ORCID Profile
0000-0001-8396-2771
Current Organisation
University of Southampton
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Wiley
Date: 17-08-2023
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C7CS00084G
Abstract: Composed from discrete units, porous molecular materials (PMMs) possess properties not observed for conventional, extended solids. Molecular simulations provide crucial understanding for the design and characterisation of these unique materials.
Publisher: Wiley
Date: 23-10-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8FD90030B
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C8FD90034E
Publisher: Proceedings of the National Academy of Sciences
Date: 30-05-2023
Abstract: Crystal structure prediction is becoming an increasingly valuable tool for assessing polymorphism of crystalline molecular compounds, yet invariably, it overpredicts the number of polymorphs. One of the causes for this overprediction is in neglecting the coalescence of potential energy minima, separated by relatively small energy barriers, into a single basin at finite temperature. Considering this, we demonstrate a method underpinned by the threshold algorithm for clustering potential energy minima into basins, thereby identifying kinetically stable polymorphs and reducing overprediction.
Publisher: American Chemical Society (ACS)
Date: 05-04-2016
DOI: 10.1021/JACS.6B01120
Abstract: Structures of the α and β phases of resorcinol, a major commodity chemical in the pharmaceutical, agrichemical, and polymer industries, were the first polymorphic pair of molecular crystals solved by X-ray analysis. It was recently stated that "no additional phases can be found under atmospheric conditions" (Druzbicki, K. et al. J. Phys. Chem. B 2015, 119, 1681). Herein is described the growth and structure of a new ambient pressure phase, ε, through a combination of optical and X-ray crystallography and by computational crystal structure prediction algorithms. α-Resorcinol has long been a model for mechanistic crystal growth studies from both solution and vapor because prisms extended along the polar axis grow much faster in one direction than in the opposite direction. Research has focused on identifying the absolute sense of the fast direction-the so-called "resorcinol riddle"-with the aim of identifying how solvent controls crystal growth. Here, the growth velocity dissymmetry in the melt is analyzed for the β phase. The ε phase only grows from the melt, concomitant with the β phase, as polycrystalline, radially growing spherulites. If the radii are polar, then the sense of the polar axis is an essential feature of the form. Here, this determination is made for spherulites of β resorcinol (ε, point symmetry 222, does not have a polar axis) with additives that stereoselectively modify growth velocities. Both β and ε have the additional feature that in idual radial lamellae may adopt helicoidal morphologies. We correlate the appearance of twisting in β and ε with the symmetry of twist-inducing additives.
Publisher: Wiley
Date: 03-05-2023
Abstract: Hydrogen‐bonded organic frameworks (HOFs) with low densities and high porosities are rare and challenging to design because most molecules have a strong energetic preference for close packing. Crystal structure prediction (CSP) can rank the crystal packings available to an organic molecule based on their relative lattice energies. This has become a powerful tool for the a priori design of porous molecular crystals. Previously, we combined CSP with structure‐property predictions to generate energy‐structure‐function (ESF) maps for a series of triptycene‐based molecules with quinoxaline groups. From these ESF maps, triptycene trisquinoxalinedione (TH5) was predicted to form a previously unknown low‐energy HOF (TH5‐A) with a remarkably low density of 0.374 g cm −3 and three‐dimensional (3D) pores. Here, we demonstrate the reliability of those ESF maps by discovering this TH5‐A polymorph experimentally. This material has a high accessible surface area of 3,284 m 2 g −1 , as measured by nitrogen adsorption, making it one of the most porous HOFs reported to date.
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/D0TA00219D
Abstract: A hydrogen-bonded organic framework is an effective photocatalyst for producing hydrogen from water. Its crystal structure is key to its activity a chemically identical, amorphous version is almost inactive, as rationalized by crystal structure prediction.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6SM00607H
Abstract: Eighteen N-aryl-N'-alkyl urea gelators were synthesised in order to understand the effect of head substituents on gelation performance. Minimum gelation concentration values obtained from gel formation studies were used to rank the compounds and revealed the remarkable performance of 4-methoxyphenyl urea gelator 15 in comparison to 4-nitrophenyl analogue 14, which could not be simply ascribed to substituent effects on the hydrogen bonding capabilities of the urea protons. Crystal structure prediction calculations indicated alternative low energy hydrogen bonding arrangements between the nitro group and urea protons in gelator 14, which were supported experimentally by NMR spectroscopy. As a consequence, it was possible to relate the observed differences to interference of the head substituents with the urea tape motif, disrupting the order of supramolecular packing. The combination of unbiased structure prediction calculations with NMR is proposed as a powerful approach to investigate the supramolecular arrangement in gel fibres and help understand the relationships between molecular structure and gel formation.
Publisher: Wiley
Date: 03-05-2023
Abstract: Hydrogen‐bonded organic frameworks (HOFs) with low densities and high porosities are rare and challenging to design because most molecules have a strong energetic preference for close packing. Crystal structure prediction (CSP) can rank the crystal packings available to an organic molecule based on their relative lattice energies. This has become a powerful tool for the a priori design of porous molecular crystals. Previously, we combined CSP with structure‐property predictions to generate energy‐structure‐function (ESF) maps for a series of triptycene‐based molecules with quinoxaline groups. From these ESF maps, triptycene trisquinoxalinedione (TH5) was predicted to form a previously unknown low‐energy HOF (TH5‐A) with a remarkably low density of 0.374 g cm −3 and three‐dimensional (3D) pores. Here, we demonstrate the reliability of those ESF maps by discovering this TH5‐A polymorph experimentally. This material has a high accessible surface area of 3,284 m 2 g −1 , as measured by nitrogen adsorption, making it one of the most porous HOFs reported to date.
Publisher: American Chemical Society (ACS)
Date: 16-05-2019
DOI: 10.26434/CHEMRXIV.8135267.V1
Abstract: Organic molecules tend to close pack to form dense structures when they are crystallized from organic solvents. Porous molecular crystals defy this rule: they typically crystallize with lattice solvent in the interconnected pores. However, the design and discovery of such structures is often challenging and time consuming, in part because it is difficult to predict solvent effects on crystallization. Here, we combine crystal structure prediction (CSP) with a high-throughput crystallization screening method to accelerate the discovery of stable hydrogen-bonded frameworks. We exemplify this strategy by finding new phases of two well-studied molecules in a computationally targeted way. Specifically, we find a new porous polymorph of trimesic acid, δ- TMA , that has a guest free hexagonal pore structure, as well as three new solvent-stabilized diamondoid frameworks of adamantane-1,3,5,7-tetracarboxylic acid ( ADTA ).
Publisher: Wiley
Date: 14-08-2023
Publisher: American Chemical Society (ACS)
Date: 27-06-2020
DOI: 10.1021/JACS.0C04885
Publisher: Wiley
Date: 09-10-2018
Abstract: Dispersion-corrected density-functional theory (DFT-D) methods have become the workhorse of many computational protocols for molecular crystal structure prediction due to their efficiency and convenience. However, certain limitations of DFT, such as delocalisation error, are often overlooked or are too expensive to remedy in solid-state applications. This error can lead to artificial stabilisation of charge transfer and, in this work, it is found to affect the correct identification of the protonation site in multicomponent acid-base crystals. As such, commonly used DFT-D methods cannot be applied with any reliability to the study of acid-base co-crystals or salts, while hybrid functionals remain too restrictive for routine use. This presents an impetus for the development of new functionals with reduced delocalisation error for solid-state applications the structures studied herein constitute an excellent benchmark for this purpose.
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2CC04682B
Abstract: This paper crosses the area of computational chemistry, supramolecular chemistry and materials to develop new porous materials.
Publisher: Royal Society of Chemistry (RSC)
Date: 2018
DOI: 10.1039/C7SC04665K
Abstract: Polymorphism is common in molecular crystals, whose energy landscapes usually contain many structures with similar stability, but very different physical–chemical properties. Machine-learning techniques can accelerate the evaluation of energy and properties by side-stepping accurate but demanding electronic-structure calculations, and provide a data-driven classification of the most important molecular packing motifs.
Publisher: Royal Society of Chemistry (RSC)
Date: 2019
DOI: 10.1039/C9SC02832C
Abstract: New crystal forms of two well-studied organic molecules are identified in a computationally targeted way, by combining structure prediction with a robotic crystallisation screen, including a ‘hidden’ porous polymorph of trimesic acid.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Graeme Day.