MOLECULAR FACE — A NOVEL MOLECULAR MODEL SHOWING BOTH MOLECULAR SPATIAL CONTOUR AND FRONTIER ELECTRON DENSITY

2008 ◽  
Vol 07 (03) ◽  
pp. 303-315 ◽  
Author(s):  
DONG-XIA ZHAO ◽  
ZHONG-ZHI YANG
Keyword(s):  
Electron Density ◽  
Molecular Model ◽  
Molecular Shape ◽  
Spatial Knowledge ◽  
Significant Feature ◽  
Molecular Fingerprint ◽  
Molecular Electron ◽  
Frontier Electron Density ◽  
Van Der Waals Surface ◽  
Accessible Surface

The spatial knowledge is the first one of all information about an object. Molecular shape and size, molecular van der Waals surface and/or solvent-accessible surface etc. have been widely studied and applied. This paper is to show that a molecular face (MF) for a molecule may be defined uniquely and intrinsically via the molecular intrinsic characteristic contours (MICC) with coding the molecular electron density (ED) as the fourth dimension. The significant feature of an MF provides both molecular spatial appearance and its frontier electron density, being an intuitive picture as a molecular fingerprint or face. With simple examples, the physical significance of an MF is then demonstrated.

A Fundamental Relation of Molecular Informatics on the Information-Carrying Properties of Density Functions

2007 ◽  
Vol 72 (2) ◽  
pp. 153-163 ◽  
Author(s):  
Paul G. Mezey
Keyword(s):  
Electron Density ◽  
Complete Information ◽  
Molecular Shape ◽  
Density Theorem ◽  
Fundamental Relation ◽  
Electron Densities ◽  
Large Molecules ◽  
Topological Features ◽  
Fundamental Information ◽  
Molecular Electron

The molecular electron density carries the complete information about the molecule. This information is stored in the shape and more general topological features of molecular electron densities. A fundamental relation of molecular informatics, building on the Hohenberg-Kohn theorem, is the holographic electron density theorem: any nonzero volume part of a molecular electron density in a non-degenerate electronic ground state contains the complete information about all properties of the entire molecule. This fundamental feature of all molecules applies to all exhibited and also to all latent molecular properties, where latent properties are those not normally exhibited, only in response to some external stimulus. Recently it has become feasible to compute ab initio quality electron densities and approximate forces acting on individual nuclei in large molecules, even those beyond the thousand atom range, such as proteins. The newly expanded size range where reliable modelling methods can be also applied extends the role of detailed molecular shape analysis to macromolecules. In this context, it has become possible to study how the fundamental information-carrying properties of electron density take a newly recognized role influencing the predominance of specific nuclear conformations within the family of astronomically many potentially stable conformations of some macromolecules. Some special problems and results are discussed.

Understanding the molecular mechanism of the stereoselective conversion of N-trialkylsilyloxy nitronates into bicyclic isoxazoline derivatives

2021 ◽  
Author(s):  
Agnieszka Kącka-Zych ◽  
Radomir Jasinski
Keyword(s):  
Density Functional Theory ◽  
Molecular Mechanism ◽  
Electron Density ◽  
Density Functional ◽  
Dft Method ◽  
Functional Theory ◽  
Molecular Electron ◽  
Molecular Electron Density Theory

Conversion of N-trialkylsilyloxy nitronates into bicyclic isoxazoline derivatives has been explored using Density Functional Theory (DFT) method within the context of the Molecular Electron Density Theory (MEDT) at the B97XD(PCM)/6-311G(d,p)...

scholarly journals A molecular electron density theory study of the [3 + 2] cycloaddition reaction of nitrones with ketenes

2017 ◽  
Vol 15 (7) ◽  
pp. 1618-1627 ◽  
Author(s):  
Mar Ríos-Gutiérrez ◽  
Andrea Darù ◽  
Tomás Tejero ◽  
Luis R. Domingo ◽  
Pedro Merino
Keyword(s):  
Electron Density ◽  
Cycloaddition Reaction ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Electrophilic Character

The zw-type 32CA reactions of nitrones with ketenes are controlled by the nucleophilic character of the nitrone and the electrophilic character of the ketene. They are chemo- and regio-selective and the use of electrophilic ketenes changes the mechanism from one-step to two-step.

scholarly journals FOLDING ELASTIC TRANSMEMBRANE HELICES TO FIT IN A LOW-RESOLUTION IMAGE BY ELECTRON MICROSCOPY

2011 ◽  
Vol 09 (supp01) ◽  
pp. 37-50 ◽  
Author(s):  
YUTAKA UENO ◽  
KAZUNORI KAWASAKI ◽  
OSAMU SAITO ◽  
MASAFUMI ARAI ◽  
MAKIKO SUWA
Keyword(s):  
Membrane Proteins ◽  
Structure Prediction ◽  
Molecular Model ◽  
Imaging Techniques ◽  
Transmembrane Helix ◽  
Prediction Method ◽  
Molecular Shape ◽  
Coarse Grained ◽  
Transmembrane Helices ◽  
Low Resolution

Structure prediction of membrane proteins could be constrained and thereby improved by introducing data of the observed molecular shape. We studied a coarse-grained molecular model that relied on residue-based dummy atoms to fold the transmembrane helices of a protein in the observed molecular shape. Based on the inter-residue potential, the α-helices were folded to contact each other in a simulated annealing protocol to search optimized conformation. Fitting the model into a three-dimensional volume was tested for proteins with known structures and resulted in a fairly reasonable arrangement of helices. In addition, the constraint to the packing transmembrane helix with the two-dimensional region was tested and found to work as a very similar folding guide. The obtained models nicely represented α-helices with the desired slight bend. Our structure prediction method for membrane proteins well demonstrated reasonable folding results using a low-resolution structural constraint introduced from recent cell-surface imaging techniques.

Unveiling the Regioselectivity in Electrophilic Aromatic Substitution Reactions of Deactivated Benzenes through Molecular Electron Density Theory

2021 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
María José Aurell
Keyword(s):  
Electron Density ◽  
Electrophilic Aromatic Substitution ◽  
Benzene Derivatives ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Molecular Electron ◽  
Molecular Electron Density Theory

The origin of the meta regioselectivity in electrophilic aromatic substitution (EAS) reactions of deactivated benzene derivatives is herein analysed through Molecular Electron Density Theory (MEDT). To this end, the EAS...

scholarly journals Unveiling the Unexpected Reactivity of Electrophilic Diazoalkanes in [3+2] Cycloaddition Reactions within Molecular Electron Density Theory

2020 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
Nivedita Acharjee
Keyword(s):  
Electron Density ◽  
Complete Agreement ◽  
Slowing Down ◽  
Molecular Electron ◽  
One Step ◽  
Molecular Electron Density Theory ◽  
Electrophilic Character ◽  
Step Mechanism ◽  
Computational Level ◽  
Density Transfer

The [3+2] cycloaddition (32CA) reactions of strongly nucleophilic norbornadiene (NBD) with simplest diazoalkane (DAA) and three DAAs of increased electrophilicity have been studied within the Molecular Electron Density Theory (MEDT) at the MPWB1K/6-311G(d,p) computational level. These pmr-type 32CA reactions follow an asynchronous one-step mechanism with activation enthalpies ranging from 17.7 to 27.9 kcal·mol-1 in acetonitrile. The high exergonic character of these reactions makes them irreversible. The presence of electron-withdrawing (EW) substituents in the DAA increases the activation enthalpies, in complete agreement with the experimental slowing-down of the reactions, but contrary to the Conceptual DFT prediction. Despite the nucleophilic and electrophilic character of the reagents, the global electron density transfer at the TSs indicates rather non-polar 32CA reactions. The present MEDT study allows establishing that the depopulation of the NNC core in this series of DAAs with the increase of the EW character of the substituents present at the carbon center is responsible for the experimentally found deceleration.

scholarly journals Understanding the domino reaction between 1-diazopropan-2-one and 1,1-dinitroethylene. A molecular electron density theory study of the [3 + 2] cycloaddition reactions of diazoalkanes with electron-deficient ethylenes

RSC Advances ◽  
2017 ◽  
Vol 7 (25) ◽  
pp. 15586-15595 ◽  
Author(s):  
Luis R. Domingo ◽  
Mar Ríos-Gutiérrez ◽  
Saeedreza Emamian
Keyword(s):  
Electron Density ◽  
Domino Reaction ◽  
Cycloaddition Reactions ◽  
Molecular Electron ◽  
Molecular Electron Density Theory

The domino reaction between 1-diazopropan-2-one and 1,1-dinitroethylene yielding a pyrazole and a gem-dinitrocyclopropane has been studied using molecular electron density theory.

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