Building blocks for electron density in free molecules and in condensed matter phases

In spite of being rare, actinide elements provide the building blocks for many fascinating condensed-matter systems, both from an experimental and theoretical perspective. Experimental observations of actinide materials are difficult because of rarity, toxicity, radioactivity, and even safety and security. Theory, on the other hand, has its own challenges. Complex crystal and electronic structures are often encountered in actinide materials, as well as pronounced electron correlation effects. Consequently, theoretical modeling of actinide materials and their 5f electronic states is very difficult. Here, we review recent theoretical efforts to describe and sometimes predict the behavior of actinide materials and complexes, such as phase stability including density functional theory (DFT), DFT in conjunction with an additional Coulomb repulsion U (DFT+U), and DFT in combination with dynamical mean-field theory (DFT+DMFT).

Download Full-text

Number of free electrons in condensed matter as a function of electron density

Astrophysics ◽

10.1007/bf01003025 ◽

1974 ◽

Vol 7 (4) ◽

pp. 391-395

Author(s):

A. M. Rezikyan

Keyword(s):

Electron Density ◽

Condensed Matter ◽

Free Electrons

Download Full-text

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

European Journal of Organic Chemistry ◽

10.1002/ejoc.200601074 ◽

2007 ◽

Vol 2007 (17) ◽

pp. 2759-2768 ◽

Cited By ~ 18

Author(s):

Simon Grabowsky ◽

Thomas Pfeuffer ◽

Lilianna Chęcińska ◽

Manuela Weber ◽

Wolfgang Morgenroth ◽

...

Keyword(s):

Protease Inhibitors ◽

Electron Density ◽

Building Blocks ◽

Model Compounds ◽

Density Determination

Download Full-text

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

Zeitschrift für Naturforschung B ◽

10.1515/znb-2020-0170 ◽

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.

Download Full-text

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

European Journal of Organic Chemistry ◽

10.1002/ejoc.200790032 ◽

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

Download Full-text

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

Mini-Reviews in Organic Chemistry ◽

10.2174/1570193x18666210422121054 ◽

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.

Download Full-text