Understanding the Behavior of π–π Interactions in Crystal Structures in Light of Geometry Corrected Statistical Analysis: Similarities and Differences with the Theoretical Models

2019 ◽  
Vol 19 (4) ◽  
pp. 2245-2252 ◽  
Author(s):  
Arka Banerjee ◽  
Arijit Saha ◽  
Binoy K. Saha
Keyword(s):  
Statistical Analysis ◽  
Crystal Structures ◽  
Theoretical Models ◽  
Π Interactions ◽  
Similarities And Differences

Similarities and differences in the crystal packing of halogen-substituted indole derivatives

2018 ◽  
Vol 74 (4) ◽  
pp. 376-384 ◽  
Author(s):  
Rahul Shukla ◽  
Paramveer Singh ◽  
Piyush Panini ◽  
Deepak Chopra
Keyword(s):  
Quantum Theory ◽  
Crystal Structures ◽  
Crystal Packing ◽  
Topological Analysis ◽  
Indole Derivatives ◽  
Π Interactions ◽  
Supramolecular Motifs ◽  
Exchange Repulsion ◽  
Similarities And Differences

The role of different intermolecular interactions in the crystal structures of halogen-substituted indoles which are fused with six-membered or seven-membered cyclic rings is investigated here. Several crystal structures show isostructural characteristics due to the presence of similar supramolecular motifs. In the absence of any strong hydrogen bonds, the molecular packing of reported structures is primarily stabilized by the presence of non-classical N—H...π and C—H...π interactions in addition to C—H...X (X = F/Cl/Br) interactions. The nature and energetics of primary and secondary dimeric motifs are partitioned into the electrostatics, polarization, dispersion and exchange–repulsion components using the PIXEL method. Short and directional N—H...π interactions are further explored by a topological analysis of the electron density based on quantum theory of atoms in molecules.

scholarly journals Crystal Chemical Relations in the Shchurovskyite Family: Synthesis and Crystal Structures of K2Cu[Cu3O]2(PO4)4 and K2.35Cu0.825[Cu3O]2(PO4)4

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 807
Author(s):  
Ilya V. Kornyakov ◽  
Sergey V. Krivovichev
Keyword(s):  
Crystal Structure ◽  
Crystal Structures ◽  
Structural Complexity ◽  
Crystal Chemical ◽  
X Ray Diffraction ◽  
Complexity Measures ◽  
X Ray ◽  
The Family ◽  
Similarities And Differences ◽  
Related Compounds

Single crystals of two novel shchurovskyite-related compounds, K2Cu[Cu3O]2(PO4)4 (1) and K2.35Cu0.825[Cu3O]2(PO4)4 (2), were synthesized by crystallization from gaseous phase and structurally characterized using single-crystal X-ray diffraction analysis. The crystal structures of both compounds are based upon similar Cu-based layers, formed by rods of the [O2Cu6] dimers of oxocentered (OCu4) tetrahedra. The topologies of the layers show both similarities and differences from the shchurovskyite-type layers. The layers are connected in different fashions via additional Cu atoms located in the interlayer, in contrast to shchurovskyite, where the layers are linked by Ca2+ cations. The structures of the shchurovskyite family are characterized using information-based structural complexity measures, which demonstrate that the crystal structure of 1 is the simplest one, whereas that of 2 is the most complex in the family.

scholarly journals Crystal structures of three newN-halomethylated quaternary ammonium salts

2015 ◽  
Vol 71 (10) ◽  
pp. 1230-1235
Author(s):  
Carolina Múnera-Orozco ◽  
Rogelio Ocampo-Cardona ◽  
David L. Cedeño ◽  
Rubén A. Toscano ◽  
Luz Amalia Ríos-Vásquez
Keyword(s):  
Crystal Structures ◽  
Intermolecular Interactions ◽  
Quaternary Ammonium ◽  
Quaternary Ammonium Salts ◽  
Ammonium Salts ◽  
Compound I ◽  
Nlo Properties ◽  
Π Interactions

In the crystals of the titleN-halomethylated quaternary ammonium salts, C19H23IN+·I−, (I) [systematic name:N-(4,4-diphenylbut-3-en-1-yl)-N-iodomethyl-N,N-dimethylammonium iodide], C20H25IN+·I−, (II) [systematic name:N-(5,5-diphenylpent-4-en-1-yl)-N-iodomethyl-N,N-dimethylammonium iodide], and C21H27IN+·I−, (III) [systematic name:N-(6,6-diphenylhex-5-en-1-yl)-N-iodomethyl-N,N-dimethylammonium iodide], there are short I...I−interactions of 3.564 (4), 3.506 (1) and 3.557 (1) Å for compounds (I), (II) and (III), respectively. Compound (I) crystallizes in the Sohncke groupP21as an `enantiopure' compound and is therefore a potential material for NLO properties. In the crystal of compound (I), molecules are linked by C—H...I−and C—H...π interactions which, together with the I...I−interactions, lead to the formation of ribbons along [100]. In (II), there are only C—H...I−interactions which, together with the I...I−interactions, lead to the formation of helices along [010]. In (III), apart from the I...I−interactions, there are no significant intermolecular interactions present.

scholarly journals Similarities and Differences of Lithuanian Functional Styles: A Quantitative Perspective

2020 ◽  
Author(s):  
Justina Mandravickaitė ◽  
Tomas Krilavičius
Keyword(s):  
Statistical Analysis ◽  
Multivariate Statistical Analysis ◽  
Multivariate Statistical ◽  
Similarities And Differences ◽  
Quantitative Indicators

We report an analysis of similarities and differences in terms of selected characteristics of 3 Lithuanian functional styles (FS): administrative, scientific, and publicistic. We combined 8 quantitative indicators and multivariate statistical analysis for this task. We also analyzed tendencies of indicators to be more or less pronounced in particular FS.

Crystal structures and Hirshfeld surface analysis of four 1,4-bis(methoxyphenyl)-2,3-diazabuta-1,3-dienes: comparisons of the intermolecular interactions in related compounds

2019 ◽  
Vol 234 (1) ◽  
pp. 59-71 ◽  
Author(s):  
Ligia R. Gomes ◽  
John N. Low ◽  
Nathasha R. de L. Correira ◽  
Thais C.M. Noguiera ◽  
Alessandra C. Pinheiro ◽  
...  
Keyword(s):  
Hydrogen Bonds ◽  
Crystal Structures ◽  
Intermolecular Interactions ◽  
Three Dimensional ◽  
Hirshfeld Surface ◽  
Dimensional Structure ◽  
Intermolecular Hydrogen Bonds ◽  
Π Interactions ◽  
Isomeric Compound ◽  
Related Compounds

Abstract The crystal structures of four azines, namely 1-3-bis(4-methoxyphenyl)-2,3-diaza-1,4-butadiene, 1, 1,3-bis(2,3-dimethoxyphenyl)-2,3-diaza-1,4-butadiene, 2, 1,3-bis(2-hydroxy-3-methoxyphenyl)-2,3-diaza-1,4-butadiene, 3, and 1,3-bis(2-hydroxy-4-methoxyphenyl)-2,3-diaza-1,4-butadiene, 4, are reported. Molecules of 3 and 4, and both independent molecules of 2, Mol A and Mol B, possess inversion centers. The central C=N–N=C units in each molecule is planar with an (E,E) conformation. The intermolecular interactions found in the four compounds are C–H···O, C–H–N, C–H---π and π---π interactions. However, there is no consistent set of intermolecular interactions for the four compounds. Compound, 1, has a two-dimensional undulating sheet structure, generated from C–H···O and C–H···N intermolecular hydrogen bonds. The only recognized intermolecular interaction in 2 is a C–H···O hydrogen bond, which results in a zig-zag chain of alternating molecules, Mol A and Mol B. While 3 forms a puckered sheet of molecules, solely via C–H···π interactions, its isomeric compound, 4, has a more elaborate three-dimensional structure generated from a combination of C–H···O hydrogen bonds, C–H···π and π···π interactions. The findings in this study, based on both PLATON and Hirshfeld approaches, for the four representative compounds match well the reported structural findings in the literature of related compounds, which are based solely on geometric parameters.

Folded conformations due to arene interactions in dissymmetric and symmetric butylidene-linker models based on pyrazolo[3,4-d]pyrimidine, purine and 7-deazapurine

2014 ◽  
Vol 70 (6) ◽  
pp. 555-561 ◽  
Author(s):  
Kamlakar Avasthi ◽  
Lakshmi Shukla ◽  
Ruchir Kant ◽  
Krishnan Ravikumar
Keyword(s):  
Solid State ◽  
Crystal Structures ◽  
Crystalline State ◽  
Nmr Analysis ◽  
First Report ◽  
Π Interactions ◽  
H Nmr

The butylidene-linker models 1-[2-(2,6-dimethylsulfanyl-9H-purin-9-yl)-2-methylidenepropyl]-4,6-bis(methylsulfanyl)-1H-pyrazolo[3,4-d]pyrimidine, C18H20N8S4, (XI), 7,7′-(2-methylidenepropane-1,3-diyl)bis[3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one], C20H22N6O2S2, (XIV), and 7-[2-(4,6-dimethylsulfanyl-1H-pyrazolo[3,4-d]pyrimidin-1-yl)-2-methylidenepropyl]-3-methyl-2-methylsulfanyl-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one, C19H21N7OS3, (XV), show folded conformations in solution, as shown by1H NMR analysis. This folding carries over to the crystalline state. Intramolecular π–π interactions are observed in all three compounds, but only (XIV) shows additional intramolecular C—H...π interactions in the solid state. As far as can be established, this is the first report incorporating the pyrrolo[2,3-d]pyrimidine nucleus for such a study. In addition to the π–π interactions, the crystal structures are also stabilized by other weak intermolecular C—H...S/N/O and/or S...N/S interactions.

scholarly journals X-ray and Gamma-ray Observations of Pulsars

1981 ◽  
Vol 95 ◽  
pp. 241-250 ◽  
Author(s):  
R. Buccheri
Keyword(s):  
Gamma Ray ◽  
Theoretical Models ◽  
Radio Pulsars ◽  
X Ray ◽  
Special Regard ◽  
Energy Domain ◽  
Similarities And Differences

Measurements of pulsars in the energy domain above ~ 1 keV have provided in the last few years new and interesting results. This paper presents a review of the observational features of PSR 0531+21 and PSR 0833–45 (the Crab and Vela pulsars). Searches for pulsed emission from old radio pulsars in the same energy domain are also reviewed and results assessed. The comparison of the observed features with each other and with the corresponding features observed at lower energies reveals similarities and differences capable to constrain theoretical models with special regard to the geometry of the emission mechanisms.

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