Challenges in the Synthesis of Metal-Organic Frameworks Jeffrey R. - PowerPoint PPT Presentation

Challenges in the Synthesis of Metal-Organic Frameworks Jeffrey R. Long Departments of Chemistry and Chemical & Biomolecular Engineering University of California, Berkeley Materials Sciences Division, Lawrence Berkeley National Laboratory Center for Gas Separations, a DoE Energy Frontier Research Center

Metal-Organic Frameworks (MOFs) BET surface areas up to 7100 m 2 /g Density as low as 0.13 g/cm 3 Tunable pore sizes up to 10 nm Channels connected in 1-, 2-, or 3-D Internal surface can be functionalized Production on ton scale at BASF and various new start-up companies Zn 4 O(1,4-benzenedicarboxylate) 3 Yaghi et al. Nature 2003 , 423 , 705 Kitagawa et al. Angew. Chem., Int. Ed. 2004 , 43 , 2334 MOF-5 Férey Chem. Soc. Rev. 2008 , 37 , 191

High Surface Area Adsorbents for Gas Separations gas mixture in pure gas out MOF-loaded bed ฀ High surface area leads to a high working capacity for removing one component from a gas mixture ฀ Requires that the MOF selectively adsorbs just one component of the mixture

Metal-Organic Framework Synthesis metal ion ? or cluster + temperature? reactant ratio? solvent? cosolvent? organic linker acid/base added? metal-organic framework (MOF) ฀ An enormous number of structures are possible; most are not highly porous ฀ Impossible to predict conditions leading to pure, crystalline target structure

Synthesis Depends Critically on Reaction Conditions Mg(NO 3 ) 2 ·6H 2 O + H 2 BPDC ∆ DMA/MeOH 1% H 2 O 2% H 2 O 4% H 2 O Mg 3 (BPDC) 3 (DMA) 4 Mg(BPDC)(MeOH) Mg(BPDC)(H 2 O) 2

Challenges in MOF Synthesis 1. What reaction conditions will lead to a target structure? 2. How do we fully activate a MOF? 3. How do MOF crystals nucleate and grow? 4. Can we control the size and shape of MOF crystals? 5. Can we create MOFs with new adsorption properties?

Test: Zn(NO 3 ) 2 ·6H 2 O + 1,4-Benzenedicarboxylic Acid

Automated Dispensing of Solids and Liquids  Solid powders dosed from hoppers with a precision of ±0.1 mg  Delivery of solids and liquids to 96 reaction vials can be accomplished in ca. 2 h

High-Throughput Synthesis Instrument

High- Throughput Powder X-Ray Diffraction

Powder Diffraction Data Analysis

A Framework with Exposed Mn 2+ Coordination Sites 1) 70 ° C, DMF/MeOH 2) MeOH soak 3) 150 ° C, in vacuo Mn 3 [(Mn 4 Cl) 3 (BTT) 8 ] 2 ·20MeOH ฀ One of the first MOFs shown to contain coordinatively-unsaturated metal sites Dinca, Dailly, Liu, Brown, Neumann, Long J. Am. Chem. Soc. 2006 , 128 , 16876

Variation of the Metal Center? MCl 2 + ? temperature? reactant ratio? solvent? cosolvent? acid? H 3 BTT M 3 [(M 4 Cl) 3 (BTT) 8 ] 2 ⋅ x solvent

Screening Acid Concentration and Solvent ? CoCl 2 + H 3 BTT Co 3 [(Co 4 Cl) 3 (BTT) 8 ] 2 · x solvent 100 ° C, 2 days 20 mM 20 mM 100 mM HCl (MeOH) total of 0.55 mL of solvent per vial

Screening Acid Concentration and Solvent ? CoCl 2 + H 3 BTT Co 3 [(Co 4 Cl) 3 (BTT) 8 ] 2 · x solvent 100 ° C, 2 days 20 mM 20 mM 100 mM HCl (MeOH) total of 0.55 mL of solvent per vial Only these conditions afforded the target MOF in pure form

Variation of the Metal via High-Throughput Synthesis MCl 2 + H 3 BTT M 3 [(M 4 Cl) 3 (BTT) 8 ] 2 ⋅ x solvent (M = Mg, Ca, Cr, Mn, Fe, Co, Ni, Cu, Cd)  Different metals can require very different conditions often with mixed solvents Sumida, Horike, Kaye, Herm, Queen, Brown, Grandjean, Long, Dailly, Long Chem. Sci. 2010 , 1 , 184

Challenges in MOF Synthesis 1. What reaction conditions will lead to a target structure? 2. How do we fully activate a MOF? 3. How do MOF crystals nucleate and grow? 4. Can we control the size and shape of MOF crystals? 5. Can we create MOFs with new adsorption properties?

High-Throughput NMR Porosity Screening ฀ Low-cost benchtop NMR instrument ฀ Solvent (proton) relaxation times can afford pore size distribution information ฀ Enables rapid high-throughput evaluation of porosity of new materials Chen, Mason, Bloch, Gygi, Long, Reimer Micropor. Mesopor. Mater. 2015 , 205 , 65

NMR Porosity Screening ฀ Strong correlation with Langmuir surface area, even for paramagnetic frameworks

High-Throughput Multicomponent Gas Adsorption Analysis ฀ Equilibrium adsorption measurements based upon mass spec analysis ฀ Can measure 28 samples in parallel for mixture including CO 2 , N 2 , H 2 O, O 2 , SO 2 Mason, McDonald, Bae, Bachman, Sumida, Dutton, Kaye, Long, J. Am Chem. Soc. 2015 , 137 , 4787

Challenges in MOF Synthesis 1. What reaction conditions will lead to a target structure? 2. How do we fully activate a MOF? 3. How do MOF crystals nucleate and grow? 4. Can we control the size and shape of MOF crystals? 5. Can we create MOFs with new adsorption properties?

Classical Nucleation Theory ฀ At the critical radius, the free energy of stable crystal outweighs surface energy ฀ Expanded forms of classical nucleation theory include heterogeneous nucleation Dubrovskii, Nucleation Theory and Growth of Nanostructures, NanoScience and Technology , DOI: 10.1007/978-3-642-39660-1_1

Non-Classical Theories of Nucleation and Growth ฀ Some MOFs have been shown to form multiple products sequentially Cölfen, Mann Angew. Chem., Int. Ed. 2003 , 42 , 2350

Studying Nucleation and Growth Nucleation : extremely small Growth : in general, very small length- and time-scales; fraction of atoms/molecules on structural complexity can surface; particles dispersed in prove challenging; solution solution; solid/liquid interface phase but precipitating

Methods for Studying MOF and Zeolite Growth In situ X-ray Diffraction Transmission Electron Microscopy Atomic Force Microscopy Pairwise Distribution Function Analysis Nuclear Magnetic Resonance Ex situ Scanning Electron Microscopy Patterson, et al . J. Am. Chem. Soc. 2015 , 137 , 7322; Cubillas, et al. J. Phys. Chem. C. 2014 , 118 , 23092 O’Donnell, et al. J.Am. Chem. Soc. 2007 , 129 , 1578; Vistad, et al. Chem. Mater. 2003 , 15 , 8939

Studying Crystal Zeolite Growth via AFM ฀ Height differences as a function of time can give structural information Brent, Anderson Angew. Chem. Int. Ed . 2008 , 47 , 5327

Growth of HKUST-1 on Gold SAM via AFM ฀ Step heights and facets indicate layer-by-layer growth along the [111] direction John, Scherb, Shoaee, Anderson, Attfield, Bein Chem. Commun. 2009 , 6294

Challenges in MOF Synthesis 1. What reaction conditions will lead to a target structure? 2. How do we fully activate a MOF? 3. How do MOF crystals nucleate and grow? 4. Can we control the size and shape of MOF crystals? 5. Can we create MOFs with new adsorption properties?

Channel-Containing MOFs Often Grow as Rods Co(NO 3 ) 2 ·6H 2 O + 1:1:1 DMF:EtOH:H 2 O H 4 dobdc ฀ Crystals of Co 2 (dobdc) (Co-MOF-74) generally form as agglomerates of long rods

Morphology Dictates Heat and Mass Transport plate rod ฀ For equal volume, average time to site within MOF depends on aspect ratio ฀ Plate morphology favors rapid transport and can enable use in membranes Rousseau, Handbook of Separation Process Technology , John Wiley and Sons: 1987, pp. 669-671

Modulators can Influence Crystal Morphology Coordination Metal salt Ligand MOF formation Modulator Solvent ฀ Modulators such as terminal carboxylates often not incorporated in bulk ฀ These additives can influence many equilibria simultaneously ฀ We have little understanding of how this works

Challenges in MOF Synthesis 1. What reaction conditions will lead to a target structure? 2. How do we fully activate a MOF? 3. How do MOF crystals nucleate and grow? 4. Can we control the size and shape of MOF crystals? 5. Can we create MOFs with new adsorption properties?

A MOF with a High Density of Exposed M 2+ Sites MX 2 ·6H 2 O + H 4 dobdc M 2 (dobdc), M-MOF-74 (M = Mg, Mn, Fe, Co, Ni, Cu, Zn) Rosi, Kim, Eddaoudi, Chen, O’Keeffe, Yaghi J. Am. Chem. Soc. 2005 , 127 , 1504 Dietzel, Morita, Blom, Fjellvåg Angew. Chem., Int. Ed. 2005 , 44 , 6354 Caskey, Wong-Foy, Matzger J. Am. Chem. Soc . 2008 , 130 , 10870 Bloch, Murray, Queen, Maximoff, Chavan, Bigi, Krishna, Peterson, Grandjean, Long, Smit, Bordiga, Brown, Long J. Am. Chem. Soc. 2011 , 133 , 14814

A MOF with a High Density of Exposed M 2+ Sites MX 2 ·6H 2 O + CH 3 OH 2+ H 4 dobdc M 2 (dobdc), M-MOF-74 (M = Mg, Mn, Fe, Co, Ni, Cu, Zn)

A MOF with a High Density of Exposed M 2+ Sites MX 2 ·6H 2 O + 2+ H 4 dobdc M 2 (dobdc), M-MOF-74 (M = Mg, Mn, Fe, Co, Ni, Cu, Zn) ฀ Activated frameworks have Langmuir surface areas of 1280-2060 m 2 /g ฀ Record high density of open metal coordination sites per unit mass or volume

Open Fe 2+ Sites Enable Olefin/Paraffin Separations 45 ° C Fe 2 (dobdc)·2C 2 D 4 ฀ Selectivity based upon interaction of π electrons with the cationic metal center ฀ Extremely high separation capacities can be achieved owing to the high density of metals Bloch, Queen, Krishna, Zadrozny, Brown, Long Science 2012 , 335 , 1606