scholarly journals Tangible symmetry elements and space-group models to guide from molecular to solid-state composition

2022 ◽  
Vol 55 (1) ◽  
Author(s):  
Nico Graw ◽  
Dietmar Stalke
Keyword(s):  
Solid State ◽  
Spatial Arrangement ◽  
Lecture Hall ◽  
Complete Space ◽  
Space Groups ◽  
3D Objects ◽  
Rotation Axes ◽  
Hands On ◽  
Spatial Imagination ◽  
State Composition

The ability to imagine symmetry and the spatial arrangement of atoms and molecules is crucial in chemistry in general. Teaching and understanding crystallography and the composition of the solid state therefore require understanding of symmetry elements and their relationships. To foster the student's spatial imagination, models representing a range of concepts from individual rotation axes to complete space groups have been designed and built. These models are robust and large enough to be presented and operated in a lecture hall, and they enable students to translate conventional 2D notations into 3D objects and vice versa. Tackling them hands-on means understanding them.

scholarly journals Inexpensive Hands-On Activities in Solid State Lighting

2016 ◽  
Author(s):  
Kathleen Meehan ◽  
Andrew Phillips
Keyword(s):  
Solid State ◽  
Solid State Lighting ◽  
Hands On

Rilievo: Artistic Scene Authoring via Interactive Height Map Extrusion in VR

Leonardo ◽  
2020 ◽  
Vol 53 (4) ◽  
pp. 438-441
Author(s):  
Sevinc Eroglu ◽  
Patric Schmitz ◽  
Carlos Aguilera Martinez ◽  
Jana Rusch ◽  
Leif Kobbelt ◽  
...  
Keyword(s):  
Spatial Arrangement ◽  
Input Image ◽  
Artistic Creation ◽  
Image Structure ◽  
3D Objects ◽  
Input Material ◽  
Authoring Environment ◽  
2D Images

The authors present a virtual authoring environment for artistic creation in VR. It enables the effortless conversion of 2D images into volumetric 3D objects. Artistic elements in the input material are extracted with a convenient VR-based segmentation tool. Relief sculpting is then performed by interactively mixing different height maps. These are automatically generated from the input image structure and appearance. A prototype of the tool is showcased in an analog-virtual artistic workflow in collaboration with a traditional painter. It combines the expressiveness of analog painting and sculpting with the creative freedom of spatial arrangement in VR.

Polymorphism of urea–barbituric acid co-crystals

2008 ◽  
Vol 64 (5) ◽  
pp. 623-632 ◽  
Author(s):  
Marlena Gryl ◽  
Anna Krawczuk ◽  
Katarzyna Stadnicka
Keyword(s):  
Barbituric Acid ◽  
Spatial Arrangement ◽  
Structural Components ◽  
Space Groups ◽  
The Third ◽  
Tautomeric Forms ◽  
Polymorphic Forms ◽  
Graph Set ◽  
Graph Set Analysis ◽  
Level Analysis

The crystal structures of three polymorphs found for the addition complex of urea and barbituric acid are described and compared. Two polymorphs are monoclinic, space groups P21/c and Cc, whereas the third is triclinic, P\bar 1. The displacement of electron density towards the mesomeric forms, corresponding to the tautomeric forms of higher stability, of the barbituric acid molecule seem to influence the type of hydrogen bonds formed, which in turn determines the different packing topology in the polymorphs. While the polymorphic forms can be easily differentiated at the first-level graph-set analysis of their hydrogen-bonding patterns, a higher-level analysis enables important features of the mutual spatial arrangement of the structural components to be revealed.

Article

1998 ◽  
Vol 76 (11) ◽  
pp. 1616-1632
Author(s):  
Bozena Borecka-Bednarz ◽  
Alan V Bree ◽  
Brian O Patrick ◽  
John R Scheffer ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Second Harmonic Generation ◽  
Harmonic Generation ◽  
Second Harmonic ◽  
Crystallographic Analysis ◽  
Organic Salts ◽  
Harmonic Intensity ◽  
Space Groups ◽  
Order Of Magnitude ◽  
Optically Pure

Second-harmonic generation in the solid state is restricted to materials that crystallize in non-centrosymmetric space groups. Unfortunately, the vast majority of solids crystallize in centrosymmetric space groups and are therefore SHG-inactive. The requirement for solid-state asymmetry is addressed in a new series of organic salts. The acid p-nitrophenylglycine, SHG-inactive due to its centrosymmetric (P1) packing, was coupled to six optically pure amines to form salts and (or) complexes that, by virtue of their chiral counterion, crystallized in non-centrosymmetric space groups. The 1064 nm output from a Nd:YAG laser produced 532 nm second-harmonic generation from each of the six salts, with three of the salts producing second-harmonic intensities at least an order of magnitude greater than that of our standard, urea. X-ray crystallographic analysis was carried out on five of the six salts, and an attempt was made to rationalize the second-harmonic intensity of each of these five salts based on the orientation of its molecular charge-transfer axis in the unit cell and on its chromophore density.Key words: second-harmonic generation, nonlinear optics, chiral organic salts, crystal structures.

Interaction of diiodine with some tetra-substituted dithiooxamides. Crystal and molecular structure of bis(morpholinothiocarbonyl)bis(diiodine)

1988 ◽  
Vol 66 (6) ◽  
pp. 1483-1489 ◽  
Author(s):  
Davide Atzei ◽  
Paola Deplano ◽  
Emanuele F. Trogu ◽  
Francesco Bigoli ◽  
Maria Angela Pellinghelli ◽  
...  
Keyword(s):  
Molecular Structure ◽  
Charge Transfer ◽  
Solid State ◽  
Torsion Angle ◽  
Crystal And Molecular Structure ◽  
Formation Constants ◽  
Dalton Trans ◽  
X Ray ◽  
Space Groups ◽  
Spectrophotometric Methods

The reaction of some tetra-substituted dithiooxamides R2NC(S)C(S)NR2 (R = CH3:Me4dto; R = C2H5:Et4dto; R2N = OC4H8N:Mo2dto) with diiodine has been investigated by spectrophotometric methods in CHCl3. The formation in solution of 1:1 and 1:2 charge-transfer (c.t.) complexes between the reagents has been observed. A new computer program, derived from "SUPERQUAD" (P. Gans, A. Sabatini, and A. Vacca. J. Chem. Soc. Dalton Trans. 1195 (1985)), has been applied to evaluate the formation constants. The 1:2 c.t. complexes have been isolated in the solid state, and an X-ray structure analysis of the [OC4H8NC(S)C(S)NC4H8O]•2I2 compound indicated that the crystals are triclinic, space groups [Formula: see text], with a = 14.659(6), b = 15.111(6), c = 9.317(5) Å, α = 92.29(2), β = 99.71(2), γ = 99.48(2)° and Z = 4. In particular the torsion angle S—C—C—S (≈90°) shows that the conformation of the dithiooxamide is not trans.

Preparation and Characterization of the New Y257 Superconductors

2013 ◽  
Vol 770 ◽  
pp. 22-25 ◽  
Author(s):  
Thitipong Kruaehong
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
Critical Temperature ◽  
Solid State ◽  
Superconducting Phase ◽  
Lattice Parameters ◽  
Peritectic Temperature ◽  
Space Group ◽  
Space Groups

The new Y257 superconductor in YBaCuO family was synthesized by standard solid state reaction. The Y257 samples were measured the critical temperature (Tc) by the four-probes method that found at 90 K. The XRD technique and FULLPROF program were used to determine the lattice parameters, space group and phase compositions. It was found that the Y257 exhibited in both of superconducting and non-superconducting phase. The Pmmm space group was fit well on superconducting phase with the lattice parameters as a=3.8108 Å, b=3.8544 Å and c=26.4967 Å. The non-superconducting phase exhibited in two space groups of Pccm (a=12.9770 Å, b=20.54780 Å and c=11.3530 Å) and Im-3m (a= 18.2104 Å, b=18.2104 Å and c=18.2104 Å). The peritectic temperature at 976.73°C was measured by differential thermal analysis.

scholarly journals MicroED Elucidation of Diverse Solid-State Packing in a Family of Electron-Deficient Expanded Helicenes

2020 ◽  
Author(s):  
Adrian Samkian ◽  
Gavin R. Kiel ◽  
Christopher G. Jones ◽  
Harrison Bergman ◽  
Julia Oktawiec ◽  
...  
Keyword(s):  
Solid State ◽  
Electron Diffraction ◽  
Rapid Assessment ◽  
Nanometer Scale ◽  
Proof Of Concept ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Indispensable Tool ◽  
Solid State Structures

Solid-state packing plays a defining role in the properties of a molecular organic material, but it is difficult to elucidate in the absence of single crystals that are suitable for X-ray diffraction. Here, we demonstrate the coupling of divergent synthesis with microcrystal electron diffraction (MicroED) for rapid assessment of solid-state packing motifs, using a class of chiral nanocarbons – expanded helicenes – as a proof of concept. Two highly selective oxidative dearomatizations of a readily-accessible helicene provided a divergent route to four electron-deficient analogues containing quinone or quinoxaline units. Crystallization efforts consistently yielded microcrystals that were unsuitable for single crystal X-ray diffraction, but ideal for MicroED. This technique facilitated the elucidation of solid-state structures of all five compounds with <1.1 Å resolution. The otherwise-inaccessible data revealed a range of notable packing behavior, including four different space groups, homochirality in a crystal for a helicene with an extremely low enantiomerization barrier, and nanometer scale cavities. The results of this study suggest that MicroED will soon become an indispensable tool for high-throughput investigations in pursuit of next-generation organic materials.

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