A theoretical study of the oxidation of benzene by manganese oxide clusters: formation of quinone intermediates.

Manganese oxides (MnO) have been widely applied in various chemical industrial processes owing to their long lifetime, low cost and high abundance. They have been used as co-reactants for the elimination of volatile organic compounds (VOCs); however, their oxidation mechanism is not clearly established. In this theoretical study, interaction capacities between benzene (CH) and MnO clusters, which were modeled with MnO and MnO molecules, were investigated by quantum chemical computations using density functional theory (DFT) with the PBE-D3 functional.

Interactions between Paracetamol and Formaldehyde: Theoretical Investigation and Topological Analysis.

In this work, noncovalent interactions including hydrogen bonds, C···C, N···O, and van der Waals forces between paracetamol and formaldehyde were investigated using the second-order perturbation theory MP2 in conjunction with the correlation consistent basis sets (aug-cc-pVDZ and aug-cc-pVTZ). Two molecular conformations of paracetamol were considered. Seven equilibrium geometries of dimers were found from the result of the interactions with formaldehyde for each conformation of paracetamol.

How are Hydroxyl Groups Localized on a Graphene Sheet?

Arrangements of hydroxyl groups on graphene sheets were systematically investigated using density functional theory calculations that included van der Waals interactions. Results show that hydroxyl groups tend to gather at -positions on graphene sheets to generate perfect ring-like hexahydroxyl group adsorption. The close proximity of hydroxyl groups is in good agreement with the experimental separation between unoxidized, aromatic and oxidized, saturated regions in graphene oxide.

Correction to Temperature and Pressure-Dependent Rate Constants for the Reaction of Propargyl Radical with Molecular Oxygen.

[This corrects the article DOI: 10.1021/acsomega.2c04316.

Temperature and Pressure-Dependent Rate Constants for the Reaction of the Propargyl Radical with Molecular Oxygen.

Ab initio CCSD(T)/CBS(T,Q,5)//B3LYP/6-311++G(3df,2p) calculations have been conducted to map the CHO potential energy surface. The temperature- and pressure-dependent reaction rate constants have been calculated using the Rice-Ramsperger-Kassel-Marcus Master Equation model. The calculated results indicate that the prevailing reaction channels lead to CHCO + CO and CHCO + HCO products.

Mechanistic insights into the dehydrogenation of formaldehyde, formic acid and methanol using the Pt cluster as a promising catalyst.

Reaction mechanisms of the dehydrogenation of formaldehyde, formic acid and methanol on the Pt cluster were computationally investigated using density functional theory (DFT) with the B3LYP functional in the conjunction with the aug-cc-pVTZ basis sets for H, C and O atoms, and the cc-pVDZ-PP basis set for Pt. Herein, the key mechanistic aspects of three possible pathways of the dehydrogenation of these compounds are summarized. The results indicate that the formation of H and CO or CO molecules is more energetically favorable than the generation of H and HO, HCHO products.

Investigating the influence of excipient batch variation on the structure, consistency and physical stability of polysorbate 60-based topical vehicles.

Fatty alcohol-polysorbate 60-water ternary systems were used as models to represent the continuous phases of the respective semisolid oil-in-water emulsions for topical delivery of cosmetic and medicinal agents. The influence of batch variation of polysorbate 60 and fatty alcohol on structure and consistency of these systems was investigated using microscopy, rheology, differential scanning calorimetry and X-ray scattering techniques. The polysorbate 60 : cetostearyl alcohol mixed emulsifying wax showed swelling in water, that is, the lamellar repeat distance continually augmented from 93 to 125 Å with water percentage 20-90%.

Structures, Electronic Properties, and Interactions of Cetyl Alcohol with Cetomacrogol and Water: Insights from Quantum Chemical Calculations and Experimental Investigations.

The complexes of cetyl alcohol, cetomacrogol-1000, and water were successfully synthesized. The complexes were characterized by freeze-drying scanning electron microscopy, small-angle X-ray diffraction (SAXD), and ultra-SAXD. Furthermore, structures, electronic properties (the HOMO-LUMO gap, ionization potential, electron affinity, electronegativity, hardness, softness, dipole moment, and polarizability), and Raman spectra of cetyl alcohol, cetomacrogol-1000, and their binary and ternary complexes with water were also studied using density functional theory.

Advances in Synthesis of π-Extended Benzosilole Derivatives and Their Analogs.

Benzosiloles and their π-extended derivatives are present in many important advanced materials due to their excellent physical properties. Especially, they have found many potential applications in the development of novel electronic materials such as OLEDs, semiconductors and solar cells. In this review, we have summarized several main approaches to construct (di)benzosilole derivatives and (benzo)siloles fused to aromatic five- and six-membered heterocycles.

Investigating molecular mechanism for the stability of ternary systems containing cetrimide, fatty alcohol and water by using computer simulation.

Computer simulations using atomistic model are carried out to investigate the stability of ternary systems of pure or mixed fatty alcohols, cetrimide, and water. These semi-solid oil-in-water systems are used as the main component of pharmaceutical creams. Experiments show that the mixed alcohol systems are more stable than pure ones.

Optical properties of the hydrated charged silver tetramer and silver hexamer encapsulated inside the sodalite cavity of an LTA-type zeolite.

The optical spectra in the UV-VIS region of the hydrated doubly charged tetramer Ag4(2+) and hydrated multiply charged hexamer Ag6(p+) silver clusters encapsulated inside the sodalite cavity of an LTA-type zeolite have been systematically predicted using DFT, TD-DFT and CASSCF/CASPT2 methods. The optical behaviour of the model hydrated clusters [Ag6(H2O)8(Si24H24O36)](p+) is very sensitive to their charge. Among the cations [Ag6(H2O)8(Si24H24O36)](p+), only the embedded hydrated quadruply charged silver hexamer [Ag6(H2O)8(Si24H24O36)](4+) shows a strong absorption band at ∼420 nm (blue light) and emits light in red color.

Simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures by RP-HPLC, derivative and wavelet transforms of UV ratio spectra.

The application of chemometrics-assisted UV spectrophotometry and RP-HPLC to the simultaneous determination of chloramphenicol, dexamethasone and naphazoline in ternary and quaternary mixtures is presented. The spectrophotometric procedure is based on the first-order derivative and wavelet transforms of ratio spectra using single, double and successive divisors. The ratio spectra were differentiated and smoothed using Savitzky-Golay filter; whereas wavelet transform realized with wavelet functions (i.

Reaction dynamics of O(¹D) + HCOOD/DCOOH investigated with time-resolved Fourier-transform infrared emission spectroscopy.

We investigated the reaction dynamics of O((1)D) towards hydrogen atoms of two types in HCOOH. The reaction was initiated on irradiation of a flowing mixture of O3 and HCOOD or DCOOH at 248 nm. The relative vibration-rotational populations of OH and OD (1 ≦ v ≦ 4, J ≤ 15) states were determined from time-resolved IR emission recorded with a step-scan Fourier-transform spectrometer.

Theoretical study on the reaction of the methylidyne radical, CH(X(2)Π), with formaldehyde, CH2O.

A theoretical study of the mechanism and kinetics of the CH(X(2)Π) + H2C═O reaction was carried out by ab initio molecular orbital theory based on the CCSD(T)/aug-cc-pVTZ//BHandHLYP/aug-cc-pVDZ method in conjunction with statistical theoretical kinetic VTST and RRKM Master Equation calculations. The potential energy surface for the cis/trans-HCOH + CH reactions was also examined. Calculated results show that the association reaction of CH and CH2O occurs by addition of the CH radical onto the oxygen atom, cycloaddition onto the C═O bond, and, for a small fraction, insertion of CH into a C-H bond, forming CH2C-O-CH, cyclic H2COCH, and CH2CHO, respectively.

UV spectrophotometric simultaneous determination of paracetamol and ibuprofen in combined tablets by derivative and wavelet transforms.

The application of first-order derivative and wavelet transforms to UV spectra and ratio spectra was proposed for the simultaneous determination of ibuprofen and paracetamol in their combined tablets. A new hybrid approach on the combined use of first-order derivative and wavelet transforms to spectra was also discussed. In this application, DWT (sym6 and haar), CWT (mexh), and FWT were optimized to give the highest spectral recoveries.

UV spectrophotometric simultaneous determination of cefoperazone and sulbactam in pharmaceutical formulations by derivative, Fourier and wavelet transforms.

Signal processing methods based on the use of derivative, Fourier and wavelet transforms were proposed for the spectrophotometric simultaneous determination of cefoperazone and sulbactam in powders for injection. These transforms were successfully applied to UV spectra and ratio spectra to find suitable working wavelengths. Wavelet signal processing was proved to have distinct advantages (i.

Theoretical modeling of optical properties of Ag8 and Ag14 silver clusters embedded in an LTA sodalite zeolite cavity.

Optical properties of silver Ag(n) nanoclusters are demonstrated to be dependent on their size, structure and charge state. It is found that when being contained in the sodalite cavity of LTA zeolite the tetradecanuclear hexacation silver cluster Ag14(6+) is stable. Its lower-lying states and optical spectrum are theoretically determined using the quantum chemical TD-DFT method.

Dynamics of the reactions of O(1D) with CD3OH and CH3OD studied with time-resolved Fourier-transform IR spectroscopy.

We investigated the reactivity of O((1)D) towards two types of hydrogen atoms in CH(3)OH. The reaction was initiated on irradiation of a flowing mixture of O(3) and CD(3)OH or CH(3)OD at 248 nm. Relative vibration-rotational populations of OH and OD (1 ≤ v ≤ 4) states were determined from their infrared emission recorded with a step-scan time-resolved Fourier-transform spectrometer.

Kinetic study of the 2-naphthyl (C10H7) radical reaction with C2H2.

The kinetics for the gas-phase reaction of 2-naphthyl radical with acetylene has been measured by monitoring the C10H7O2 radical in the visible region employing cavity ringdown spectrometry (CRDS) using 2-C10H7Br as a radical source photolyzing at 193 nm in the presence of a small fixed amount of O2 at 40 Torr pressure with Ar as a diluent. Absolute rate constants measured at temperatures between 303 and 448 K can be expressed by the following Arrhenius equation: k(T) = (3.36 +/- 0.

Ab initio study on the oxidation of NCN by OH: prediction of the individual and total rate constants.

The mechanism for the reaction of NCN with OH has been investigated by ab initio molecular orbital and transition-state theory calculations. The potential energy surface (PES) was calculated by the highest level of the modified GAUSSIAN-2 (G2M) method, G2M(CC1). The barrierless association process of OH + NCN --> OH.

Electronic structure of 1,3,5-triaminobenzene trication and related triradicals: doublet versus quartet ground state.

Quantum chemical calculations have been carried out to determine the electronic ground state of the parent 1,3,5-triaminobenzene trication triradical (TAB3+,C6H9N3 3+) containing a six-membered benzene ring coupled with three exocyclic amino NH(*+)2 groups, each containing an unpaired electron, as the simplest model for high-spin polyarylamine polycations. Related triradicals, including the 1,3,5-trimethylenebenzene (TMB, C9H9) and its nitrogen derivatives such as the monocation C8H9N+, the dication C7H9N2 2+, and the neutral C8H8N, C7H7N2, and C6H6N3 systems containing NH groups, have also been considered. Results obtained using the CASSCF [multiconfigurational complete active space (SCF--self-consistent field)] method, with active spaces ranging from (9e/9o) to (15e/12o), followed by second-order perturbation theory [CASPT2 and MS-CASPT2 (MS--multistate)] with polarized 6-311G(d,p) and natural orbital (ANO-L) basis sets reveal the following: (i) both TAB3+ and TMB (D3h) have a quartet 4A"1 ground state with doublet-quartet 2B1-4A"1 energy gaps of 8.

Pulsed laser photolysis and quantum chemical-statistical rate study of the reaction of the ethynyl radical with water vapor.

The rate coefficient of the gas-phase reaction C(2)H + H(2)O-->products has been experimentally determined over the temperature range 500-825 K using a pulsed laser photolysis-chemiluminescence (PLP-CL) technique. Ethynyl radicals (C(2)H) were generated by pulsed 193 nm photolysis of C(2)H(2) in the presence of H(2)O vapor and buffer gas N(2) at 15 Torr. The relative concentration of C(2)H radicals was monitored as a function of time using a CH* chemiluminescence method.