Carbonyl Composition and Electrophilicity in Vaping Emissions of Flavored and Unflavored E-Liquids

It has been demonstrated that propylene glycol (PG), vegetable glycerin (VG), and flavoring chemicals can thermally degrade to form carbonyls during vaping, but less is known about carbonyl emissions produced by transformation of flavoring chemicals and the interactive effects among e-liquid constituents. This study characterized carbonyl composition and levels in vaping emissions of PG-VG (e-liquid base solvents) and four e-liquid formulations flavored with trans-2-hexenol, benzyl alcohol, l-(-)-menthol, or linalool. Utilizing gas chromatography (GC)- and liquid chromatography (LC)-mass spectrometry (MS) methods, 14 carbonyls were identified and quantified. PG-VG emitted highest levels of formaldehyde, acetaldehyde, and acrolein. However, flavored e-liquids contributed to the production of a wider variety of carbonyls, with some carbonyls directly corresponding to the oxidation of alcohol moieties in flavoring compounds (e.g., trans-2-hexenol and benzyl alcohol transformed into trans-2-hexenal and benzaldehyde, respectively). Detections of formaldehyde-GSH and trans-2-hexenal-GSH adducts signify interactions of carbonyls with biological nucleophiles. The global reactivity descriptors (I, A, μ, η, and ω) and condensed Fukui parameters (fk0, fk−, fk+, and dual-descriptor) were computed to elucidate site reactivities of selected simple and α,β-unsaturated carbonyls found in vaping emissions. Overall, this study highlights carbonyl emissions and reactivities and their potential health risk effects associated with vaping.

Study of the Stability and Chemical Reactivity of a Series of Tetrazole Pyrimidine Hybrids by the Density Functional Theory Method (DFT)

Our theoretical study of stability and reactivity was carried out on six (06) molecules of a series of pyrimidine tetrazole hybrids (PTH) substituted with H, F, Cl, Br, OCH3 and CH3 atoms and groups of atoms using the density function theory (DFT). Analysis of the thermodynamic formation quantities confirmed the formation and existence of the series of molecules studied. Quantum chemical calculations at the B3LYP / 6-311G (d, p) level of theory determined molecular descriptors. Global reactivity descriptors were also determined and analyzed. Thus, the results showed that the compound PTH_1 is the most stable, and PTH_5 is the most reactive and nucleophilic. Similarly, the compound PTH_4 is the most electrophilic. The analysis of the local descriptors and the boundary molecular orbitals allowed us to identify the preferred atoms for electrophilic and nucleophilic attacks.

A simple theoretical approach to converging of Myoglobin-Assay with different pH values

Many metal carbonyl complexes have been synthesized and analyzed as CO-releasing agents. As in many bioactivity assays, differences between in-vitro and in-vivo studies in Myoglobin Assay have been observed. Adjustment of in-vitro conditions to in-vivo conditions is one way to overcoming this problem. Changing the conditions of each in-vivo assay is not possible considering the available grant, material, and labor facilities. In-silico methods are suitable as they provide better in-vitro conditions before experimental procedures. A method which is easy to employ on a basic computer could be more suitable to observe the assay convergence. In this study, global reactivity descriptors were used as an approach to investigate pH differences in myoglobin assay. Global reactivity descriptors of the molecules were compared with myoglobin assay results at different pH values and molecular docking results performed with optimized molecules in different solvents. The following complexes were studied: [Mn(CO)3(bpy)(L)]PF6 (bpy: 2,2-bipyridyl, L: benzylbenzimidazole, 4-chlorobenzylbenzimidazole).

Deep Eutectic Solvent Assisted Synthesis of Dihydropyrimidinones/thiones via Biginelli Reaction: Theoretical Investigations on their Electronic and Global Reactivity Descriptors

Deep eutectic solvents formed from hydrated metal chlorides and hydrogen bond donors (Type 4) were prepared and their catalytic activity was compared for the synthesis of dihydropyrimidinones/ thiones via Biginelli...

Quantum Chemical Calculations on Locked Nucleic Acid based Antisense Modifications: A Density Functional Theory (DFT) Study at Monomer Level

<p>Antisense technology has been developed as the next generation drug discovery methodology by which unwanted gene expression can be inhibited by targeting mRNA specifically with antisense oligonucleotides. It has been observed that a good number of these molecules entered into clinical trials at a faster rate and some of them got approved. The computational studies of antisense modifications based on phosphorothioate (PS), methoxyethyl (MOE), locked nucleic acids (LNA) may help to design better novel modifications. In the present study, newer LNA based modifications have been proposed. The conformational search and density functional theory (DFT) calculations have been used to investigate the quantum chemical parameters of PS, LNA, MOE, and novel LNA based proposed modifications. The conformational search has been done to identify the most and alternative stable conformations. The geometry optimization followed by single point energy calculation has been done at B3LYP/6-31G(d,p) level for gas phase and B3LYP/6-311G(d,p) level for the solvent phase of all modifications. The electronic properties and the quantum chemical descriptors for the frontier molecular orbitals of all the antisense modifications were derived and compared. The local and global reactivity descriptors, such as hardness, chemical potential, electronegativity, electrophilicity index, Fukui function calculated at DFT level for the optimized geometries. These are used for understanding the reactive nature and reactive sites of the modifications. A comparison of global reactivity descriptors confirmed that LNA based modifications are the most reactive modifications and prone to the chemical reactions. It may form stable duplex when it is bound to complementary nucleotides, compared to other modifications. Therefore, we are proposing that one of our proposed antisense modification (A3) may show strong binding to the complementary nucleotide as LNA and may also show reduced toxic effects like MOE.</p>

Quantum Chemical Calculations on Locked Nucleic Acid based Antisense Modifications: A Density Functional Theory (DFT) Study at Monomer Level

<p>Antisense technology has been developed as the next generation drug discovery methodology by which unwanted gene expression can be inhibited by targeting mRNA specifically with antisense oligonucleotides. It has been observed that a good number of these molecules entered into clinical trials at a faster rate and some of them got approved. The computational studies of antisense modifications based on phosphorothioate (PS), methoxyethyl (MOE), locked nucleic acids (LNA) may help to design better novel modifications. In the present study, newer LNA based modifications have been proposed. The conformational search and density functional theory (DFT) calculations have been used to investigate the quantum chemical parameters of PS, LNA, MOE, and novel LNA based proposed modifications. The conformational search has been done to identify the most and alternative stable conformations. The geometry optimization followed by single point energy calculation has been done at B3LYP/6-31G(d,p) level for gas phase and B3LYP/6-311G(d,p) level for the solvent phase of all modifications. The electronic properties and the quantum chemical descriptors for the frontier molecular orbitals of all the antisense modifications were derived and compared. The local and global reactivity descriptors, such as hardness, chemical potential, electronegativity, electrophilicity index, Fukui function calculated at DFT level for the optimized geometries. These are used for understanding the reactive nature and reactive sites of the modifications. A comparison of global reactivity descriptors confirmed that LNA based modifications are the most reactive modifications and prone to the chemical reactions. It may form stable duplex when it is bound to complementary nucleotides, compared to other modifications. Therefore, we are proposing that one of our proposed antisense modification (A3) may show strong binding to the complementary nucleotide as LNA and may also show reduced toxic effects like MOE.</p>

Enhancing Charge Transfer and Photoelectric Characteristics for Organic Solar Cells

The main purpose of this work is to analyze the effect of steric hindrance on the photoelectric performance of three different donor sensitizers (ZHG5, ZHG6, and ZHG7) by molecular theory simulation engineering. Photoelectric physical and photoelectric chemical parameters are investigated by means of frontier molecular orbital, global reactivity descriptors, optical absorption properties, fluorescent lifetime, charge density difference, and influence of external electric field. The results showed that the performance of the quinoxaline sensitizer was deteriorated by gradually increasing the steric hindrance to auxiliary donors. The optical properties of the hybridization of cir-coronene graphene quantum dot (GR) with the three dyes have been revealed, and the results show that graphene quantum dots can indeed improve the optical properties of solar cells. In addition, nine new molecules were designed by inserting six functional groups; it is found that inserting -CN in the acceptor part of the molecular structure is beneficial to the performance of the sensitizer.

Interactions in flavanone and chalcone derivatives: Hirshfeld surface analysis, energy frameworks and global reactivity descriptors

The present study examines a series of flavanone and chalcone derivatives substituted with electron-withdrawing groups (Cl or Br) and electron-donating groups (OH, CH3 and OCH3), namely, 7-methoxy-2-phenyl-3,4-dihydro-2H-1-benzopyran-4-one, C16H14O3, 2-(4-methoxyphenyl)-3,4-dihydro-2H-1-benzopyran-4-one, C16H14O3, 2-(4-methoxyphenyl)-6-methyl-3,4-dihydro-2H-1-benzopyran-4-one, C17H16O3, 2-(4-chlorophenyl)-3,4-dihydro-2H-1-benzopyran-4-one, C15H11ClO2, 8-bromo-6-methyl-2-phenyl-3,4-dihydro-2H-1-benzopyran-4-one, C16H13BrO2, (2E)-1-(2-hydroxyphenyl)-3-(4-methoxyphenyl)prop-2-en-1-one, C16H14O3, and (2E)-1-(2-hydroxyphenyl)-3-(4-hydroxyphenyl)prop-2-en-1-one, C15H12O3. It compares the two groups of derivatives with regard to their intermolecular interactions in the crystal lattice and lattice energy calculations, together with energy framework visualization and global reactivity descriptors (chemical hardness, chemical potential and electrophilicity index). It also discusses the relationships between different noncovalent interactions derived from Hirshfeld surface analysis, crystal lattice energy and global reactivity descriptors of the compounds.