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Crystal Engineering (crystal + engineering)
Selected AbstractsCrystal Structures of Conformationally Locked Cyclitols: An Analysis of Hydrogen-Bonded Architectures and their Implications in Crystal EngineeringEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2007Goverdhan Mehta Abstract A qualitative study has been carried out on selected polycyclitols to evaluate the potential of conformational locking of hydroxy groups in lending predictability to the O,H···O hydrogen-bonding network observed in the crystal structures of such compounds. The polycyclitols employed in this study are conformationally locked with all the hydroxy groups destined to be axial owing to the trans ring fusion(s) in the polycyclic carbon framework. The consequent formation of intramolecular O,H···O hydrogen bonds between the 1,3- syn diaxial hydroxy groups now permits any packing pattern in the polycyclitols to be described in terms of a small group of intramolecularly bonded molecular motifs linked to their respective neighbors by four O,H···O bonds. By using this model and the results of CSD analyses of polyols as a guide, the O,H···O hydrogen-bonded packing motifs most likely to be observed in the crystal structure of each polycyclitol were proposed and compared with those obtained experimentally. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Reversed Crystal Growth: Implications for Crystal EngineeringADVANCED MATERIALS, Issue 28 2010Wuzong Zhou Abstract The discovery of reversed crystal growth routes in zeolite analcime and zeolite A implies that crystal growth does not always follow the classic theory established 100 years ago. Aggregation of nanoparticles may dominate in the early stages of crystal growth, followed by surface crystallization, and then extension from surface to core of the disordered aggregates. A perfect polyhedral morphology can be developed in a thin surface crystalline layer of a particle with a disordered core. Evidence of such a novel crystal growth phenomenon can be also found in many other materials. This article highlights the recent achievements in this topic, which might have a significant impact on crystal engineering, materials science, and mineralogy. [source] Supramolecular Crystal Engineering at the Solid,Liquid Interface from First Principles: Toward Unraveling the Thermodynamics of 2D Self-AssemblyADVANCED MATERIALS, Issue 13 2009Carlos-Andres Palma Abstract The formation of highly ordered 2D supramolecular architectures self-assembled at the solid,solution interfaces is subject to complex interactions between the analytes, the solvent, and the substrate. These forces have to be mastered in order to regard self-assembly as an effective bottom-up approach for functional-device engineering. At such interfaces, prediction of the thermodynamics governing the formation of spatially ordered 2D arrangements is far from being fully understood, even for the physisorption of a single molecular component on the basal plane of a flat surface. Two recent contributions on controlled polymorphism and nanopattern formation render it possible to gain semi-quantitative insight into the thermodynamics of physisorption at interfaces, paving the way towards 2D supramolecular crystal engineering. Although in these two works different systems have been chosen to tackle such a complex task, authors showed that the chemical design of molecular building blocks is not the only requirement to fulfill when trying to preprogram self-assembled patterns at the solid,liquid interface. [source] Molecular Modeling in Crystal Engineering for Processing of Energetic MaterialsPROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2003Stéphane Bénazet Abstract Nowadays molecular modeling is available to explain molecular phenomena. This approach helps to compute crystal surface property effects that can be used both for morphology studies and optimal design of "bonding agents" to prevent filler-binder detachment. The principles of crystal growth and of interaction energy computing have been applied to Hexanitrohexaazaisowurtzitane (HNIW). Crystallization experiments validate our calculations. Three families of additives of crystal growth are distinguished: the retarding (and inhibitor) agents, the promoters and finally the "tailor-mades". Retarding and inhibitor agents are the most interesting one to find bonding agents. HNIW is used to present our methodology, but engineering using molecular modeling could be generalized to other fillers. [source] Titelbild: Two-Dimensional Crystal Engineering: A Four-Component Architecture at a Liquid,Solid Interface (Angew. Chem.ANGEWANDTE CHEMIE, Issue 40 200940/2009) Vier Komponenten bilden ein supramolekulares Muster auf atomar flachem Graphit, wie S. De,Feyter et,al. in ihrer Zuschrift auf S.,7489,ff. schildern. Durch einfaches Mischen der vier Komponenten in einem konventionellen Lösungsmittel und Auftropfen auf die Oberfläche entstehen Kagomé-Gitter mit spezifisch gebundenen Templatmolekülen. Die Strukturen wurden durch Rastertunnelmikroskopie an der Flüssig-fest-Grenzfläche aufgeklärt. [source] Two-Dimensional Crystal Engineering: A Four-Component Architecture at a Liquid,Solid Interface,ANGEWANDTE CHEMIE, Issue 40 2009Jinne Adisoejoso Glückliches Zusammentreffen: Zweidimensionale Vierkomponentenkristalle wurden an einer Flüssig-fest-Grenzfläche erzeugt und durch Rastertunnelmikroskopie visualisiert. Einfaches Mischen der vier Komponenten und Aufbringen der Lösung auf die Graphit-Oberfläche führen zur spontanen Selbstorganisation der 2D-Kristalle. Bestimmte Gastmoleküle erzeugen aus dem nichtporösen Netzwerk eine poröse Struktur, indem sie innerhalb der Poren adsorbiert werden. [source] Synthesis of m-Terphenyl Derivatives for Potential Use as Tectons in Crystal Engineering.CHEMINFORM, Issue 52 2003Ryan S. Wright Abstract For Abstract see ChemInform Abstract in Full Text. [source] ChemInform Abstract: Aurophilicity as a Cofactor in Crystal Engineering.CHEMINFORM, Issue 23 2002Au(I) Bimetallic Assembly., Dicyanoaurate(I) Anion as a Building Block in a Novel Co(II) Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Triple Hydrogen Bonds Direct Crystal Engineering of Metal-Assembled Complexes: The Effect of a Novel Organic,Inorganic Module on Supramolecular StructureCHEMISTRY - A EUROPEAN JOURNAL, Issue 22 2005Keiichi Adachi Dr. Abstract Novel triply hydrogen bonded suprastructures based on [M(tdpd)2(L)2]2, (H2tdpd=1,4,5,6-tetrahydro-5,6-dioxo-2,3-pyrazinedicarbonitrile, L=solvent) and melamine-analogous cations have been synthesized and characterized. The use of anions containing two AAA sets from [M(tdpd)2(L)2]2, together with cations containing one DDD set (A=hydrogen-bond acceptor, D=hydrogen-bond donor) leads to the formation of complementary triply hydrogen bonded modules in the solid state. In all cases, the building module is further extended via additional hydrogen-bonding interactions to produce a tape, and tapes are assembled into sheets. These results show that a hydrogen-bonded module consisting of different kinds of building blocks, one of which is a metal complex that includes hydrogen-bond acceptor sites and the other is a hydrogen-bond donor molecule, will be attractive for constructing metal-containing supramolecular systems by the self-assembly technique. [source] Engineering of pharmaceutical materials: An industrial perspectiveJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2008Kwok Chow Abstract Crystal engineering provides a rational approach to solving formulation, processing and product performance problems. This review discusses how the concept of crystal engineering can be judiciously utilized to manipulate the solid-state properties of drugs and excipients for successful pharmaceutical formulation and process development. Existing and emerging manufacturing as well as co-processing technologies being applied in the pharmaceutical industry are also presented together with selected examples of crystal form design, crystal form selection and crystal modifications for illustration purposes. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 2855,2877, 2008 [source] Crystal engineering with heteroboranes.ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2003The title compound, 1,2-(COOH)2 -1,2- closo -C2B10H10·0.5C2H6O or C4H12B10O4·0.5C2H6O, forms a tetramer by incorporating ethanol (solvent) molecules through hydrogen bonding. Two eight-membered rings [graph set R(8)] are formed by hydrogen bonding between two carboxylic acid groups, whereas two ten-membered rings [R(10)] are formed by hydrogen bonding between two carboxylic acid groups and the OH group of an ethanol molecule (solvent). Two crystallographically independent tetramers are present in the crystal structure. [source] Reversed Crystal Growth: Implications for Crystal EngineeringADVANCED MATERIALS, Issue 28 2010Wuzong Zhou Abstract The discovery of reversed crystal growth routes in zeolite analcime and zeolite A implies that crystal growth does not always follow the classic theory established 100 years ago. Aggregation of nanoparticles may dominate in the early stages of crystal growth, followed by surface crystallization, and then extension from surface to core of the disordered aggregates. A perfect polyhedral morphology can be developed in a thin surface crystalline layer of a particle with a disordered core. Evidence of such a novel crystal growth phenomenon can be also found in many other materials. This article highlights the recent achievements in this topic, which might have a significant impact on crystal engineering, materials science, and mineralogy. [source] Supramolecular Crystal Engineering at the Solid,Liquid Interface from First Principles: Toward Unraveling the Thermodynamics of 2D Self-AssemblyADVANCED MATERIALS, Issue 13 2009Carlos-Andres Palma Abstract The formation of highly ordered 2D supramolecular architectures self-assembled at the solid,solution interfaces is subject to complex interactions between the analytes, the solvent, and the substrate. These forces have to be mastered in order to regard self-assembly as an effective bottom-up approach for functional-device engineering. At such interfaces, prediction of the thermodynamics governing the formation of spatially ordered 2D arrangements is far from being fully understood, even for the physisorption of a single molecular component on the basal plane of a flat surface. Two recent contributions on controlled polymorphism and nanopattern formation render it possible to gain semi-quantitative insight into the thermodynamics of physisorption at interfaces, paving the way towards 2D supramolecular crystal engineering. Although in these two works different systems have been chosen to tackle such a complex task, authors showed that the chemical design of molecular building blocks is not the only requirement to fulfill when trying to preprogram self-assembled patterns at the solid,liquid interface. [source] Engineering of pharmaceutical materials: An industrial perspectiveJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2008Kwok Chow Abstract Crystal engineering provides a rational approach to solving formulation, processing and product performance problems. This review discusses how the concept of crystal engineering can be judiciously utilized to manipulate the solid-state properties of drugs and excipients for successful pharmaceutical formulation and process development. Existing and emerging manufacturing as well as co-processing technologies being applied in the pharmaceutical industry are also presented together with selected examples of crystal form design, crystal form selection and crystal modifications for illustration purposes. © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 2855,2877, 2008 [source] The role of specific interactions in crystalline complex formation.JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 5 200210-bis(4-bromophenyl)-, 10-dihydroanthracene with dimethyl sulfoxide, 10-dihydroxy-, Structural, thermochemical analysis of inclusion compounds of cis -, trans - Abstract Referring to a crucial problem in crystal engineering and co-crystallization of host,guest complexes, whether the non-covalent supramolecular interactions existing in a pre-crystalline solution state may determine the subsequent crystal structure, the particular inclusion properties of host compounds 1, cis - and 2, trans -9,10-bis(4-bromophenyl)-9,10-dihydroxy-9,10-dihydroanthracene, with dimethyl sulfoxide (DMSO) were studied by using x-ray structure analysis and calorimetric methods. Both hosts form crystalline inclusion complexes with DMSO showing 2:3 (1·DMSO) and 1:4 (2·DMSO) host:guest composition. The crystal structure of 1·DMSO (2:3) is dominated by a strong bifurcated acceptor-type H bond interaction involving 1 and one of the DMSO molecules. Titration calorimetric investigations in solution also confirm the formation of a stable 1·DMSO (1:1) complex unit, suggesting that for crystal nuclei of 1·DMSO (2:3) the pre-formed 1:1 host,guest complex is the relevant building block while the additional molecules of DMSO fill lattice voids. In contrast, compound 2 with a trans configuration of the two hydroxy groups gives much weaker complexation with DMSO in solution, which is in agreement with single H-bond interaction, also realized in the crystal structure of the respective inclusion complex. Thermal decomposition (TG,DSC) measurements of the crystalline complexes supply supporting data for these findings. Copyright © 2002 John Wiley & Sons, Ltd. [source] Engineering functional materials by halogen bondingJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2007Pierangelo Metrangolo Abstract Engineering functional materials endowed with unprecedented properties require the exploitation of new intermolecular interactions, which can determine the characteristics of the bulk materials. The great potential of Halogen Bonding (XB), namely any noncovalent interaction involving halogens as electron acceptors, in the design of new and high-value functional materials is now emerging clearly. This Highlight will give a detailed overview on the energetic and geometric features of XB, showing how some of them are quite constant in most of the formed supramolecular complexes (e.g., the angle formed by the covalent and the noncovalent bonds around the halogen atom), while some others depend strictly on the nature of the interacting partners. Then, several specific examples of halogen-bonded supramolecular architectures, whose structural aspects as well as applications in fields as diverse as enantiomers' separation, crystal engineering, liquid crystals, natural, and synthetic receptors, will be fully described. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: PolymChem 45: 1,15, 2007 [source] Structural stability and formability of ABO3 -type perovskite compoundsACTA CRYSTALLOGRAPHICA SECTION B, Issue 6 2007Huan Zhang On the basis of the bond-valence model (BVM) and structure-map technology, the structural stability and formability of ABO3 -type perovskite compounds were investigated in 376 ABO3 -type compounds. A new criterion of structural stability for ABO3 -type perovskite compounds has been established by the bond-valence calculated tolerance factors, which are in the range 0.822,1.139. All global instability indices for ABO3 -type perovskite compounds are found to be less than 1.2,v.u. (valence units) and increase with a decrease in oxidation state of the B cations (i.e. structural stability in the formation of an ideal cubic perovskite follows the order A+B5+O3 -type > A2+B4+O3 -type > A3+B3+O3 -type). Three new two-dimensional structure maps were constructed based on the ideal A,O and B,O bond distances derived from the BVM. These maps indicate the likelihood of particular perovskite compounds being formed. The present work enables novel perovskite and perovskite-related compounds to be explored by screening all the possible elemental combinations in future crystal engineering. [source] Tricaesium tris(oxalato-,2O1,O2)chromate(III) dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 6 2010Lee Martin The title compound, Cs3[Cr(C2O4)3]·2H2O, has been synthesized for the first time and the spatial arrangement of the cations and anions is compared with those of the other members of the alkali metal series. The structure is built up of alternating layers of either the d or l enantiomers of [Cr(oxalate)3]3,. Of note is that the distribution of the [Cr(oxalate)3]3, enantiomers in the Li+, K+ and Rb+ tris(oxalato)chromates differs from those of the Na+ and Cs+ tris(oxalato)chromates, and also differs within the corresponding BEDT-TTF [bis(ethylenedithio)tetrathiafulvalene] conducting salts. The use of tris(oxalato)chromate anions in the crystal engineering of BEDT-TTF salts is discussed, wherein the salts can be paramagnetic superconductors, semiconductors or metallic proton conductors, depending on whether the counter-cation is NH4+, H3O+, Li+, Na+, K+, Rb+ or Cs+. These materials can also be superconducting or semiconducting, depending on the spatial distribution of the d and l enantiomers of [Cr(oxalate)3]3,. [source] Hydrogen-bonded network in the trichloroacetate salts of 2-amino-5-chloropyridinium and 2-methyl-5-nitroanilinium monohydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Jan Janczak In the crystal structures of 2-amino-5-chloropyridinium trichloroacetate, C5H6ClN2+·C2Cl3O2,, (I), and 2-methyl-5-nitroanilinium trichloroacetate monohydrate, C7H9N2O2+·C2Cl3O2,·H2O, (II), the protonated planar 2-amino-5-chloropyridinium [in (I)] and 2-methyl-5-nitroanilinium [in (II)] cations interact with the oppositely charged trichloroacetate anions to form hydrogen-bonded one-dimensional chains in (I) and, together with water molecules, a three-dimensional network in (II). The crystals of (I) exhibit nonlinear optical properties. The second harmonic generation efficiency in relation to potassium dihydrogen phosphate is 0.77. This work demonstrates the usefulness of trichloroacetic acid in crystal engineering for obtaining new materials for nonlinear optics. [source] A three-dimensional hydrogen-bonded network in bis(4-hydroxyanilinium) selenate(VI) dihydrateACTA CRYSTALLOGRAPHICA SECTION C, Issue 3 2009Jan Janczak The title compound, 2C6H8NO+·SeO42,·2H2O, contains 4-hydroxyanilinium cations, selenate(VI) anions and water molecules. One of the two independent cations is nearly planar (excluding the ammonium H atoms), while the other is markedly nonplanar, with the hydroxy and ammonium groups displaced from the plane of the benzene ring. This results from the antiparallel orientation of the cations, which interact through oppositely polarized ammonium and hydroxy groups. Ionic and hydrogen-bonding interactions join the oppositely charged units into a three-dimensional network. This work demonstrates the usefulness of 4-aminophenol in the crystal engineering of organic,inorganic hybrid compounds. [source] Arene,perfluoroarene interactions in crystal engineering.ACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2001In the title complex, C6F6·C14H12, nearly parallel molecules of trans -stilbene and librationally disordered hexafluorobenzene form a mixed stack, with each molecule lying on an independent inversion centre. Adjacent stacks pack together in a herring-bone manner. [source] Systematic study on crystal-contact engineering of diphthine synthase: influence of mutations at crystal-packing regions on X-ray diffraction qualityACTA CRYSTALLOGRAPHICA SECTION D, Issue 10 2008Hisashi Mizutani It is well known that protein crystallizability can be influenced by site-directed mutagenesis of residues on the molecular surface of proteins, indicating that the intermolecular interactions in crystal-packing regions may play a crucial role in the structural regularity at atomic resolution of protein crystals. Here, a systematic examination was made of the improvement in the diffraction resolution of protein crystals on introducing a single mutation of a crystal-packing residue in order to provide more favourable packing interactions, using diphthine synthase from Pyrococcus horikoshii OT3 as a model system. All of a total of 21 designed mutants at 13 different crystal-packing residues yielded almost isomorphous crystals from the same crystallization conditions as those used for the wild-type crystals, which diffracted X-rays to 2.1,Å resolution. Of the 21 mutants, eight provided crystals with an improved resolution of 1.8,Å or better. Thus, it has been clarified that crystal quality can be improved by introducing a suitable single mutation of a crystal-packing residue. In the improved crystals, more intimate crystal-packing interactions than those in the wild-type crystal are observed. Notably, the mutants K49R and T146R yielded crystals with outstandingly improved resolutions of 1.5 and 1.6,Å, respectively, in which a large-scale rearrangement of packing interactions was unexpectedly observed despite the retention of the same isomorphous crystal form. In contrast, the mutants that provided results that were in good agreement with the designed putative structures tended to achieve only moderate improvements in resolution of up to 1.75,Å. These results suggest a difficulty in the rational prediction of highly effective mutations in crystal engineering. [source] Van der Waals and Polar Intermolecular Contact Distances: Quantifying Supramolecular SynthonsCHEMISTRY - AN ASIAN JOURNAL, Issue 5 2008Parthasarathy Ganguly Prof. Abstract Crystal structures are viewed as being determined by ranges and constraints on interatomic contact distances between neighboring molecules. These distances are considered to arise from environment-dependent atomic sizes, that is, larger sizes for isotropic, van der Waals type contacts and smaller sizes for more-polar, possibly ionic contacts. Although the idea of different, or anisotropic, radii for atoms is not new, we developed a method of obtaining atomic sizes that is based on a theoretical framework. Using different atomic sizes for the same atom in different environments, we were able to rationalize some structural observations and anomalies. For example, benzene with the Pbca structure may be described in terms of two types of C,,,H interactions: a longer contact largely of the van der Waals type, and a shorter, structure-determining type (C,,,,,H,+), which we term "n-polar". Our approach is illustrated with three examples: 1),the equivalence in crystal packing of fluorobenzene, benzonitrile, pyridine N -oxide, and pyridine/HF 1:1 molecular complex, all of which take the not-so-common tetragonal P41212 space group and are practically isomorphous; 2),the similarity of the Pa3 acetylene and Pbca benzene crystal structures; and 3),the equivalence between an increase in pressure and an increase in the "n-polar" contacts in Pbca benzene; in other words, the equivalence between hydrostatic pressure and chemical pressure. In the context of crystal engineering, we describe a method whereby the topological information conveyed in a supramolecular synthon is recast in a more quantitative manner. A particular synthon, and in turn the crystal structure to which it leads, is viable within small ranges of distances of its constituent atoms, and these distances are determined by chemical factors. [source] | ||||||||||||||||||||||||||||