Supramolecular assemblies of organotin(iv)–diphosphoryl adducts: insights from X-rays and DFT

RSC Advances ◽  
2015 ◽  
Vol 5 (119) ◽  
pp. 98610-98617 ◽  
Author(s):  
Khodayar Gholivand ◽  
Akram Gholami ◽  
Kurt J. Schenk ◽  
Mehdi D. Esrafili ◽  
Kaveh Farshadfar
Keyword(s):  
Crystal Structures ◽  
Theoretical Calculations ◽  
Supramolecular Assemblies ◽  
Geometrical Parameters ◽  
X Rays ◽  
Hirshfeld Analysis

The influence of tin-bonded substituents on the organization of the crystal structures and also coordination interactions were discussed using geometrical parameters, Hirshfeld analysis and theoretical calculations.

scholarly journals Relation between Crystal Structures of Precursors and Final Products: Example of Vitamin D Intermediates

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1802
Author(s):  
Monika Wanat ◽  
Maura Malinska ◽  
Andrzej Kutner ◽  
Krzysztof Woźniak
Keyword(s):  
Vitamin D ◽  
Crystal Structures ◽  
Theoretical Calculations ◽  
Geometrical Parameters ◽  
Space Groups ◽  
Vitamin D Analogues ◽  
Vitamin D Analog ◽  
Exocyclic Methylene ◽  
Solid Form ◽  
Methylene Group

In this paper, we proved that the solid-state structure of vitamin D analog is well represented by the structures of its structural fragments. This is important in predicting the biological activity of vitamin D analogs that are not available in the solid form. The previously published crystal structure of advanced vitamin D intermediate provided additional insights into vitamin D properties. A similar analysis based on simple vitamin D intermediate analogues showed that precursors crystallized in the space groups typical for vitamins D; geometrical parameters were related to the corresponding parameters in the vitamin D analogues; and crystal structures of the basic intermediates and their final products contained similar intermolecular interactions, essential for the infinite hydrogen bond motif observed in the vitamin D analogues. The energy of these interactions is related as shown by theoretical calculations, that is, energy frameworks analysis. Moreover, analysis of the hydrogen bonds motifs revealed a relation between these motifs and the absolute configuration of basic intermediates as well as the space orientation of the exocyclic methylene group in the final structures.

MINDO-Forces Study on Substituted Nitromethane ⇋ aci-Nitromethane Tautomerism

2005 ◽  
Vol 60 (1-2) ◽  
pp. 47-53
Author(s):  
Bareehan M. Salim ◽  
Salim M. Khalil
Keyword(s):  
Theoretical Calculations ◽  
Geometry Optimization ◽  
Heats Of Formation ◽  
Geometrical Parameters ◽  
Free Energies ◽  
Electron Densities ◽  
Isodesmic Reactions ◽  
Complete Geometry Optimization

MINDO-Forces calculations with complete geometry optimization have been performed on nitromethane, aci-nitromethane and X-substituted nitromethane and aci-nitromethane (X = F, OH, NH2, CH3, CN, CF3, NO2, CHO). It is found that nitromethane is more stable than aci-nitromethane by 9.337 kcal/mol. This agrees with theoretical calculations. Thermodynamically, substituted aci-nitro tautomers are more stable than the corresponding nitromethane, except in case of the substituent F. Geometrical parameters, heats of formation, electron densities, Gibbs free energies and isodesmic reactions are reported.

Ruthenium(ii) and palladium(ii) homo- and heterobimetallic complexes: synthesis, crystal structures, theoretical calculations and biological studies

2019 ◽  
Vol 48 (42) ◽  
pp. 15869-15887 ◽  
Author(s):  
Banafshe Askari ◽  
Hadi Amiri Rudbari ◽  
Nicola Micale ◽  
Tanja Schirmeister ◽  
Thomas Efferth ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Proliferative Activity ◽  
Theoretical Calculations ◽  
Coordination Modes ◽  
Heterobimetallic Complexes ◽  
Biological Studies

Four Ru–Pd heterobimetallic complexes, each one in two different coordination modes (NNSS and NS) were prepared of dialkyldithiooxamidate ligands. All stable NS complexes showed anti-proliferative activity.

The lines-of-force landscape of interactions between molecules in crystals; cohesive versus tolerant and `collateral damage' contact

2010 ◽  
Vol 66 (3) ◽  
pp. 396-406 ◽  
Author(s):  
Angelo Gavezzotti
Keyword(s):  
Crystal Structures ◽  
Structure Prediction ◽  
Crystal Packing ◽  
Minimum Energy ◽  
Lattice Energy ◽  
Interaction Force ◽  
Coordination Shell ◽  
Geometrical Parameters ◽  
Interaction Energies ◽  
Organic Salts

A quantitative analysis of relative stabilities in organic crystal structures is possible by means of reliable calculations of interaction energies between pairs of molecules. Such calculations have been performed by the PIXEL method for 1108 non-ionic and 98 ionic organic crystals, yielding total energies and separate Coulombic polarization and dispersive contributions. A classification of molecule–molecule interactions emerges based on pair energy and its first derivative, the interaction force, which is estimated here explicitly along an approximate stretching path. When molecular separation is not at the minimum-energy value, as frequently happens, forces may be attractive or repulsive. This information provides a fine structural fingerprint and may be relevant to the mechanical properties of materials. The calculations show that the first coordination shell includes destabilizing contacts in ∼ 9% of crystal structures for compounds with highly polar chemical groups (e.g. CN, NO2, SO2). Calculations also show many pair contacts with weakly stabilizing (neutral) energies; such fine modulation is presumably what makes crystal structure prediction so difficult. Ionic organic salts or zwitterions, including small peptides, show a Madelung-mode pairing of opposite ions where the total lattice energy is stabilized from sums of strongly repulsive and strongly attractive interactions. No obvious relationships between atom–atom distances and interaction energies emerge, so analyses of crystal packing in terms of geometrical parameters alone should be conducted with due care.

scholarly journals Multilayer Laue Lens: A Path Toward One Nanometer X-Ray Focusing

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Hanfei Yan ◽  
Hyon Chol Kang ◽  
Ray Conley ◽  
Chian Liu ◽  
Albert T. Macrander ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Numerical Aperture ◽  
Thin Film Deposition ◽  
Film Deposition ◽  
Diffraction Effect ◽  
X Rays ◽  
Dynamical Diffraction ◽  
Characterization Methods ◽  
X Ray ◽  
Laue Lens

The multilayer Laue lens (MLL) is a novel diffractive optic for hard X-ray nanofocusing, which is fabricated by thin film deposition techniques and takes advantage of the dynamical diffraction effect to achieve a high numerical aperture and efficiency. It overcomes two difficulties encountered in diffractive optics fabrication for focusing hard X-rays: (1) small outmost zone width and (2) high aspect ratio. Here, we will give a review on types, modeling approaches, properties, fabrication, and characterization methods of MLL optics. We show that a full-wave dynamical diffraction theory has been developed to describe the dynamical diffraction property of the MLL and has been employed to design the optimal shapes for nanofocusing. We also show a 16 nm line focus obtained by a partial MLL and several characterization methods. Experimental results show a good agreement with the theoretical calculations. With the continuing development of MLL optics, we believe that an MLL-based hard x-ray microscope with true nanometer resolution is on the horizon.

Phthalazine-trione as a blue-green light-emitting moiety: crystal structures, photoluminescence and theoretical calculations

2019 ◽  
Vol 43 (3) ◽  
pp. 1313-1321
Author(s):  
Felipe Terra Martins ◽  
Lauro June Queiroz Maia ◽  
Gisane Gasparotto ◽  
Ana Karoline Silva Medanha Valdo ◽  
José Antônio Nascimento Neto ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Theoretical Calculations ◽  
Green Light ◽  
Substitution Pattern ◽  
Light Emitting

Phthalazine-trione was found to be a new robust blue-green light-emitting fluorophore, regardless of the substitution pattern.

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