Shape mimicry as a design tool in crystal engineering
TL;DR: The pseudosymmetric chiral sulphoxide 1 was designed with two segments of nearly identical shape but with significantly different electron-donor/acceptor properties as discussed by the authors, resulting in a polar axis for the crystal and net additivity of the vectors from nitrogen to sulphur (the direction of polarizability for the molecules).
Abstract: The pseudosymmetric chiral sulphoxide 1 was designed with two segments of nearly identical shape but with significantly different electron-donor/acceptor properties. Based on the known high statistical preference for organics to pack in one of the centrosymmetric space groups, formation of molecular crystals of enantiomerically pure 1 was predicted to occur with pseudocentrosymmetry with 1 also playing the role of its enantiomer and packing as would the racemate. Such a packing motif would lack true centrosymmetry, resulting in a polar axis for the crystal and net additivity of the vectors from nitrogen to sulphur (the direction of polarizability for the molecules). Enantiomeric sulphoxide 1 does from molecular crystals with false centrosymmetry, mimicking P21/c, and with a substantial net directionality of polarizability vectors. In contrast, enantiomeric sulphoxides 3 and 4 form molecular crystals where the vectors from nitrogen to sulphur in neighbouring molecules are essentially opposed.
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TL;DR: The most surprising outcome of this systematic comparison lies in the role of chirality: with enantiopure proline three different coordination polymers have been obtained, whereas racemic proline yields isomorphous mononuclear complexes under the same reaction conditions.
Abstract: Reactions of manganese(II) chloride, bromide and iodide with proline as an enantiopure and racemic ligand result in six crystalline solids for which diffraction experiments have been performed at 100 K. For two of these compounds, crystal structures at ambient temperature had been reported previously. The most surprising outcome of our systematic comparison lies in the role of chirality: with enantiopure proline three different coordination polymers have been obtained, whereas racemic proline yields isomorphous mononuclear complexes under the same reaction conditions.
17 citations
01 Jan 1999
TL;DR: The commitment at the Data Centre to the development of increasingly powerful software for 3-dimensional search, analysis, and display is changing the landscape of the study of crystal packing.
Abstract: Many applications of crystalline materials depend not just on the underlying molecular structures, but equally on the alignment of molecules in the crystals. An understanding of molecular arrangements is critical to the design of materials with specific bulk properties. Crystal structure reports have traditionally contained little significant discussion (frequently no mention at all) of molecular arrangements in the crystal, presumably because the motivation for many studies was the elucidation of some molecular feature. The Cambridge Structural Database [1] makes available crystal data for many thousands of organic and organometallic crystal structures, together with continually evolving retrieval and analysis software. The commitment at the Data Centre to the development of increasingly powerful software for 3-dimensional search, analysis, and display is changing the landscape of the study of crystal packing. This superb set of tools facilitates many important and innovative programs of study that are slowly but surely increasing our understanding of molecular solid state structure. This systematic study is, in turn, fueling significant progress in crystal engineering, one of the major themes of this School. Useful reviews in this area include those by Desiraju [2] and by Braga and Grepioni [3] (both of these surveying a broad range of intermolecular interactions) and those by Aakeroy [4, 5] and Zaworotko [6] (focusing more specifically on the exploitation of hydrogen-bonding as a design tool).
3 citations
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TL;DR: In this paper, the electronic origins of nonlinear optical effects in organic π electronic systems are reviewed, with special emphasis being given to second-order nonlinear effects, and the critical relationships of the propagation characteristics of light to observed non-linear optical effect and to solid-state structure are discussed.
Abstract: Nonlinear optical properties are a sensitive probe of the electronic and solid-state structure of organic compounds and as a consequence find various applications in many areas of optoelectronics including optical communications, laser scanning and control functions, and integrated optics technology. Because of their strongly delocalized π electronic systems, polymeric and non-polymeric aromatic compounds show highly nonlinear optical effects. Nowadays, polymer chemists are able to tailor specific materials properties for various applications. Some organic substances with π electronic systems exhibit the largest known nonlinear coefficients, often considerably larger than those of the more conventional inorganic dielectrics and semiconductors, and thus show promise for thin-film fabrication, allowing the enormous function and cost advantages of integrated electronic circuitry. The electronic origins of nonlinear optical effects in organic π electronic systems are reviewed, with special emphasis being given to second-order nonlinear optical effects. Methods for measuring nonlinear optical responses are outlined, and the critical relationships of the propagation characteristics of light to observed nonlinear optical effects and to solid-state structure are discussed. Finally, the synthesis and characterization of organic crystals and polymer films with large second-order optical nonlinearities are summarized.
898 citations
TL;DR: Property and important materials constants of current commercial materials and of new, promising, inorganic and organic molecular and polymeric materials with potential in second- and third-order nonlinear optical applications are presented.
Abstract: The current state of materials development in nonlinear optics is summarized, and the promise of these materials is critically evaluated. Properties and important materials constants of current commercial materials and of new, promising, inorganic and organic molecular and polymeric materials with potential in second- and third-order nonlinear optical applications are presented.
839 citations
Book•
01 Jan 1987
TL;DR: Theoretically, the most related work to ours is as mentioned in this paper, which proposes a combination of Solid State Chemistry and X-Ray Crystallography for the prediction of chemical reactivity within organic solids.
Abstract: Organic Solid State Reactions: Topochemistry and Mechanism. Geometric Requirements for Intramolecular Photochemical Hydrogen Atom Abstraction: Studies Based on a Combination of Solid State Chemistry and X-Ray Crystallography (J.R. Scheffer). Topotactic and Topochemical Photodimerisation of Benzylidenecyclopentanones (C.R. Theocharis, W. Jones). The Prediction of Chemical Reactivity Within Organic Crystals Using Geometric Criteria (S.K. Kearsley). Phonon Spectroscopy of Organic Solid State Reactions (P.N. Prasad). Four-Center Type Photopolymerization of Diolefin Crystals (M. Hasegawa). Some Stereochemical Questions: Pure and Applied Chemistry. Organic Molecules in Constrained Environments (J.M. Thomas, K.D.M. Harris). Clathrates (G. Tsoucaris). Solid State Chemistry of Phenols and Possible Industrial Applications (R. Perrin et al.). Gas-Solid Reactions and Polar Crystals (I.C. Paul, D.Y. Curtin). Intermolecular Interactions: From Crystallography to Chemical Physics. Phase Transitions in Organic Solids (C.N.R. Rao). Molecular Motions in Organic Crystals: The Structural Point of View (A. Gavezzotti, M. Simonetta). Interatomic Potentials and Computer Simulations of Organic Molecules in the Solid State (S. Ramdas, N.W. Thomas,). Conformational Polymorphism (J. Bernstein). Crystal Engineering A 4 A - Short Axis Structure for Planar Chloro Aromatics (G.R. Desiraju).
241 citations
167 citations