Imperial College London

ProfessorKimJelfs

Faculty of Natural SciencesDepartment of Chemistry

Professor in Computational Materials Chemistry
 
 
 
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Contact

 

+44 (0)20 7594 3438k.jelfs Website

 
 
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Location

 

207AMolecular Sciences Research HubWhite City Campus

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Summary

 

Publications

Publication Type
Year
to

171 results found

Avci G, Jelfs KE, 2024, Enhancing discovery of host-guest binders., Nat Comput Sci, Vol: 4, Pages: 161-162

Journal article

Molinska P, Tarzia A, Male L, Jelfs KE, Lewis JEMet al., 2023, Diastereoselective Self-Assembly of Low-Symmetry Pdn L2n Nanocages through Coordination-Sphere Engineering., Angew Chem Int Ed Engl, Vol: 62

Metal-organic cages (MOCs) are popular host architectures assembled from ligands and metal ions/nodes. Assembling structurally complex, low-symmetry MOCs with anisotropic cavities can be limited by the formation of statistical isomer libraries. We set out to investigate the use of primary coordination-sphere engineering (CSE) to bias isomer selectivity within homo- and heteroleptic Pdn L2n cages. Unexpected differences in selectivities between alternative donor groups led us to recognise the significant impact of the second coordination sphere on isomer stabilities. From this, molecular-level insight into the origins of selectivity between cis and trans diastereoisomers was gained, highlighting the importance of both host-guest and host-solvent interactions, in addition to ligand design. This detailed understanding allows precision engineering of low-symmetry MOC assemblies without wholesale redesign of the ligand framework, and fundamentally provides a theoretical scaffold for the development of stimuli-responsive, shape-shifting MOCs.

Journal article

Molinska P, Tarzia A, Male L, Jelfs KE, Lewis JEMet al., 2023, Diastereoselective Self‐Assembly of Low‐Symmetry Pd<sub><i>n</i></sub>L<sub>2<i>n</i></sub> Nanocages through Coordination‐Sphere Engineering**, Angewandte Chemie, Vol: 135, ISSN: 0044-8249

<jats:title>Abstract</jats:title><jats:p>Metal‐organic cages (MOCs) are popular host architectures assembled from ligands and metal ions/nodes. Assembling structurally complex, low‐symmetry MOCs with anisotropic cavities can be limited by the formation of statistical isomer libraries. We set out to investigate the use of primary coordination‐sphere engineering (CSE) to bias isomer selectivity within homo‐ and heteroleptic Pd<jats:sub><jats:italic>n</jats:italic></jats:sub>L<jats:sub>2<jats:italic>n</jats:italic></jats:sub> cages. Unexpected differences in selectivities between alternative donor groups led us to recognise the significant impact of the second coordination sphere on isomer stabilities. From this, molecular‐level insight into the origins of selectivity between <jats:italic>cis</jats:italic> and <jats:italic>trans</jats:italic> diastereoisomers was gained, highlighting the importance of both host–guest and host‐solvent interactions, in addition to ligand design. This detailed understanding allows precision engineering of low‐symmetry MOC assemblies without wholesale redesign of the ligand framework, and fundamentally provides a theoretical scaffold for the development of stimuli‐responsive, shape‐shifting MOCs.</jats:p>

Journal article

Schmidt JA, Wolpert EH, Sparrow GM, Johnson ER, Jelfs KEet al., 2023, Effect of [n]-Helicene Length on Crystal Packing., Cryst Growth Des, Vol: 23, Pages: 8909-8917, ISSN: 1528-7483

Chiral π-conjugated organic molecules hold potential for emerging technologies as they are capable of introducing novel functionalities into electronic devices owing to their strong chiroptical properties. However, capitalizing on chiral molecules for electronic devices is reliant on their molecular packing-a factor that impacts their charge-transport properties. The solid-state behavior of molecules is sensitive to subtle differences in molecular interactions, chirality, and shape, but these relationships are not fully understood. Here, we employ crystal structure prediction (CSP) as a tool to probe the lattice-energy landscape for a family of chiral organic molecules: [n]helicenes, where n ranges from 3 to 12. Our results show excellent agreement between the CSP landscapes and experimentally reported structures. By analyzing the packing motifs within the polymorph landscapes, we begin to develop an understanding of how helicene length affects the shape and π-π stacking interactions seen in the polymorphs. Furthermore, we propose how helicene length can be used as a tool to design new functional organic electronics.

Journal article

Zhou J, Mroz A, Jelfs KE, 2023, Deep generative design of porous organic cages via a variational autoencoder., Digit Discov, Vol: 2, Pages: 1925-1936

Porous organic cages (POCs) are a class of porous molecular materials characterised by their tunable, intrinsic porosity; this functional property makes them candidates for applications including guest storage and separation. Typically formed via dynamic covalent chemistry reactions from multifunctionalised molecular precursors, there is an enormous potential chemical space for POCs due to the fact they can be formed by combining two relatively small organic molecules, which themselves have an enormous chemical space. However, identifying suitable molecular precursors for POC formation is challenging, as POCs often lack shape persistence (the cage collapses upon solvent removal with loss of its cavity), thus losing a key functional property (porosity). Generative machine learning models have potential for targeted computational design of large functional molecular systems such as POCs. Here, we present a deep-learning-enabled generative model, Cage-VAE, for the targeted generation of shape-persistent POCs. We demonstrate the capacity of Cage-VAE to propose novel, shape-persistent POCs, via integration with multiple efficient sampling methods, including Bayesian optimisation and spherical linear interpolation.

Journal article

Mroz AM, Turcani L, Jelfs KE, 2023, Computational workflow for steric assessment using the electric field-derived size, Electronic Structure, Vol: 5, ISSN: 2516-1075

Molecular structure plays an important role in the selectivity and performance of catalysts. Understanding the impact of structural differences on catalyst performance via quantitative structure-selectivity relationships is key to developing high-performing catalytic systems. There are several methods that have been introduced to quantify steric contributions, including Tolman cone angles, Charton parameters, and A-values. While these have shown promise in predicting selectivity, they access similar, general steric contributions and are largely empirically derived. Alternatively, Sterimol parameters offer a specific multi-directional measure of steric bulk in the form of three vectors in units of distance. Recently, these parameters revealed strong correlations between structure and selectivity in asymmetric catalysis. Yet, despite their demonstrated performance, Sterimol parameters are commonly derived using van der Waals radii, which approximate molecular size using hard-spheres. This method may not accurately describe highly polarized systems. Recently, a new chemical system size metric based on the electric-field of a molecule was developed, which accesses the occupied space of a molecule. Here, we demonstrate that the electric field-derived Sterimol parameters reveal similar structure-selectivity relationships in asymmetric catalysis as conventional Sterimol parameters. Specifically, we present a computational workflow for calculating Sterimol parameters based on the size of a molecule's electric field, and validate our method using several asymmetric catalysis reactions.

Journal article

Bruno NC, Mathias R, Lee YJ, Zhu G, Ahn Y-H, Rangnekar ND, Johnson JR, Hoy S, Bechis I, Tarzia A, Jelfs KE, McCool BA, Lively R, Finn MGet al., 2023, Solution-processable polytriazoles from spirocyclic monomers for membrane-based hydrocarbon separations, Nature Materials, Vol: 22, Pages: 1540-1547, ISSN: 1476-1122

The thermal distillation of crude oil mixtures is an energy-intensive process, accounting for nearly 1% of global energy consumption. Membrane-based separations are an appealing alternative or tandem process to distillation due to intrinsic energy efficiency advantages. We developed a family of spirocyclic polytriazoles from structurally diverse monomers for membrane applications. The resulting polymers were prepared by a convenient step-growth method using copper-catalysed azide-alkyne cycloaddition, providing very fast reaction rates, high molecular weights and solubilities in common organic solvents and non-interconnected microporosity. Fractionation of whole Arabian light crude oil and atmospheric tower bottom feeds using these materials enriched the low-boiling-point components and removed trace heteroatom and metal impurities (comparable performance with the lighter feed as the commercial polyimide, Matrimid), demonstrating opportunities to reduce the energy cost of crude oil distillation with tandem membrane processes. Membrane-based molecular separation under these demanding conditions is made possible by high thermal stability and a moderate level of dynamic chain mobility, leading to transient interconnections between micropores, as revealed by the calculations of static and swollen pore structures.

Journal article

Tarzia A, Wolpert EH, Jelfs KE, Pavan GMet al., 2023, Systematic exploration of accessible topologies of cage molecules via minimalistic models., Chem Sci, Vol: 14, Pages: 12506-12517, ISSN: 2041-6520

Cages are macrocyclic structures with an intrinsic internal cavity that support applications in separations, sensing and catalysis. These materials can be synthesised via self-assembly of organic or metal-organic building blocks. Their bottom-up synthesis and the diversity in building block chemistry allows for fine-tuning of their shape and properties towards a target property. However, it is not straightforward to predict the outcome of self-assembly, and, thus, the structures that are practically accessible during synthesis. Indeed, such a prediction becomes more difficult as problems related to the flexibility of the building blocks or increased combinatorics lead to a higher level of complexity and increased computational costs. Molecular models, and their coarse-graining into simplified representations, may be very useful to this end. Here, we develop a minimalistic toy model of cage-like molecules to explore the stable space of different cage topologies based on a few fundamental geometric building block parameters. Our results capture, despite the simplifications of the model, known geometrical design rules in synthetic cage molecules and uncover the role of building block coordination number and flexibility on the stability of cage topologies. This leads to a large-scale and systematic exploration of design principles, generating data that we expect could be analysed through expandable approaches towards the rational design of self-assembled porous architectures.

Journal article

Greenaway RLL, Jelfs KEE, Spivey ACC, Yaliraki SNNet al., 2023, From alchemist to AI chemist, NATURE REVIEWS CHEMISTRY, Vol: 7, Pages: 527-528

Journal article

Tan R, Wang A, Ye C, Li J, Liu D, Darwich BP, Petit L, Fan Z, Wong T, Alvarez-Fernandez A, Furedi M, Guldin S, Breakwell CE, Klusener PAA, Kucernak AR, Jelfs KE, McKeown NB, Song Qet al., 2023, Thin film composite membranes with regulated crossover and water migration for long-life aqueous redox flow batteries., Advanced Science, Vol: 10, Pages: 1-11, ISSN: 2198-3844

Redox flow batteries (RFBs) are promising for large-scale long-duration energy storage owing to their inherent safety, decoupled power and energy, high efficiency, and longevity. Membranes constitute an important component that affects mass transport processes in RFBs, including ion transport, redox-species crossover, and the net volumetric transfer of supporting electrolytes. Hydrophilic microporous polymers, such as polymers of intrinsic microporosity (PIM), are demonstrated as next-generation ion-selective membranes in RFBs. However, the crossover of redox species and water migration through membranes are remaining challenges for battery longevity. Here, a facile strategy is reported for regulating mass transport and enhancing battery cycling stability by employing thin film composite (TFC) membranes prepared from a PIM polymer with optimized selective-layer thickness. Integration of these PIM-based TFC membranes with a variety of redox chemistries allows for the screening of suitable RFB systems that display high compatibility between membrane and redox couples, affording long-life operation with minimal capacity fade. Thickness optimization of TFC membranes further improves cycling performance and significantly restricts water transfer in selected RFB systems.

Journal article

Wolpert EH, Tarzia A, Jelfs KE, 2023, The effect of disorder in multi-component covalent organic frameworks, Chemical Communications, Vol: 59, Pages: 6909-6912, ISSN: 1359-7345

We examined the effect of two different types of linker distribution---random or correlated distribution---on the pore size and shape within single-layers of three multi-component COFs. We reveal a relationship between linker distribution and the porosity of COF solid solutions. The methods presented in this paper are generalisable and could be used in further studies to examine the properties of disordered framework materials.

Journal article

Kearsey RJ, Tarzia A, Little MA, Brand MC, Clowes R, Jelfs KE, Cooper AI, Greenaway RLet al., 2023, Competitive aminal formation during the synthesis of a highly soluble, isopropyl-decorated imine porous organic cage., Chemical Communications, Vol: 59, Pages: 3731-3734, ISSN: 1359-7345

The synthesis of a new porous organic cage decorated with isopropyl moieties (CC21) was achieved from the reaction of triformylbenzene and an isopropyl functionalised diamine. Unlike structurally analogous porous organic cages, its synthesis proved challenging due to competitive aminal formation, rationalised using control experiments and computational modelling. The use of an additional amine was found to increase conversion to the desired cage.

Journal article

Davies JA, Tarzia A, Ronson TK, Auras F, Jelfs KE, Nitschke JRet al., 2023, Tetramine Aspect Ratio and Flexibility Determine Framework Symmetry for Zn<sub>8</sub>L<sub>6</sub> Self-Assembled Structures, ANGEWANDTE CHEMIE-INTERNATIONAL EDITION, Vol: 62, ISSN: 1433-7851

Journal article

Wang A, Tan R, Liu D, Lu J, Wei X, Alvarez-Fernandez A, Ye C, Breakwell C, Guldin S, Kucernak AR, Jelfs KE, Brandon NP, McKeown NB, Song Qet al., 2023, Ion-selective microporous polymer membranes with hydrogen-bond and salt-bridge networks for aqueous organic redox flow batteries, Advanced Materials, Vol: 35, Pages: 1-12, ISSN: 0935-9648

Redox flow batteries (RFBs) have great potential for long-duration grid-scale energy storage. Ion conducting membranes are a crucial component in RFBs, allowing charge-carrying ions to transport while preventing the cross-mixing of redox couples. Commercial Nafion membranes are widely used in RFBs, but their unsatisfactory ionic and molecular selectivity as well as high costs limit the performance and the widespread deployment of this technology. To extend the longevity and reduce the cost of RFB systems, inexpensive ion-selective membranes are highly desired that concurrently deliver low ionic resistance and high selectivity towards redox-active species. In this work, high-performance RFB membranes are fabricated from blends of carboxylate- and amidoxime-functionalized polymers of intrinsic microporosity (PIMs) that exploit the beneficial properties of both polymers. The enthalpy-driven formation of cohesive interchain interactions, including hydrogen bonds and salt bridges, facilitates the microscopic miscibility of the blends, while ionizable functional groups within the sub-nanometer pores allow optimization of membrane ion transport functions. The resulting microporous membranes demonstrate fast cation conduction with low crossover of redox-active molecular species, enabling improved power ratings and reduced capacity fade in aqueous RFBs using anthraquinone and ferrocyanide as redox couples. This article is protected by copyright. All rights reserved.

Journal article

Davies JA, Tarzia A, Ronson TK, Auras F, Jelfs KE, Nitschke JRet al., 2023, Tetramine Aspect Ratio and Flexibility Determine Framework Symmetry for Zn<sub>8</sub>L<sub>6</sub>Self‐Assembled Structures, Angewandte Chemie, Vol: 135, ISSN: 0044-8249

<jats:title>Abstract</jats:title><jats:p>We derive design principles for the assembly of rectangular tetramines into Zn<jats:sub>8</jats:sub>L<jats:sub>6</jats:sub>pseudo‐cubic coordination cages. Because of the rectangular, as opposed to square, geometry of the ligand panels, and the possibility of either Δ or Λ handedness of each metal center at the eight corners of the pseudo‐cube, many different cage diastereomers are possible. Each of the six tetra‐aniline subcomponents investigated in this work assembled with zinc(II) and 2‐formylpyridine in acetonitrile into a single Zn<jats:sub>8</jats:sub>L<jats:sub>6</jats:sub>pseudo‐cube diastereomer, however. Each product corresponded to one of four diastereomeric configurations, with<jats:italic>T</jats:italic>,<jats:italic>T</jats:italic><jats:sub>h</jats:sub>,<jats:italic>S</jats:italic><jats:sub>6</jats:sub>or<jats:italic>D</jats:italic><jats:sub>3</jats:sub>symmetry. The preferred diastereomer for a given tetra‐aniline subcomponent was shown to be dependent on its aspect ratio and conformational flexibility. Analysis of computationally modeled individual faces or whole pseudo‐cubes provided insight as to why the observed diastereomers were favored.</jats:p>

Journal article

Anipa V, Tarzia A, Jelfs KEE, Alexandrov EVV, Addicoat MAAet al., 2023, Pore topology analysis in porous molecular systems, ROYAL SOCIETY OPEN SCIENCE, Vol: 10, ISSN: 2054-5703

Journal article

Bennett S, Jelfs KE, 2023, Porous Molecular Materials: Exploring Structure and Property Space with Software and Artificial Intelligence, AI-Guided Design and Property Prediction for Zeolites and Nanoporous Materials, Pages: 251-282, ISBN: 9781119819752

Porous molecular materials exhibit permanent porosity in the solid-state; however, unlike network materials such as metal–organic frameworks (MOFs) and zeolites, porous molecular materials lack a continuous network of covalent bonds but are instead formed from the self-assembly of discrete molecules. Porous molecular materials achieve porosity through either an internal cavity in the molecule (intrinsic porosity) or through inefficient packing in the solid-state, such that the molecule is unable to pack in a way that removes all void space (extrinsic porosity). The focus of this chapter will be the application of computational techniques to rationalize the structures and properties of porous molecular materials, including the development of software and artificial intelligence techniques to assist in the understanding and discovery of these systems. The chapter will include a discussion of examples of experimental realization of computational predictions, as well as an analysis of the challenges associated with accelerating the discovery of these materials using artificial intelligence.

Book chapter

Jelfs KE, 2022, Computational modeling to assist in the discovery of supramolecular materials, ANNALS OF THE NEW YORK ACADEMY OF SCIENCES, Vol: 1518, Pages: 106-119, ISSN: 0077-8923

Journal article

Wolpert EHH, Jelfs KEE, 2022, Coarse-grained modelling to predict the packing of porous organic cages, CHEMICAL SCIENCE, Vol: 13, Pages: 13588-13599, ISSN: 2041-6520

Journal article

Wade J, Salerno F, Kilbride R, Kim DK, Schmidt J, Smith J, LeBlanc L, Wolpert E, Adeleke A, Johnson E, Nelson J, Mori T, Jelfs K, Heutz S, Fuchter Met al., 2022, Controlling anisotropic properties by manipulating the orientation of chiral small molecules, Nature Chemistry, Vol: 14, Pages: 1383-1389, ISSN: 1755-4330

Chiral π-conjugated molecules bring new functionality to technological applications and represent an exciting, rapidly expanding area of research. Their functional properties, such as the absorption and emission of circularly polarised light or the transport of spin-polarised electrons, are highly anisotropic. As a result, the orientation of chiral molecules criticallydetermines the functionality and efficiency of chiral devices. Here we present a strategy to control the orientation of a small chiral molecule (2,2’-dicyano[6]helicene, CN6H): the use of organic and inorganic templating layers. Such templating layers can either force CN6H molecules to adopt a face-on orientation and self-assemble into upright supramolecular columns oriented with their helical axis perpendicular to the substrate, or an edge-onorientation with parallel-lying supramolecular columns. Through such control, we show that low- and high-energy chiroptical responses can be independently ‘turned on’ or ‘turned off’. The templating methodologies described here provide a simple way to engineer orientational control, and by association, anisotropic functional properties of chiral molecular systems for a range of emerging technologies.

Journal article

Li R-J, Tarzia A, Posligua V, Jelfs KE, Sanchez N, Marcus A, Baksi A, Clever GH, Fadaei-Tirani F, Severin Ket al., 2022, Orientational self-sorting in cuboctahedral Pd cages, CHEMICAL SCIENCE, Vol: 13, Pages: 11912-11917, ISSN: 2041-6520

Journal article

Mroz AM, Posligua V, Tarzia A, Wolpert EH, Jelfs KEet al., 2022, Into the Unknown: How Computation Can Help Explore Uncharted Material Space, JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, Vol: 144, Pages: 18730-18743, ISSN: 0002-7863

Journal article

Fleck-Kunde T, Wolpert EH, Zur LZ, Oestreich R, Janiak C, Jelfs KE, Schmidt BMet al., 2022, Observation of Rare Tri <sup>6</sup>di <sup>9</sup>Imine Cages Using Highly Fluorinated Building Blocks, Organic Materials, Vol: 4, Pages: 255-260

The first synthesis of organic Tri6Di9 cages is presented. Two structurally distinct Tri6Di9 cages were synthesised by combining a highly fluorinated aldehyde with two ditopic amines. Although the pure compounds could not be isolated despite many attempts, the information obtained is critical for the future design of large supramolecular structures. Computational and experimental methods indicate that the addition of perfluorinated aromatic linkers in the assembly of porous organic cages opens up new possibilities for influencing the reaction pathway towards rare and unknown structures.

Journal article

Bechis I, Sapnik AF, Tarzia A, Wolpert EH, Addicoat MA, Keen DA, Bennett TD, Jelfs KEet al., 2022, Modeling the Effect of Defects and Disorder in Amorphous Metal-Organic Frameworks, CHEMISTRY OF MATERIALS, ISSN: 0897-4756

Journal article

Ess DH, Jelfs KE, Kulik HJ, 2022, Chemical design by artificial intelligence, JOURNAL OF CHEMICAL PHYSICS, Vol: 157, ISSN: 0021-9606

Journal article

Wang A, Tan R, Breakwell C, Wei X, Fan Z, Ye C, Malpass-Evans R, Liu T, Zwijnenburg M, Jelfs K, McKeown N, Chen J, Song Qet al., 2022, Solution-processable redox-active polymers of intrinsic microporosity for electrochemical energy storage, Journal of the American Chemical Society, Vol: 144, Pages: 17198-17208, ISSN: 0002-7863

Redox-active organic materials have emerged as promising alternatives to conventional inorganicelectrode materials in electrochemical devices for energy storage. However, the deployment of redoxactive organic materials in practical lithium-ion battery devices is hindered by their undesired solubilityin electrolyte solvents, sluggish charge transfer and mass transport, as well as processing complexity.Here, we report a new molecular engineering approach to prepare redox-active polymers of intrinsicmicroporosity (PIMs) that possess an open network of sub-nanometer pores and abundant accessiblecarbonyl-based redox sites for fast lithium-ion transport and storage. Redox-active PIMs can be solutionprocessed into thin films and polymer-carbon composites with a homogeneously dispersedmicrostructure, while remaining insoluble in electrolyte solvents. Solution-processed redox-active PIMelectrodes demonstrate improved cycling performance in lithium-ion batteries with no apparent capacitydecay. Redox-active PIMs with combined properties of intrinsic microporosity, reversible redox activityand solution processability may have broad utility in a variety of electrochemical devices for energystorage, sensors and electronic applications.

Journal article

Ye C, Tan R, Wang A, Chen J, Comesaña Gándara B, Breakwell C, Alvarez-Fernandez A, Fan Z, Weng J, Bezzu CG, Guldin S, Brandon N, Kucernak A, Jelfs K, McKeown N, Song Qet al., 2022, Long-life aqueous organic redox flow batteries enabled by amidoxime-functionalized ion-selective polymer membranes, Angewandte Chemie International Edition, Vol: 61, ISSN: 1433-7851

Redox flow batteries (RFBs) based on aqueous organic electrolytes are a promising technology for safe and cost-effective large-scale electrical energy storage. Membrane separators are a key component in RFBs, allowing fast conduction of charge-carrier ions but minimizing the cross-over of redox-active species. Here, we report the molecular engineering of amidoxime-functionalized polymers of intrinsic microporosity (AO-PIMs) by tuning their polymer chain topology and pore architecture to optimize membrane ion transport selectivity. AO-PIM membranes are integrated with three emerging aqueous organic flow battery chemistries, and the synergetic integration of ion-selective membranes with molecular engineered organic molecules in neutral-pH electrolytes leads to significantly enhanced cycling stability.

Journal article

Perez NH, Sherin PS, Posligua V, Greenfield JL, Fuchter MJ, Jelfs KE, Kuimova MK, Lewis JEMet al., 2022, Emerging properties from mechanical tethering within a post-synthetically functionalised catenane scaffold, Chemical Science, Vol: 13, Pages: 11368-11375, ISSN: 2041-6520

Maintaining close spatial proximity of functional moieties within molecular systems can result in fascinating emergent properties. Whilst much work has been done on covalent tethering of functional units for myriad applications, investigations into mechanically linked systems are relatively rare. Formation of the mechanical bond is usually the final step in the synthesis of interlocked molecules, placing limits on the throughput of functionalised architectures. Herein we present the synthesis of a bis-azide [2]catenane scaffold that can be post-synthetically modified using CuAAC ‘click’ chemistry. In this manner we have been able to access functionalised catenanes from a common precursor and study the properties of electrochemically active, emissive and photodimerisable units within the mechanically interlocked system in comparison to non-interlocked analogues. Our data demonstrates that the greater (co-)conformational flexibility that can be obtained with mechanically interlocked systems compared to traditional covalent tethers paves the way for developing new functional molecules with exciting properties.

Journal article

Wolpert E, Jelfs K, 2022, Coarse-grained modelling to predict the packing of porous organic cages

<jats:p>How molecules pack has vital ramifications for their applications as functional molecular materials. Small changes in a molecule’s functionality can lead to large, non-intuitive, changes in their global solid-state packing, resulting in difficulty in targeted design. Predicting the crystal structure of organic molecules from only their molecular structure is a well-known problem plaguing crystal engineering. Although relevant to the properties of many organic molecules, the packing behaviour of modular porous materials, such as porous organic cages (POCs), greatly impacts the properties of the material. We present a novel way of predicting the solid-state phase behaviour of POCs by using a simplistic model containing the dominant degrees of freedom driving crystalline phase formation. We employ coarse-grained simulations to systematically study how chemical functionality of pseudo-octahedral cages can be used to manipulate the solid-state phase formation of POCs. While presenting a lower computational cost route for predicting molecular crystal packing, coarse-grained models also allow for the development of design rules.</jats:p>

Journal article

Ye C, Wang A, Breakwell C, Tan R, Bezzu G, Hunter-Sellars E, Williams D, Brandon N, Klusener P, Kucernak A, Jelfs K, McKeown N, Song Qet al., 2022, Development of efficient aqueous organic redox flow batteries using ion-sieving sulfonated polymer membranes, Nature Communications, Vol: 13, ISSN: 2041-1723

Redox flow batteries using aqueous organic-based electrolytes are promising candidates for developing cost-effective grid-scale energy storage devices. However, a significant drawback of these batteries is the cross-mixing of active species through the membrane, which causes battery performance degradation. To overcome this issue, here we report size-selective ion-exchange membranes prepared by sulfonation of a spirobifluorene-based microporous polymer and demonstrate their efficient ion sieving functions in flow batteries. The spirobifluorene unit allows control over the degree of sulfonation to optimize the transport of cations, whilst the microporous structure inhibits the crossover of organic molecules via molecular sieving. Furthermore, the enhanced membrane selectivity mitigates the crossover-induced capacity decay whilst maintaining good ionic conductivity for aqueous electrolyte solution at pH 9, where the redox-active organic molecules show long-term stability. We also prove the boosting effect of the membranes on the energy efficiency and peak power density of the aqueous redox flow battery, which shows stable operation for about 120 h (i.e., 2100 charge-discharge cycles at 100 mA cm−2) in a laboratory-scale cell.

Journal article

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