivity data. To calculate the selectivity of CO 2 over other gases, all isotherm data at 195, 273 and 293 K were fitted using a non-linear virial-type expression (3) employed previously to model gas sorption in MOFs. 7 ln( p) = ln( n) + m i ( 1/ T ) ai n + o i= 0 j= 0 b n j j (3) where p is the pressure expressed, n is the amount adsorbed, T is the temperature, a i and b j are virial coefficients, and m and o represent the number of coefficients required to adequately describe the isotherms. The Henry s constant (K H ) can be extracted from the values of the virial coefficients a 0 and b 0 using expression (4), where T is the temperature. 11 K H = exp( b ) exp( a0 / 0 T ) (4) To reveal the trapping ability of CO 2, the adsorption and hysteretic desorption isotherms of CO 2 data at 195 K were fitted separately (Table S10), and the Henry s Law selectivity for component i(co 2 ) over other gas component j(ch 4, N 2, O 2, Ar or H 2 ) was estimated based on the ratio of their Henry s constants (equation 5). S = K / K ij Hi Hj (5) The results of the fitting for all isotherms at 195, 273 and 293 K gives R 2 greater than 0.99 and the Henry constants for each component at 195, 273 and 293 K were extracted from the virial coefficients (Tables S10-S12). The selectivity data from virial fittings and Henry s Law analysis are confined to the low surface coverage situation. 38 NATURE MATERIALS

39 SUPPLEMENTARY INFORMATION Gas uptake (mmol/g) CO 2 ads Ar ads CO 2 des Ar des CH 4 ads H 2 ads CH 4 des H 2 des N 2 N 2 O 2 O 2 ads des ads des Pressure (bar) Figure S34. Comparisons of CO 2, CH 4, N 2, Ar, O 2 and H 2 sorption isotherms for NOTT-202a up to 1.0 bar at 273 K. Gas uptake (mmol/g) CO 2 ads Ar ads CO 2 des Ar des CH 4 ads H 2 ads CH 4 des H 2 des N 2 N 2 O 2 O 2 ads des ads des Pressure (bar) Figure S35. Comparisons of CO 2, CH 4, N 2, Ar, O 2 and H 2 sorption isotherms for NOTT-202a up to 1.0 bar at 293 K. NATURE MATERIALS 39

40 a b c d e f 40 NATURE MATERIALS

41 SUPPLEMENTARY INFORMATION g Figure S36: Virial fitting graphs for CO 2 adsorption (a), CO 2 desorption (b), CH 4 (c), N 2 (d), Ar (e), H 2 (f) and O 2 (g) isotherms of NOTT-202a at 195 K. Table S10. Virial fitting results and Henry s constants K H for CO 2, CH 4, N 2, H 2, O 2 and Ar isotherm data at 195 K for NOTT-202a. CO 2 CO 2 CH 4 N 2 H 2 O 2 Ar adsorption desorption K H /mmol.g -1 mbar (6) 0.840(19) 8.27(6) e (24) e (2)e (1) e (1) e -3 Fitting R 2 > >0.999 >0.999 >0.999 >0.999 >0.999 Residual standard error NATURE MATERIALS 41

42 a b c d e Figure S37. The virial fitting graphs for CO 2 (a), CH 4 (b), N 2 (c), Ar (d), and O 2 (e) adsorption isotherms of NOTT-202a at 273 K. 42 NATURE MATERIALS

43 SUPPLEMENTARY INFORMATION Table S11. The virial fitting results and Henry s constants K H for CO 2, CH 4, N 2, H 2, O 2 and Ar isotherm data at 273 K. CO 2 CH 4 N 2 H 2 O 2 Ar adsorption K H /mmol.g -1 mbar (4) e (40) e (14) e -5 ~0 9.51(18) e (2) e -4 Fitting R 2 >0.999 >0.999 >0.999 n.a * >0.999 >0.999 Residual standard error n.a * * The uptake of H 2 isotherm at 273 K (below 0.01 wt%) is too low to obtain a reasonable virial fitting curve, and the Henry constant is therefore considered to be approximately 0. a b NATURE MATERIALS 43

44 c d e Figure S38. The virial fitting graphs for (a) CO 2, (b) CH 4, (c) N 2, (d) Ar and (e) O 2 adsorption isotherms for NOTT-202a at 293 K. Table S12. The virial fitting results and Henry s constants K H for CO 2, CH 4, N 2, H 2, O 2 and Ar isotherm data at 293 K for NOTT-202a. CO 2 adsorption CH 4 N 2 H 2 O 2 Ar K H /mmol.g -1 mbar (1) e (4) e (8) e -4 ~0 5.17(14) e (2) e -4 Fitting R 2 >0.999 >0.999 >0.999 n.a * >0.999 >0.999 Residual standard error n.a * * The uptake of H 2 isotherm at 293 K (below 0.01 wt%) is too low to obtain a reasonable virial fitting curve, and the Henry constant is therefore considered to be approximately zero. 44 NATURE MATERIALS

45 SUPPLEMENTARY INFORMATION The virial analysis restricted to low pressure data has been carried out by two methods using i. a non-linear virial fitting method 7 and ii. a linear virial fitting method Virial equations: Method 1 (non-linear): 7 m o i p) = ln( n) + ( 1/ T ) ai n + j ln( bjn (3) i= 0 j= 0 K H = exp( b0 ) exp( a0 / T ) (4) Method 2 (non-linear): 8 2 ln( n / p) = A + A n + A n... (1) Equation 1 is converted to equation 6 to give a linear approximation at low surface coverage: 9,10 ln( / p) = A + A n. (6) n 0 1 K exp( A ) H = 0.. (7) Henry s constants obtained from these different virial fitting methods are very similar, confirming the selectivity data shown in the manuscript. The standard deviation for the selectivity data are also given in the Tables Table S13. Comparison of the Henry s constants K H (K H /mmol.g -1 mbar -1 ) from two virial fitting results for CO 2, CH 4, N 2, O 2 and Ar isotherm data at 195 K for NOTT-202a. CO 2 adsorption CO 2 desorption CH 4 N 2 O 2 Ar Method 1 (non-linear) 0.196(6) 0.840(19) 8.27(6) e (24)e (1) e (1) e -3 Method 2 (linear) 0.185(6) 0.833(23) 8.17(2) e (1) e (1) e (1) e -3 Table S14. Comparison of the Henry s Law selectivity data from two virial fitting results at 195 K for NOTT-202a. Adsorption data CO 2 /CH 4 CO 2 /N 2 CO 2 /O 2 CO 2 /Ar Method1 (non-linear) 23.7(7) 285(13) 145(5) 138(4) Method 2 (linear) 22.6(7) 124(4) 136(5) 130(4) Desorption data CO 2 /CH 4 CO 2 /N 2 CO 2 /O 2 CO 2 /Ar Method 1(non-linear) 102(2) 1220(51) 622(15) 592(14) Method 2 (linear) 102(3) 559(16) 613(18) 587(17) NATURE MATERIALS 45

46 Table S15. Comparison of the Henry s constants K H (K H /mmol.g -1 mbar -1 ) from two virial fitting results for CO 2, CH 4, N 2, O 2 and Ar isotherm data at 273 K for NOTT-202a. CO 2 adsorption CH 4 N 2 O 2 Ar Method1(non-linear) 2.60(4) e (40) e (14) e (18) e (2) e -4 Method 2 (linear) 2.41(1) e (1) e (1) e (1) e (1) e -4 Table S16. Comparison of the Henry s Law selectivity data from two virial fitting results at 273 K for NOTT-202a. CO 2 /CH 4 CO 2 /N 2 CO 2 /O 2 CO 2 /Ar Method1(non-linear) 2.92(14) 26.7(6) 27.3(7) 22.6(5) Method 2 (linear) 3.06(1) 10.4(1) 10.6(1) 10.1(1) Table S17. Comparison of the Henry s constants K H (K H /mmol.g -1 mbar -1 ) from two virial fitting results for CO 2, CH 4, N 2, O 2 and Ar isotherm data at 293 K for NOTT-202a. CO 2 adsorption CH 4 N 2 O 2 Ar Method1(non-linear) 1.55(1) e (4) e (8) e (14) e (2) e -4 Method 2 (linear) 1.50(1) e (8) e (6) e (7) e (2) e -4 Table S18. Comparison of the Henry s Law selectivity data from two virial fitting results at 293 K for NOTT-202a. CO 2 /CH 4 CO 2 /N 2 CO 2 /O 2 CO 2 /Ar Method 1(non-linear) 1.41(5) 4.25(10) 3.00(8) 6.51(7) Method 2 (linear) 2.47(4) 4.12(7) 3.20(5) 6.47(7) 46 NATURE MATERIALS

47 SUPPLEMENTARY INFORMATION Equation y = a + b*x Adj. R-Square Value Standard Error B Intercept B Slope ln(n/p) ln(mol/g Pa) B Linear Fit of B CO 2 loadings (mol/g) Figure S39. The linear virial fitting graph for CO 2 adsorption isotherm for NOTT-202a at 195 K mbar data were used for this fitting. ln(n/p) ln(mol/g Pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope CO 2 loadings (mol/g) Figure S40. The linear virial fitting graph for CO 2 desorption isotherm for NOTT-202a at 195 K mbar data were used for this fitting. NATURE MATERIALS 47

48 Equation y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope ln (n/p) ln(mol/g Pa) F Linear Fit of F CH 4 loadings (mol/g) Figure S41. The linear virial fitting graph for CH 4 adsorption isotherm for NOTT-202a at 195 K mbar data were used for this fitting. ln(n/p) ln(mol/g Pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope N 2 loadings (mol/g) Figure S42. The linear virial fitting graph for N 2 adsorption isotherm for NOTT-202a at 195 K mbar data were used for this fitting. 48 NATURE MATERIALS

49 SUPPLEMENTARY INFORMATION Equation y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope ln (n/p) ln(mol/g Pa) F Linear Fit of F O 2 loadings (mol/g) Figure S43. The linear virial fitting graph for O 2 adsorption isotherm for NOTT-202a at 195 K mbar data were used for this fitting. ln(n/p) ln(mol/g Pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept E-4 F Slope Ar loadings (mol/g) Figure S44. The linear virial fitting graph for Ar adsorption isotherm for NOTT-202a at 195 K mbar data were used for this fitting. NATURE MATERIALS 49

50 ln(n/p) ln(mol/g Pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope CO 2 loadings (mol/g) Figure S45. The linear virial fitting graph for CO 2 adsorption isotherm for NOTT-202a at 273 K mbar data were used for this fitting Equation y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope ln(n/p) ln(mol/g Pa) F Linear Fit of F CH 4 loadings (mol/g) Figure S46. The linear virial fitting graph for CH 4 adsorption isotherm for NOTT-202a at 273 K mbar data were used for this fitting. 50 NATURE MATERIALS

51 SUPPLEMENTARY INFORMATION Equation y = a + b*x Adj. R-Square Value Standard Error F Intercept E-4 F Slope ln(n/p) ln(mol/g Pa) F Linear Fit of F N 2 loadings (mol/g) Figure S47. The linear virial fitting graph for N 2 adsorption isotherm for NOTT-202a at 273 K mbar data were used for this fitting Equation y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope ln(n/p) ln(mol/g Pa) F Linear Fit of F O 2 loadings (mol/g) Figure S48. The linear virial fitting graph for O 2 adsorption isotherm for NOTT-202a at 273 K mbar data were used for this fitting. NATURE MATERIALS 51

52 ln(n/p) ln(mol/g Pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept E-4 F Slope Ar loadings (mol/g) Figure S49. The linear virial fitting graph for Ar adsorption isotherm for NOTT-202a at 273 K mbar data were used for this fitting. ln(n/p) ln(mol/g.pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope CO 2 loadings (mol/g) Figure S50. The linear virial fitting graph for CO 2 adsorption isotherm for NOTT-202a at 293 K mbar data were used for this fitting. 52 NATURE MATERIALS

53 SUPPLEMENTARY INFORMATION ln(n/p) ln(mol/g Pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope CH 4 loadings (mol/g) Figure S51. The linear virial fitting graph for CH 4 adsorption isotherm for NOTT-202a at 293 K mbar data were used for this fitting. ln(n/p) ln(mol/g Pa) F Fit Curve 1 Equation y = a + b*x Adj. R-Squa Value Standard Err F Intercept F Slope N 2 loadings (mol/g) Figure S52. The linear virial fitting graph for N 2 adsorption isotherm for NOTT-202a at 293 K mbar data were used for this fitting. NATURE MATERIALS 53

54 Equation y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope ln(n/p) ln(mol/g Pa) F Linear Fit of F O 2 loadings (mol/g) Figure S53. The linear virial fitting graph for O 2 adsorption isotherm for NOTT-202a at 293 K mbar data were used for this fitting. ln(n/p) ln(mol/g Pa) Equation F Linear Fit of F y = a + b*x Adj. R-Square Value Standard Error F Intercept F Slope Ar loadings (mol/g) Figure S54. The linear virial fitting graph for Ar adsorption isotherm for NOTT-202a at 293 K mbar data were used for this fitting. 54 NATURE MATERIALS

55 SUPPLEMENTARY INFORMATION Table S19. Physical parameters of selected gases. Adsorbate Boiling point Triple point (K) Liquid density Kinetic Quadruple (K) (g/cc) diameter (Å) moment (e -39 Cm 2 ) H D N Ar O CO CH Grand canonical Monte Carlo simulations of CO 2 adsorption into NOTT-202a A model framework has been constructed, as shown in Figure S55, in which 87.2% of the volume is occupied by doubly-interpenetrated (2.0) net, 4.8% by 6Å wide slit pores and 8.0% by 10Å slit pores. During simulations, positions of framework atoms remained fixed. Host-guest and guest-guest interactions have been calculated with Lennard-Jones plus Coulomb potential. Lennard-Jones parameters for CO 2 molecules have been taken from the TraPPE force field, 12 and for atoms of NOTT-202a from the DREIDING force field. 13 Partial charges on CO 2 molecules were taken from the TraPPE force field so that a point charge of +0.7 was placed at the centre of mass of carbon atom and a charge of assigned to oxygen atoms. Partial charges on atoms of NOTT-202a were calculated using B3LYP density functional with the 6-31G* basis set for all atoms apart from In for which LANL2DZ basis set was used. The adsorption isotherm was computed using grand canonical Monte Carlo method. Figure S55. Model structure of NOTT-202a, which consists of 2.0 framework, 6 Å and 10 Å slit pores NATURE MATERIALS 55

56 (a) 2.0 framework (b) 2.0 with 6 Å slit pore c) 2.0 with 10 Å slit pore Figure S56. (a) 2.0 framework, (b) 2.0 with 6 Å slit pore and (c) 2.0 with 10 Å slit pore Step 1 Step 2 Step 3 Figure S57. Simulation (green solid line; numerical data presented below) and experimental adsorption isotherms for CO 2 uptake in NOTT-202a. Step1: <42 kpa; Step 2: kpa; Step 3 > 88 kpa. Pressure (kpa) mmol/g NATURE MATERIALS

57 SUPPLEMENTARY INFORMATION NATURE MATERIALS 57

58 (a) P = 10kpa (b) P = 40kpa (c) P = 50kpa (d) P = 100kpa Figure S58. Adsorption of CO 2 into the model framework with 6Å slit pore under different pressures: (a) P=10kpa, (b) P=40kpa, (c) P=50kpa and (d) P=100kpa As an additional test of the simulation technique, the sorption of Ar into NOTT-202a has also been produced. No steps were shown in sorption isotherms for Ar in both pure 2.0 net and in a model net containing 6Å slit pore. It can therefore be concluded that both the presence of quadrupole moment of CO 2 and MOF geometry play crucial role in step formation during adsorption process into NOTT-202a. References: 1. G. M. Sheldrick, Acta Crystallogr. Sect. A, 2008, 64, A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7; P. v. D. Sluis and A. L. Spek, Acta Crystallogr., Sect. A, 1990, 46, P. I. Ravikovitch, D. Wei, W. T. Chueh, G. L. Haller and A. V. Neimark, J. Phys. Chem. B. 1997, 101, X. Lin, J. Jia, X. B. Zhao, K. M. Thomas, A. J Blake, N. R. Champness, P. Hubberstey and M. Schröder, Angew. Chem. Int. Ed., 2006, 45, B. Chen, X. Zhao, A. Putkham, K. Hong, E. B. Lobkovsky, E. J. Hurtado, A. J. Fletcher and K. M. Thomas, J. Am. Chem. Soc., 2008, 130, X. Lin, I. Telepeni, A. J. Blake, A. Dailly, C. Brown, J. Simmons, M. Zoppi, G. S. Walker, K. M. Thomas, T. J. Mays, P. Hubberstey, N. R. Champness and M. Schröder, J. Am. Chem. Soc. 2009, 131, L. Czepirski and J. Jagiello, Chem. Eng. Sci. 1989, 44, J.H. Cole, D.H. Everett, C.T. Marshall, A.R. Paniego, J.C. Powl, F. Rodriguez-Reinoso, J. Chem. Soc. Faraday Trans. 1974, 70, A.M. Williams, Proc. Roy. Soc. A Mathematical, Physical and Engineering Sciences 1919, 96, D.C. Henry, Philosophical Magazine 1922, 44, C. R Reid and K. M Thomas, Langmuir 1999, 15, J.J. Potoff and J.I. Siepmann. AIChE Journal. 2002, 47, S.L. Mayo, B.D. Olafson, and W.A. Goddard III. J. Phys. Chem., 1990, 94, NATURE MATERIALS