Nature of Isomerism of Solid Isothiourea Salts, Inhibitors of Nitric Oxide Synthases, As Studied by 1H–14N Nuclear Quadrupole Double Resonance, X-ray, and Density Functional Theory/Quantum Theory of Atoms in Molecules

2012 ◽  
Vol 116 (5) ◽  
pp. 1445-1463 ◽  
Author(s):  
J. N. Latosińska ◽  
M. Latosińska ◽  
J. Seliger ◽  
V. Žagar ◽  
J. K. Maurin ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Density Functional Theory ◽  
Quantum Theory ◽  
Density Functional ◽  
Double Resonance ◽  
Nitric Oxide Synthases ◽  
Atoms In Molecules ◽  
Functional Theory ◽  
X Ray ◽  
Nuclear Quadrupole

Density Functional Theory and Quantum Theory of Atoms in Molecules Analysis: Influence of Intramolecular Interactions on Pirouetting Movement in Tetraalkylsuccinamide[2]rotaxanes

2017 ◽  
Vol 17 (11) ◽  
pp. 5845-5857 ◽  
Author(s):  
Marcos A. P. Martins ◽  
Leticia V. Rodrigues ◽  
Alexandre R. Meyer ◽  
Clarissa P. Frizzo ◽  
Manfredo Hörner ◽  
...  
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Density Functional ◽  
Intramolecular Interactions ◽  
Atoms In Molecules ◽  
Functional Theory

A Quantum Theory of Atoms-in-Molecules Perspective and DFT Study of Two Natural Products: Trans-Communic Acid and Imbricatolic Acid

2017 ◽  
Vol 70 (3) ◽  
pp. 328 ◽  
Author(s):  
Sarvesh Kumar Pandey ◽  
Mohammad Faheem Khan ◽  
Shikha Awasthi ◽  
Reetu Sangwan ◽  
Sudha Jain
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Density Functional ◽  
Chemical Reactivity ◽  
Atoms In Molecules ◽  
Reactivity Index ◽  
Chemical Hardness ◽  
Functional Theory ◽  
Bond Path ◽  
Topological Features

The topological features of the charge densities, ρ(r), and the chemical reactivity of two most biologically relevant and chemically interesting scaffold systems i.e. trans-communic acid and imbricatolic acid have been determined using density functional theory. To identify, characterize, and quantify efficiently, the non-covalent interactions of the atoms in the molecules have been investigated quantitatively using Bader's quantum theory of atoms-in-molecules (QTAIM) technique. The bond path is shown to persist for a range of weak H···H as well as C···H internuclear distances (in the range of 2.0–3.0 Å). These interactions exhibit all the hallmarks of a closed-shell weak interaction. To get insights into both systems, chemical reactivity descriptors, such as HOMO–LUMO, ionization potential, and chemical hardness, have been calculated and used to probe the relative stability and chemical reactivity. Some other useful information is also obtained with the help of several other electronic parameters, which are closely related to the chemical reactivity and reaction paths of the products investigated. Trans-communic acid seems to be chemically more sensitive when compared with imbricatolic acid due to its experimentally observed higher half-maximal inhibitory concentration (bioactivity parameter) value, which is in accordance with its higher chemical reactivity as theoretically predicted using density functional theory-based reactivity index. The quantum chemical calculations have also been performed in solution using different solvents, and the relative order of their structural and electronic properties as well as QTAIM-based parameters show patterns similar to those observed in gas phase only. This study further exemplifies the use and successful application of the bond path concept and the quantum theory of atoms-in-molecules.

Competing mechanisms for the reaction of dichloropropynylborane with 2-tert-butylbutadiene. Diels–Alder reaction versus alkynylboration

RSC Advances ◽  
2015 ◽  
Vol 5 (86) ◽  
pp. 70147-70155 ◽  
Author(s):  
Margarita M. Vallejos ◽  
Silvina C. Pellegrinet
Keyword(s):  
Density Functional Theory ◽  
Quantum Theory ◽  
Density Functional ◽  
Alder Reaction ◽  
Diels Alder ◽  
Atoms In Molecules ◽  
Functional Theory ◽  
Diels Alder Reaction

Density functional theory and the quantum theory of atoms in molecules approach were used to study two competing process: the Diels–Alder reaction and the 1,4-alkynylboration.

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