Chemical Shift Calculations
Mostrando 1-12 de 15 artigos, teses e dissertações.
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1. Facial Selectivity between Carbohydrates and Aromatic Amino Acids Explained by a Combination of NCI, NBO and EDA Techniques with NMR Spectroscopy
The influence of electrostatic and dispersion components of intermolecular interactions on the recognition of carbohydrates by aromatic protein residues is important for many biological processes. Interactions between glucose and galactose and aromatic moieties of tryptophan, phenylalanine and histidine were investigated through 1H nuclear magnetic resonance
J. Braz. Chem. Soc.. Publicado em: 08/04/2019
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2. Simulação de desdobramentos complexos de espectros de RMN de ¹H
Complex ¹H NMR spectra multiplets that cannot be easily understood by simple inspection are rather frequent in the daily work of the organic chemistry analyst. The multiple and excellent new techniques available from modern instruments usually provide satisfactory solutions, but there are still many cases where a simulation is necessary, at least to obtain
Química Nova. Publicado em: 2006-02
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3. Silício poroso obtido por ataque químico / Porous silicon obtained by chemical etching
This work reports on a detailed study of porous Si layers produced by chemical etch in p+-type (001) Si wafers with solutions of HF:HNO3 at concentrations of 50:1 and 500:1 added with NaNO2 diluted at 0.1 g/L. Sets of samples with etching times from 1 to 30 min were fabricated. Porous layers etched with the 500:1 solution during 1 to 10 min were found to be
Publicado em: 2006
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4. Análises das propriedades ópticas, morfológicas e estruturais de pontos quânticos de PbS sintetizados a partir de diferentes concentrações de dopantes
PbS quantum dots has been grown in oxide glasses by two distinct methodologies according to the dopants, using the fusing method at 1200C. The host glass matrices used were SNAB (SiO2.Na2CO3.Al2O3.B2O3) and SNABP (SiO2.Na2CO3.Al2O3.B2O3.PbO2), with PbS bulk and S (sulphur) added as dopants, respectively. Thermal treatments were applied in a systematic way in
Publicado em: 2006
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5. Espectroscopia e transferÃncia de energia em eidros La2O3-Nb2O5-B2O3
Glasses are amorphous materials with structures that can, in general, be described by a random non-periodic network model. Although for many glasses, mainly silicates, this model is appropriate, there are systems that present short and medium-range order (first and second coordination spheres) for which more sophisticated models are needed to describe their
Publicado em: 2003
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6. FunÃÃes de bases localmente densas em cÃlculos ab initio de deslocamento quÃmico de 13C e 1H
à proposta uma nova metodologia de DistribuiÃÃo de FunÃÃes de Base Localmente Densas (LDBS) de modo a diminuir a demanda computacional e manter a precisÃo dos cÃlculos ab initio de deslocamentos quÃmicos de 13C e 1H. Os sistemas moleculares foram divididos em trÃs aproximaÃÃes: balanceada, em que todos os Ãtomos foram descritos com a funÃÃo de
Publicado em: 2002
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7. Estudos de ressonancia magnetica nuclear de 2-metilpropenos 3-substituidos
The aim of the present work has been the investigation of the substituent effects in the Carbon-13 and Hydrogen-1 chemical shifts of some 3-substituted 2-methylpropenes ( I ), which bear a closely related geometry to a -substitued propanones. The following compounds (I) have been obtained in good yields. through usual methods where changes were introduced ei
Publicado em: 1987
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8. Sintese : estrutura e reatividade de sais derivados de N-aminopiridinio e rearranjo (3,3) em sais de N-(aril) N-(metanosulfonilamino) peridino
N(aryllamino) pyridinium halides and tetrafluoroborates were synthetised according to the method of 2,4-dinitrophenylpiridinium chloride cleavage by arylhydrazines, followed by thermal cyclization. Solvent effects on the yield were verified ( acetic acid and dioxanewater). The intermediary hydrazones were characterized by means of UV, IR and mass spectroscop
Publicado em: 1987
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9. Intermolecular shielding contributions studied by modeling the 13C chemical-shift tensors of organic single crystals with plane waves
In order to predict accurately the chemical shift of NMR-active nuclei in solid phase systems, magnetic shielding calculations must be capable of considering the complete lattice structure. Here we assess the accuracy of the density functional theory gauge-including projector augmented wave method, which uses pseudopotentials to approximate the nodal structu
American Institute of Physics.
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10. Theoretical Study of the Electrostatic and Steric Effects on the Spectroscopic Characteristics of the Metal-Ligand Unit of Heme Proteins. 2. C-O Vibrational Frequencies, 17O Isotropic Chemical Shifts, and Nuclear Quadrupole Coupling Constants
The quantum chemical calculations, vibronic theory of activation, and London-Pople approach are used to study the dependence of the C-O vibrational frequency, 17O isotropic chemical shift, and nuclear quadrupole coupling constant on the distortion of the porphyrin ring and geometry of the CO coordination, changes in the iron-carbon and iron-imidazole distanc
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11. Indium-cadmium-oxide films having exceptional electrical conductivity and optical transparency: Clues for optimizing transparent conductors
Materials with high electrical conductivity and optical transparency are needed for future flat panel display, solar energy, and other opto-electronic technologies. InxCd1-xO films having a simple cubic microstructure have been grown on amorphous glass substrates by a straightforward chemical vapor deposition process. The x = 0.05 film conductivity of 17,000
The National Academy of Sciences.
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12. Enkephalin: conformational analysis by means of empirical energy calculations.
Low-energy conformations of methionine-enkephalin were generated by means of an empirical method of computation. Many compact conformations, including those containing various standard bends, were of comparable energy. However, one conformation was found to have a potential energy about 5 kcal/mol (21 X 10(3) J/mol) below that of the large group of compact c