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Packing Pattern (packing + pattern)
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] Structural motifs in ,-pyridyl- and ,-furylcinnamic acid assemblies, A molecular modeling studyINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 2 2001I. Pálinkó Abstract The aggregation properties of stereoisomeric 2-(3,-furyl)-3-phenylpropenoic acids (FU3E, FU3Z, ,-furylcinnamic acids) and 2-(4,-pyridyl)-3-phenylpropenoic acids (PY4E, PY4Z, ,-pyridylcinnamic acids) were studied by the PM3 semiempirical quantum chemical method. Calculations revealed that (aromatic)CH,N(O) hydrogen bonds made possible the attachment of dimer units; thus, virtually infinite chains can be built out of FU3Z, PY4E, and PY4Z. The energy-minimized structure had zig-zag configuration. PY4Z dimers allowed the formation of ribbonlike network; however, the number of structural units could not be increased infinitely. One of the furyl derivatives (FU3E) could not be stabilized either in the ribbon or the chain form; however, (aromatic)CH,, or (aromatic),,(aromatic), interactions contribute to the packing pattern of the two dimers. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem 84: 269,275, 2001 [source] [2,6-Bis(5-methyl-2-pyridyl)phenyl-,3N,C1,N,]chloridoplatinum(II)ACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2007Taichi Abe In the title compound, [Pt(C18H15N2)Cl], the PtII centre adopts a distorted square-planar coordination geometry due to the pincer-type monoanionic N,C,N tridentate ligand. The planar complexes stack via,,, interactions to form two-dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer-type N,C,N complexes, which exhibit a one-dimensional columnar stacking. [source] C,H..., interactions in five ethynyl-substituted [2.2]paracyclophanes: further examples of the `7,11' packing patternACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2007Peter G. Jones The monosubstituted derivative 4-ethynyl[2.2]paracyclophane, C18H16, (I), and the four disubstituted isomers, 4,12-, (II), 4,13-, (III), 4,15-, (IV), and 4,16-diethynyl[2.2]paracyclophane, (V), all C20H16, show the usual distortions of the [2.2]paracyclophane framework. The crystal packing is analyzed in terms of C,H..., interactions, some with H..., as short as 2.47,Å, in which the cyclophane rings and/or the triple-bond systems may act as acceptors. For compounds (I) and (IV), the known `7,11'-type cyclophane packing is observed, with a herring-bone pattern of molecules in a layer structure. [source] Mercury CSD 2.0, new features for the visualization and investigation of crystal structuresJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2008Clare F. Macrae The program Mercury, developed by the Cambridge Crystallographic Data Centre, is designed primarily as a crystal structure visualization tool. A new module of functionality has been produced, called the Materials Module, which allows highly customizable searching of structural databases for intermolecular interaction motifs and packing patterns. This new module also includes the ability to perform packing similarity calculations between structures containing the same compound. In addition to the Materials Module, a range of further enhancements to Mercury has been added in this latest release, including void visualization and links to ConQuest, Mogul and IsoStar. [source] Spatial arrangement of molecules in homomolecular Z' = 2 structuresACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2006Elna Pidcock The Box Model of crystal packing describes unit cells in terms of a limited number of arrangements of molecular building blocks. An analysis of Z,, 1 structures has shown that cell dimensions are related to molecular dimensions in a systematic way and that the spatial arrangement of molecules in crystal structures is very similar, irrespective of Z or space group. In this paper it is shown that the spatial arrangement of molecules in Z, = 2 structures are, within the context of the Box Model, very similar to that found for Z,, 1 structures. The absence of crystallographic symmetry does not appear to affect correlations between molecular dimensions and cell dimensions, or between the packing patterns and the positions of molecules in the unit cell, established from the analysis of Z,, 1 structures. The preference shown by Z, = 2 structures for low surface-area packing patterns and the observation that strong energetic interactions are most often found between the large faces of the independent molecules reaffirms the importance of molecular shape in crystal packing. [source] A new polymorph of tetraphenyldiboroxaneACTA CRYSTALLOGRAPHICA SECTION C, Issue 10 2007Linda Kaufmann A new polymorph of tetraphenyldiboroxane [or oxybis(diphenylborane)], C24H20B2O, (Ia), has been found. It is monoclinic, like the already known form, (Ib), and can be refined in the same space group, namely P21/c, or in the equivalent setting P21/n. The molecular conformations of the two polymorphs differ in the rotations of two of the phenyl rings about the B,C bonds, leading to markedly different packing patterns and cell dimensions. [source] | ||||||||||