Search results for "AROMA"

Method and basis set dependence of the NICS indexes of aromaticity for benzene

2018

The role of theory level in prediction of benzene magnetic indexes of aromaticity is analysed and compared with calculated nuclear magnetic shieldings of 3 He used as NMR probe. Three closely related nucleus-independent chemical shift (NICS) based indexes were calculated for benzene at SCF-HF, MP2, and DFT levels of theory and the impact of basis set on these quantities was studied. The changes of benzene NICS(0), NICS(1), and NICS(1)zz parameters calculated using SCF-HF, MP2 and several density functionals were within 1 to 3 ppm. Similar deviations between magnetic indexes of aromaticity were observed for values calculated with selected basis sets. Only very small effect of polar solvent o…

Local aromaticity in polyacenes manifested by individual proton and carbon shieldings: DFT mapping of aromaticity

2019

Exponential dependencies between locally calculated geometric and magnetic indexes of aromaticity, harmonic oscillator model of aromaticity (HOMA) and nucleus independent chemical shifts (NICS)(0), NICS(1) and NICS(1)zz, and the number of conjugated benzene rings in linear acenes, from benzene to decacene were observed at B3LYP/6-311+G** level of theory. Correlations between HOMA and NICS indexes showed exponential dependencies and were fitted with simple three-parameter function. Similar correlations between both indexes of aromaticity and proton and carbon nuclear isotropic shieldings of individual acene rings were observed. Contrary to proton data, the predicted 13 C nuclear isotropic sh…

NMR Spectra of Anilines

2009

1 Introduction 2 Ring and N-Substituted Anilines 3 Multinuclear NMR Studies of p-F-Aniline Derivatives 4 Dynamic NMR of Aniline Derivatives 5 Anilines with Other (Fused) Aromatic Rings 6 NMR Relaxation Studies of Aniline Derivatives 7 Solid State NMR Studies 8 Theoretical Calculations of Aniline NMR Parameters Keywords: aniline NMR spectra; aniline (aminobenzene, phenylamine); ring and N-substituted anilines; dual-substituent-parameter (DSP) analysis; cyclic amine structures; dynamic NMR of aniline derivatives; H NMR spectroscopy as measure of donor strengths; aniline derivative NMR relaxation studies

Shape-dependency activity of nanostructured CeO2 in the total oxidation of polycyclic aromatic hydrocarbons

2013

11 figures, 2 tables.-- © 2012. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/

Retro-nasal aroma release is correlated with variations in the in-mouth air cavity volume after empty deglutition.

2012

International audience; We hypothesized that interindividual differences in motor activities during chewing and/or swallowing were determining factors for the transfer of volatile aroma from the in-mouth air cavity (IMAC) toward the olfactory mucosa. In our first experiment, we looked for changes in IMAC volume after saliva deglutition in 12 healthy subjects. The mean IMAC volume was measured after empty deglutition using an acoustic pharyngometer device. Based on the time course of the IMAC volume after swallowing, we discerned two groups of subjects. The first group displayed a small, constant IMAC volume (2.26 mL ±0.62) that corresponded to a high tongue position. The second group displa…

Microencapsulation of antioxidant compounds through innovative technologies and its specific application in meat processing

2018

Background Meat has a complex physical structure and chemical composition that is very prone to oxidation. Plants are sources of biologically active compounds (antioxidants) of interest as potential raw materials for meat processing, primary as replacements for synthetic additives. Some examples are essential oils from aromatic plants that are usually unstable under common processing and storage conditions and exhibit strong smell and off flavour. Hence, stable delivery systems like encapsulation are required. Scope and approach Encapsulation, and particularly spray-drying, offers protection of active compounds, their controlled and targeted release in food products and ability to mask unac…

Proton tautomerism in 2-nitramino-C-nitropyridine derivatives - Experimental and quantum chemical study

2019

Abstract The structures of 2-nitramino-3-nitropyridine and 2-nitramino-5-nitropyridine have been characterized by X-ray diffraction and Density Functional Theory (DFT) studies. In the crystals, both compounds exist as the imino forms. The DFT calculations were performed in order to explore the amino-imino tautomerism of the studied compounds in the gas phase and the influence of solvent polarity on the tautomeric equilibrium. The Harmonic Oscillator Model of Aromaticity index (HOMA) and Nucleus Independent Chemical Shift (NICS) calculated for the pyridine rings of the studied systems, demonstrated a noticeable decrease in aromaticity of the imino forms. This study showed also that the highe…

Understanding the Mechanism of Nitrobenzene Nitration with Nitronium Ion: A Molecular Electron Density Theory Study

2019

Complete sequencing of Novosphingobium sp. PP1Y reveals a biotechnologically meaningful metabolic pattern.

2014

Background Novosphingobium sp. strain PP1Y is a marine α-proteobacterium adapted to grow at the water/fuel oil interface. It exploits the aromatic fraction of fuel oils as a carbon and energy source. PP1Y is able to grow on a wide range of mono-, poly- and heterocyclic aromatic hydrocarbons. Here, we report the complete functional annotation of the whole Novosphingobium genome. Results PP1Y genome analysis and its comparison with other Sphingomonadal genomes has yielded novel insights into the molecular basis of PP1Y’s phenotypic traits, such as its peculiar ability to encapsulate and degrade the aromatic fraction of fuel oils. In particular, we have identified and dissected several highly …

A condensed-to-atom nucleophilicity index. An application to the director effects on the electrophilic aromatic substitutions

2009

Abstract The local nucleophilicity of simple substituted aromatic systems is shown to be described on a quantitative basis by using a condensed-to-atoms nucleophilicity index. This quantity constitutes an extension of the global nucleophilicity descriptor, N introduced for reagents in cycloaddition reactions and other organic molecules [Journal of Organic Chemistry 73 (2008) 4615–4624; Journal of Molecular Structure (THEOCHEM) 865 (2008) 68–72]. The local projection N k is performed on the basis of the normalization condition of the Fukui functions. It is shown that such a simple index provides useful clues about the director effects of the substituents on the electrophilic aromatic substit…