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Crystal Growth & Design

Thijs van Westen, Robert D Groot
We study the effect of temperature cycling on the rate of Ostwald ripening (or coarsening) of spherical particles dispersed in a binary solution. A widespread view, which states a temperature cycle generally enhances the rate of Ostwald ripening by first dissolving the smallest particles (heating) and then regrowing the dissolved amount of material on the remaining particles (cooling), is shown to be inadequate as it does not include transient effects. On the basis of a simulation method that assumes mass transfer as the limiting growth mechanism, we show that each temperature cycle is followed by a significant relaxation of the particle-size distribution, during which the number of particles remains constant, and the average particle size decreases ...
September 5, 2018: Crystal Growth & Design
Stan F S P Looijmans, Dario Cavallo, Lian Yu, Gerrit W M Peters
Cross-nucleation is defined as the nucleation of one polymorph on the surface of another polymorph of the same substance. Although the description of this particular form of heterogeneous nucleation is mainly phenomenological, recently dedicated quantitative studies are performed on several systems. In this work we propose a model framework that captures the phenomenon of cross-nucleation for a spherulitic seed-surface geometry, as well as the kinetic competition between the seed growth and the cross-nucleus formation, by the introduction of a tangential growth rate of the daughter polymorph...
July 5, 2018: Crystal Growth & Design
Paul A Vermeulen, Joost Calon, Gert H Ten Brink, Bart J Kooi
Reversible amorphous-crystalline phase transitions are studied using complementary ultrafast differential scanning calorimetry and transmission electron microscopy techniques, which together allow a wealth of thermal and structural properties to be determined. The SeTe(As) system is investigated because these chalcogenide based materials have favorable properties as a phase-change memory material and in optical systems. Using calorimetry, we find that the addition of 10 at. % As to SeTe alloys strongly increases their glass forming ability, increasing both glass transition and crystallization temperatures while reducing critical quench rate...
June 6, 2018: Crystal Growth & Design
Jian Lü, Cristina Perez-Krap, Fabien Trousselet, Yong Yan, Nada H Alsmail, Bahar Karadeniz, Nicholas M Jacques, William Lewis, Alexander J Blake, François-Xavier Coudert, Rong Cao, Martin Schröder
Controlled assembly of two-dimensional (2D) supramolecular organic frameworks (SOFs) has been demonstrated through a binary strategy in which 1,4-bis-(4-(3,5-dicyano-2,6-dipyridyl)pyridyl)naphthalene ( 2 ), generated in situ by oxidative dehydrogenation of 1,4-bis-(4-(3,5-dicyano-2,6-dipyridyl)dihydropyridyl)naphthalene ( 1 ), is coupled in a 1:1 ratio with terphenyl-3,3',4,4'-tetracarboxylic acid ( 3 ; to form SOF-8 ), 5,5'-(anthracene-9,10-diyl)diisophthalic acid ( 4 ; to form SOF-9 ), or 5,5'-bis-(azanediyl)-oxalyl-diisophthalic acid ( 5 ; to form SOF-10 )...
April 4, 2018: Crystal Growth & Design
Thijs van Westen, Robert D Groot
The quality of stored frozen products such as foods and biomaterials generally degrades in time due to the growth of large ice crystals by recrystallization. While there is ample experimental evidence that recrystallization within such products (or model systems thereof) is often dominated by diffusion-limited Ostwald ripening, the application of Ostwald-ripening theories to predict measured recrystallization rates has only met with limited success. For a model system of polycrystalline ice within an aqueous solution of sugars, we here show recrystallization rates can be predicted on the basis of Ostwald ripening theory, provided (1) the theory accounts for the fact the solution can be nonideal, nondilute and of different density than the crystals, (2) the effect of ice-phase volume fraction on the diffusional flux of water between crystals is accurately described, and (3) all relevant material properties (involving binary Fick diffusion coefficients, the thermodynamic factor of the solution, and the surface energy of ice) are carefully estimated...
April 4, 2018: Crystal Growth & Design
Senja Barthel, Eugeny V Alexandrov, Davide M Proserpio, Berend Smit
We consider two metal-organic frameworks as identical if they share the same bond network respecting the atom types. An algorithm is presented that decides whether two metal-organic frameworks are the same. It is based on distinguishing structures by comparing a set of descriptors that is obtained from the bond network. We demonstrate our algorithm by analyzing the CoRe MOF database of DFT optimized structures with DDEC partial atomic charges using the program package ToposPro.
March 7, 2018: Crystal Growth & Design
Eleanor R Townsend, Willem J P van Enckevort, Paul Tinnemans, Melian A R Blijlevens, Jan A M Meijer, Elias Vlieg
A multitude of ultrathin crystal needles are formed during the evaporation of saturated aqueous NaCl solution droplets in the presence of amide containing additives. The needles are as small as 300 nm wide and 100-1000 μm in length. Heating experiments, X-ray diffraction, and energy dispersive X-ray spectroscopy showed that the needles are cubic sodium chloride crystals with the needle length direction pointing toward [100]. This shape, not expected for the 43̅ m point group symmetry of NaCl, has been explained using a model, based on tip formation by initial morphological instability followed by time dependent adsorption of additive molecules blocking the growth of the needle side faces...
February 7, 2018: Crystal Growth & Design
M M H Smets, G Baaklini, A Tijink, L Sweers, C H F Vossen, C Brandel, H Meekes, H M Cuppen, G Coquerel
Tailor-made additives can prove an effective method to prolong the lifetime of metastable forms of pharmaceutical compounds by surface stabilization. Pyrazinamide (PZA) is a pharmaceutical compound with four polymorphic forms. The high temperature γ form, which can be produced by spray drying or sublimation growth, is metastable at room temperature and transforms within days when produced by spray drying, and within several months up to years for single crystals produced by sublimation. However, when PZA is cospray dried with 1,3-dimethylurea (DMU), it has been reported to remain in its γ form for several years...
February 7, 2018: Crystal Growth & Design
Bin Chen, Dennis de Wal, Gert H Ten Brink, George Palasantzas, Bart J Kooi
Chalcogenide-based phase change materials (PCMs) are promising candidates for the active element in novel electrical nonvolatile memories and have been applied successfully in rewritable optical disks. Nanostructured PCMs are considered as the next generation building blocks for their low power consumption, high storage density, and fast switching speed. Yet their crystallization kinetics at high temperature, the rate-limiting property upon switching, faces great challenges due to the short time and length scales involved...
February 7, 2018: Crystal Growth & Design
Christopher R Taylor, Graeme M Day
We present a periodic density functional theory study of the stability of 350 organic cocrystals relative to their pure single-component structures, the largest study of cocrystals yet performed with high-level computational methods. Our calculations demonstrate that cocrystals are on average 8 kJ mol-1 more stable than their constituent single-component structures and are very rarely (<5% of cases) less stable; cocrystallization is almost always a thermodynamically favorable process. We consider the variation in stability between different categories of systems-hydrogen-bonded, halogen-bonded, and weakly bound cocrystals-finding that, contrary to chemical intuition, the presence of hydrogen or halogen bond interactions is not necessarily a good predictor of stability...
February 7, 2018: Crystal Growth & Design
Wester de Poel, Joris A W Münninghoff, Johannes A A W Elemans, Willem J P van Enckevort, Alan E Rowan, Elias Vlieg
Surfaces with controllable topography and chemistry were prepared to act as substrates for protein crystallization, in order to investigate the influence of these surface properties on the protein crystallization outcome. Three different methods were investigated to deposit 1,3,5-tris(10-carboxydecyloxy)benzene (TCDB) on a muscovite mica substrate to find the best route for controlled topography. Of these three, sublimation worked best. Contact angle measurements revealed that the surfaces with short exposure to the TCDB vapor (20 min or less) are hydrophilic, while surfaces exposed for 30 min or longer are hydrophobic...
February 7, 2018: Crystal Growth & Design
Rana Hussein, Mohamed Ibrahim, Ruchira Chatterjee, Leighton Coates, Frank Müh, Vittal K Yachandra, Junko Yano, Jan Kern, Holger Dobbek, Athina Zouni
Photosystem II (PSII) catalyzes the photo-oxidation of water to molecular oxygen and protons. The water splitting reaction occurs inside the oxygen-evolving complex (OEC) via a Mn4 CaO5 cluster. To elucidate the reaction mechanism, detailed structural information for each intermediate state of the OEC is required. Despite the current high-resolution crystal structure of PSII at 1.85 Å and other efforts to follow the structural changes of the Mn4 CaO5 cluster using X-ray free electron laser (XFEL) crystallography in addition to spectroscopic methods, many details about the reaction mechanism and conformational changes in the catalytic site during water oxidation still remain elusive...
January 3, 2018: Crystal Growth & Design
Wester de Poel, Paul T Tinnemans, Alexander L L Duchateau, Maarten Honing, Floris P J T Rutjes, Elias Vlieg, René de Gelder
The use of an achiral metal-organic framework for structure determination of chiral compounds is demonstrated for camphene and pinene. The structure of enantiopure β-pinene can be resolved using the crystalline sponge method. However, α-pinene cannot be resolved using enantiopure material alone because no ordering of guest molecules takes place in that case. Interestingly, enantiomeric pairs order inside the channels of the host framework when impure (+)-camphene is offered to the host, which is also the case when a racemic mixture of α-pinene is used...
January 3, 2018: Crystal Growth & Design
Rahimah Othman, Goran T Vladisavljević, Elena Simone, Zoltan K Nagy, Richard G Holdich
Microcrystals of piroxicam (PRX) monohydrate with a narrow size distribution were prepared from acetone/PRX solutions by antisolvent crystallization via metallic membranes with ordered pore arrays. Crystallization was achieved by controlled addition of the feed solution through the membrane pores into a well-stirred antisolvent. A complete transformation of an anhydrous form I into a monohydrate form of PRX was confirmed by Raman spectroscopy and differential scanning calorimetry. The size of the crystals was 7-34 μm and was controlled by the PRX concentration in the feed solution (15-25 g L-1 ), antisolvent/solvent volume ratio (5-30), and type of antisolvent (Milli-Q water or 0...
December 6, 2017: Crystal Growth & Design
Maximilian O Besenhard, Peter Neugebauer, Otto Scheibelhofer, Johannes G Khinast
Size, shape, and polymorphic form are the critical attributes of crystalline particles and represent the major focus of today's crystallization process design. This work demonstrates how crystal properties can be tuned efficiently in solution via a tubular crystallizer that facilitates rapid temperature cycling. Controlled crystal growth, dissolution, and secondary nucleation allow a precise control of the crystal size and shape distribution, as well as polymorphic composition. Tubular crystallizers utilizing segmented flow such as the one presented in our work can provide plug flow characteristics, fast heating and cooling, allowing for rapid changes of the supersaturation...
December 6, 2017: Crystal Growth & Design
Leyla-Cann Sögütoglu, Martin Lutz, Hugo Meekes, René de Gelder, Elias Vlieg
The crystal structure of para -methyl-l-phenylalanine at 230 K resembles that of the para-fluorinated analogue from the literature but is commensurately modulated with seven molecules in the asymmetric unit ( Z ' = 7). At 100 K, the superstructure loses its modulation, leading to a unit cell with Z ' = 1, with clear disorder in the phenyl ring orientations. The methyl-substituent in para -methyl-l-phenylalanine has, in contrast to fluorine, no polar interactions with protons of neighboring molecules, which might allow for the well-defined modulation of the crystal structure at 230 K...
December 6, 2017: Crystal Growth & Design
Anthonius H J Engwerda, Pim van Schayik, Henjo Jagtenberg, Hugo Meekes, Floris P J T Rutjes, Elias Vlieg
The scope of Viedma ripening and temperature cycling with respect to chiral molecules has remained mostly limited to molecules with a single stereogenic center, while racemization proceeds through inversion at that particular stereocenter. In this article we demonstrate for the first time that atropisomers, chiral rotamers that possess an axis of chirality, can be successfully deracemized in the solid phase by either applying temperature cycling or Viedma ripening.
October 4, 2017: Crystal Growth & Design
Doris E Braun, Sreenivas R Lingireddy, Mark D Beidelschies, Rui Guo, Peter Müller, Sarah L Price, Susan M Reutzel-Edens
The solid form landscape of 5-HT2a antagonist 3-(4-(benzo[d]isoxazole-3-yl)piperazin-1-yl)-2,2-dimethylpropanoic acid hydrochloride (B5HCl) proved difficult to establish. Many crystalline materials were produced by solid form screening, but few forms readily grew high quality crystals to afford a clear picture or understanding of the solid form landscape. Careful control of crystallization conditions, a range of experimental methods, computational modeling of solvate structures, and crystal structure prediction were required to see potential arrangements of the salt in its crystal forms...
October 4, 2017: Crystal Growth & Design
Kyle A Nordquist, Kevin M Schaab, Jierui Sha, Andrew H Bond
Systematic surface energy modifications to glass substrates can induce nucleation and improve crystallization outcomes for small molecule active pharmaceutical ingredients (APIs) and proteins. A comparatively broad probe for function is presented in which various APIs, proteins, organic solvents, aqueous media, surface energy motifs, crystallization methods, form factors, and flat and convex surface energy modifications were examined. Replicate studies ( n ≥ 6) have demonstrated an average reduction in crystallization onset times of 52(4)% (alternatively 52 ± 4%) for acetylsalicylic acid from 91% isopropyl alcohol using two very different techniques: bulk cooling to 0 °C using flat surface energy modifications or microdomain cooling to 4 °C from the interior of a glass capillary having convex surface energy modifications that were immersed in the solution...
August 2, 2017: Crystal Growth & Design
Anthonius H J Engwerda, Niels Koning, Paul Tinnemans, Hugo Meekes, F Matthias Bickelhaupt, Floris P J T Rutjes, Elias Vlieg
Despite the importance of enantiopure chiral sulfoxides, few methods exist that allow for their deracemization. Here, we show that an enantiopure sulfoxide can be produced from the corresponding racemate using Viedma ripening involving rearrangement-induced racemization. The suitable candidate for Viedma ripening was identified from a library of 24 chiral sulfoxides through X-ray structure determination. Starting from the racemic sulfoxide, an unprecedented application of a 2,3-sigmatropic rearrangement type racemization in a Viedma ripening process allowed for complete deracemization...
August 2, 2017: Crystal Growth & Design
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