Theoretical study of keto-enol tautomerism by quantum mechanical calculations (the QM/MC/FEP method)

2012 ◽  
Vol 25 (12) ◽  
pp. 1097-1104 ◽  
Author(s):  
Thanayuth Kaweetirawatt ◽  
Toru Yamaguchi ◽  
Tsutomu Higashiyama ◽  
Michinori Sumimoto ◽  
Kenji Hori
Keyword(s):  
Theoretical Study ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations

scholarly journals Syntone Chemistry. Theoretical Study on the Formation of Cysteine, Aspartic Acid, Asparagine and Threonine

2020 ◽  
Vol 71 (7) ◽  
pp. 278-283
Author(s):  
Gheorghe Surpateanu ◽  
Ileana Denisa Nistor ◽  
Ana-Maria Georgescu ◽  
Neculai Catalin Lungu
Keyword(s):  
Amino Acids ◽  
Carbon Monoxide ◽  
Theoretical Model ◽  
Aspartic Acid ◽  
Low Temperatures ◽  
Theoretical Study ◽  
Chemical Reactivity ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Reaction With Water

In this paper is presented a theoretical study of chemical reactivity on the formation of four proteinogenic amino acids: cysteine, aspartic acid, asparagine and threonine. According to a theoretical model based on three syntons: methylene, nitrene and carbon monoxide at low temperatures, aziridinone would be formed first. This one, with methylene and carbon monoxide forms further the precursors intermediates of these four proteinogenic amino acids. Finally, the precursors in reaction with water, a key component of the primary atmosphere, lead to amino acids specified above. The study is mainly based on quantum mechanical calculations, B88-LYP DFT. Methylaziridonil, aziridonilacetyl and ethylaziridonil radicals should be formed at low temperature, which finally in reaction with water will form cysteine, aspartic acid, asparagine and threonine.

scholarly journals Theoretical Study to Predict the Ability to Use Different Organic Substituents as Carrier Linkages for Diclofenac

2021 ◽  
Vol 33 (9) ◽  
pp. 2105-2118
Author(s):  
Rehab Majed Kubba ◽  
Aisha Muthana Shanshal
Keyword(s):  
Physical Properties ◽  
Theoretical Study ◽  
Reaction Path ◽  
Activation Energies ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Geometrical Structures ◽  
Program Comparison ◽  
Total Energies ◽  
Sodium And Potassium

The research includes unrestricted (UDFT) and (UPM3) quantum mechanical calculations for studying the reaction path of bonds rupture energies of (O-R) and (C-OAr) in twelve diclofenac derivatives containing different substituted organic groups. All the calculations were performed at the optimize geometries in vacuum phase by using Gaussian 09 program. Comparison was done between the studied diclofenac derivatives and the standard ionic diclofenac of sodium and potassium included geometrical structures, physical properties, total energies of the reactants and products, activation energies and transition states. The results showed that some substituted organic groups could be used to form good carrier bonds for the acidic drug diclofenac, while others were less efficient depending on the nature of the substituted carrier, and that there is a preference for carriers of the type (–R) over the carriers of the type (–Ar).

Crystal Forms of Semisynthetic Ergot Alkaloid Terguride

2002 ◽  
Vol 67 (4) ◽  
pp. 479-489 ◽  
Author(s):  
Michal Hušák ◽  
Bohumil Kratochvíl ◽  
Ivana Císařová ◽  
Ladislav Cvak ◽  
Alexandr Jegorov ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Ergot Alkaloid ◽  
Simplified Model ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
X Ray Diffraction ◽  
Torsion Angles ◽  
Crystal Forms ◽  
X Ray ◽  
Independent Molecules

Two new structures of semisynthetic ergot alkaloid terguride created by unusual number of symmetry-independent molecules were determined by X-ray diffraction methods at 150 K. Form A (monoclinic, P212121, Z = 12) contains three symmetry-independent terguride molecules and two molecules of water in the asymmetric part of the unit cell. The form CA (monoclinic, P21, Z = 8) is an anhydrate remarkable by the presence of four symmetry-independent molecules in the crystal structure. Conformations of twelve symmetry-independent molecules that were found in four already described terguride structures are compared with torsion angles obtained by ab initio quantum-mechanical calculations for the simplified model of N-cyclohexyl-N'-diethylurea.

Chemical accuracy from ‘Coulomb hole’ extrapolated molecular quantum-mechanical calculations

2001 ◽  
Vol 567-568 ◽  
pp. 375-384 ◽  
Author(s):  
K.L Bak ◽  
A Halkier ◽  
P Jørgensen ◽  
J Olsen ◽  
T Helgaker ◽  
...  
Keyword(s):  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
Coulomb Hole
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