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Crystal Growth & Design

Giuseppe Belletti, Hugo Meekes, Floris P J T Rutjes, Elias Vlieg
Temperature cycling, alongside Viedma ripening, has been established as a reliable method for deracemizing racemic mixtures of chiral compounds that crystallize as a conglomerate. Here we report that the speed of temperature cycling can be increased by using chiral additives. We also demonstrate that the chirality of the additive determines the final enantiomeric state of the solid phase. Viedma ripening experiments using equivalent conditions, with and without chiral additives, are always found to be slower...
November 7, 2018: Crystal Growth & Design
Willem J P van Enckevort, Wim L Noorduin, Sander Graswinckel, Paul Verwer, Elias Vlieg
A growth cell suitable for microscopic in situ observation of well-controlled crystal growth from the vapor phase is used to study the heteroepitaxial growth of anthraquinone crystals on a (100) NaCl substrate. In this, the morphology, orientation, nucleation, and growth rate of the crystals is studied as a function of driving force, Δμ/ kT . At the lowest Δμ/ kT , the crystals are block-shaped and show no preferential orientation with respect to the substrate. Increasing the driving force leads to the growth of oriented block- and needle-shaped crystals, which nucleate from macrosteps on the substrate...
September 5, 2018: 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
Ida Mattsson, Manu Lahtinen, Anssi Peuronen, Abhijit Sau, Andreas Gunell, Tiina Saloranta-Simell, Reko Leino
The major diastereomer formed in the Barbier-type metal-mediated allylation of d-mannose has previously been shown to adopt a perfectly linear conformation, both in solid state and in solution, resulting in the formation of hydrogen-bonded networks and subsequent aggregation from aqueous solution upon stirring. Here, a comprehensive study of the solid state structure of both the allylated d-mannose and its racemic form has been conducted. The binary melting point diagram of the system was determined by differential scanning calorimetry analysis, and the obtained results, along with structure determination by single crystal X-ray diffraction, confirmed that allylated mannose forms a true racemate...
May 2, 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
Yitian M Chen, Naír Rodríguez-Hornedo
Weakly basic drugs are predisposed to order of magnitude decreases in solubility and dissolution as pH increases from 1 to 7 along the gastrointestinal tract. Such behavior is known to be detrimental to drug absorption. The work presented here shows how cocrystals of basic drugs with acidic coformers can mitigate these negative effects. Cocrystals of ketoconazole (KTZ) with adipic, fumaric, and succinic acids exhibit a parabolic solubility dependence on pH such that with increasing pH, solubility decreases, reaches a minimum, and increases...
March 7, 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
Mireille M H Smets, Mateusz B Pitak, Joseph Cadden, Vincent R Kip, Gilles A de Wijs, Ernst R H van Eck, Paul Tinnemans, Hugo Meekes, Elias Vlieg, Simon J Coles, Herma M Cuppen
The rich landscape of enantiotropically related polymorphic forms and their solid-state phase transitions of dl-2-aminoheptanoic acid (dl-AHE) has been explored using a range of complementary characterization techniques, and is largely exemplary of the polymorphic behavior of linear aliphatic amino acids. As many as five new polymorphic forms were found, connected by four fully reversible solid-state phase transitions. Two low temperature forms were refined in a high Z ' crystal structure, which is a new phenomenon for linear aliphatic amino acids...
January 3, 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
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