Hydrogen Bonding
Mostrando 1-12 de 579 artigos, teses e dissertações.
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1. Polyacrylamides as co-depressant in hematite and quartz microflotation
Abstract In the present study, microflotation experiments were performed on pure minerals systems involving hematite and quartz in the presence of etherdiamine as collector. The influence of polyacrylamides as co-depressant was investigated in a blend with starch depressant. The results obtained demonstrated that all the polyacrylamides used were efficient i
REM, Int. Eng. J.. Publicado em: 2021-09
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2. Structure-Physical Properties Relationship of Eutectic Solvents Prepared from Benzyltriethylammonium Chloride and Carboxylic Acids
Deep eutectic solvents (DESs) have attracted the attention of the researchers as alternative solvents due to desirable properties such as easy preparation and high thermal stability. In this work, it was reported the preparation of five DESs from benzyltriethylammonium chloride (BTEAC) as quaternary ammonium salt (QAS) and carboxylic acids (oxalic, malonic o
J. Braz. Chem. Soc.. Publicado em: 2021-03
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3. Evaluation of the Direct Interaction between Amino Acids and Glutathione-Coated CdTe Quantum Dots and Application in Urinalysis for Histidine Determination
The present work aimed to direct amino acid (AA) sensing by quantum dots (QD) and development of an analytical method for potential fast clinical tests. Notably, AA with a positive charge or neutral polar chains, namely L-histidine (His) and L-threonine (Thr), responded to glutathione-coated CdTe (GSH-CdTe) (ΔF ≤ 90%, variation of fluorescence intensity).
J. Braz. Chem. Soc.. Publicado em: 2021-03
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4. Crystal Structure and Hirshfeld Surface Analysis of 1,4-Pentadien-3-one, (1E,4E)-1,5-diphenyl-2-(2,4-dinitrophenyl)hydrazone
The compound 1,4-pentadien-3-one,(1E,4E)-1,5-diphenyl-2-(2,4-dinitrophenyl)hydrazone presents the molecular formula C23H18N4O4 and was prepared in an undergraduate laboratory. The hydrazone was synthesized from the condensation between dibenzalacetone and 2,4-dinitrophenylhydrazine (DNPH) and crystallized employing water/acetone liquid-liquid diffusion. The
J. Braz. Chem. Soc.. Publicado em: 2021-02
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5. ESTUDOS DE QSAR PARA SARS-CoV-2
The generation of mathematical models through the quantitative relationship between the chemical structure and the biological activity (QSARs) of compounds was used in this investigation. Mathematical models were generated from compounds available in literature that predicting the biological activity against SARS-CoV-2. The data indicate that the parameters
Quím. Nova. Publicado em: 2020-09
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6. Antibacterial Activity of 2-Amino-1,4-naphthoquinone Derivatives against Gram-Positive and Gram-Negative Bacterial Strains and Their Interaction with Human Serum Albumin
A series of 2-amino-1,4-naphthoquinone derivatives (NQA-NQF) was synthesized by alternative methods (ultrasonication and microwave irradiation), with yields ranging from 40 to 71%, and without the need of further recrystallization. Each compound was evaluated against four Gram-positive (Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus and Baci
J. Braz. Chem. Soc.. Publicado em: 2020-09
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7. A UNIFIED FORMULA FOR HYDROCARBONS WITH APPLICATIONS TO FUNCTIONAL GROUPS
Was supposed a numerical relationship between atoms of Hydrogen and Carbon in a hydrocarbon, assumption valid for all types of chains. In the proposed equation, variables such as number and types of carbon bonds are present, as well as the possible cycles. It was shown that the equation reduces to the known “general formulas” when applied to the type of
Quím. Nova. Publicado em: 20/07/2020
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8. CHARACTERIZATION OF INTERACTION BETWEEN BUDDLEOSIDE AND BOVINE SERUM ALBUMIN
The primary objective of this study was to investigate the binding of buddleoside to bovine serum albumin (BSA) by different analytical techniques. The analytical principles of affinity capillary electrophoresis (ACE) and fluorescence spectroscopy used in the experiments were different. Mobility (M) that is independent of viscosity of the operating buffer an
Quím. Nova. Publicado em: 20/07/2020
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9. UNRAVELING THE SOLVATOCHROMISM OF A TRIARYLMETHANE DYE BY RESONANCE RAMAN SPECTROSCOPY
The effect of the solvent on the electronic properties of the triarylmethane dye rosolic acid (RA) is investigated by means of UV-VIS and resonance Raman (RR) spectroscopies. The comparison of the solvatochromic behavior of both neutral and dianionic species of RA in acetonitrile, dimethylsulfoxide, and methanol illustrates the effect of polarity and hydroge
Quím. Nova. Publicado em: 05/12/2019
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10. Chemosensor Development of Cu2+ Recognition Using 1,5-Diphenylthiocarbazone: Optimization, COSMO-RS and DFT Studies
The sensitive and selective chemosensor for copper(II) ions (Cu2+) was successfully optimized using the 1,5-diphenylthiocarbazone (DPT) compound. The result showed that dimethyl sulfoxide (DMSO) in a 9:1 (DMSO:water) ratio at a pH of 3 was the optimum medium for DPT to act as chemosensor of Cu2+ recognition. The DPT chemosensor did not encounter any interfer
J. Braz. Chem. Soc.. Publicado em: 16/09/2019
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11. ORGANOCATÁLISE ENANTIOSSELETIVA: EVOLUÇÃO E ASPECTOS RECENTES
In the last two decades, enantioselective organocatalysis has established itself as one of the three pillars of asymmetric catalysis. The rapid growth in the area is due to the rationalization of organocatalysis based on the generic modes of catalyst activation, being applied to several types of reactions, in a rather generic and predictable way and providin
Quím. Nova. Publicado em: 27/05/2019
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12. Catalytic Dehydration of 1-Propanol Over Silica Containing Sulfonic Acid Groups
Mesoporous silica with strongly acid sulfonic sites were synthesized and used as catalytic supports for catalytic dehydration of 1-propanol. This porous material with a large surface area and high porosity were prepared by a simplified sol-gel in an acidic medium and impregnated easily by -SO3H groups. The experimental results indicate that the very strong a
Mat. Res.. Publicado em: 28/03/2019