Aromatic Properties Research Articles

Cyclo[18]carbon: Insight into Electronic Structure, Aromaticity, and Surface Coupling.

Cyclo[18]carbon (C18) is studied computationally at the density functional theory (DFT) and ab initio levels to obtain insight into its electronic structure, aromaticity, and adsorption properties on a NaCl surface. DFT functionals with a small amount of Hartree-Fock exchange fail to determine the experimentally observed polyyne molecular structure, revealing a cumulene-type geometry. Exchange-correlation functionals with a large amount of Hartree-Fock exchange as well as ab initio CASSCF calculations yield the polyyne structure as the ground state and the cumulene structure as a transition state between the two inverted polyyne structures through a Kekule distortion. The polyyne and the cumulene structures are found to be doubly Hückel aromatic. The calculated adsorption energy of cyclo[18]carbon on the NaCl surface is small (37 meV/C) and almost the same for both structures, implying that the surface does not stabilize a particular geometry.

Comparative assessment of amino acids and volatile compounds role in the formation of wines sensor properties by means of covariation analysis

The objects of study were 150 samples of natural dry red and white grape wines of Russian origin, obtained by traditional technologies from European and hybrid grape varieties grown in wineries in Krasnodar Krai in 2010–2016. Natural red (Cabernet, Merlot) and white (Aligote, Riesling, Pinot Noir) (alcohol content of 9–13 % by volume, acidity of 4–7 g/dm3), as well as blend wines based on Cabernet Sauvignon, Merlot and Pinot Noir wines made under experimental conditions were analyzed. Chromatographic and electrophoretic methods were used to determine the content of volatile components and amino acids in the studied samples. A sensory assessment of wine quality was carried out by wine specialists working in the wine industry and having professional experience in the field of sensory analysis. Using statistical modeling we carried out a comparative assessment of the role of amino acids - threonine, proline, arginine and volatile compounds - methanol, acetic acid, furfural in the perception of taste and aromatic properties of wines, a general indicator of which is the average tasting rating. High adequacy of the regression model constructed using covariance analysis indicates that mainly amino acids and volatile compounds determine the sensory properties of wines. The dominant role of amino acids in the perception of taste and aromatic characteristics compared to other wine components is mathematically justified in accordance with the criterion of one-dimensional significance. It has been shown that more than 82% of the sensory characteristics of the analyzed wines group fall on the amino acids and volatile compounds under consideration, and less than 18% - on all the others, including titrated acids, free amino acids, mineral components, phenols, etc.

Use of Pseudocereals Preferment Made with Aromatic Yeast Strains for Enhancing Wheat Bread Quality.

Usually, aromatic yeasts are designed to ferment wheat substrates for baking purposes but identification of new substrates for these strains and consequently new formulations for dough could lead to diversified bakery products with improved nutritional qualities and specific sensorial properties. The purpose of our study was to optimize the fermentation of quinoa and amaranth flours with non-conventional yeast strains in order to obtain a preferment with high potential in enhancing nutritional, textural and sensorial features of white wheat bread. Two biotypes of Saccharomyces cerevisiae yeast—a wine yeast strain and a beer yeast strain—commercialized for their aromatic properties were used. Both aromatic yeast strains revealed good performance on fermenting pseudocereal substrates. Utilization of the obtained preferment in white wheat breadmaking led to bread with higher protein, fibres, mineral, total polyphenols content, with specific texture and aroma profile and high consumers’ acceptability.

Effects of Core Modification on Electronic Properties of para-Benziporphyrins.

In contrast to the nonaromatic meta-benziporphyrins, the para-benziporphyrins possess aromatic character depending on the type of five-membered ring present in the macrocyclic core. The effects of changing the para-benziporphyrinic core from C2N3 to C2NSN, C2NSeN, and C2NTeN by replacing the pyrrole with other five-membered heterocycles such as thiophene, selenophene, and tellurophene on aromatic properties of p-benziporphyrins are described here using spectral, electrochemical, X-ray, and density functional theory (DFT) studies. The missing core-modified p-benziporphyrins with C2NSeN and C2NTeN cores were synthesized by condensing 1 equiv of benzitripyrrane and 1,3-benzene-bis((4-phenyl)methanol with an appropriate diol such as 2,5-bis[(p-tolyl)hyroxymethyl]selenophene and 2,5-bis(hydroxymethyl)tellurophene under mild acid-catalyzed conditions at room temperature and characterized in detail by high-resolution mass spectrometry (HR-MS), one- & two-dimensional NMR, and X-ray crystallography of the one of the macrocycles, Selena p-benziporphyrin. The X-ray structure of Selena p-benziporphyrin revealed that the macrocycle was almost planar apart from the p-phenylene ring, which was deviated by 49.71° from the mean plane of the macrocycle defined by four meso carbons, unlike Selena m-benziporphyrin, which is relatively more distorted. NMR studies revealed that, as the core changes from C2N3 to C2NSN, C2NSeN, and C2NTeN, the diatropic ring current decreases, indicating that the aromatic character also decreases in the same order. X-ray structure and DFT studies also revealed that the distortion in the macrocycle increases as the pyrrole ring of p-benziporphyrin was replaced with other heterocycles such as furan, thiophene, selenophene, and tellurophene and that the tellura p-benziporphyrin was the most distorted macrocycle among core-modified p-benziporphyrins. Absorption and electrochemical properties were in agreement with these observations. Our repeated attempts on metalation of these p-benziporphyrins resulted in the successful synthesis of a Pd(II) complex of tellura p-benziporphyrin. The Pd(II) complex was characterized by HR-MS and NMR techniques, and the structure was optimized by DFT. The studies indicated that the Pd(II) ion was bonded to one of the pyrrolic nitrogens, tellurophene, tellurium, and two chloride ions in distorted square-planar geometry.

A novel antioxidant rich compound 2-hydoxy 4-methylbenzaldehyde from Decalepis arayalpathra induces apoptosis in breast cancer cells

Decalepis arayalpathra is an endangered and endemic medicinal plant, mainly used for its aromatic and ethno-medical properties. In this study, we reported the biomedical potentials of 2-hydoxy 4-methylbenzaldehyde (2H4MB) from D. arayalpathra. The compound 2H4MB was isolated from fresh root barks of the plants using steam-hydro distillation extraction method and quantified using HPLC analysis, which yielded 6.5 ± 0.8 μg g−1 of purified compound. Further, the antioxidant and anticancer effects in vitro were studied in detail using MDA-MB-231 cells by cell-based assays. 2H4MB was observed to display the features such as generation of reactive oxygen species (ROS), improved cytotoxicity, loss of mitochondrial membrane (Δψm) potential, and nuclear DNA fragmentations, cellular apoptosis and cell cycle arrest. Further, the bioavailability of 2H4MB may facilitate its use as a potential cancer therapeutic agent.

Transcriptome Landscape Variation in the Genus Thymus.

Among the Lamiaceae family, the genus Thymus is an economically important genera due to its medicinal and aromatic properties. Most Thymus molecular research has focused on the determining the phylogenetic relationships between different species, but no published work has focused on the evolution of the transcriptome across the genus to elucidate genes involved in terpenoid biosynthesis. Hence, in this study, the transcriptomes of five different Thymus species were generated and analyzed to mine putative genes involved in thymol and carvacrol biosynthesis. High-throughput sequencing produced ~43 million high-quality reads per sample, which were assembled de novo using several tools, then further subjected to a quality evaluation. The best assembly for each species was used as queries to search within the UniProt, KEGG (Kyoto Encyclopedia of Genes and Genomes), COG (Clusters of Orthologous Groups) and TF (Transcription Factors) databases. Mining the transcriptomes resulted in the identification of 592 single-copy orthogroups used for phylogenetic analysis. The data showed strongly support a close genetic relationship between Thymus vulgaris and Thymus daenensis. Additionally, this study dates the speciation events between 1.5–2.1 and 9–10.2 MYA according to different methodologies. Our study provides a global overview of genes related to the terpenoid pathway in Thymus, and can help establish an understanding of the relationship that exists among Thymus species.

Preparation and luminescence properties of isoquinoline-nucleated polycyclic aromatics

Two isoquinoline-nucleated polycyclic aromatic compounds, 4,5-diphenyl-7H-dibenzo[de,g]quinolin-7-one (A) and 3,4-diphenyl-6H-phenanthro[3,4,5-defg]quinolin-6-one (B), were synthesized in high yields through three-component reaction of phenanthrene diketone or pyrene diketone, ammonium acetate and 1,2-diphenylethyne in one-pot. Their structures, thermal stabilities, photophysical properties and energy levels are investigated systematically. Both compounds emit very weak fluorescence in acetone, but their luminescence intensity increased significantly when the water content reaches 50% for A and 40% for B, exhibiting aggregation-induced emission (AIE) characteristics, and showing that the AIE effect of the compound A is stronger than that of the compound B. The vacuum-processed doped devices based on the compound B showed green emission with a maximum brightness of 2162 cd/m2, a maximum current efficiency of 2.97 cd/A and a maximum external quantum efficiency (EQE) of 2.23%.

The limited facilitating effect of dissolved organic matter extracted from organic wastes on the transport of titanium dioxide nanoparticles in acidic saturated porous media

The complexity of natural dissolved organic matter (DOM) motivates the determination of how DOM from diverse sources affects the environmental behaviors of engineered nanoparticles. Here, three types of DOM, DOM extracted from swine manure (SWDOM), sludge (SLDOM) and sediment (SEDOM), were characterized, and their effects on the transport of titanium dioxide nanoparticles (TiO2 NPs, 30 nm in diameter) were evaluated and compared with those of humic acid (HA). Characterization tests showed differences in the aromaticity and weight-average molecular weight (Mw) properties among the three extracted DOM solutions, and greater distinctions were found between the extracted DOM and HA. All the extracted DOM facilitated TiO2 NPs transport in acidic porous media. Nevertheless, the enhancing effects varied among the different extracted DOM types. SWDOM had a promoting effect on TiO2 NPs mobility that was equivalent to that of SEDOM and much higher than that of SLDOM. However, the facilitating effects of all three extracted DOM types were limited compared to that of HA. Based on the combined analysis of DOM properties and TiO2 NPs transport behaviors, it could be concluded that aromaticity and Mw were the key properties determining the limited promoting effects of DOM on TiO2 NPs mobility, and the specific UV absorbance at 280 nm (normalized by concentration, SUVA280) was a facile and useful indicator of the DOM-promoted transport of TiO2 NPs. These findings revealed that transport potential in the presence of DOM would be overestimated if either HA or fulvic acid were chosen as the DOM model in studies.

Zinc supplementation of lactating dairy cows: effects on chemical-nutritional quality and volatile profile of Caciocavallo cheese.

ObjectiveThe aim of the present study was to investigate the effect of dietary zinc supplementation of Friesian cows on chemical-nutritional and aromatic properties of Caciocavallo cheese after 7 days (C7) and 120 days (C120) of ripening.MethodsTwenty eight Friesian cows, balanced for parity, milk production and days in milk, were randomly assigned to 2 groups. The control group (CG) was fed with a conventional complete diet, while the experimental group (zinc group, ZG) received a daily zinc supplementation of 60 mg for kg of dry complete feed. During the experimental period, the milk yield was monitored and samples of milk and caciocavallo cheese were collected and analyzed for chemical-nutritional composition and aromatic profile.ResultsThe enrichment of dairy cows diet with zinc, did not influence milk yield and composition, however a marked reduction of somatic cell count was evidenced. Both in milk and cheese the ZG samples were characterized by a lower concentration of satured fatty acids and an increase in oleic, vaccenic and rumenic acids. The aromatic profile of dairy products was also positively affected by dietary zinc intake, with an increase in concentration of carboxylic acids, esters and lactones.ConclusionThe present results suggest a positive role of dietary zinc intake in improving the quality of bovine milk and related cheese, in particular for the increase in concentration of bioactive fatty acids such as rumenic acid. The changes evidenced in cheese through the analysis of the volatile profile, would be consistent with the development of interesting organoleptic properties, although further evaluations should be performed to confirm the consumer acceptability of these changes.

Global Aromaticity in Macrocyclic Polyradicaloids: Hückel's Rule or Baird's Rule?

Aromaticity is one of the most important concepts in organic chemistry to understand the electronic properties of cyclic π-conjugated molecules. Over a century, different aromaticity rules have been developed and validated. For planar monocyclic conjugated polyenes (also known as [n]annulenes), they will be aromatic if they contain [4N + 2] π electrons according to Hückel's rule, or antiaromatic if they have [4N] π electrons. Topological change from a planar to a half-twisted Möbius strip will lead to [4N] ([4N + 2]) aromaticity (antiaromaticity), which is just inverse to Hückel's rule. When the molecules are excited into the first triplet excited state, the Hückel (anti)aromaticity observed in the ground state will become reversed according to Baird's rule. Strictly speaking, these basic rules are only applicable for monocyclic conjugated systems, but some polycyclic systems such as porphyrinoids may also follow these rules if there is a dominant [n]annulene-like conjugation pathway. On the other hand, all-benzenoid polycyclic aromatic hydrocarbons usually display local aromaticity with π electrons predominantly localized at certain benzene rings according to Clar's aromatic sextet rule. In recent years, some proaromatic and antiaromatic molecules with even number of paired electrons have been found to exhibit open-shell diradical character and unique optical, electronic, and magnetic activities. One of the major driving forces is their intrinsic tendency to become aromatic in the open-shell diradical/polyradical forms. A number of stable diradicaloids and linear polyradicaloids have been successfully synthesized by using thermodynamic and kinetic stabilizing strategies. Herein, our particular interest is a type of macrocyclic polyradicaloid in which multiple frontier π-electrons are antiferromagnetically coupled with each other in a cyclic mode. Formally, these free electrons may behave like normal π-electrons in the [n]annulenes, and thus, it raises questions about their possible global aromaticity and which rule they will follow. In the past 5 years, our group has synthesized a series of macrocyclic polyradicaloids and systematically investigated their global aromaticity and electronic properties. Some important findings include: (1) global (anti)aromaticity is generally observed, but there is a balance between local aromaticity and global aromaticity; (2) most of these molecules follow Hückel's rule in the singlet state and display respective (anti)aromatic characteristics; (3) in some special cases, both Hückel's rule and Baird's rule can be applicable, and a unique annulene-within-an-annulene super-ring structure was demonstrated for the first time; (4) global antiaromaticity in the transition state is also important and a slow valence tautomerization process was observed in a supercyclobutadiene tetraradicaloid. These studies demonstrate how these open-shell macrocyclic polyradicaloids adapt their geometry and spin state to reach the lowest-energy state (aromatic). In this Account, we will mainly discuss their synthesis, global aromaticity, and the fundamental structure-radical character-aromaticity-properties relationships. Various experimental methods (e.g., NMR, X-ray crystallographic analysis, and electronic absorption spectroscopy) and theoretical calculations (e.g., anisotropy of the induced current density, nucleus independent chemical shift, and isochemical shielding surface) have been used to elaborate their (anti)aromatic character. At the end, a perspective on the possible three-dimensional global aromaticity in fully conjugated cagelike diradicaloids or polyradicaloids will be also discussed.

Theoretical Study on the Geometry, Aromaticity, and Electronic Properties of Benzo[3,4]cyclobutathiophenes and Their Homologues.

The geometry, aromaticity, and electronic properties of benzo[3,4]cyclobutathiophenes (BCTs) and their homologues have been examined theoretically using density functional theory calculations. The harmonic oscillator measure of aromaticity and nucleus-independent chemical shift analyses revealed the aromaticity characteristics of the two regioisomers benzo[3,4]cyclobuta[1,2-b]thiophene and benzo[3,4]cyclobuta[1,2-c]thiophene. When the aromaticity of one of the six-π-electron rings increases, it concomitantly decreases in the other ring. The anti-aromaticity of the four-membered ring varies depending on the π-electron density of the shared bond with the thiophene ring. This leads to a large difference of the highest occupied molecular orbital-lowest unoccupied molecular orbital gap between the isomers. Linear BCT homologues show medium diradical characters and the smallest EGap values. In the angular and branched homologues, the π-electrons of central benzene rings are localized avoiding the shared bonds, which results in a nonaromatic character. These data were compared to those of the parent hydrocarbons. Because of the diene character of the thiophene ring, the number and position of annulated thiophenocyclobutadieno moieties significantly influence the aromaticity and EGap values of BCT homologues. The present study does not only provide insight into the aromaticity and the properties of organic compounds containing four-membered rings but also affords helpful design guidelines of novel organic semiconductors.

Aromaticity analysis of fused heterometallacycles containing M[sbnd]M(M = Cr, Mo and W) quintuple bond

Transition-metal-containing aromatic compounds, which contain both aromatic properties and the characteristics of organometallic compounds, have attracted great attention due to their unique structure, electronic properties and fascinating reactivities. In this work, the aromaticity of the fused five-membered ring in M2[N(CH3)CHN(CH3)]2 containing MM (Cr, Mo and W) quintuple bond is analyzed. The calculated results show that aromaticity of Cr2[N(CH3)CHN(CH3)]2 is weak, the five-membered rings in M2[N(CH3)CHN(CH3)]2 (M = Cr, Mo, W) exhibit obvious π aromatic character. The contribution of σ aromaticity and δ aromaticity to the five-membered rings can be neglected.

The Aromatic Properties of Polyurea-Encapsulated Lavender Oil Microcapsule and Their Application in Cotton Fabrics

Lavender fragrance loaded polyurea microparticles were successfully prepared via interfacial polymerization. The microcapsulated lavender essence was directly impregnated into the fabrics as an aromatic reagent. And the encapsulation efficiency measured was 75.68% when the core-wall ratio (Mlavender: MHDI) was 2:1. Laser light particle size analyzer showed that the size of spherical nanocapsule varied in the range 2-20 μm. The release process of microcapsules conformed to pseudo-first order kinetics. And the release contents of main lavender fragrance components involved D-limonene, cineole, linalool and propyl propionate from the cotton fabrics were accurately calculated. These aroma compounds of the cotton fabrics impregnated with microcapsulated lavender only lost less than 50% of their aroma after 12 weeks of deposition. Gas chromatography/hydrogen flame ionization detection (GC-FID) indicated that aromatic fabrics treated with microcapsulated lavender exhibited a better sustained-release properties than that of fragrance emulsion.

Основные принципы формирования вкусо-ароматических свойств мясных продуктов при использовании мяса хряков

Основные принципы формирования вкусо-ароматических свойств мясных продуктов при использовании мяса хряков

B2 N2 -Embedded Polycyclic Aromatic Hydrocarbons with Furan and Thiophene Derivatives Functionalized in Crossed Directions.

A series of polycyclic aromatic hydrocarbons (PAHs), consisting of two pairs of BN units, have been designed and their synthesis has been achieved by electrophilic C-H borylation. Two conjugation extension directions can be found in these B2 N2 -embedded PAHs. The B2 N2 -containing backbone with shorter effective conjugation length is isoelectronic with diaryl-fused anthracene, whereas the second derivative, with longer effective conjugation length, is isoelectronic with bis(trans-arylvinyl)benzene. By incorporating different aryl groups, i.e., furyl, thienyl, benzo[b]furyl, and benzo[b]thienyl groups, into the two crossed directions of the B2 N2 -embedded PAHs, their electronic and optical properties have been comparatively investigated by photophysical, electrochemical, and theoretical approaches. It is found that both the substituents and their conjugation extension directions have significant effects on the aromatic and photophysical properties of the B2 N2 -embedded PAHs. The conjugation extension in the shorter backbone is more pronounced on the effective conjugation length than the longer backbone. Moreover, all the B2 N2 -embedded PAHs behave as both Lewis acids and Lewis bases, and reversible photoluminescence switching can be observed by simply neutralizing the added Lewis acid or Lewis base.

Dietary selenium intake in lactating dairy cows modifies fatty acid composition and volatile profile of milk and 30-day-ripened caciotta cheese

The aim of this study was to investigate the effect of dietary selenium supplementation of dairy cows on chemical–nutritional and aromatic properties of milk and related caciotta cheese. 34 Friesian cows were randomly assigned to two groups. The control group (CG) received a conventional feeding strategy, while the experimental group (EG) was fed with a daily selenomethionine supplementation. Dietary selenium integration did not induce variations on milk yield and composition, but induced a marked decrease in somatic cell count. Both in milk and cheese the EG samples showed an increase in linoleic and rumenic acids. The volatile profile of dairy products was also positively affected by dietary selenium intake, with a decrease in concentration of hexanoic acid, hexanal, heptanal, and an increase in ethyl hexanoate, δ-octalactone, δ-decalactone, 2-heptanone, and 2-nonanone. Such findings could contribute to the production of cheeses with interesting nutritional and organoleptic properties, although further sensorial evaluations should be performed to deeply investigate the consumer acceptability.

Chemical Characterization and Evaluation of the Antibacterial Activity of Essential Oils from Fibre-Type Cannabis sativa L. (Hemp).

Volatile terpenes represent the largest group of Cannabis sativa L. components and they are responsible for its aromatic properties. Even if many studies on C. sativa have been focused on cannabinoids, which are terpenophenolics, little research has been carried out on its volatile terpenic compounds. In the light of all the above, the present work was aimed at the chemical characterization of seventeen essential oils from different fibre-type varieties of C. sativa (industrial hemp or hemp) by means of GC-MS and GC-FID techniques. In total, 71 compounds were identified, and the semi-quantitative analysis revealed that α- and β-pinene, β-myrcene and β-caryophyllene are the major components in all the essential oils analysed. In addition, a GC-MS method was developed here for the first time, and it was applied to quantify cannabinoids in the essential oils. The antibacterial activity of hemp essential oils against some pathogenic and spoilage microorganisms isolated from food and food processing environment was also determined. The inhibitory effects of the essential oils were evaluated by both the agar well diffusion assay and the minimum inhibitory concentration (MIC) evaluation. By using the agar diffusion method and considering the zone of inhibition, it was possible to preliminarily verify the inhibitory activity on most of the examined strains. The results showed a good antibacterial activity of six hemp essential oils against the Gram-positive bacteria, thus suggesting that hemp essential oil can inhibit or reduce bacterial proliferation and it can be a valid support to reduce microorganism contamination, especially in the food processing field.

Corrigendum: Investigating the Effect of Selected Non-Saccharomyces Species on Wine Ecosystem Function and Major Volatiles.

[This corrects the article DOI: 10.3389/fbioe.2018.00169.].

Theoretical Calculations of Refractive Index of Synthesized One and Two Substituted Derivatives of Functionalized Bithiophene Compounds

In order to study the variation of electronic properties, a set of bithiophene derivatives has been ‎developed. Here, the effect of substitution on the aromaticity properties of some cyclic ‎bithiophene derivative compounds was investigated using theoretical calculations. Calculations ‎were performed at B3LYP/6-31+G (d,p) level; and calculated properties included energy, dipole ‎moment, total charge on sulfur atom, energy gap, hardness and dipole polarizability. ‎Experimental polarizability values were comparable with the theoretical values. Theoretical ‎refractive indices were obtained using average polarizability in Lorentz-Lorentz equation. The ‎results of comparison between theoretical and experimental refractive indices demonstrated that ‎the scaling factors for refractive index and polarizability were 0.99-1.14 and 0.98-1.28, ‎respectively. ‎

Synergistic effects of low-/medium-vacuum carbonization on physico-chemical properties and stability characteristics of biochars

Vacuum carbonization is considered to be an effective and promising thermochemical-tool for resource and energy recovery by collecting and reusing pyrolysis products and volatiles. In this study, thermochemical conversion of orange peel to biochar under low- and medium-vacuum pyrolysis conditions were investigated for product distribution and stability characteristics of biochar. The pyrolysis experiments were executed under three different conditions i.e., N2 atmosphere (without vacuum), low-vacuum (1013.2 Pa) and medium-vacuum (101.3 Pa) in the temperature range of 300–700 °C. The derived biochars were characterized for its aromaticity, polarity, elemental composition, pH, electrical conductivity, surface area, thermal decomposition, FTIR spectroscopy and chemical oxidation properties. Results revealed that low and medium-vacuum pyrolysis had an overriding effect on the H/C (aromaticity) and O/C (polarity) ratios, surface functional groups, as well as on the chemical oxidation potential of derived biochars. A significant reduction in biochar yield (1.1–1.9 folds), increased aromaticity with low H/C (1.3–2.0 folds) and O/C (1.95–4.75 folds) values was observed with increased pyrolysis temperature, under low- and medium-vacuum pyrolysis compared to the N2 atmosphere. It was also found that biochar produced in the temperature range of 300–700 °C, under low and medium-vacuum pyrolysis were comparatively preferable to biochar stability. It is concluded that biochar produced at low-medium vacuum pyrolysis conditions shows higher carbon sequestration potential compared to the N2 atmosphere.