scholarly journals Space Groups for Solid State Scientists (Burns, Gerald; Glazer, A.M.)

1979 ◽  
Vol 56 (10) ◽  
pp. A326
Author(s):  
Hugo F. Franzen
Keyword(s):  
Solid State ◽  
Space Groups

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.

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.

2000 Alfred Bader Award LectureIn the footsteps of Pasteur: asymmetric induction in the photochemistry of crystalline ammonium carboxylate salts

2001 ◽  
Vol 79 (4) ◽  
pp. 349-357 ◽  
Author(s):  
John R Scheffer
Keyword(s):  
Solid State ◽  
Asymmetric Synthesis ◽  
Ammonium Ion ◽  
Chiral Auxiliaries ◽  
Organic Salts ◽  
Space Groups ◽  
Chiral Induction ◽  
Organic Amines ◽  
Asymmetric Environment ◽  
Optically Pure

This review describes the development of a new, synthetically useful method of asymmetric synthesis in organic photochemistry. Similar in many ways to the Pasteur procedure for resolving racemic carboxylic acids and organic amines, the method relies on the use of crystalline organic salts in which the enantioselectivity of a photochemical reaction of an achiral organic ion (for example, a carboxylate anion) is governed in the solid state by the presence of an optically pure counterion (for example, an optically active ammonium ion). Such optically pure counterions are termed ionic chiral auxiliaries. Salts containing ionic chiral auxiliaries are required to crystallize in chiral space groups, which provide the asymmetric environment necessary for chiral induction. Using this methodology, we have obtained near-quantitative optical yields in a wide variety of photochemical reactions.Key words: photochemistry, solid state, chiral auxiliaries, asymmetric synthesis, crystal structure–reactivity relationships.

Structural characterization of Cd3(O3PC2H4CO2)2·2H2O from in-house X-ray powder data and NMR

2005 ◽  
Vol 61 (6) ◽  
pp. 669-674 ◽  
Author(s):  
Naima Bestaoui ◽  
Xiang Ouyang ◽  
Florence Fredoueil ◽  
Bruno Bujoli ◽  
Abraham Clearfield
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Structural Characterization ◽  
Title Compound ◽  
Solid State Nmr ◽  
Hydrothermal Reaction ◽  
X Ray ◽  
Space Groups ◽  
Nmr Data

The title compound poly[[bis(μ-2-carboxylatoethylphosphonato)cadmium] dihydrate], Cd3(O3PC2H4CO2)2·2H2O, was prepared by a hydrothermal reaction and its crystal structure determined from in-house powder data. The structure was solved in both P21/c and P21 space groups. The refinement converged with Rp = 0.1046, R wp = 0.1378 and Rf = 0.0763 in P21/c. However, the solid-state NMR data could not be explained. The structure was then solved in P21 and the refinement converged with Rp = 0.0750, R wp = 0.1022 and Rf = 0.0409 and satisfied the NMR requirements.

New layered supertetrahedral compounds T2-MSiAs2, T3-MGaSiAs3 and polytypic T4-M4Ga5SiAs9 (M = Sr, Eu)

2020 ◽  
Vol 75 (11) ◽  
pp. 983-989
Author(s):  
Valentin Weippert ◽  
Arthur Haffner ◽  
Dirk Johrendt
Keyword(s):  
Electrical Resistivity ◽  
Solid State ◽  
Single Crystal ◽  
Hall Effect ◽  
Optical Band Gap ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Space Groups ◽  
Layer Stacking

AbstractThe new supertetrahedral compounds MSiAs2, MGaSiAs3 and mC/tI-M4Ga5SiAs9 (M = Sr, Eu) have been synthesized by solid-state reactions at high temperatures. The structures were determined by single crystal or powder X-ray diffraction. MSiAs2 and MGaSiAs3 crystallize in the monoclinic TlGaSe2- and RbCuSnS3-type structures, respectively (space group C2/c). These are topologically hierarchical variants of the tetragonal HgI2-type structure with stacked layers of T2 or T3 supertetrahedra. The T4 compounds M4Ga5SiAs9 are dimorphic and form new structure types in the space groups C2/c and I41/amd, respectively. The latter exhibits coinciding layer stacking as known from tetragonal HgI2. The T4 compounds close the gap between the longer known T2 types and the recently reported compounds with T5 and T6 supertetrahedra. Measurements of the optical band gap, electrical resistivity and Hall Effect support the semiconducting nature of M4Ga5SiAs9. Magnetization measurements confirm Eu2+ in Eu4Ga5SiAs9 and indicate ferromagnetism below T = 2 K.

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