Separation of rare gases and chiral molecules by selective binding in porous organic cages

Chen, Linjiang; Reiss, Paul S.; Chong, Samantha Y.; Holden, Daniel; Jelfs, Kim E.; Hasell, Tom; Little, Marc A.; Kewley, Adam; Briggs, Michael E.; Stephenson, Andrew; Thomas, K. Mark; Armstrong, Jayne; Bell, Jon G.; Busto, J.H.; Noël, Raymond; Liu, Jian; Strachan, Denis M.; Thallapally, Praveen K.; Cooper, Andrew I.

doi:10.1038/nmat4035

Cited by 552 publications

(578 citation statements)

References 47 publications

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“…For example, CC3 (Figure 2c) has demonstrated exceptional potential for noble gas and enantioselective separations. 70 This dynamic behavior has required novel computational approaches to successfully comprehend the selectivity observed in these materials. …”

Section: Porosity Adsorption and Kineticsmentioning

confidence: 99%

Application of computational methods to the design and characterisation of porous molecular materials

et al. 2017

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Composed from discete units, porous molecular materials (PMMs) possess unique properties not observed for conventional, extended, solids, such as solution processibility and permanent porosity in the liquid phase. However, identifying the origin of porosity is not a trivial process, especially for amorphous or liquid phases. Furthermore, the assembly of molecular components is typically governed by a subtle balance of weak intermolecular forces that makes structure prediction challenging. Accordingly, in this review we canvass the crucial role of molecular simulations in the characterisation and design of PMMs. We will outline strategies for modelling porosity in crystalline, amorphous and liquid phases and also describe the state-of-the-art methods used for high-throughput screening of large datasets to identify materials that exhibit novel performance characteristics.

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Section: Porosity Adsorption and Kineticsmentioning

confidence: 99%

Application of computational methods to the design and characterisation of porous molecular materials

et al. 2017

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“…The crystal packing in porous molecular crystals defines the pore dimensions, which in turn define properties such as guest selectivity. 4,5 The same challenge-control over solid state structure-applies to all 2 functional molecular crystals because crystal packing defines physical properties such as electronic band gap and thermal or electrical conductivity.A central paradigm in crystal engineering is to synthesize building blocks, or 'tectons', with strong, directional interactions, such as hydrogen bonding 6 or metal-ligand binding, 7 which direct assembly into a targeted three-dimensional superstructure (Fig. 1).…”

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Reticular synthesis of porous molecular 1D nanotubes and 3D networks

et al. 2016

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Synthetic control over pore size and pore connectivity is the crowning achievement for porous metal-organic frameworks. The same level of control has not been achieved for molecular crystals, which are not defined by strong, directional intermolecular coordination bonds. Hence, molecular crystallization is inherently less controllable than framework crystallization, and there are fewer examples of 'reticular synthesis'-where multiple building blocks can be assembled according to a common assembly motif.Here, we apply a chiral recognition strategy to a new family of tubular covalent cages, to create both 1-D porous nanotubes and 3-D diamondoid pillared porous networks.The diamondoid networks are analogous to metal-organic frameworks prepared from tetrahedral metal nodes and linear, ditopic organic linkers. The crystal structures can be rationalized by computational lattice energy searches, which provide an in silico screening method to evaluate candidate molecular building blocks. These results are a blueprint for applying the 'node and strut' principles of reticular synthesis to molecular crystals.Despite many advances in supramolecular chemistry, it is still challenging to control molecular crystallization to create a specific, useful property. 1,2 This is important in the emerging area of porous molecular solids, 3 which have practical advantages such as solution processability. The crystal packing in porous molecular crystals defines the pore dimensions, which in turn define properties such as guest selectivity. 4,5 The same challenge-control over solid state structure-applies to all 2 functional molecular crystals because crystal packing defines physical properties such as electronic band gap and thermal or electrical conductivity.A central paradigm in crystal engineering is to synthesize building blocks, or 'tectons', with strong, directional interactions, such as hydrogen bonding 6 or metal-ligand binding, 7 which direct assembly into a targeted three-dimensional superstructure (Fig. 1). 1,2,8,9 For metal-organic frameworks (MOFs) and porous coordination polymers (PCPs), directional metal-ligand bonds are used to do this (Fig. 1a). [10][11][12][13][14] Likewise, hydrogen bonding can be used to create organic molecular crystals with defined network structures (Fig. 1b). 9,15,16 We have used chiral recognition to assemble porous organic cages 3 (POCs) into structures with 3-D pore channels (Fig. 1c). 3 POCs are rigid molecules with a permanent internal void that is accessible to guests via 'windows' in the cage. [17][18][19] Control of structure and function for POCs can be difficult, however, because slight changes in the molecular structure 19 or the crystallization solvent 20 can cause a profound change in the crystal packing. Chiral window-towindow interactions (Fig. 1e,f) can direct these POCs to assemble into 3-D pore networks in several cases, 19,21,22 but this is not ubiquitous. For example, some cages require specific solvents to template the window-to-window packing. 20 The chiral cage CC3-S (...

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“…CC3α-(R,S) has slightly smaller cell dimensions, which results from the previously reported stronger interaction between heterochiral CC3 pairs compared to homochiral pairs. 62 The PLEs for CDB12 are shown in Figure 5 and Table 3 We know from the experimental reports of Chen et al, 25 that both Xe and Kr are able to diffuse through the CC3-R system and thus a window opening time of ∼8% for Xe is sufficient to allow diffusion, albeit slower than that for Kr (opening time of ∼60%). This in combination with the stronger binding energy for Xe over Kr is the rationale for the observed separation outcome of their breakthrough experiments.…”

Section: Pore Limiting Envelopesmentioning

confidence: 97%

Computational Screening of Porous Organic Molecules for Xenon/Krypton Separation

et al. 2017

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1 AbstractWe performed a computational screening of previously reported porous molecular materials, including porous organic cages, cucurbiturils, cyclodextrins and cryptophanes, for Xe/Kr separation. Our approach for rapid screening through analysis of single host molecules, rather than the solid state structure of the materials, is evaluated.We use a set of tools including in-house software for structural evaluations, electronic structure calculations for guest binding energies and molecular dynamics and metadynamics simulations to study the effect of the hosts' flexibility upon guest diffusion. Our final results confirm that the CC3 cage molecule, previously reported as high performing for Xe/Kr separation, is the most promising of this class of materials reported to date. The Noria molecule was also found to be promising and we therefore synthesised two related Noria molecules and tested their performance for Xe/Kr separation in the laboratory.

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Separation of rare gases and chiral molecules by selective binding in porous organic cages

Cited by 552 publications

References 47 publications

Application of computational methods to the design and characterisation of porous molecular materials

Application of computational methods to the design and characterisation of porous molecular materials

Reticular synthesis of porous molecular 1D nanotubes and 3D networks

Computational Screening of Porous Organic Molecules for Xenon/Krypton Separation

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