Quantum Calculations
Mostrando 13-24 de 179 artigos, teses e dissertações.
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13. Absolute Configuration of (−)-Cubebin, a Classical Lignan with Pharmacological Potential, Defined by Means of Chiroptical Spectroscopy
This work describes the first determination of the absolute configuration (AC) of (−)-cubebin by means of electronic circular dichroism (ECD), supported by quantum chemical calculations. The comparison of experimental ECD with the corresponding quantum chemical prediction for the proper diastereoisomer resulted in the definitive assignment of the AC of the
J. Braz. Chem. Soc.. Publicado em: 2020-10
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14. TD-DFT Analysis of the Dissymmetry Factor in Camphor
The fact that the dissymmetry lgeb (g-factor) of camphor is large has been known for decades, and the interpretation of the observed data has also been known for a long time. However, due to the ability of quantum chemical methods to describe chiroptical phenomena more appropriately, additional approaches based on these methods have been successful employed.
J. Braz. Chem. Soc.. Publicado em: 2020-03
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15. RM1 Semiempirical Model: Chemistry, Pharmaceutical Research, Molecular Biology and Materials Science
In this review, we show improvements to the semiempirical quantum chemical method RM1 and present a wide range of its applications as reported by researchers of various areas, such as theoretical, organic, physical, analytical, and inorganic chemistry, as well as their interfaces with medicinal chemistry, biology, and materials science. Success of RM1 is see
J. Braz. Chem. Soc.. Publicado em: 2019-04
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16. SYNTHESIS, ELECTRONIC AND SPECTRAL PROPERTIES OF NEW 1,3,4-THIADIAZOLE COMPOUNDS AND THE SPECTRAL ANALYSIS OF THEIR CONFORMERS USING DENSITY FUNCTIONAL THEORY
In this study, new 1,3,4-thiadiazole compounds were synthesised and characterised by FT-IR, 1H-NMR, UV-vis spectroscopy and elemental analysis, Furthermore, the relationship between the electronic and spectral data of the 16 conformers of each compound was investigated by theoretical calculations; the theoretical data were compared with the experimental resu
Quím. Nova. Publicado em: 2019-02
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17. Experimental and Theoretical Study of Corrosion Inhibition of Mild Steel in 1.0 M HCl Medium by 2(-4( hloro phenyl-1H- benzo[d]imidazol)-1-yl)phenyl)methanone
The 2(-4(chloro phenyl-1H- benzo[d]imidazol)-1-yl)phenyl)methanone (CBIPM) was synthesized and tested as a corrosion inhibitor for mild steel in 1.0 M HCl solution using electrochemical and spectroscopy measurements. Results obtained showed that this compound has a good inhibition properties for mild steel corrosion in acidic medium which its inhibition effi
Mat. Res.. Publicado em: 06/12/2018
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18. Syntheses, Experimental and Theoretical Studies on Absorption/Emission Properties of Pyrazoline-Containing Aryl/Methoxynaphthyl Substituents
5-Aryl-3-(2-methoxynaphthalen-6-yl)-1-phenylpyrazoline derivatives were synthesized starting from (E)-1-(3-aryl)-(2-methoxynaphthalen-6-yl)-prop-2-en-1-one and phenylhydrazine. The compounds were characterized by 1H and 13C nuclear magnetic resonance (NMR), elemental analyses and mass spectrometry. Some compounds showed promising luminescence properties in s
J. Braz. Chem. Soc.. Publicado em: 2018-06
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19. Computer-Guided Total Synthesis of Natural Products. Recent Examples and Future Perspectives
Quantum chemical calculations of nuclear magnetic resonance (NMR) shifts and coupling constants have been extensively employed in recent years mainly to facilitate structural elucidation of organic molecules. When the results of such calculations are used to determine the most likely structure of a natural product in advance, guiding the subsequent synthetic
J. Braz. Chem. Soc.. Publicado em: 2018-05
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20. AVALIAÇÃO DO DESEMPENHO DE UMA FASE SENSORA DE POLIURETANO POR MEIO DA ENERGIA DE GIBBS DE SOLVATAÇÃO E ESPECTROSCOPIA DE INFRAVERMELHO PARA DETERMINAÇÃO DE TOLUENO EM ÁGUA
A novel sensing phase of polyurethane was predicted by quantum chemical calculations as capable of detecting toluene, with the experimental results revealing a limit of detection of 1.4 mg L-1 in the determination of toluene in water samples. The quantum chemical computational strategy was validated by assessing the impact of the polymer matrix sensing phase
Quím. Nova. Publicado em: 2018-04
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21. EXPERIMENTAL AND THEORETICAL ANALYSIS OF NA OXAZINOQUINOXALINE DERIVATIVE FOR CORROSION INHIBITION OF AISI 1018 STEEL
The inhibitory ability of an oxazinoquinoxaline derivative (OAQX) against the corrosion of AISI 1018 mild steel induced by aqueous 0.6 mol L-1 NaCl solution is herein evaluated. Linear polarization resistance studies showed the inhibitory efficiency of OAQX varying from 62.75% to 75.93% with OAQX concentration ranged from 0.259 x 10-4 mol L-1 to 3.243 x 10-4
Quím. Nova. Publicado em: 2018-03
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22. ELUCIDATION OF THE ELECTRONIC SPECTRUM CHANGES OF KA-Al3+ COMPLEX BY POTENTIOMETRIC TITRATION, FTIR, 13C RMN AND QUANTUM MECHANICS
Kojic acid (KA) is an organic acid widely used in pharmaceutical industry, mainly as a skin lightening agent. Based on the ability of KA to form complexes with ions, we found the most possible kind of complex formed with cation aluminum. KA-Al3+ complex structures were studied using potentiometric and spectrophotometric (UV) titrations, FTIR and 13C NMR. The
Quím. Nova. Publicado em: 2017-08
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23. Structural Analysis of High-Spin States of S0-S4 at OEC Complex: A Theoretical Approach of Small Models
S-states at oxygen evolving complex (OEC) are widely studied due to its large importance in photo-oxidation water process. The structural aspects involving S0, S1, S2, S3 and S4 states are still not solved theoretically. Particularly, spin states have been analyzed as an important aspect in S-state models. Seeking to obtain a relevant and simple model to cov
J. Braz. Chem. Soc.. Publicado em: 2017-02
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24. NATURALEZA DE LAS INTERACCIONES Mδ+...δ+C-Oδ- EN CARBONILOS METÁLICOS. UN ESTUDIO BASADO EN LA TOPOLOGÍA DE LA DENSIDAD DE CARGA ELECTRÓNICA Y SU FUNCIÓN LAPLACIANA
The nature of the metal-ligand interactions, in the [Ti(CO)6]2-, [V(CO)6]-, [Cr(CO)6], [Mn(CO)6]+, [Fe(CO)6]2+ and [Co(CO)6]3+ complexes has been studied by means of topological analyses of the electron charge density, using the Quantum Theory of Atoms in Molecules (QTAIM) and Electron Function Localization (ELF). The calculations were made using B3LYP metho
Quím. Nova. Publicado em: 2016-07