Chemical Shifts
Mostrando 1-12 de 286 artigos, teses e dissertações.
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1. Synthesis, Spectroscopic Characterization, DFT Calculations and Preliminary Antifungal Activity of New Piperine Derivatives
Four new piperine derivatives, PC1-PC4, were synthesized, and their structures were fully characterized by infrared (IR) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopies. Quantum chemical calculations were performed using density functional theory (DFT) with the B3LYP-D3/6-31G(d,p) and 6-311+G(2d,p) basis sets. Electronic properties, such as th
J. Braz. Chem. Soc.. Publicado em: 2021-03
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2. INSIGHT INTO THE CONFORMATIONAL SPACE OF N-BENZYL-N-(FURAN-2-YLMETHYL)ACETAMIDE BY NMR SPECTROSCOPY AND DFT CALCULATIONS
In this study, the conformational behavior of N-benzyl-N-(furan-2-ylmethyl) acetamide in chloroform was addressed by using a combined experimental/theoretical strategy using NMR spectroscopy and quantum chemical calculations. The 1H and 13C one-dimensional NMR spectra, as well as the two-dimensional HSQC-DEPT and HMBC-DEPT NMR spectra, evinced the presence o
Quím. Nova. Publicado em: 2021-01
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3. Evaluation of Lignins of Trunk and Roots from Citrus sinensis L. Osbeck: A Large Available Brazilian Biomass
Citrus biomass is a source of biobased products and presents extensive chemical diversity. Among the structural macromolecules, lignins have been used in resins, bioplastics, and nanoencapsulation. Brazil has a large source of lignins, which are orange trees removed from groves that need to be renewed. However, the knowledge about these lignins is limited an
J. Braz. Chem. Soc.. Publicado em: 2021-01
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4. 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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5. Understanding Solvent/Bixin Interactions by Raman Spectroscopy
In this work, Raman spectroscopy and density functional theory (DFT) calculations have been used in order to understand the nature of the interaction between the carotenoid bixin and organic solvents with dielectric constant varying from ca. 2 (toluene) to ca. 47 (dimethyl sulfoxide). Raman shifts registered for the main carotenoid marker band, the C=C stret
J. Braz. Chem. Soc.. Publicado em: 2020-07
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6. Erro de administração de medicamentos anti-infeciosos por omissão de doses
Resumo Objetivos: Mensurar a taxa de erro de administração de medicamentos anti-infeciosos por omissão de doses em Unidade de Terapia Intensiva Adulto. Métodos: Estudo descritivo, transversal e prospectivo, realizado nos meses de outubro e novembro de 2018, em Unidade de Terapia Intensiva adulto de um Hospital de Ensino do Distrito Federal. A amostra f
Acta paul. enferm.. Publicado em: 02/12/2019
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7. FOODÔMICA POR RMN DE 1H PARA MONITORAMENTO DA ESTABILIDADE OXIDATIVA DE MARGARINAS SUBMETIDAS AO TRATAMENTO TÉRMICO
Foods with high lipid contents are susceptible to deterioration by oxidative processes that lead to the formation of food rancid. Determining the chemical nature of lipid oxidation products presents a nutritional and health interest due to the possibility of formation of compounds related to the development of degenerative diseases such as Parkinson’s and
Quím. Nova. Publicado em: 21/10/2019
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8. 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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9. Soil microbial and chemical properties influenced by continuous cropping of banana
ABSTRACT: The impacts of continuous cropping of banana on soil microbiological and biochemical properties are little understood. In this study, we evaluated the variations in soil bacterial community abundance and diversity, microbial biomass carbon (MBC) and nitrogen (MBN) as well as soil enzyme activities involved in C, N and P cycles as affected by contin
Sci. agric. (Piracicaba, Braz.). Publicado em: 2018-09
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10. 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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11. Conformational Analysis, Experimental and GIAO-DFT 13C NMR Chemical Shift Calculation on 2’-Hydroxy-3,4,5-trimethoxy-chalcone
In this paper we investigated the ability of the GIAO-mPW1PW91/6-31G(d)//mPW1PW91/6-31G(d) level of theory to predict the 13C nuclear magnetic resonance (NMR) chemical shifts of the 2’-hydroxy-3,4,5-trimethoxy-chalcone molecule. Two different approaches were used. First: the absolute shieldings σ for all carbon atoms in each geometrically optimized confor
J. Braz. Chem. Soc.. Publicado em: 2017-11
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12. Detailed 1H and 13C NMR Spectral Data Assignment for Two Dihydrobenzofuran Neolignans
In this work we present a complete proton (1H) and carbon 13 (13C) nuclear magnetic resonance (NMR) spectral analysis of two synthetic dihydrofuran neolignans (±)-trans-dehydrodicoumarate dimethyl ester and (±)-trans-dehydrodiferulate dimethyl ester. Unequivocal assignments were achieved by 1H NMR, proton decoupled 13C (13C{1H}) NMR spectra, gradient-selec
J. Braz. Chem. Soc.. Publicado em: 2016-01