scholarly journals Computational Study of Enzymatic Catalysis Based on Large Scale Quantum Chemical Calculations: Recent Progress and Future Prospects

2013 ◽  
Vol 53 (6) ◽  
pp. 326-327
Author(s):  
Toyokazu ISHIDA
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Large Scale ◽  
Recent Progress ◽  
Computational Study ◽  
Enzymatic Catalysis ◽  
Future Prospects

scholarly journals Conformational behavior and electronic structure of silylketenes studied with quantum chemical calculations and photoelectron spectroscopy

1997 ◽  
Vol 75 (12) ◽  
pp. 1851-1861 ◽  
Author(s):  
Heidi M. Muchall ◽  
Nick H. Werstiuk ◽  
Jiangong Ma ◽  
Thomas T. Tidwell ◽  
Kuangsen Sung
Keyword(s):  
Electronic Structure ◽  
Quantum Chemical Calculations ◽  
Photoelectron Spectroscopy ◽  
Quantum Chemical ◽  
Computational Study ◽  
Photoelectron Spectra ◽  
Conformational Behavior ◽  
Torsional Angle ◽  
Orbital Interaction ◽  
Orbital Energies

The He(I) photoelectron spectra of silylketenes (Me3Si)2C=C=O (1), Me5Si2CH=C=O (2), Me2Si(CH=C=O)2 (3), MeSi(CH=C=O)3 (4), (SiMe2CH=C=O)2 (5), and (CH2SiMe2CH=C=O)2 (6) have been recorded and their structures and orbital energies have been calculated by ab initio methods. Orbital energies for disilanes 2 and 5 are strongly dependent on a Si-Si-C-C torsional angle due to σ–π orbital interaction. Comparisons between experimental and simulated spectra show that 2 and 5 prefer conformations in which the Si—Si bond and ketene group(s) are approximately orthogonal (113° and 111°, respectively). Silylalkenes Me5Si2CH=CH2 (7) and (SiMe2CH=CH2)2 (8), which have been included in the computational study, show the same behavior as their corresponding silylketenes. Silylbis- and trisketenes 3–6 do not exhibit π–π interaction of any significance. For Si—Si containing compounds, the best agreement between experimental and computed data was obtained when Becke3LYP/6-31G*//HF/3-21G* was employed. Keywords: conformational behavior, electronic structure, photoelectron spectroscopy, quantum chemical calculations, silylketenes.

A new approach for the acceleration of large-scale serial quantum chemical calculations of docking complexes

2018 ◽  
Vol 67 (6) ◽  
pp. 1100-1103 ◽  
Author(s):  
N. A. Anikin ◽  
A. M. Andreev ◽  
M. B. Kuz’minskii ◽  
A. S. Mendkovich
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Large Scale ◽  
New Approach

scholarly journals Matrix-isolation and computational study of the HKrCCH⋯HCCH complex

RSC Advances ◽  
2015 ◽  
Vol 5 (45) ◽  
pp. 35783-35791 ◽  
Author(s):  
Knut Willmann ◽  
Thomas Vent-Schmidt ◽  
Markku Räsänen ◽  
Sebastian Riedel ◽  
Leonid Khriachtchev
Keyword(s):  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Computational Study ◽  
Matrix Isolation

The HKrCCH⋯HCCH complex is identified in a Kr matrix with the H–Kr stretching bands at 1316.5 and 1305 cm−1. The assignment is fully supported by extensive quantum chemical calculations.

The decomposition of benzenesulfonyl azide: a matrix isolation and computational study

2017 ◽  
Vol 19 (5) ◽  
pp. 3792-3799 ◽  
Author(s):  
Guohai Deng ◽  
Xuelin Dong ◽  
Qifan Liu ◽  
Dingqing Li ◽  
Hongmin Li ◽  
...  
Keyword(s):  
Quantum Chemical Calculations ◽  
Direct Observation ◽  
Quantum Chemical ◽  
Computational Study ◽  
Matrix Isolation ◽  
The Novel ◽  
Curtius Rearrangement

The stepwise Curtius-rearrangement of benzenesulfonyl azide, PhS(O)2N3, has been proven experimentally by the direct observation of the novel intermediates sulfonyl nitrene PhS(O)2N and N-sulfonyl imine PhNSO2 and theoretically by quantum chemical calculations.

Structure and bonding of 2,2,2-trichloroethylacetate: An experimental gas phase and computational study

2016 ◽  
Vol 71 (12) ◽  
pp. 1253-1260 ◽  
Author(s):  
Sebastian Blomeyer ◽  
Christian G. Reuter ◽  
Diego M. Gil ◽  
María E. Tuttolomondo ◽  
Aída Ben Altabef ◽  
...  
Keyword(s):  
Gas Phase ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Density Functional ◽  
Dynamic Models ◽  
Computational Study ◽  
Structural Parameters ◽  
Interacting Quantum Atoms ◽  
The One ◽  
Gas Phase Structure

AbstractThe structural and conformational properties of 2,2,2-trichloroethylacetate, H3CCO2CH2CCl3, have been determined in the gas phase using gas electron diffraction (GED). The experimental measurements were complemented by MP2 and DFT quantum-chemical calculations. Two conformers separated by a shallow rotational barrier have been identified, one of C1 (syn-gauche) and the other of Cs symmetry (syn-anti). All calculations indicate that syn-gauche is preferred in terms of enthalpy, whereas syn-anti seems to be slightly more stable regarding Gibbs free energy. In the gas-phase structure determination, dynamic models based on different potential energy surface scans were used. The one from dispersion-corrected density functional theory, predicting a preference of syn-gauche by 1.7kJmol−1, was found to describe the experimental data best. One- and two-conformer models had to be rejected due to correlations and unrealistically large amplitudes. Experimentally determined structural parameters are in good agreement with both, quantum-chemical calculations as well as GED data for related compounds. Interacting quantum atoms (IQA) analyses revealed that interplay between the carbonyl group and the hydrogen as well as chlorine atoms of the trichloroethyl group accounts for most of the stabilisation of the C1 conformer. With intramolecular symmetry-adapted perturbation theory (I-SAPT) analyses it was possible to further elucidate the nature of dominant interactions in the two conformers. Herein, preference of syn-gauche can for the most part be attributed to electrostatic and to some extent to induction and dispersion interplays. In contrast this conformer is severely destabilised through steric repulsion. These results were supported by NBO analyses.

scholarly journals Experimental and Computational Study on the Debenzylation of (2,4-dimethoxybenzyl)-protected 1,3-diazaoxindoles

2017 ◽  
Vol 61 (4) ◽  
pp. 264
Author(s):  
Eszter Kókai ◽  
Benjámin Kováts ◽  
Balázs Komjáti ◽  
Balázs Volk ◽  
József Nagy
Keyword(s):  
Reaction Mechanism ◽  
Quantum Chemical Calculations ◽  
Quantum Chemical ◽  
Computational Study ◽  
Protecting Group ◽  
Electronic Effects ◽  
Triflic Acid ◽  
Drug Candidates ◽  
Insight Into

The introduction and removal of the 2,4-dimethoxybenzyl (DMB) moiety was studied in order to use it as a protecting group in the synthesis of diverse drug candidates containing the 1,3-diazaoxindole scaffold. The debenzylation of C(5)-unsubstituted and C(5)-isopropylidene-substituted 1,3-diazaoxindoles was investigated under various conditions. The DMB group could only be removed from the latter derivative using triflic acid. This observation can most likely be explained with electronic effects. In order to get a deeper insight into the reaction mechanism, quantum chemical calculations have been performed.

scholarly journals Computational Study of Electronic Influence of Guanidine Substitution on Diels-Alder Reactions of Heterocyclic Dienes

2019 ◽  
Vol 92 (2) ◽  
pp. 279-286
Author(s):  
Ivana Antol ◽  
Luka Barešić ◽  
Zoran Glasovac ◽  
Davor Margetić
Keyword(s):  
Transition State ◽  
Quantum Chemical Calculations ◽  
Electronic Structures ◽  
Quantum Chemical ◽  
Computational Study ◽  
Cycloaddition Reaction ◽  
Diels Alder ◽  
Reaction Barriers ◽  
Reactivity Order

Quantum-chemical calculations of cycloaddition properties of cyclic heterodienes substituted with guanidine functionality were carried out. Molecular and electronic structures of series of dienes (pyrrole, furan, thiophene, isoindole and 1,3-butadiene) were calculated and reactivity order established on the basis of FMO theory. Transition state calculations of model [4+2] cycloaddition reaction with acetylene indicate that guanidine substitution influences reaction barriers in moderate extent (up to ~4 kcal mol–1). The substitution position plays an important role on the sign and magnitude of the effect and protonation of nitrogen possessing substituents increases reactivity of dienes.

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