scholarly journals Properties of metal oxalate materials from electron density. Modelling the building blocks and evaluation of framework interaction

2011 ◽  
Vol 67 (a1) ◽  
pp. C820-C821
Author(s):  
A. S. Chimpri ◽  
P. Macchi
Keyword(s):  
Electron Density ◽  
Building Blocks ◽  
Metal Oxalate ◽  
Density Modelling

scholarly journals Quantum Crystallography in the Last Decade: Developments and Outlooks

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 473 ◽  
Author(s):  
Alessandro Genoni ◽  
Piero Macchi
Keyword(s):  
Electron Density ◽  
Review Article ◽  
Quantum Mechanical ◽  
Spin Models ◽  
The Past ◽  
Core Electrons ◽  
Mechanical Information ◽  
Quantum Crystallography ◽  
Density Modelling

In this review article, we report on the recent progresses in the field of quantum crystallography that has witnessed a massive increase of production coupled with a broadening of the scope in the last decade. It is shown that the early thoughts about extracting quantum mechanical information from crystallographic experiments are becoming reality, although a century after prediction. While in the past the focus was mainly on electron density and related quantities, the attention is now shifting toward determination of wavefunction from experiments, which enables an exhaustive determination of the quantum mechanical functions and properties of a system. Nonetheless, methods based on electron density modelling have evolved and are nowadays able to reconstruct tiny polarizations of core electrons, coupling charge and spin models, or determining the quantum behaviour at extreme conditions. Far from being routine, these experimental and computational results should be regarded with special attention by scientists for the wealth of information on a system that they actually contain.

Electron-Density Determination of Electrophilic Building Blocks as Model Compounds for Protease Inhibitors

2007 ◽  
Vol 2007 (17) ◽  
pp. 2759-2768 ◽  
Author(s):  
Simon Grabowsky ◽  
Thomas Pfeuffer ◽  
Lilianna Chęcińska ◽  
Manuela Weber ◽  
Wolfgang Morgenroth ◽  
...  
Keyword(s):  
Protease Inhibitors ◽  
Electron Density ◽  
Building Blocks ◽  
Model Compounds ◽  
Density Determination

scholarly journals Spin resolved electron density study of YTiO3 in its ferromagnetic phase: signature of orbital ordering

IUCrJ ◽  
2019 ◽  
Vol 6 (5) ◽  
pp. 884-894
Author(s):  
Ariste Bolivard Voufack ◽  
Iurii Kibalin ◽  
Zeyin Yan ◽  
Nicolas Claiser ◽  
Saber Gueddida ◽  
...  
Keyword(s):  
Electron Density ◽  
Density Functional ◽  
Density Functional Theory Calculations ◽  
Ferromagnetic State ◽  
Ferromagnetic Phase ◽  
Ferromagnetic Transition ◽  
Orbital Ordering ◽  
Synchrotron Source ◽  
Refinement Strategy ◽  
Density Modelling

The present work reports on the charge and spin density modelling of YTiO3 in its ferromagnetic state (T C = 27 K). Accurate polarized neutron diffraction and high-resolution X-ray diffraction (XRD) experiments were carried out on a single crystal at the ORPHÉE reactor (LLB) and SPRING8 synchrotron source. The experimental data are modelled by the spin resolved pseudo-atomic multipolar model (Deutsch et al., 2012). The refinement strategy is discussed and the result of this electron density modelling is compared with that from XRD measured at 100 K and with density functional theory calculations. The results show that the spin and charge densities around the Ti atom have lobes directed away from the O atoms, confirming the filling of the t 2g orbitals of the Ti atom. The d xy orbital is less populated than d xz and d yz , which is a sign of a partial lift of degeneracy of the t 2g orbitals. This study confirms the orbital ordering at low temperature (20 K), which is already present in the paramagnetic state above the ferromagnetic transition (100 K).

Electron density of a nanohoop [2]rotaxane based on invariom refinement

2021 ◽  
Vol 76 (2) ◽  
pp. 97-102
Author(s):  
Peter Luger ◽  
Birger Dittrich
Keyword(s):  
Electron Density ◽  
Topological Analysis ◽  
Potential Gradient ◽  
Building Blocks ◽  
Pyridyl Ring ◽  
Bond Orders ◽  
X Ray Diffraction ◽  
Phenyl Rings ◽  
Non Covalent Interactions ◽  
Average Bond

Abstract Rotaxanes as well as catenanes are known as potential building blocks of molecular machines. The nanohoop [2]rotaxane investigated is composed of a macrocycle derived from a [6]cycloparaphenylene (CCP, designated as a carbon nanohoop), where one of the six para-linked phenyl rings is replaced by a 2,6-substituted pyridyl ring. This macrocycle is mechanically interlocked with a thread, a linear rod-shaped diyne fragment sitting in the cavity of the macrocycle. Two bulky 3,5-di-t-butyl-phenyl rests as end groups keep the thread fixed. The interplay between macrocycle and thread was examined by means of the electron density distribution (EDD) obtained by application of the invariom formalism, relying on X-ray diffraction data collected earlier. The so-obtained EDD was subjected to topological analysis using the QTAIM formalism. Moreover, molecular Hirshfeld and electrostatic potential (ESP) surfaces were calculated. The 73 C–C bonds were analysed in terms of bond topological properties. For the 46 single and the 22 aromatic bonds, the analysis gave average bond orders of 1.03 and 1.61. The five C–C bonds in the diyne fragment can clearly be distinguished into three types: formal triple bonds with bond orders above 3.0, arene bonds with bond orders of 1.6 and finally bond orders of 1.3 in the adjacent C–C bonds, which indicate a considerable electron delocalization in this fragment. Mapping the ED onto the Hirshfeld surfaces of the macrocycle and the thread does not show strong signals. This shows that in between the molecules only weak non-covalent interactions are present. The electrostatic potentials (ESPs) were mapped onto molecular EDD isosurfaces. For all phenyl rings, small regions of negative ESP are visible on the delocalized π systems. A potential gradient between the mostly positive ESP of the macrocycle and the diyne region of the thread exist, which can be considered the dominant force to hold this rotaxane together.

Cover Picture: Electron-Density Determination of Electrophilic Building Blocks as Model Compounds for Protease Inhibitors (Eur. J. Org. Chem. 17/2007)

2007 ◽  
Vol 2007 (17) ◽  
pp. 2735-2735
Author(s):  
Simon Grabowsky ◽  
Thomas Pfeuffer ◽  
Lilianna Chęcińska ◽  
Manuela Weber ◽  
Wolfgang Morgenroth ◽  
...  
Keyword(s):  
Protease Inhibitors ◽  
Electron Density ◽  
Building Blocks ◽  
Model Compounds ◽  
Density Determination

Applications of 3-Substituted 2-Alkoxy- and 2-Alkylthiopropenals in Organic Synthesis

2021 ◽  
Vol 18 ◽  
Author(s):  
Nadezhda V. Vchislo ◽  
Ekaterina A. Verochkina
Keyword(s):  
Natural Products ◽  
Electron Density ◽  
Organic Synthesis ◽  
Heterocyclic Compounds ◽  
Building Blocks ◽  
The Real ◽  
Broad Applicability ◽  
Unsaturated Aldehydes

: α-Functionally substituted α,β-unsaturated aldehydes belong to the highly reactive class of compounds. They are used as versatile building blocks in organic synthesis. Due to the presence of several reactive sites in their structure, α,β-unsaturated aldehydes are widely employed as precursors of various acyclic and heterocyclic compounds, as well as complex natural products. At the same time, the acrylic systems with heteroatomic substituents (OAlk, SAlk) in the α-position are poorly studied. Therefore, it is impossible to reliably establish the distribution of electron density and to evaluate the real reactivity of each new representative of this class of compounds. This minireview summarizes the works demonstrating the broad applicability of 3-substituted 2-alkoxy and 2-alkylthiopropenals in organic synthesis.

Photochemical Evolution of Interstellar/Precometary Organic Material

1997 ◽  
Vol 161 ◽  
pp. 23-47 ◽  
Author(s):  
Louis J. Allamandola ◽  
Max P. Bernstein ◽  
Scott A. Sandford
Keyword(s):  
Origin Of Life ◽  
Building Blocks ◽  
Complex Species ◽  
Infrared Observations ◽  
Interstellar Ice ◽  
Polycyclic Aromatic ◽  
Ultraviolet Photolysis ◽  
The Origin Of Life ◽  
Simple Molecules ◽  
Complex Organic

AbstractInfrared observations, combined with realistic laboratory simulations, have revolutionized our understanding of interstellar ice and dust, the building blocks of comets. Since comets are thought to be a major source of the volatiles on the primative earth, their organic inventory is of central importance to questions concerning the origin of life. Ices in molecular clouds contain the very simple molecules H2O, CH3OH, CO, CO2, CH4, H2, and probably some NH3and H2CO, as well as more complex species including nitriles, ketones, and esters. The evidence for these, as well as carbonrich materials such as polycyclic aromatic hydrocarbons (PAHs), microdiamonds, and amorphous carbon is briefly reviewed. This is followed by a detailed summary of interstellar/precometary ice photochemical evolution based on laboratory studies of realistic polar ice analogs. Ultraviolet photolysis of these ices produces H2, H2CO, CO2, CO, CH4, HCO, and the moderately complex organic molecules: CH3CH2OH (ethanol), HC(= O)NH2(formamide), CH3C(= O)NH2(acetamide), R-CN (nitriles), and hexamethylenetetramine (HMT, C6H12N4), as well as more complex species including polyoxymethylene and related species (POMs), amides, and ketones. The ready formation of these organic species from simple starting mixtures, the ice chemistry that ensues when these ices are mildly warmed, plus the observation that the more complex refractory photoproducts show lipid-like behavior and readily self organize into droplets upon exposure to liquid water suggest that comets may have played an important role in the origin of life.

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