Supporting Information

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1 Supporting Information A Porous Two-Dimensional Monolayer Metal-Organic Framework Material and its Use for the Size-Selective Separation of Nanoparticles Yi Jiang, 1 Gyeong Hee Ryu, 1, 3 Se Hun Joo, 4 Xiong Chen, 1 Sun Hwa Lee, 1 Xianjue Chen, 1 Ming Huang, 1, 3 Xiaozhong Wu, 1, Da Luo, 1 Yuan Huang, 1 Jeong Hyeon Lee, 4 Bin Wang, 1 Xu Zhang, 1 Sang Kyu Kwak, 4 Zonghoon Lee, 1, 3 1, 2, 3,* and Rodney S. Ruoff 1 Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS), Ulsan 44919, Republic of Korea 2 Department of Chemistry Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea 3 School of Materials Science and Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea 4 School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 44919, Republic of Korea * correspondence and requests for materials should be addressed to R. S. R. (ruofflab@gmail.com) Present address: College of Chemical Engineering, China University of Petroleum, Qingdao , People s Republic of China S1

2 1. Thermal gravimetric analysis (TGA) of the MOF powder. Figure S1. TGA of the MOF powder. S2

3 2. O1s XPS spectrum of the MOF powder. Figure S2. O1s XPS spectrum of the MOF powder. S3

4 3. Computational details To investigate the structural and magnetic properties of the MOF, spin-polarized density functional theory (DFT) calculations were performed using the Cambridge Serial Total Energy Package (CASTEP) 1 program. The generalized gradient approximation (GGA) with Perdew-Burke-Ernzerhof (PBE) functional 2 was used to represent the exchange-correlation energy of electrons. The electron-ion interactions were described by the ultrasoft pseudopotential and the van der Waals interactions were corrected using the Grimme s method 3. The wavefunctions were expanded in a plane-wave basis set with a kinetic energy cutoff of 400 ev and Brillouin zone was integrated using a k-point set with a Monkhorst-Pack scheme 4. For self-consistent field calculations, the convergence criterion was set to ev/atom and an electron smearing of 0.1 ev was applied in all calculations. For geometry optimization, the convergence criteria were set to ev/atom for energy, 0.01 ev/å for force, 0.02 GPa for stress, and Å for displacement. The spin on each atom was estimated by the Mulliken population analysis 5. Using the gauge including projector augmented wave (GIPAW) approach of Pickard and Mauri 6, the g values were calculated for the isolated Cu (II) acetylacetonate complex and the optimized 2D MOF. The Cu (II) acetylacetonate complex was modeled as an isolated molecule placed in an orthorhombic box with a vacuum space of ~10 Å. The on-the-fly generated ultrasoft pseudopotential with a kinetic energy cutoff of ev was employed. The total g tensor was calculated using the following equation, g = g e + Δg, where g e = g e I, I is the identity matrix, g e is the electronic Zeeman g factor, and Δg is the total change in g tensor per Cu atom. S4

5 Figure S3. The isosurface of spin density and Mulliken spin for the Cu (II) acetylacetonate complex. The blue isosurface represents the spin density of 0.01 e/å 3 and the Mulliken spins are shown for the Cu and O atoms. S5

6 4. CO 2 sorption isotherm of the processed MOF powder at 273 K. Figure S4. CO 2 sorption isotherm of the precessed MOF powder at 273 K. S6

7 5. Optical microscope (OM) image of a MOF film deposited on 300 nm SiO 2 /Si wafer piece. Figure S5. OM image of a MOF film deposited on a 300 nm SiO 2 /Si wafer substrate. Scale bar is 50 μm. (The dotted line shows the film location, which is in the upper right section.) S7

8 6. AFM image of the MOF film with a thickness of ~2 nm. Figure S6. AFM image of a MOF film ( μm 2 ) with a thickness of ~2 nm. The MOF film was deposited onto a 300 nm SiO 2 /Si wafer substrate. S8

9 7. A TEM image of the monolayer MOF Film obtained using a cryo-holder. Figure S7. A TEM image of the monolayer MOF Film obtained using a cryo-holder. S9

10 8. UV-vis spectra of the ligand L1 and the 2D MOF film. Figure S8. UV-vis spectra of L1 and the 2D monolayer MOF film. S10

11 9. XPS spectra of the 2D MOF monolayer film. Figure S9. (a) Survey, (b) C1s, (c) Cu2p, and (d) O1s XPS spectra of the 2D MOF monolayer film; the film was transferred onto a 300 nm SiO 2 /Si wafer substrate directly from the LB trough. S11

12 10. TEM image and the corresponding particle size histogram of Au NPs from sample Au NP1 with diameters of 4.4 ± 0.3 nm before filtration. Figure S10. a, TEM image of particles in the sample Au NP1 before filtration. b, The corresponding particle size histogram of Au NP1 with diameters of 4.4 ± 0.3 nm before filtration. S12

13 11. Photographs of the MOF membrane on the supporting Anodisc filter before and after filtration of the Au NP1 sample. Figure S11. Photographs of the MOF membrane on the supporting Anodisc filter (a) before and (b) after the filtration of the Au NPs in Au NP1. S13

14 12. Further studies of the filtration and its meaning. Additional measurements of N 2 sorption of the unprocessed MOF samples obtained by filtration of the MOF dispersion in water that were used for separating the gold nanoparticles were made. (The MOF sample for the N 2 sorption measurement in Figures 3d and 3e was processed by washing with methanol and acetone several times, and was then dried under vacuum at 120 C for 24 h.) As shown in Figure S12b, another two peaks centered at around 1.2 nm and 2.5 nm were observed for this unprocessed sample. Thus, gold nanoparticles no more than 2.4 nm in size could (at least in principle) pass the MOF membrane through the 2.5 nm pores. We have also modeled the MOF structure using the eclipsed stacking sequence as shown in Figure S12c, and have found that the pore size of the MOF with this stacking configuration is calculated to be 2.2 nm. We speculate that roughly 12% of the overall MOF sample (this percentage is determined from the cumulative pore volume data on the unprocessed powder sample type) could adopt the eclipsed stacking configuration in the presence of water, which might affect the size-selective filtration of the gold nanoparticles. Thus, we suggest that the pores in the MOF sample regions having the eclipsed stacking configuration, along with the possibility of gaps formed by the way the MOF components stack, could contribute to the cutoff observed for the filtration of the Au NPs by the MOF membrane. S14

15 Figure S12. a, N 2 adsorption and desorption isotherm curves of the unprocessed MOF sample. b, Pore size distributions of the unprocessed MOF samples. c, Space-filling model of the MOF in the eclipsed stacking configuration. S15

16 13. Study of the MOF membrane when on a cellular acetate substrate for the filtration of gold nanoparticles. As shown in Figure S13, when the MOF membrane on the cellular acetate substrate was used for the filtration of Au NP2, similar results were observed compared to those from the Anodisc substrate (Figures 5b, 5d, and 5f). The light absorption of the filtrate also decreased compared with that of the Au NP2 solution before filtration and the Au NP size cutoff was also determined to be ~2.4 nm. Thus, the substrate shows no influence on the nanoparticle filtering and size-selectivity. Figure S13. Use of the MOF membrane on the cellular acetate substrate for the sizeselective separation of nanoparticles. a, UV-vis spectra of aqueous solutions of Au NP2 before and after filtration. b, TEM image of Au NP2 deposited on Pelco single layer graphene on holey silicon nitride after filtration. c, the corresponding particle size histograms of (b). Scale bar in b: 10 nm. S16

17 References (1) Clark, S. J.; Segall, M. D.; Pickard, C. J. H., P. J. ; Probert, M. I. J.; Refson, K.; Payne, M. C. First Principles Methods Using CASTEP. Z. Kristallogr. 2005, 220, (2) Perdew, J. P.; Burke, K.; Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 1996, 77, (3) Grimme, S. Semiempirical GGA-type Density Functional Constructed with A Long- Range Dispersion Correction. J. Comput. Chem. 2006, 27, (4) Monkhorst, H. J.; Pack, J. D. Special Points for Brillonin-zone Integrations. Phys. Rev. B 1976, 13, (5) Mulliken, R. S. Electronic Population Analysis on LCAO-MO Molecular Wave Functions. I. J. Chem. Phys. 1955, 23, (6) Pickard, C. J.; Mauri, F. First-principles Theory of the EPR g Tensor in Solids: Defects in Quartz. Phys. Rev. Lett. 2002, 88, S17