Sorption 101: Types of sorption Chemical vs. physical Physisorption Weak forces (van der Waals, polarization) = easily Recyclable Low selectivity Typically fast Chemisorption Strong forces (chemical bonds) = hard to recycle High selectivity Typically slow 1

Sorption 201:Types of physisorbent Classification by pore size Mesoporous 2 – 50 nm Microporous < 2.0 nm Ultramicroporous < 0.7 nm 2

THE RIGHT PORE SIZE MEANS EVERYTHING Sorption 301: Ultramicroporous materials Size really, really matters THE RIGHT PORE SIZE MEANS EVERYTHING Abe Stern and Brian Space, 2008, unpublished results 3

My favourite space group Brian Space Tony Pham 4

What about pore chemistry? Pore chemistry affects sorption properties in rht MOFs 1 PCN-61 Ligand size 1.36 1.41 Space gp Fm3barm Cell volume 74901 (3) 78379 (7) CubOh size 1.2 T-Td size 1.16 1.18 T-Oh size 1.87 1.88 SLang/SBET 3570/3160 3500/3000 VPore 1.27 CO2 uptake 23.5 20bar 21.5 20bar (23.5) 35bar Qst (CO2) 26.2 22.0 CO2 isotherms N2 isotherms CO2 Qst B. Zheng, J. Bai, J. Duan, L. Wojtas, M.J. Zaworotko, J. Am. Chem. Soc. 2011 133, 748-751 5

Properly activated and sorption studied in early 2012 SIFSIX-3-Zn: [Zn(pyrazine)2(SiF6)]n Structure reported in 2009 by Uemura et al. Properly activated and sorption studied in early 2012 3.8 Å = ultramicropores SIFSIX Hybrid Ultramicroporous Material (HUM) HUMs ≠ MOFs Stephen Burd Amanda Diaz Amy Engel 6

HUMs offer design principles Narrow pores + inorganic walls Binding sites with strong interactions = high selectivity High density of binding sites = good working capacity Single binding site = high Qst across loading CO2/N2 Selectivty > 2500 Nature, 2013 C2H2/C2H4 Selectivity > 50 Science, 2016 Carol Hua (ChemComm 53, 5946-5949, 2017) 7

First observation of flexibility Sorption 401: What if sorbent changes structure? Flexible porous materials can transform suddenly or gradually 1995 2005 2015 First observation of flexibility S. Kitagawa Bull. Chem. Soc. Jpn, 1998 MIL-53 G. Ferey, JACS, 2002 DMOF-1 Angew, 2004 MIL-88 Science, 2007 Co(bdp) JACS, 2008, 2010 Nature, 2015 Nature, 2016 DUT-49 8

Natural gas (NG) storage A virtual experiment suggests that rigid materials are unsuited 200cc/cc is the minimally needed working capacity for adsorbed NG at 70 atm No porous material is yet close to the (DOE) targets for volumetric capacity and simulations on 650,000 compounds suggest that rigid porous materials are unlikely to meet the ARPA-E targets for working capacity C. M. Simon, et al., Eng. Environ. Sci. 2015, 8, 1190. 9